Method and device for supporting SMS service using store and forward operation of satellite

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. Disclosed is a method for processing a control signal in a wireless communication system of a communication system, the method comprising the steps of: receiving a first control signal transmitted from a terminal; processing the received first control signal; and transmitting, to the terminal, a second control signal generated on the basis of the processing.

Description

Method and device for supporting SMS service using the STORE AND FORWARD operation of satellite

[0001] The present disclosure relates to a method and device for transmitting / receiving SMS using a store and forward (S&F) operation of a satellite in a communication system.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

[0004] Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

[0005] In addition, standardization of radio interface architecture / protocols is also in progress for technologies such as the Industrial Internet of Things (IIoT), which supports new services through linkage and convergence with other industries; Integrated Access and Backhaul (IAB), which provides nodes for expanding network service areas by integrating wireless backhaul links and access links; Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover; and 2-step RACH for NR, which simplifies random access procedures. Furthermore, standardization of system architecture / services is also in progress for 5G baseline architectures (e.g., Service-based Architecture, Service-based Interface) for the integration of Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC), which provides services based on the location of the terminal.

[0006] Once 5G mobile communication systems are commercialized, an explosive increase in connected devices is expected to be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] In order to support communication services in shaded areas or outside the coverage of a communication system, an LTE EPC (Evolved Packet Core) entity or a 5G NF (network function) may be located on a satellite, and a terminal may perform service registration and request to directly use a communication service using an eNodeB or gNB in ​​the satellite. In a 4G system or an evolved 5G system, some or all of the system components may be located on one or more satellites, and a method for providing connection between the control plane and the user plane may be required in such a system architecture. In particular, in order to use the SMS (Short Message Service) service through the control plane, different mobility management entities (MMEs) supporting 'SMS in MME' may be located on the satellite and the ground base station, or SMS-GMSC (Short Message Service-Gateway Mobile Switching Center) / SMS-IWMSC (Short Message Service-Interworking Mobile Switching Center) may be located on the satellite and the ground base station, respectively. The position of a low-orbit satellite may change over time. Accordingly, the connection of the service link between the satellite and the terminal and the feeder link between the satellite and the ground base station can be established or terminated, respectively.

[0009] In the present invention, a method and device for supporting an SMS service utilizing connection status information of a service link between a satellite and a terminal and connection status information of a feeder link between a satellite and a ground base station according to a change in the position of a low-orbit satellite are proposed.

[0010] The present invention proposes a method for performing an operation in which an MME or AMF in a satellite, which receives a mobile originated (MO) and mobile terminated (MT) SMS message from a terminal or a service center (SC), buffers the MO SMS and MT SMS in an SMS-GMSC or a short message service function (SMSF) according to the status information of the satellite's service link and feeder link, and then transmits the corresponding information to the terminal or SC after the service and feeder link are connected, and a method for transmitting information to support the corresponding operation.

[0011] In order to solve the above problem, the present invention provides a method performed in a first MME (Mobility Management Entity) in a wireless communication system, the method comprising: receiving, from a user equipment (UE), an UL (Uplink) NAS (Non-Access-Stratum) Transport message including a MO (Mobile Oriented) short message service (SMS); transmitting, to the UE, a DL (Downlink) NAS Transport message including information indicating whether the MO SMS has been received when a feeder link is not connected; and transmitting, to a second MME, the MO SMS when the feeder link is connected, the first MME and the second MME being separate.

[0012] In one embodiment, the first MME is located in a satellite, and the second MME is located in a ground base station.

[0013] In one embodiment, the method further comprises the step of buffering the MO SMS transmission for a predetermined period of time when there is no connection to the feeder link.

[0014] In one embodiment, the method further comprises the step of storing the MO SMS when there is no connection to the feeder link.

[0015] In addition, in another embodiment of the present invention, a method performed in a user equipment (UE) in a wireless communication system characterized by the step of transmitting, to a first mobility management entity (MME), an uplink (UL) NAS (Non-Access-Stratum) Transport message including a mobile oriented (MO) short message service (SMS); and, when there is no connection of a feeder link, receiving, from the first MME, a downlink (DL) NAS Transport message including information indicating whether the MO SMS has been received, wherein, when the feeder link is connected, the MO SMS is transmitted from the first MME to a second MME, and the first MME and the second MME are characterized in that they are separated.

[0016] In addition, in another embodiment of the present invention, in a wireless communication system, a first Mobility Management Entity (MME) includes a transceiver capable of transmitting and receiving at least one signal; and a control unit coupled to the transceiver, wherein the control unit is configured to: receive, from a user equipment (UE), an UL (Uplink) NAS (Non-Access-Stratum) Transport message including a MO (Mobile Oriented) short message service (SMS), and, when there is no feeder link connection, transmit a DL (Downlink) NAS Transport message including information indicating whether the MO SMS has been received to the UE, and / when the feeder link is connected, transmit the MO SMS to a second MME, and the first MME and the second MME are characterized in that they are separated.

[0017] In addition, in another embodiment of the present invention, in a wireless communication system, a user equipment (UE) includes a transceiver capable of transmitting and receiving at least one signal; and a control unit coupled to the transceiver, wherein the control unit is configured to transmit, to a first mobility management entity (MME), an uplink (UL) NAS (Non-Access-Stratum) Transport message including a mobile oriented (MO) short message service (SMS), and, when there is no feeder link connection, receive, from the first MME, a downlink (DL) NAS Transport message including information indicating whether the MO SMS has been received, and when the feeder link is connected, the MO SMS is transmitted from the first MME to a second MME, and the first MME and the second MME are characterized in that they are separated.

[0018] Based on the connection status information and link connection availability time information of the service link between the satellite and the terminal and the feeder link between the satellite and the ground station, taking into account the change in the position of the low-orbit satellite, the EPC entity within the satellite or the 5G NF can support SMS service.

[0019] FIG. 1A is a diagram illustrating a network structure and interface of a 5G system according to one embodiment of the present disclosure.

[0020] FIG. 1b is a diagram illustrating a network structure and interface for supporting an SMS service on a satellite using a 4G system-based control plane according to one embodiment of the present disclosure.

[0021] FIG. 1c is a diagram illustrating a network structure and interface for supporting an SMS service using a 5G system-based control plane in a satellite according to one embodiment of the present disclosure.

[0022] FIG. 2aa is a flowchart for transmitting network structure and related information for supporting MO SMS service requested by a terminal through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0023] FIG. 2ab is a flowchart for transmitting network structure and related information for supporting MO SMS service requested by a terminal through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0024] FIG. 2ba is a flowchart for transmitting network structure and related information for supporting MO SMS service requested by a terminal through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0025] FIG. 2bb is a flowchart for transmitting network structure and related information for supporting MO SMS service requested by a terminal through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0026] FIG. 3a is a flowchart illustrating a network structure and a flowchart for transmitting related information to support a MO SMS service requested by a terminal through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0027] FIG. 3b is a flowchart illustrating a network structure and a flowchart for transmitting related information to support a MO SMS service requested by a terminal through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0028] FIG. 4a is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0029] FIG. 4b is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0030] FIG. 4c is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through multiple satellites using a 4G system-based control plane according to an embodiment of the present disclosure.

[0031] FIG. 4d is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through multiple satellites using a 4G system-based control plane according to an embodiment of the present disclosure.

[0032] FIG. 5a is a flowchart illustrating a network structure and a flowchart for transmitting related information to support a MO SMS service requested by a terminal through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0033] FIG. 5b is a flowchart illustrating a network structure and a flowchart for transmitting related information to support a MO SMS service requested by a terminal through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0034] FIG. 6a is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0035] FIG. 6b is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0036] FIG. 6c is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through multiple satellites using a 4G system-based control plane according to an embodiment of the present disclosure.

[0037] FIG. 7a is a flowchart illustrating a network structure and a flowchart for transmitting related information to support a MO SMS service requested by a terminal through a satellite using a 5G system-based control plane according to an embodiment of the present disclosure.

[0038] FIG. 7b is a flowchart illustrating a network structure and a flowchart for transmitting related information to support a MO SMS service requested by a terminal through a satellite using a 5G system-based control plane according to an embodiment of the present disclosure.

[0039] FIG. 8a is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC using a 5G system-based control plane according to an embodiment of the present disclosure.

[0040] FIG. 8b is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC using a 5G system-based control plane according to an embodiment of the present disclosure.

[0041] FIG. 8c is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through multiple satellites using a 5G system-based control plane according to an embodiment of the present disclosure.

[0042] FIG. 8d is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through multiple satellites using a 5G system-based control plane according to an embodiment of the present disclosure.

[0043] FIG. 9 is a diagram illustrating the structure of a terminal according to one embodiment of the present invention.

[0044] FIG. 10 is a diagram illustrating the structure of a network entity according to one embodiment of the present invention.

[0045] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the attached drawings.

[0046] In describing this disclosure, descriptions of technical details that are well-known in the technical field to which this disclosure pertains and are not directly related to this disclosure will be omitted. This is to avoid obscuring the gist of this disclosure by omitting unnecessary explanations and to convey it more clearly. Furthermore, the terms described below are defined based on their functions in this disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the contents of this specification as a whole.

[0047] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0048] Hereinafter, a base station (BS) is an entity that performs resource allocation of a terminal, and may be at least one of a gNode B, an eNode B, a Node B (or an xNode B (where x is an alphabet including g or e)), a wireless access unit, a base station controller, a satellite, an airborn, or a node on a network. A user equipment (UE) may include a mobile station (MS), a vehicle, a satellite, an airborn, a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, a downlink (DL) is a wireless transmission path of a signal transmitted from a base station to a terminal, and an uplink (UL) means a wireless transmission path of a signal transmitted from a terminal to an air station. Additionally, a sidelink (SL) may exist, which means a wireless transmission path of a signal transmitted from a terminal to another terminal.

[0049] In addition, although LTE, LTE-A, or 5G systems may be described below as examples, embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, this may include 5G-Advance or NR-Advance, or 6th generation mobile communication technology (6G) developed after 5G mobile communication technology (or new radio, NR), and the 5G described below may also include existing LTE, LTE-A, and other similar services. In addition, the present disclosure may be applied to other communication systems with some modifications within a range that does not significantly deviate from the scope of the present disclosure, as determined by a person having skilled technical knowledge.

[0050] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0051] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0052] Here, the term '~ part' used in this embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and the '~ part' performs certain roles. However, the '~ part' is not limited to software or hardware. The '~ part' may be configured to be on an addressable storage medium or may be configured to play one or more processors. Therefore, as an example, the '~ part' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ parts' may be combined into a smaller number of components and '~ parts' or further separated into additional components and '~ parts'. Additionally, the components and '~parts' may be implemented to activate one or more CPUs within a device or secure multimedia card. In addition, in an embodiment, the '~parts' may include one or more processors.

[0053] The Third Generation Partnership Project (3GPP), responsible for cellular mobile communication standards, is currently standardizing a new core network architecture called 5G Core (5GC) to facilitate the evolution of 4G LTE systems to 5G systems. Compared to the Evolved Packet Core (EPC), the network core for 4G, 5GC supports the following differentiated features.

[0054] 5GC introduces the Network Slice feature. As a requirement of 5G, 5GC must support a variety of terminal types and services. These various terminal types and services may include, for example, enhanced Mobile Broadband (eMBB), Ultra-Reliable Low Latency Communications (URLLC), and massive Machine Type Communications (mMTC). Each of these terminals and services has different requirements for the core network. For example, eMBB services may require high data rates, while URLLC services may require high reliability and low latency. To meet these diverse service requirements, Network Slice technology has been proposed.

[0055] Network slicing can refer to a method of creating multiple logical networks (e.g., network slices) based on the virtualization of a single physical network. An activated network slice can be referred to as a network slice instance, and each network slice instance (NSI) can have different characteristics. By configuring a network function (NF) for each NSI according to its characteristics, mobile carriers can satisfy various service requirements for different terminals / services. For example, mobile carriers can efficiently support various 5G services (e.g., eMBB, URLLC, or mMTC) by allocating an NSI that matches the characteristics of the service required for each terminal.

[0056] 5GC can easily support the network virtualization paradigm by separating mobility management functions from session management functions. In 4G LTE, all terminals can receive services from the network through signaling exchanges with a single core entity called the mobility management entity (MME), which is responsible for registration, authentication, mobility management, and session management. In 5G, the number of terminals (including MTC terminals) will explode, and the mobility, traffic, and session characteristics that must be supported depending on the terminal type will become more specialized. Therefore, supporting all functions from a single entity (such as the MME) will inevitably reduce scalability by adding entities for each required function. Therefore, various functions are being developed based on a structure that separates mobility management and session management functions to improve scalability in terms of the functional or implementation complexity of the core entity responsible for the control plane and signaling load.

[0057] FIG. 1A is a diagram illustrating a network structure and interface of a 5G system according to one embodiment of the present disclosure.

[0058] A network entity included in the network structure of the 5G system of Fig. 1a may include a network function (NF) depending on the system implementation.

[0059] Referring to FIG. 1a, the network structure of a 5G system (100) may include various network entities. For example, the 5G system (100) may include an authentication server function (AUSF) entity (108), an access and mobility management function (AMF) entity (103), a session management function (SMF) entity (105), a policy control function (PCF) entity (106), an application function (AF) entity (107), a unified data management (UDM) entity (109), a data network (DN) (110), a network exposure function (NEF) entity (113), a network slicing selection function (NSSF) entity (114), a user plane function (UPF) entity (104), a (radio) access network, (R)AN)(102), or a terminal, for example, a user equipment (UE)(101).

[0060] Each NF entity of the 5G system (100) supports the following functions.

[0061] AUSF (108) processes and stores data for authentication of UE (101).

[0062] AMF (103) provides functions for access and mobility management per UE, and one UE can be connected to one AMF by default. Specifically, the AMF (103) provides signaling between CN nodes for mobility between 3GPP access networks, termination of a radio access network (RAN) CP interface (i.e., N2 interface), termination of non-access stratum (NAS) signaling (N1), NAS signaling security (NAS ciphering and integrity protection), AS security control, registration management (registration area management), connection management, idle mode UE reachability (including control and performance of paging retransmission), mobility management control (subscription and policy), intra-system mobility and inter-system mobility support, support for network slicing, SMF selection, lawful intercept (for AMF events and interfaces to the LI system), provision of forwarding of session management (SM) messages between UE and SMF, transparent proxy for SM message routing, access authentication, access authorization including roaming authorization check. It supports functions such as authorization, provision of SMS message transmission between UE and SMSF, security anchor function (SAF) and / or security context management (SCM). Some or all of the functions of an AMF entity (103) may be supported within a single instance of an AMF entity.

[0063] DN (110) refers to, for example, an operator service, Internet access, or a third-party service. DN (110) transmits a downlink protocol data unit (PDU) to the UPF entity (104) or receives a PDU transmitted from the UE (101) from the UPF entity (104).

[0064] The PCF entity (106) receives information about packet flows from the application server and provides a function to determine policies such as mobility management and session management. Specifically, the PCF entity (106) supports functions such as supporting a unified policy framework for controlling network operations, providing policy rules so that control plane function entity(ies) (e.g., AMF entity, SMF entity, etc.) can enforce the policy rules, and implementing a front end for accessing related subscription information for policy determination within a user data repository (UDR).

[0065] The SMF entity (105) provides a session management function, and when the UE (101) has multiple sessions, each session can be managed by a different SMF entity. Specifically, the SMF entity (105) supports functions such as session management (e.g., session establishment, modification, and termination, including tunnel maintenance between the UPF entity (104) and (R)AN (102) nodes), UE IP address allocation and management (optionally including authentication), selection and control of UP functions, traffic steering setup to route traffic from the UPF entity (104) to the appropriate destination, termination of the interface to policy control functions, enforcement of the control portion of policies and quality of service (QoS), lawful intercept of SM events and interfaces to the LI system, termination of the SM portion of NAS messages, downlink data notification, initiation of AN specific SM information (delivered to the (R)AN (102) via N2 via the AMF entity (103)), determination of the session and service continuity (SSC) mode of the session, roaming functions, etc. Some or all of the functions of an SMF entity (105) may be supported within a single instance of an SMF entity.

[0066] The UDM entity (109) stores user subscription data, policy data, etc. The UDM entity (109) may include at least one of two parts: an application front end (FE) and a user data repository (UDR).

[0067] An FE may include a UDM FE, which is responsible for location management, subscription management, and credential processing, and a PCF entity, which is responsible for policy control. The UDR stores data required for the functions provided by the UDM-FE and policy profiles required by the PCF entity. The data stored in the UDR includes user subscription data and policy data, including subscription identifiers, security credentials, access and mobility-related subscription data, and session-related subscription data. The UDM-FE accesses subscription information stored in the UDR and supports functions such as authentication credential processing, user identification handling, access authentication, registration / mobility management, subscription management, and SMS management.

[0068] The UPF entity (104) forwards the downlink PDU received from the DN (110) to the UE (101) via the (R)AN (102), and forwards the uplink PDU received from the UE (101) via the (R)AN (102) to the DN (110). Specifically, the UPF entity (104) supports functions such as an anchor point for intra / inter RAT (radio access technology) mobility, an external PDU session point for interconnection to the Data Network, a user plane portion of packet routing and forwarding, packet inspection and policy rule enforcement, an uplink classifier to support lawful intercept, traffic usage reporting, routing of traffic flows to the Data Network, a branching point to support multi-homed PDU sessions, QoS handling for the user plane (e.g., packet filtering, gating, uplink / downlink rate enforcement), uplink traffic validation (service data flow (SDF) to QoS flow mapping), transport level packet marking in the uplink and downlink, downlink packet buffering and downlink data notification triggering. Some or all of the functions of a UPF entity (104) may be supported within a single instance of a UPF.

[0069] The AF entity (107) interacts with the 3GPP core network to provide services (e.g., supporting functions such as application impact on traffic routing, access to network capability exposure, and interaction with the policy framework for policy control).

[0070] (R)AN(102) is a general term for a new radio access network that supports both evolved E-UTRA, an evolved version of 4G radio access technology, and new radio (NR) (e.g., gNB).

[0071] The gNB provides functions for radio resource management (i.e., radio bearer control, radio admission control, connection mobility control, dynamic allocation of resources to the UE in uplink / downlink (i.e., scheduling), IP (internet protocol) header compression, encryption and integrity protection of user data streams, selection of an AMF upon attachment of the UE if routing to the AMF is not determined from the information provided to the UE, routing of user plane data to UPF(s), routing of control plane information to the AMF, connection setup and teardown, scheduling and transmission of paging messages (originating from the AMF), scheduling and transmission of system broadcast information (originating from the AMF or operating and maintenance (O&M)), measurement and measurement reporting setup for mobility and scheduling, transport level packet marking in uplink, session management, support for network slicing, and QoS flows. It supports features such as mapping to management and data radio bearers, support for UEs in inactive mode, distribution of NAS messages, NAS node selection, radio access network sharing, dual connectivity, and tight interworking between NR and E-UTRA.

[0072] UE (101) refers to a user equipment. The user equipment may be referred to by terms such as terminal, mobile equipment (ME), or mobile station (MS). Furthermore, the user equipment may be a portable device such as a laptop, mobile phone, personal digital assistant (PDA), smartphone, or multimedia device, or may be a non-portable device such as a personal computer (PC) or vehicle-mounted device.

[0073] The NEF (113) provides a means to securely expose services and capabilities provided by 3GPP network functions, for example, for third parties, internal exposure / re-exposure, application functions, and edge computing. The NEF (113) receives information from other NF (s) (based on the exposed capability(s) of other NF (s)). The NEF (113) can store the received information as structured data using a standardized interface to a data storage network function. The stored information can be re-exposed to other NF entity(s) and AF entity(s) by the NEF entity (113) and used for other purposes, such as analysis.

[0074] NRF (115) supports service discovery. It receives NF discovery requests from NF instances and provides information about discovered NF instances to the NF instances. It also maintains available NF instances and the services they support.

[0075] Meanwhile, for convenience of explanation, FIG. 1a illustrates a reference model for a case where a UE (101) accesses one DN (110) using one PDU session, but the present disclosure is not limited thereto.

[0076] A UE (101) can access two or more (e.g., local and central) data networks simultaneously using multiple PDU sessions. In this case, two or more SMFs can be selected for different PDU sessions. However, each SMF can have the ability to control both the local UPF and the central UPF within the PDU session.

[0077] Additionally, the UE (101) may simultaneously access two or more (i.e., local and central) data networks provided within a single PDU session.

[0078] In the 3GPP system, a conceptual link connecting NFs within a 5G system is defined as a reference point. For example, the reference point(s) included in the 5G system (100) of FIG. 1a are as follows.

[0079] - N1: Reference point between UE (101) and AMF (103)

[0080] - N2: Reference point between (R)AN(102) and AMF(103)

[0081] - N3: Reference point between (R)AN(102) and UPF(104)

[0082] - N4: Reference point between SMF (105) and UPF (104)

[0083] - N5: Reference point between PCF (106) and AF (107)

[0084] - N6: Reference point between UPF (104) and DN (110)

[0085] - N7: Reference point between SMF (105) and PCF (106)

[0086] - N8: Reference point between UDM (109) and AMF (103)

[0087] - N9: Reference point between two core UPFs (104)

[0088] - N10: Reference point between UDM (109) and SMF (105)

[0089] - N11: Reference point between AMF (103) and SMF (105)

[0090] - N12: Reference point between AMF (103) and AUSF (108)

[0091] - N13: Reference point between UDM (109) and AUSF (108)

[0092] - N14: Reference point between two AMFs (103)

[0093] - N15: Reference point between PCF and AMF in non-roaming scenario, reference point between PCF and AMF in visited network in roaming scenario.

[0094] FIG. 1b is a diagram illustrating a network structure and interface for supporting an SMS service on a satellite using a 4G system-based control plane according to one embodiment of the present disclosure.

[0095] According to one embodiment of the present disclosure, an MME and SMS-GMSC-ON or SMS-GMS-SAT may be located as EPC entities for supporting an SMS service using a control plane within a satellite, and an HSS (Home Subscriber Server) and SMS-GMSC-T / SC or SMS-GMSC-Ground / SC may be located within a ground base station to configure a network structure for supporting an SMS service using a 4G system-based control plane within a satellite. When a terminal requests an SMS service, it may request a service based on 'SMS in MME' instead of an SMS service using an existing MSC-based control plane. If the MME within the satellite can support a function for supporting an SMS service within an existing MSC in order to support 'SMS in MME', the service connection request may be accepted. In addition, SMS-GMS-SAT (or SMS-GMSC-ON) and SMS-GMSC-Ground (or SMS-GMSC-T) may be connected using an existing satellite. As described above, when SMS-GMSC is located in a satellite and a ground base station, respectively, in order to support MT SMS service, the SMS-GMSC of the ground base station may include the satellite's SMS-GMSC information in the SendRoutingInfo for Short Msg transmission / reception message requesting MT SMS transmission location information through the HSS.

[0096] FIG. 1C is a diagram illustrating a network structure and interface for supporting SMS service using a 5G system-based control plane in a satellite according to an embodiment of the present disclosure. According to an embodiment of the present disclosure, an AMF and an SMSF may be located as 5G NFs for supporting SMS service using a control plane in a satellite, and SMS-GMSC / SC and UDM may be located in a ground base station. In order to support the 'SMS over NAS' function requested by a terminal when registering a service, the AMF may accept the service request if the SMSF is located in the satellite or the ground base station. According to an embodiment of the present disclosure, the AMF may forward the MO SMS message transmitted by the terminal to the SMSF. The SMSF, upon receiving the MO SMS message or MT SMS message, may check with the AMF whether the service link between the terminal and the satellite is connected, and if the service link is connected but the terminal is in a CM-Idle state, may perform a NAS connection operation through a paging operation and then forward an SMS-related message to the terminal. If the feeder link between the terminal and the ground station is not connected, the SMSF can receive the Available reachability timer for service link information from the AMF, buffer the information for the corresponding amount of time, and then transmit the SMS-related message to the ground station.

[0097]

[0098] FIGS. 2aa and 2ab are flowcharts for transmitting network structure and related information for supporting MO SMS service requested by a terminal from a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0099] According to one embodiment of the present disclosure, an MME may be located as a 4G EPC entity for supporting SMS service using a control plane within a satellite, and SMS-IWMSC / SMS-GMSC / SC and HSS may be located in a ground base station.

[0100] In steps 201 and 202, if the terminal (200) cannot find a connection to a separate terrestrial enodeB, it can perform a network registration procedure and a service request procedure using the satellite's enodeB. The request for the corresponding operation can be performed when the service link between the terminal and the satellite is connected. At this time, when performing the network registration or service request procedure, the terminal (200) can request the 'SMS in MME' service, which is a control message-based SMS service using the terminal's MME, instead of the existing control message-based SMS service using the MSC. In addition, the network determines whether the MME in the satellite supports the corresponding operation and determines whether the 'SMS in MME' service is accepted, and if the MME in the satellite supports the corresponding operation, it can support the service requested by the terminal.

[0101] In step 203, the terminal (200) can include a MO SMS message in a UL NAS Transport message and transmit it to the MME (250) to use the SMS service.

[0102] In steps 204a and 204b, the MME (250) that receives the MO SMS message from the terminal (200) can transmit to the terminal (200) whether or not the MO SMS message was received via the DL NAS Transport. If there is no feederlink connection between the satellite and the ground base station, the DL NAS Transport can transmit together the Reception of MO SMS message indicating whether or not the MO SMS message was received, and the Available time for feederlink, which is information on the time when the Delivery of MO SMS can be transmitted from the SC. After receiving the Available time for feederlink information, the terminal can predict that the Delivery of MO SMS can be transmitted within the corresponding time, and does not perform a retransmission operation of the MO SMS message before the corresponding time. If the terminal does not receive the Delivery of MO SMS message after the Available time for feederlink time, the terminal can perform a retransmission operation of the MO SMS message. If the Servicelink between the terminal and the satellite is connected after a certain period of time following the feederlink connection between the satellite and the ground station, the MME can set an additional offset of 5 to 15 minutes in the Available time for feederlink to inform the terminal of the time when it can receive the Delivery of MO SMS.

[0103] In step 205a, if the feederlink between the terminal and the satellite is not connected, buffering operation can be performed for the amount of time equal to the Available time for feederlink.

[0104] In step 205b, if the feederlink between the terminal and the satellite is connected, the MME (250) can transmit the MO SMS message received from the terminal to the SMS-IWMSC (270) in the ground base station. If the feederlink between the terminal and the satellite is not connected, the MME (250) can perform a buffering operation for the amount of time equal to the Available time for feederlink as in step 205a, and then transmit the MO SMS message received from the terminal to the SMS-IWMSC (270) in the ground base station.

[0105] In step 206, the SC (280) may generate a Delivery report of MO SMS message that notifies that the MO SMS message transmitted by the terminal has been successfully transmitted to the SC after receiving the MO SMS message via SMS-IWMSC (270).

[0106] At step 207, SMS-IWMSC (270) can receive a Delivery report of MO SMS message from SC (280).

[0107] At step 208, SMS-IWMSC (270) can forward the Delivery report of MO SMS message received from SC (280) to MME (250) within the satellite.

[0108] The MME (250) that received the Delivery report of MO SMS message in step 208a can check the service link information between the satellite and the terminal.

[0109] In step 208b, if the service link between the satellite and the terminal is not connected, the Delivery report of MO SMS message can be buffered for the amount of time equal to the Available time for service link.

[0110] In step 208c, if the service link between the satellite and the terminal is connected but in CM-IDLE state, paging and service request operations for control plane connection through the terminal's service link connection can be performed.

[0111] In step 209, the MME (250) can transmit the Delivery report of MO SMS message received from the SMS-IWMSC (270) to the terminal (200) via a DL NAS Transport message.

[0112] In step 210, the terminal (200) can transmit acknowledges receipt of the delivery report information, indicating that it has successfully received the Delivery report of MO SMS message, to the satellite MME (250) via a UL NAS Transport message.

[0113]

[0114] FIG. 2ba and FIG. 2bb are flowcharts for transmitting network structure and related information for supporting MO SMS service requested by a terminal from a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0115] According to one embodiment of the present disclosure, an MME may be located as a 4G EPC entity for supporting SMS service using a control plane within a satellite, and SMS-IWMSC / SMS-GMSC / SC and HSS may be located in a ground base station.

[0116] In steps 221 and 222, if the terminal (200) cannot find a connection to a separate terrestrial enodeB, it can perform a network registration procedure and a service request procedure using the satellite's enodeB. At this time, when performing the network registration or service request procedure, the terminal (200) can request the 'SMS in MME' service, which is a control message-based SMS service using the terminal's MME, instead of the existing control message-based SMS service using the MSC. In addition, the network determines whether the MME in the satellite supports the corresponding operation and determines whether the 'SMS in MME' service is accepted, and if the MME in the satellite supports the corresponding operation, it can support the service requested by the terminal.

[0117] In step 223a, the terminal (200) can include a MO SMS message in a UL NAS Transport message and transmit it to the MME (250) to use the SMS service.

[0118] In steps 224a and 224b, the MME (250) that receives the MO SMS message from the terminal (200) can transmit to the terminal (200) whether or not the MO SMS message was received via the DL NAS Transport. If there is no feederlink connection between the satellite and the ground base station, the DL NAS Transport can transmit together the Reception of MO SMS message indicating whether or not the MO SMS message was received, and the Available time for feederlink, which is information on the time when the Delivery of MO SMS can be transmitted from the SC. After receiving the Available time for feederlink information, the terminal (200) can predict that the Delivery of MO SMS can be transmitted within the corresponding time, and does not perform a retransmission operation of the MO SMS message before the corresponding time. If the terminal does not receive the Delivery of MO SMS message after the Available time for feederlink time, the terminal can perform a retransmission operation of the MO SMS message. If the Servicelink between the terminal and the satellite is connected after a certain period of time following the feederlink connection between the satellite and the ground station, the MME can set an additional offset of 5 to 15 minutes in the Available time for feederlink to inform the terminal of the time when it can receive the Delivery of MO SMS.

[0119] In step 224c, the terminal (200) may decide to retransmit the MO SMS message if it has not received the Delivery of MO SMS message after a certain period of time (Available time for feederlink and additional offset).

[0120] In step 223b, the terminal (200) can include a MO SMS message to be retransmitted in a UL NAS Transport message to use the SMS service and transmit it to the MME (250).

[0121] The MME (250) that received the MO SMS message from the terminal (200) in steps 224d and 224e can transmit whether the MO SMS message was received to the terminal (200) through DL NAS Transport.

[0122] In step 225, the MME (250) can transmit the MO SMS message received from the terminal (200) to the SMS-IWMSC (270) in the ground base station if the feederlink between the terminal and the satellite is connected.

[0123] In step 226, the SC (280) may receive the MO SMS message via SMS-IWMSC (270) and then generate a Delivery report of MO SMS message notifying that the MO SMS message transmitted by the terminal has been successfully transmitted to the SC.

[0124] At step 227, SMS-IWMSC (270) can receive a Delivery report of MO SMS message from SC (280).

[0125] At step 228, SMS-IWMSC (270) can forward the Delivery report of MO SMS message received from SC (280) to MME (250) within the satellite.

[0126] The MME (250) that received the Delivery report of MO SMS message in step 228a can check the service link information between the satellite and the terminal.

[0127] In step 228b, if the service link between the satellite and the terminal is not connected, the Delivery report of MO SMS message can be buffered for the amount of time equal to the Available time for service link.

[0128] In step 228c, if the service link between the satellite and the terminal is connected but in CM-IDLE state, paging and service request operations for control plane connection through the terminal's service link connection can be performed.

[0129] In step 229, the MME (250) can transmit the Delivery report of MO SMS message received from the SMS-IWMSC (270) to the terminal (200) via a DL NAS Transport message.

[0130] At step 230, the terminal (200) can transmit acknowledges receipt of the delivery report information, indicating that it has successfully received the Delivery report of MO SMS message, to the satellite MME (250) via a UL NAS Transport message.

[0131]

[0132] FIG. 3a and FIG. 3b are flowcharts for transmitting network structure and related information for supporting MO SMS service requested by a terminal from a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0133] According to one embodiment of the present disclosure, an MME-NT may be located as a 4G EPC entity for supporting SMS service using a control plane within a satellite, and an MME-T, SMS-IWMSC / SMS-GMSC / SC, and HSS may be located in a ground base station. In the present disclosure, MME-NT may be used interchangeably with MME-ON.

[0134] In steps 301 and 302, if the terminal (300) cannot find a connection to a separate terrestrial enodeB, it can perform a network registration procedure and a service request procedure using the satellite's enodeB. The request for the corresponding operation can be performed when the service link between the terminal and the satellite is connected. At this time, when performing the network registration or service request procedure, the terminal can request the 'SMS in MME' service, which is a control message-based SMS service using the terminal's MME, instead of the existing control message-based SMS service using the MSC. In addition, the network determines whether the MME in the satellite supports the corresponding operation, determines whether the 'SMS in MME' service is accepted, and if the MME in the satellite supports the corresponding operation, it can support the service requested by the terminal.

[0135] In step 303, the terminal (300) can include a MO SMS message in a UL NAS Transport message and transmit it to the MME-NT (320) to use the SMS service.

[0136] In steps 304a and 304b, the MME-NT (320) that receives the MO SMS message from the terminal (300) can transmit to the terminal (300) whether or not the MO SMS message was received via the DL NAS Transport. If there is no feederlink connection between the satellite and the ground base station, the DL NAS Transport can transmit together the Reception of MO SMS message indicating whether or not the MO SMS message was received, and the Available time for feederlink, which is information on the time when the Delivery of MO SMS can be transmitted from the SC. After receiving the Available time for feederlink information, the terminal (300) can predict that the Delivery of MO SMS can be transmitted within the corresponding time, and does not perform a retransmission operation of the MO SMS message before the corresponding time. If the terminal does not receive the Delivery of MO SMS message after the Available time for feederlink time, the terminal can perform a retransmission operation of the MO SMS message. If the service link between the terminal and the satellite is connected after a certain period of time following the feeder link connection between the satellite and the ground station, the MME-NT can set an additional offset of 5 to 15 minutes in the Available time for feeder link to inform the terminal of the time when it can receive the Delivery of MO SMS.

[0137] Based on the MME-NT connection status in step 305a, the MME-NT (320) may perform MO SMS buffering operation.

[0138] In step 305b, if the feederlink between the terminal and the satellite is connected, the MME-NT (320) can transmit the MO SMS message received from the terminal (300) to the MME-T (340) in the ground base station. If the feederlink between the terminal and the satellite is not connected, the MME-NT (320) can perform an operation of buffering the MO SMS message for the amount of time equal to the Available time for feederlink, as in step 305a, and then transmit the MO SMS message received from the terminal to the MME-T (340) in the ground base station.

[0139] At step 306, the MME-T (340) can forward the MO SMS message received from the MME-NT (320) to the SMS-IWMSC (370).

[0140] In step 307, the SC (380) may receive the MO SMS message via SMS-IWMSC (370) and then generate a Delivery report of MO SMS message notifying that the MO SMS message transmitted by the terminal has been successfully transmitted to the SC.

[0141] At step 308, SMS-IWMSC (370) can receive a Delivery report of MO SMS message from SC (380).

[0142] In step 309, SMS-IWMSC (370) can forward the Delivery report of MO SMS message received from SC (380) to MME-T (340) in the ground base station.

[0143] In step 310, MME-T (340) can forward the Delivery report of MO SMS message received from SMS-IWMSC (370) to MME-NT (320).

[0144] The MME-NT (320) that received the Delivery report of MO SMS message in step 311a can check the service link information between the satellite and the terminal.

[0145] In step 311b, if the service link between the satellite and the terminal is not connected, the Delivery report of MO SMS message can be buffered for the amount of time equal to the Available time for service link.

[0146] In step 311c, the MME-NT (320) can perform paging and service request operations for control plane connection through the terminal's service link connection when the service link between the satellite and the terminal is connected but in CM-IDLE state.

[0147] In step 312, the MME-NT (320) can transmit the Delivery report of MO SMS message received from the SMS-IWMSC (370) to the terminal (300) via a DL NAS Transport message.

[0148] In step 313, the terminal (300) can transmit acknowledges receipt of the delivery report information, indicating that it has successfully received the Delivery report of MO SMS message, to the MME-NT (320) within the satellite via a UL NAS Transport message.

[0149]

[0150] FIG. 4a and FIG. 4b are flowcharts for transmitting network structure and related information for supporting MT SMS service requested by SC from satellite using 4G system-based control plane according to one embodiment of the present disclosure.

[0151] According to one embodiment of the present disclosure, an MME-NT may be located as a 4G EPC entity for supporting SMS service using a control plane within a satellite, and an MME-T, SMS-IWMSC / SMS-GMSC / SC, and HSS may be located in a ground base station. In the present disclosure, MME-T may be used interchangeably with MME-G.

[0152] In step 401, SC (490) can transmit a Message transfer request message to SMS-GMSC (480) to transmit MT SMS.

[0153] In step 402, SMS-GMSC (480), which has received a request from SC (490) to deliver MT SMS to a specific user, may request the address of the message server where the user is registered to HSS (470) through the SendroutinginforMTSMS message for delivery of the MT SMS message. Based on the IMSI information in the request message, HSS (470) may deliver the address of the 4G entity capable of processing the message to which the terminal is connected (e.g., IP address of MME-T) to SMS-GSMC (480).

[0154] In step 403a, SMS-GMSC (480) may determine to generate maximum retransmission time information indicating that it supports the retransmission function of MT SMS messages if the MT SMS is not successfully transmitted before being transmitted to MME-T. In an embodiment of the present invention, SMS-GMSC (480) may transmit to MME together with Maximum retransmission time information indicating that SMS-GMSC supports the retransmission function if transmission of MT SMS messages from MME-T to MME-NT is temporarily unavailable. At this time, the Maximum retransmission time information generated by SMS-GMSC may be set differently from the existing SMS service by taking into account the characteristics of the satellite and utilizing Unavailable period information considering the orbital period of the satellite, etc.

[0155] At step 403b, SMS-GMSC (480) may forward the MT SMS message to MME-T (440) within the ground base station.

[0156] In step 404, the MME-T (440) can check whether the feeder link between the satellite and the ground base station is connected. If the feeder link between the terminal and the ground base station is connected in step 404, steps 403c to 403e can be omitted.

[0157] If the feeder link between the terminal and the satellite is not connected in step 403c, the MME-T (440) may decide to transmit to the SMS-GMSC (480) the Cause information indicating that the connection with the satellite has been temporarily lost in the delivery report related to the MT SMS message, and the Available time for feeder link information requesting when the message should be retransmitted to the MME-T.

[0158] In step 403d, SMS-GMSC (480), which receives cause information indicating that the terminal is temporarily unavailable for connection from MME-T (440) and Available timer for feederlink information, may store the MT SMS message in SMS-GMSC for a time within the Available timer for feederlink or Available time for feederlink and then decide to retransmit it to MME-T after a specified time.

[0159] In step 403e, SMS-GMSC (480) may request that the stored MT-SMS information be forwarded to MME-T (440) to be forwarded to MME-NT (420).

[0160] In step 405a, the MME-T (440) can forward the MT SMS message received from the SMS-GMSC (480) to the MME-NT (420) in the satellite if a feederlink is connected between the satellite and the ground station.

[0161] The MME-NT (420) that received the MT SMS message in step 405b can check the service link information between the satellite and the terminal.

[0162] At step 405c, the MME-NT (420) can buffer the MT SMS message for the amount of time equal to the Available time for service link if the service link between the satellite and the terminal is not connected.

[0163] At step 405d, the MME-NT (420) can perform paging and service request operations for control plane connection through the service link connection of the terminal when the service link between the satellite and the terminal is connected but in CM-IDLE state.

[0164] In step 406, the MME-NT (420) can transmit the MT SMS message received from the SMS-GMSC and MME-T to the terminal (400) via a DL NAS Transport message. The terminal (400) can transmit delivery report of MT SMS information indicating successful reception of the MT SMS message to the MME-NT (420) within the satellite via a UL NAS Transport message.

[0165] In step 407, the MME-NT (420) that has received the delivery report of MT SMS information from the terminal (400) can forward the message to the MME-T (440).

[0166] At step 408, MME-T (440) may receive a delivery report of MT SMS message and forward it to SMS-GMSC (480).

[0167] In steps 409 and 410, SMS-GMSC (480) can forward the Delivery report of MT SMS received from MME-T (440) to HSS (470) and SC (490).

[0168]

[0169] FIG. 4c and FIG. 4d are flowcharts for transmitting network structure and related information for supporting MT SMS service requested by SC through multiple satellites using a 4G system-based control plane according to one embodiment of the present disclosure.

[0170] According to one embodiment of the present disclosure, when using an MT-SMS service utilizing a satellite system composed of one or more satellites, each satellite can register a Location Update Request message including information of a user registered with the corresponding satellite, etc., with the HSS before step 402 of FIGS. 4a and 4b. Through this, the SMS-GMSC, which has received the MT SMS message from the SC through step 401, can receive, from the HSS through the SendroutinginforMTSMS message, information on the satellite supporting the corresponding terminal and MME information within the satellite mapped to the corresponding satellite information.

[0171] According to one embodiment of the present disclosure, if there is no feeder link connection between the satellite and the ground station, the MMT-T and SMS-GMSC may not be able to transmit the MT SMS message to the MT SMS forwarding message server address from the HSS. According to an embodiment of the present invention, if there is an entity that manages the mobility of a satellite in a separate ground station according to the settings of the satellite network operator, etc., and the MMT-T may request and receive status information and connection status information of a satellite requesting a connection from the entity that manages the mobility based on the address of the MT SMS forwarding message server received from the HSS as the entity that manages the mobility of the satellite.

[0172] In step 450a, if the terminal (400) cannot find a connection to a separate ground base station (enodeB), it can perform a network registration procedure and a service request procedure using enodeB of a satellite (Satellite #1) that services the location of the terminal at a specific time (T1). The request for the corresponding operation can be performed when the service link between the terminal and the satellite is connected. At this time, when performing the network registration or service request procedure, the terminal can request the 'SMS in MME' service, which is a control message-based SMS service using the MME of the terminal, instead of the existing control message-based SMS service using the MSC. In addition, the network determines whether the MME-NT in the satellite supports the corresponding operation and determines whether the 'SMS in MME' service is accepted, and then, if the MME in the satellite supports the corresponding operation, it can support the service requested by the terminal.

[0173] In step 450b, the MME-NT (431) in the satellite (Satellite #1) can perform the network registration procedure and the service request procedure by forwarding the network registration and service request message received from the UE (400) to the MME-T (440) in the ground base station.

[0174] In step 450c, the MMT-T (440) may transmit a Location Update Request message including information about a terminal (UE#1) currently connected to a satellite (Satellite #1) to the HSS (470). The Location Update Request message may include satellite-related information such as a satellite ID, information about NFs within the satellite (MME ID, etc.), IMSI, RAT Type, MME Number for MT SMS, and SMS Register Request information.

[0175] In step 450d, when T2 hours have passed since the connection to the satellite (Satellite #1), if the satellite (Satellite #2) servicing the terminal's location at that time (T1+T2) changes, the terminal can perform a network registration procedure and a service request procedure using the enodeB of the new satellite (Satellite #2). The request for this operation can be performed when the service link between the terminal and the satellite is connected.

[0176] At step 450e, the MME-NT (432) within the satellite (Satellite #2) can perform a network registration procedure and a service request procedure by forwarding the network registration and service request message received from the UE (400) to the MME-T (440) within the ground base station.

[0177] In step 450f, the MMT-T (440) may transmit a Location Update Request message including information about a terminal (UE#1) currently connected to a satellite (Satellite #2) to the HSS (470). The Location Update Request message may include satellite-related information such as a satellite ID, information about NFs within the satellite (MME ID, etc.), IMSI, RAT Type, MME Number for MT SMS, and SMS Register Request information.

[0178] In step 450f, if updated information (e.g. satellite-related information such as a new satellite ID and information on NFs within the satellite) supporting the corresponding terminal (IMSI) is transmitted, the existing satellite (Satellite #1) information is deleted, and the HSS (470) can perform an operation to update the terminal-related information based on the information in the Location Update Request message transmitted from the new satellite (Satellite #2). The HSS (470) can receive NF (MME etc.) information (e.g. IP address) within the satellite supporting the terminal directly from the satellite, or can receive satellite ID or MMME ID, etc. from the MME of the satellite, and obtain NF (MME etc.) information (e.g. IP address) within the satellite supporting the terminal based on the information provided by the satellite network operator, and store the information in the HSS.

[0179] At step 451, SC (490) may forward an MT SMS message to SMS-GMSC (480).

[0180] In step 452, SMS-GMSC (480) can request the address of the message server (MMT-NT) to which the MT SMS will be forwarded to the HSS (470) via the SendroutinginforMTSMS message. Based on the IMSI information in the request message, the HSS can forward the address (e.g. IP address) of the message server address MME-NT on board / Satellite to which the terminal is connected to the SMS-GSMC (480).

[0181] In step 453, SMS-GMSC (480) may transmit a ShortMessage message including the address (e.g. IP address) of the message server address MME-NT on board / Satellite to which the terminal is connected / registered, received from HSS (470), to MME-T (440).

[0182] In step 454, the MMT-T (440) can receive information on the status of the connection (Feederlink) with the satellite based on the entity that manages the mobility of the satellite, the address of the message server to deliver the MT SMS received from the HSS, and the satellite information. If the satellite (Satellite #1 or Satellite #2) on which the terminal is being serviced and the ground base station are connected (Feederlink), the MMT-T can transmit the MT SMS message to the terminal through the procedures from step 403e to step 410 of FIGS. 4a and 4b.

[0183] If, in step 454, MMT-T checks the status information of the connection (Feederlink) with the satellite based on the address of the message server for delivering the MT SMS received from the HSS from the entity managing the mobility of the satellite and the satellite information, and the connection (Feederlink) between the satellite and the ground station is not established, MMT-T can determine that the status is “UE is not available for MT SMS.”

[0184] In step 455, the MME-T (440) may transmit a Failure report message to the SMS-GMSC (480). The MME-T (440) may include error cause information (Absent User or UE is not reachable) in the Failure report message.

[0185] In step 456, if the SMS-GMSC (480) is unable to connect to the satellite received from the HSS (470) in step 454, the SMS-GMSC (480) may transmit to the HSS (470) that the MT-SMS message was not delivered through the SM-Delivery ReportStatus operation. The SMS-GMSC (480) may transmit to the HSS (470) a Report SM Delivery Status Request message including a User Identifier, an SM Delivery Outcome including error cause information (Absent User or UE is not reachable), and an SC address (Service Center Address).

[0186] At step 457, SMS-GMSC (480) may notify SC (490) that the MT SMS message delivery of a specific user has failed through a Failure Report operation.

[0187] In steps 445 and 459, the HSS (470) may transmit an Insert Subscriber Data Request message including a URRP-MME flag to the MME-T (440) for a subscription request for notification of the corresponding event to the HSS when the status information of the terminal changes.

[0188] In case of MME-T that does not support URRP-MME flag, i.e. URRP-MME function, after completing the network registration and service request procedure based on the forwarded information for network registration and service request from MME-NT (431, 432) in each satellite as in steps 450b and 450e, MMT-T (440) can transmit a, Update Location Request including satellite-related information and SMS-related information on which the terminal is currently registered to inform HSS (470) whether the terminal is in a connectable state.

[0189] If the MME-T supports the URRP-MME flag, i.e., the URRP-MME function, the MME-T can notify the HSS (470) whether the UE becomes reachable through the b.Notify Request message according to the policy of the network operator or service provider.

[0190] If the HSS (470) receives information that the transmission of the MT SMS to be transmitted to the terminal (UE#1) registered in the satellite in steps 454 to 456 has failed, the HSS (470) can store the corresponding reporting information in MWD (Message Waiting Data).

[0191] In step 460, if information is received from the MME-T (440) through a and b that the corresponding terminal (UE#1) has been (re)registered to a specific satellite, the HSS (470) can notify the SMS-GMSC (480) that the corresponding terminal (UE#1) is connected through the Alert-Service-Centre-Request operation.

[0192] In step 461, SMS-GMSC (480), which has been informed that UE#1 is connected, may forward this to SC (490) to request a retransmission operation of the MT SMS message related to UE#1 that has been put on hold. Thereafter, MT SMS transmission operation using a satellite may be performed to UE#1 through steps 401 to 410 of FIGS. 4a and 4b.

[0193]

[0194] FIG. 5a and FIG. 5b are flowcharts for transmitting network structure and related information for supporting MO SMS service requested by a terminal from a satellite using a 4G system-based control plane according to an embodiment of the present disclosure.

[0195] According to one embodiment of the present disclosure, MME and SMS-IWMSC-On / SMS-GMSC-On may be located as 4G EPC entities for supporting SMS service using a control plane within a satellite, and SMS-IWMSC-Ground / SMS-GMSC-Ground / SC and HSS may be located in a ground base station.

[0196] In step 500a or step 500b, if the terminal (500) cannot find a connection to a separate terrestrial enodeB, it can perform a network registration procedure and a service request procedure using the satellite's enodeB. The request for the corresponding operation can be performed when the service link between the terminal and the satellite is connected. At this time, when performing the network registration or service request procedure, the terminal can request the 'SMS in MME' service, which is a control message-based SMS service using the terminal's MME, instead of the existing control message-based SMS service using the MSC. In addition, the network determines whether the MME in the satellite supports the corresponding operation and determines whether the 'SMS in MME' service is accepted, and if the MME in the satellite supports the corresponding operation, it can support the service requested by the terminal.

[0197] In step 501, the terminal (500) can include a MO SMS message in a UL NAS Transport message and transmit it to the MME (532) to use the SMS service.

[0198] In steps 502, 503a, and 503b, the MME (532) that receives the MO SMS message from the terminal (500) can transmit to the terminal (500) whether or not the MO SMS message was received via the DL NAS Transport. If there is no feederlink connection between the satellite and the ground base station, the DL NAS Transport can transmit together the Reception of MO SMS message indicating whether or not the MO SMS message was received, and the Available time for feederlink, which is information on the time when the Delivery of MO SMS can be transmitted from the SC. After receiving the Available time for feederlink information, the terminal (500) can predict that the Delivery of MO SMS can be transmitted within the corresponding time, and does not perform a retransmission operation of the MO SMS message before the corresponding time. If the terminal does not receive the Delivery of MO SMS message after the Available time for feederlink time, the terminal can perform a retransmission operation of the MO SMS message. If a Servicelink is connected between a terminal and a satellite after a certain period of time has passed since the Feederlink connection between the satellite and the ground base station, the MME (532) can set an additional offset of 5 to 15 minutes in the Available time for feederlink to inform the terminal of the time at which it can receive the Delivery of MO SMS.

[0199] In step 504a, the MME (532) can forward the MO SMS message received from the terminal (500) to SMS-IWMSC-SAT (533) and request that the MO SMS message be forwarded to SMS-IWMSC-Ground (560) in the ground base station.

[0200] In step 505a, if SMS-IWMSC-SAT (533) receives only a MO SMS message without separate Available time for feederlink information from MME (532), SMS-IWMSC-SAT (533) may assume that the feederlink between the satellite and the ground station is connected and forward the MO SMS message to SMS-IWMSC-Ground and SC (560) in the ground station.

[0201] In step 506a, SMS-IWMSC-Ground and SC (560) may transmit a Delivery report of MO SMS message to SMS-IWMSC-SAT (533) after receiving the MO SMS message, which indicates that the MO SMS message transmitted by the terminal has been successfully transmitted to SMS-IWMSC-Ground and SC (560).

[0202] In step 507a, SMS-IWMSC-SAT (533) may forward the Delivery report of MO SMS message received from SMS-IWMSC-Ground and SC (560) to MME (532).

[0203] In step 508a, the MME (532) can check service link information between the satellite and the terminal.

[0204] If the service link between the satellite and the terminal is connected at step 509, the MME (532) can transmit the Delivery report of MO SMS message received from SMS-IWMSC-SAT (533) to the terminal (500) via a DL NAS Transport message.

[0205] If the feederlink between the terminal and the satellite is not connected when the MME (532) determines the feederlink status, the MO SMS message and the Available time for feederlink can be transmitted together to request a buffering operation so that the SMS-IWMSC-SAT (533) performs a retransmission operation of the MO SMS message after the Available time for feederlink time.

[0206] In steps 504b and 504c, SMS-IWMSC-ON or SMS-IWMSC-SAT (533) may perform an operation of buffering the MO SMS message for the amount of Available time for feederlink time if Available time for feederlink information is transmitted together with the MO SMS from the MME (532).

[0207] In step 505b, SMS-IWMSC-SAT (533) can check the feeder link connection between the satellite and the ground station after the Available time for feederlink time and then transmit the MO SMS message to SMS-IWMSC-Ground (560).

[0208] In step 506b, SMS-IWMSC-Ground and SC (560) may transmit a Delivery report of MO SMS message to SMS-IWMSC-SAT (533) after receiving the MO SMS message, which indicates that the MO SMS message transmitted by the terminal has been successfully transmitted to SMS-IWMSC-Ground and SC (560).

[0209] In step 507b, SMS-IWMSC-SAT (533) may forward the Delivery report of MO SMS message received from SMS-IWMSC-Ground and SC (560) to MME (532).

[0210] At step 508b, the MME (532) can check service link information between the satellite and the terminal.

[0211] In step 507c, if the service link between the satellite and the terminal is not connected, the MME (532) may transmit a delivery report related to the Delivery report of MO SMS message, which includes Cause information indicating that the connection with the UE is temporarily disconnected and Available time for service link information requesting when the message is to be retransmitted to the MME, to the SMS-IWMSC-SAT (533).

[0212] In steps 507d and 507e, SMS-IWMSC-SAT (533), which has received cause information indicating that the terminal is temporarily unavailable for connection from MME (532) and Available timer for servicelink information, can store the Delivery report of MO SMS message in SMS-IWMSC-SAT for a time within the Available timer for servicelink or Available time for servicelink and then retransmit it to MME (532) after a specified time.

[0213] After the service link between the satellite and the terminal is connected in step 509, the MME (532) can transmit the Delivery report of MO SMS message retransmitted by SMS-IWMSC-SAT (533) to the terminal (500) via a DL NAS Transport message.

[0214]

[0215] FIG. 6a and FIG. 6b are flowcharts for transmitting network structure and related information for supporting MT SMS service requested by SC from satellite using 4G system-based control plane according to one embodiment of the present disclosure.

[0216] In step 600, the SC can forward the MT SMS message to the SMS-GMSC. The SMS-GMSC (660) can request the message server address to which the MT SMS will be forwarded to the HSS (670) via the SendroutingInforMTSMS message. Based on the IMSI information in the request message, the HSS (670) can forward the message server address (e.g., MME, MSC address, or SMS-GMSC onboard / Satellite address (e.g., IP address) to the SMS-GSMC (660).

[0217] If the feeder link connection between the satellite and the ground station is not established, the SMS-GMSC may not receive the message server address for transmitting the MT SMS from the HSS. According to an embodiment of the present invention, if there is an entity that manages the mobility of the satellite in a separate ground station according to the settings of the satellite network operator, etc., it can be assumed that the HSS has registered and has the satellite status information and connection status information from the entity that manages the mobility of the satellite. If the HSS has received and has the satellite status information and connection status information from the entity that manages the satellite mobility through the above operation, the HSS may transmit a SendroutinginforMTSMS message or an informServiceCentre (informSC) message including the Available time for feederlink information and the cause information indicating that the satellite is temporarily unreachable (e.g., cause (temporarily unreachable)) as a response message to the message server address request message received from the SMS-GMSC when the feeder link is not established, to the SMS-GMSC.

[0218] According to one embodiment of the present disclosure, the SMS-GMSC may determine a buffering operation for MT SMS messages based on the Available time for feederlink information after receiving information that the connection is temporarily unavailable from the HSS. The SMS-GMSC may request a message server address transfer request for transferring the buffered MT SMS messages after the Available time for feederlink time received through the HSS via the SendroutinginforMTSMS message. The SMS-GMSC, which has received the message server address for transferring the MT SMS messages from the HSS, may decide to transfer them to the SMS-GMSC within the satellite.

[0219] According to one embodiment of the present disclosure, after receiving an informServiceCentre (informSC) message including information about temporary connection unavailability from an HSS, the SMS-GMSC may generate a Failure Report message notifying that the feeder link connection is temporarily unavailable based on the informSC information and transmit the message to the SC according to the network operator's policy and settings. The Failure Report message transmitted from the SMS-GMSC to the SC may include the Available time for feederlink information transmitted from the HSS. The SC, which has received the Failure Report message from the SMS-GMSC, may set the time for retransmitting the MT SMS to the SMS-GMSC to be after the Available time for feederlink based on the Available time for feederlink information in the Failure Report message. The SC may retransmit the MT SMS message to the SMS-GMSC after the Available time for feederlink.

[0220] In step 601a, the SMS-GSMC-T (660) on the ground can receive the address of the message server to which the user is connected for receiving the MT SMS from the HSS (670) from step 600. According to an embodiment of the present invention, if the user is connected to the network via a satellite, the message server can be located within the phase. The HSS can store the address of the message server that supports the SMS service via satellite of the terminal if the SMS service request information is included according to the service-related information requested by the terminal when the terminal registers the network via satellite. If the structures of the SMS-GSMC are respectively located on the ground and satellite sides as shown in FIGS. 6a and 6b, the SMS-GMSC-T can receive the address of the SMS-GMSC-ON of the satellite from the HSS. Thereafter, the SMS-GMSC-T can transmit the MT SMS message to the SMS-GMSC-On (623) in the satellite via the satellite channel if the feeder link between the ground station on the ground and the satellite is connected. If the feederlink between the satellite to which the terminal is connected and the ground station is not connected, SMS-GMSC-T (660) stores the MT SMS message and can transmit the MT SMS message to SMS-GMSC-On (623) in the satellite when the feederlink is connected. In order to receive information on whether the feederlink is connected, SMS-GMSC-T (660) can transmit information requesting information on whether the feederlink is connected to the MMT-T if there is an MME-T in the ground station that manages mobility with the satellite, or can perform a request to receive the information if a service in the form of OAM that manages between a separate satellite and the ground control station is provided in the ground station.

[0221] If Feederlink is connected in step 601a, SMS-GMSC-Ground (660) can forward MT SMS messages to SMS-GMSC-SAT (623) within the satellite.

[0222] In step 602a, SMS-GMSC-SAT (623) can transmit the MT SMS message to MME (622) within the satellite. MME (622) within the satellite can be assumed to be an MME that supports MSC function to support 'SMS in MME' service. In an embodiment of the present invention, SMS-GMSC-SAT can transmit Maximum retransmission time information indicating that SMS-GMSC-SAT supports retransmission function to MME if transmission of MT SMS message from MME to terminal is temporarily unavailable. At this time, Maximum retransmission time information transmitted from SMS-GMSC-SAT to MME can be set differently from existing SMS service by taking into account characteristics of satellite, such as Unavailable period information considering the orbital period of the satellite, etc.

[0223] In step 603, the MME (623) can check whether the service link between the satellite and the terminal is connected. If the service link between the terminal and the satellite is connected and in the ECM / RRC Connected state in step 603, step 604 can be omitted.

[0224] In step 604, if the terminal is in ECM / RRC Idle state but the service link between the satellites is connected, the MME can perform paging and service request operations to transition the terminal and satellite to ECM / RRC Connected state.

[0225] In step 602b, if the service link between the terminal and the satellite is not connected in step 603, the MME (623) may transmit Cause information indicating that the connection with the UE is temporarily lost in the delivery report related to the MT SMS message to SMS-GMSC-SAT (623) and Available time for service link information related to when to request retransmission of the message to the MME.

[0226] In step 602c, SMS-GMSC-SAT (623), which has received cause information indicating that the terminal is temporarily unavailable for connection from MME (622) and Available timer for servicelink information, may store the MT SMS message in SMS-GMSC-SAT (623) for a time within the Available timer for servicelink or Available time for servicelink and then decide to retransmit it to MME (622) after a specified time.

[0227] In step 602d, SMS-GMSC-SAT (623) may forward the stored MT SMS information to MME (622) and request that the MT SMS information be forwarded to UE (600).

[0228] In step 605, if the service link between the satellite and the terminal is connected and in the CM-Connected state, the MME (622) can transmit the MT SMS message received from SMS-GMSC-On (623) to the terminal (600) via a DL NAS Transport message.

[0229] In step 606, the terminal (600) can transmit a UL NAS Transport including a Delivery report of MT SMS message to the MME (622) to report that the MT SMS message has been delivered.

[0230] The MME that received the Delivery report of MT SMS from the terminal before step 607a or step 607b can check whether the feeder link is connected between the satellite and the ground base station.

[0231] In step 607a, the MME (622) can transmit the message as SMS-GMSC-SAT (623) if the feederlink between the satellite and the base station is connected.

[0232] In step 608a, SMS-GMSC-SAT (623) can forward the Delivery report of MT SMS received from MME (622) to SMS-GMSC-Ground and SC (660).

[0233] In step 607b, if the feederlink between the satellite and the ground station is not connected, the MME (623) can transmit the Delivery report of MT SMS information and additionally the Available timer for feederlink information to SMS-GMSC-SAT (623).

[0234] In step 607c, SMS-GMSC-SAT (623), which receives Delivery report of MT SMS information and additionally Available timer for feederlink information from MME (622), stores Delivery report of MT SMS information in SMS-GMSC-SAT for the time within the Available timer for feederlink or Available time for feederlink, and then transmits Delivery report of MT SMS to SMS-GMSC-Ground and SC (660) after a specified time.

[0235] In step 608b, SMS-GMSC-SAT (623) requests the MME for the connection status of the feederlink after a time within the Available timer for feederlink or the Available time for feederlink received from the MME (622), checks the connection status of the feederlink, and then transmits a Delivery report of MT SMS to SMS-GMSC-Ground and SC (660) to complete the operation of transmitting the MT SMS message to the terminal connected to the requested satellite.

[0236]

[0237] FIG. 6c is a flowchart illustrating a network structure and a flowchart for transmitting related information to support an MT SMS service requested by an SC through multiple satellites using a 4G system-based control plane according to an embodiment of the present disclosure.

[0238] According to one embodiment of the present disclosure, when using an MT-SMS service utilizing a satellite system composed of one or more satellites, each satellite may register a Location Update Request message including information of a user registered with the corresponding satellite, etc., with the HSS prior to step 600 of FIGS. 6a and 6b. Through this, the SMS-GMSC, which has received the MT SMS message from the SC through step 600, may receive information on the satellite supporting the corresponding terminal and information on the MME and SMS-GMSC within the satellite mapped to the corresponding satellite information from the HSS through the SendroutinginforMTSMS message.

[0239] According to one embodiment of the present disclosure, if there is no feeder link connection between the satellite and the ground station, the SMS-GMSC may not be able to transmit an MT SMS message to the MT SMS forwarding message server address from the HSS. According to an embodiment of the present invention, if there is an entity that manages the mobility of a satellite in a separate ground station according to the settings of a satellite network operator, etc., it can be assumed that the SMS-GMSC can request and receive status information and connection status information of a satellite requesting a connection from the entity that manages the mobility based on the address of the MT SMS forwarding message server received from the HSS as the entity that manages the mobility of the satellite.

[0240] In step 650a, if the terminal (600) cannot find a connection to a separate ground base station (enodeB), it can perform a network registration procedure and a service request procedure using enodeB of a satellite (Satellite #1) that provides service to the location of the terminal at a specific time (T1). The request for the corresponding operation can be performed when the service link between the terminal and the satellite is connected. At this time, when performing the network registration or service request procedure, the terminal can request the 'SMS in MME' service, which is a control message-based SMS service using the MME of the terminal, instead of the existing control message-based SMS service using the MSC. In addition, the network determines whether the MME in the satellite supports the corresponding operation and determines whether the 'SMS in MME' service is accepted, and if the MME in the satellite supports the corresponding operation, it can support the service requested by the terminal.

[0241] In step 650b, the MME (632) within the satellite (Satellite #1) may transmit a Location Update Request message including terminal information currently connected to the satellite within the ground base station to the HSS (670). The Location Update Request message may include satellite-related information such as the satellite ID, information on NFs within the satellite (MME ID, SMS-GMSC, etc.), IMSI, RAT Type, MME Number for MT SMS, and SMS Register Request information.

[0242] In step 650c, when T2 hours have passed since the connection to the satellite (Satellite #1), if the satellite (Satellite #2) servicing the terminal's location at that time (T1+T2) changes, the terminal can perform a network registration procedure and a service request procedure using the enodeB of the new satellite (Satellite #2). The request for this operation can be performed when the service link between the terminal and the satellite is connected.

[0243] In step 650d, the MME (642) within the satellite (Satellite #2) may transmit a Location Update Request message including terminal information currently connected to the satellite within the ground base station to the HSS (670). The Location Update Request message may include satellite-related information such as the satellite ID, information on NFs within the satellite (MME ID, SMS-GMSC, etc.), IMSI, RAT Type, MME Number for MT SMS, and SMS Register Request information.

[0244] In step 650d, if updated information supporting the corresponding terminal (e.g., satellite-related information such as a new satellite ID and information on NFs within the satellite) related to the terminal (IMSI) is transmitted, the existing satellite (Satellite #1) information is deleted, and the HSS can perform an operation to update the terminal-related information based on the information in the Location Update Request message transmitted from the new satellite (Satellite #2). The HSS can receive the NF (MME, SMS-GMSC, etc.) information (e.g., IP address) within the satellite supporting the terminal directly from the satellite, or can obtain the NF (MME, SMS-GMSC, etc.) information (e.g., IP address) within the satellite supporting the terminal based on the information provided by the satellite network operator by receiving the satellite ID or MMME ID from the MME of the satellite, and store the information within the HSS.

[0245] At step 650e, SC (662) may forward an MT SMS message to SMS-GMSC (661).

[0246] In step 650f, SMS-GMSC (661) can request the message server address to which the corresponding MT SMS will be forwarded to HSS (670) via the SendroutinginforMTSMS message. Based on the IMSI information in the request message, HSS (670) can forward the message server address MME, MSC address, or SMS-GMSC onboard / Satellite address (e.g. IP address) to which the corresponding terminal is connected to SMS-GSMC (661).

[0247] At step 650g, SMS-GMSC (661) can receive information on the status of the connection (Feederlink) with the satellite based on the entity that manages the mobility of the satellite, the address of the message server to deliver the MT SMS received from the HSS, and the satellite information. If the satellite (Satellite #1 or Satellite #2) on which the terminal is being serviced and the ground station are connected (Feederlink), SMS-GMSC can transmit the MT SMS message to the terminal through the procedures from step 601 to step 608b of FIGS. 6a and 6b.

[0248] If, at step 650g, SMS-GMSC (661) checks the status information of the connection (Feederlink) with the satellite based on the entity managing the mobility of the satellite, the address of the message server to deliver the MT SMS received from the HSS, and the satellite information, and if the connection (Feederlink) between the satellite and the ground station is not established, SMS-GMSC can determine that the status is “UE is not available for MT SMS.”

[0249] In step 650h, if SMS-GMSC (661) is unable to connect to the satellite received from HSS (670) in step 650g, SMS-GMSC (661) may transmit to HSS (670) that MT-SMS message was not delivered through SM-Delivery ReportStatus operation. SMS-GMSC (661) may transmit to HSS (670) a Report SM Delivery Status Request message including User Identifier, SM Delivery Outcome including error cause (Absent User or UE is not reachable) information, and SC address (Service Center Address).

[0250] At step 650i, SMS-GMSC (661) may notify SC (662) that delivery of MT SMS message of a specific user has failed through Failure Report operation.

[0251] In step 650j, if a specific terminal (UE#1) performs a network registration procedure and a service request procedure via a satellite as in steps 650a to 650d, the MME can receive information about the satellite to which the terminal (UE#1) is connected, etc., from the HSS via a Location Update request message. If the HSS (670) receives information that the transmission of the MT SMS to be transmitted to the terminal (UE#1) registered to the satellite has failed in steps 650g and 650h, the HSS can store the reporting information in the MWD (Message Waiting Data). Afterwards, if the HSS receives information that the terminal (UE#1) has been (re)registered to a specific satellite, the connection of the terminal (UE#1) can be reported to the SMS-GMSC (661) via an Alert-Service-Centre-Request operation.

[0252] In step 650k, SMS-GMSC (661), which has been informed that UE#1 is connected, may forward this to SC (662) to request a retransmission operation of the MT SMS message related to UE#1 that has been put on hold. Thereafter, MT SMS transmission operation using a satellite may be performed to UE#1 through steps 600 to 608b of FIGS. 6a and 6b.

[0253]

[0254] FIG. 7a and FIG. 7b are flowcharts for transmitting network structure and related information for supporting MO SMS service requested by a terminal from a satellite using a 5G system-based control plane according to an embodiment of the present disclosure.

[0255] According to one embodiment of the present disclosure, the AMF and SMSF may be located in a 5G NF for supporting SMS service using a control plane within a satellite, and the SMS-IWMSC / SMS-GMSC / SC and HSS may be located in a ground base station.

[0256] In step 701, if the terminal (700) cannot find a connection to a separate ground gNB, it can perform a network registration procedure and a service request procedure using a satellite gNB. The request for the operation can be performed if the service link between the terminal and the satellite is connected. At this time, the terminal can request an 'SMS over NAS'-based service in order to use an SMS service based on a control message using SMSF when performing the network registration or service request procedure. In addition, the network can determine whether the NF in the satellite supports the operation and whether the 'SMS over NAS' service is accepted, and then, if the 5G NF in the satellite supports the operation, it can decide to support the service requested by the terminal.

[0257] In step 702a, the terminal (700) can transmit a MO SMS message to AMF (730) by including it in a UL NAS Transport message in order to use an SMS service using NAS.

[0258] In step 703, the AMF (730) that received the MO SMS message from the terminal (700) can check the feeder link connection status.

[0259] In step 704a, if the feederlink between the satellite and the ground station is not connected, the AMF (730) may include the MO SMS body and the Available reachability timer for feederlink information in the Nsmf_SMService_UPlinkSMS message and transmit it to the SMSF (740).

[0260] At step 704b, SMSF (740) may notify AMF (730) that it has successfully received the MO message.

[0261] In step 702b, the AMF (730), which has been notified that the MO SMS message has been successfully received from the SMSF (740), can transmit to the terminal (700) whether the MO SMS message has been received via the DL NAS Transport. If there is no feederlink connection between the satellite and the ground station, the DL NAS Transport may include a Reception of MO SMS message indicating whether the MO SMS message has been received and an Available time for feederlink together. After the terminal receives the Available time for feederlink information, the terminal can predict that the Delivery of MO SMS can be delivered after the corresponding time, and does not perform a retransmission operation of the MO SMS message before the corresponding time. If the terminal has not received the Delivery of MO SMS message after the Available time for feederlink time, the terminal can perform a retransmission operation of the MO SMS message. If the servicelink between the terminal and the satellite is connected after a certain period of time after the feederlink connection between the satellite and the ground station, the MME-On may set an additional offset of 5 to 15 minutes in the Available time for feederlink to inform the terminal of the time at which the Delivery of MO SMS can be received.

[0262] In step 705a, SMSF (740) may perform an operation of buffering the MO SMS message for a time corresponding to the Available time for feederlink if the feederlink between the satellite and the ground station is not connected.

[0263] If the feederlink between the satellite and the ground station is connected in step 703, the AMF (730) can forward only the SMS body information in the Nsmf_SMService_UPlinkSMS message to the SMSF (740).

[0264] If the feederlink between the satellite and the ground station is connected after the Available time for feederlink in step 705b, the SMSF (740) can forward the buffered MO message to the SMS-IWMSC (770). If the feederlink between the satellite and the ground station is connected in step 703, the SMSF (740) can forward the MO message to the SMS-IWMSC (770) without any separate processing operation.

[0265] At step 706, SMS-IWMSC (770) can forward the MO SMS message received from SMSF (740) to SC (780).

[0266] In step 707, the SC (780) receives the MO SMS message through the SMS-IWMSC (770) and then generates a Delivery report of MO SMS message notifying that the MO SMS message transmitted by the terminal has been successfully transmitted to the SC, and the SMS-IWMSC (770) can receive the Delivery report of MO SMS message from the SC (780).

[0267] At step 708, SMS-IWMSC (770) can forward the Delivery report of MO SMS message received from SC (780) to SMSF (740) within the satellite.

[0268] In step 709a, SMSF (740) can transmit a Namf_MO_EnableReachability Request message requesting the connection status of the terminal for transmission of a Delivery report of MO SMS message to AMF (73).

[0269] AMF (730) that received the Namf_MO_EnableReachability Request message in step 709b can check the service link information between the satellite and the terminal.

[0270] In step 709c, if the service link between the satellite and the terminal is not connected, the AMF (730) can transmit information such as cause (temporarily unreachable), retransmission indication, or Available reachability timer for service link in the Namf_MO_EnableReachability Response message to the SMSF (740).

[0271] In step 709d, SMSF (740) can buffer the Delivery report of MO SMS message for the amount of time equal to the Available time for servicelink based on the information in the Namf_MO_EnableReachability Response message.

[0272] In step 709e, SMSF (740) can transmit a Namf_MO_EnableReachability Request message requesting the connection status of the terminal after the Available time for servicelink time to AMF (730) for transmission of the Delivery report of MO SMS message.

[0273] In step 710a, if the service link between the satellite and the terminal is connected but in CM-IDLE state, paging and service request operations for control plane connection through the terminal's service link connection can be performed.

[0274] In step 709f, AMF (730) can transmit response information indicating that the service link between the terminal and the satellite is connected to SMSF (740) via the Namf_MO_EnableReachability Request message.

[0275] At step 709g, SMSF (740) may forward the buffered Submit Report information to AMF (730) via the Namf_Communication_N1N2Message_Transfer message.

[0276] In step 710b, AMF (730) can transmit the Submit Report of MO SMS message received from SMSF (740) to the terminal (700) via a DL NAS Transport message.

[0277] In steps 710c and 710d, the terminal (700) can transmit response information indicating that it has successfully received the Submit Report of MO SMS message to the satellite AMF (730) and SMSF (740) via the UL NAS Transport message.

[0278]

[0279] FIG. 8a and FIG. 8b are flowcharts for transmitting network structure and related information for supporting MT SMS service requested by SC from satellite using 5G system-based control plane according to one embodiment of the present disclosure.

[0280] According to one embodiment of the present disclosure, the AMF and SMSF may be located in a 5G NF for supporting SMS service using a control plane within a satellite, and the SMS-IWMSC / SMS-GMSC / SC and HSS may be located in a ground base station.

[0281] At step 801, SC (880) may forward a message to SMS-GMSC (870). The message forwarded by SC (880) may be an MT SMS message.

[0282] In step 802, UDM (890) and SMS-GMSC (870) can send and receive SMSF information to be transmitted for the corresponding MT SMS. The SMSF information may be information transmitted within the SendRoutinginfo for Short message.

[0283] The SMS-GMSC (870), which received the MT SMS message from the SC (880) in step 803a, can check the feeder link connection status.

[0284] At step 803b, SMS-GMSC (870) may store the MT SMS message received from SC (880).

[0285] If a feederlink is connected between the satellite and the ground station at step 803c, the SMS-GMSC (870) can forward the MT SMS message to the SMSF (822).

[0286] In step 804a, SMSF (822) may transmit a Namf_MT_EnableReachability Request message requesting the connection status of the terminal for transmission of a Delivery report of MT SMS message to AMF (821).

[0287] AMF (821) that received the Namf_MT_EnableReachability Request message in step 804b can check the service link information between the satellite and the terminal.

[0288] In step 804c, if the service link between the satellite and the terminal is not connected, the AMF (821) can transmit information such as cause (temporarily unreachable), retransmission indication, or Available reachability timer for service link in the Namf_MT_EnableReachability Response message to the SMSF (822).

[0289] In step 804d, SMSF (822) can buffer MT SMS messages for the amount of time equal to the Available time for servicelink based on the information in the Namf_MT_EnableReachability Response message.

[0290] In step 804e, SMSF (822) may transmit a Namf_MT_EnableReachability Request message requesting the terminal's connection status after the Available time for servicelink time for transmission of MT SMS messages to AMF (821).

[0291] In step 805a, if the service link between the satellite and the terminal is connected but in CM-IDLE state, paging and service request operations for control plane connection through the terminal's service link connection can be performed.

[0292] At step 804f, AMF (821) can transmit response information indicating that the service link between the terminal and the satellite is connected to SMSF (822) via the Namf_MT_EnableReachability Request message.

[0293] At step 804g, SMSF (822) can forward the buffered SMS body information to AMF (821) via the Namf_Communication_N1N2Message_Transfer message.

[0294] In step 805b, AMF (821) can transmit the MT SMS received from SMSF (822) to the terminal (800) via a DL NAS Transport message.

[0295] In steps 805c and 805d, the terminal (800) can transmit the CP ack to the satellite AMF (821) and SMSF (822) via a UL NAS Transport message.

[0296] In steps 806a and 806b, the terminal (800) can transmit the delivery report of MT SMS to the satellite AMF (821) and SMSF (822) via the UL NAS Transport message.

[0297] At step 807a, SMSF (822) may buffer the Delivery report of MO SMS message.

[0298] At step 806c, SMS (822)F may forward a Namf_Communication_N1N2Message-Transfer (CP ack) message to AMF (821).

[0299] In step 806d, AMF (821) can transmit the CP ack received from SMSF (822) to the terminal (800) via a UL NAS Transport message.

[0300] At step 807b, SMSF (822) may forward the Delivery report of MT SMS message to SMS-GMSC (870) or SC (880) via a UL NAS Transport message.

[0301]

[0302] FIG. 8c and FIG. 8d are a flowchart for transmitting a network structure and related information for supporting an MT SMS service requested by an SC through multiple satellites using a 5G system-based control plane according to an embodiment of the present disclosure.

[0303] According to one embodiment of the present disclosure, when using an MT-SMS service utilizing a satellite system composed of one or more satellites, each satellite may transmit a Nudm_UECM_Registration message including information of a user registered with the corresponding satellite to the UDM prior to steps 801 and 802 of FIGS. 8a and 8b. Through this, the SMS-GMSC, which has received the MT SMS message from the SC through step 801, may receive, from the UDM through the Nudm_UECM_SendRoutingInfoForSM message, information on the satellite supporting the corresponding terminal and AMF and SMSF information within the satellite mapped to the corresponding satellite information from step 802.

[0304] According to one embodiment of the present disclosure, if there is no feeder link connection between the satellite and the ground station, the SMS-GMSC may not be able to transmit an MT SMS message from the UDM to the MT SMS forwarding message server (SMSF) address. According to an embodiment of the present invention, if there is an entity that manages the mobility of a satellite in a separate ground station according to the settings of a satellite network operator, etc., it can be assumed that the SMS-GMSC can request and receive status information and connection status information of a satellite requesting a connection from the entity that manages the mobility of the satellite based on the address of the MT SMS forwarding message server (SMSF) received from the UDM.

[0305] In step 850a, if the terminal (800) cannot find a connection to a separate terrestrial base station (gnodeB), it can perform a network registration procedure and a service request procedure using gnodeB of a satellite (Satellite #1) that provides service to the terminal's location at a specific time (T1). The request for this operation can be performed when the service link between the terminal and the satellite is connected.

[0306] In step 850b, the AMF (831) within the satellite (Satellite #1) may transmit a Nudm_UECM_Registration message including terminal information currently connected to the satellite within the ground base station to the UDM (890). The Nudm_UECM_Registration message may include satellite-related information such as the satellite ID and information on NFs within the satellite (AMF ID).

[0307] In step 850c, the SMSF (832) within the satellite (Satellite #1) may transmit a Nudm_UECM_Registration message including terminal information currently connected to the satellite within the ground base station to the UDM (890). The Nudm_UECM_Registration message may include satellite-related information such as a satellite ID, as well as SUPI, SMSF identity, SMSF address, Access Type(s) information, etc.

[0308] In step 850d, when T2 hours have passed since the connection to the satellite (Satellite #1), if the satellite (Satellite #2) servicing the terminal's location at that time (T1+T2) changes, the terminal can perform a network registration procedure and a service request procedure using gnodeB of the new satellite (Satellite #2). The request for this operation can be performed when the service link between the terminal and the satellite is connected.

[0309] In step 850e, the AMF (841) within the satellite (Satellite #2) may transmit a Nudm_UECM_Registration message including terminal information currently connected to the satellite within the ground base station to the UDM (890). The Nudm_UECM_Registration message may include satellite-related information such as the satellite ID and information on NFs within the satellite (AMF ID).

[0310] At step 850f, the SMSF (842) within the satellite (Satellite #2) may transmit a Nudm_UECM_Registration message including terminal information currently connected to the satellite within the ground base station to the UDM (890). The Nudm_UECM_Registration message may include satellite-related information such as a satellite ID, SUPI, SMSF identity, SMSF address, Access Type(s) information, etc.

[0311] In step 850f, if updated information (e.g., satellite-related information such as a new satellite ID and information on NFs within the satellite) supporting the corresponding terminal (SUPI) is transmitted, the existing satellite (Satellite #1) information is deleted, and the UDM can perform an operation to update the terminal-related information based on the information in the Nudm_UECM_Registration message transmitted from the new satellite (Satellite #2). The UDM can receive the NF (AMF, SMSF, etc.) information (e.g., id or IP address) within the satellite supporting the terminal directly from the satellite, or can obtain the NF (AMF, SMSF, etc.) information (e.g., IP address) within the satellite supporting the terminal based on the information provided by the satellite network operator by receiving the satellite ID or AMF ID, etc. from the AMF of the satellite, and store the information in the UDM.

[0312] At step 851, SC (880) may forward an MT SMS message to SMS-GMSC (870).

[0313] In step 852, SMS-GMSC (870) can request the address of the message server (SMSF) to which the MT SMS will be forwarded to UDM (890) via the Nudm_UECM_SendRoutingInfoForSM message. UDM (890) can forward the address of the message server to which the terminal is connected (the address of SMSF on board / Satellite (e.g. IP address)) to SMS-GSMC (870) based on SUPI information, etc. in the request message.

[0314] At step 853, SMS-GMSC (870) can receive status information on the connection (Feederlink) with the satellite based on the address of the MT SMS forwarding message server (SMSF) received from the UDM and the satellite information from the entity managing the mobility of the satellite. If the satellite (Satellite #1 or Satellite #2) on which the terminal is being serviced and the ground station are connected (Feederlink), SMS-GMSC can transmit the MT SMS message to the terminal (800) through the procedures from step 803c to step 807b of FIGS. 8a and 8b.

[0315] If, in step 853, SMS-GMSC (870) checks the status information of the connection (Feederlink) with the satellite based on the address of the message server to deliver the MT SMS received from the HSS from the entity managing the mobility of the satellite and the satellite information, and the connection (Feederlink) between the satellite and the ground station is not established, SMS-GMSC (870) determines that the status is “UE is not reachable” and generates the corresponding Cause information and transmits the information to the UDM, and then decides to perform a Failure report operation to the SC.

[0316] In steps 854 and 855, if the SMS-GMSC (870) is unable to connect to the satellite received from the UDM (890) in step 853, the SMS-GMSC (870) may transmit to the UDM (890) that the MT-SMS message was not delivered through the Nudm_ReportSMDeliveryStatus_Request message. The SMS-GMSC (870) may transmit to the UDM (890) the Nudm_ReportSMDeliveryStatus_Request message including the User Identifier, the SM Delivery Outcome including the error cause (Absent User or UE is not reachable) information, and the SC address (Service Center Address).

[0317] At step 856, SMS-GMSC (870) may notify SC (880) that the MT SMS message delivery of a specific user has failed through a Failure Report operation.

[0318] In steps 857 and 858, SMS-GMSC (870) may forward a specific UE-related event notification subscription request to UDM (890) via Nudm_EventExposure_Subscribe message to be notified of the information when the terminal becomes reachable to SMS (i.e., when the terminal is connected to AMF while SMSF is actually registered or when the terminal is registered to SMSF).

[0319] In steps 859 and 860, when a specific terminal (UE#1) performs a network registration procedure via a satellite as in steps 850a to 850f, the AMF and SMSF can receive satellite information, etc. to which the terminal (UE#1) is connected, via the Nudm_UECM_Registration message to the UDM. In steps 857 and 858, the UDM (890) can transmit a notification (UE_REACHABILITY_FOR_SMS) of a subscription event by the specific terminal (UE#1) to the SMS-GMSC (870) via the Nudm_EventExposure_Notify message.

[0320] SMS-GMSC (870), which has been notified that UE#1 is connected in step 861, may forward this to SC (880) to request a retransmission operation of the MT SMS message related to UE#1 that has been put on hold. Thereafter, MT SMS transmission operation using a satellite may be performed to UE#1 through steps 801 to 807b of FIGS. 8a and 8b.

[0321]

[0322] FIG. 9 is a diagram illustrating the structure of a terminal according to one embodiment of the present invention.

[0323] Referring to FIG. 9, the terminal may include a transceiver (905), a control unit (910), and a storage unit (915). In the present invention, the control unit may be defined as a circuit or an application-specific integrated circuit or at least one processor.

[0324] The transceiver (905) can transmit and receive signals with other network entities. The transceiver (905) can receive system information from a base station, for example, and can receive a synchronization signal or a reference signal.

[0325] The control unit (910) can control the overall operation of a network entity according to an embodiment proposed in the present invention. For example, the control unit (910) can control the signal flow between each block to perform operations according to the flowchart described above. Specifically, the control unit (910) can control the operations proposed in the present invention to transmit signals in a multi-beam-based system according to an embodiment of the present invention.

[0326] The storage unit (915) can store at least one of the information transmitted and received through the transmission and reception unit (905) and the information generated through the control unit (910).

[0327]

[0328] FIG. 10 is a diagram illustrating the structure of a network entity according to one embodiment of the present invention.

[0329] Referring to FIG. 10, a network entity may include a transceiver (1005), a control unit (1010), and a storage unit (1015). In the present invention, the control unit may be defined as a circuit or an application-specific integrated circuit or at least one processor.

[0330] The transceiver (1005) can transmit and receive signals with other network entities. For example, the transceiver (1005) can transmit system information to a terminal and transmit a synchronization signal or a reference signal.

[0331] The control unit (1010) can control the overall operation of a network entity according to an embodiment proposed in the present invention. For example, the control unit (1010) can control the signal flow between each block to perform operations according to the flowchart described above. Specifically, the control unit (1010) can control the operations proposed in the present invention to transmit signals in a multi-beam-based system according to an embodiment of the present invention.

[0332] The storage unit (1015) can store at least one of the information transmitted and received through the transmission and reception unit (1005) and the information generated through the control unit (1010).

[0333]

[0334] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0335] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs may include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of the present disclosure.

[0336] These programs (software modules, software) may be stored in a non-volatile memory including random access memory, flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc ROMs (CD-ROMs), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in a memory configured as a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0337] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

[0338] In the specific embodiments of the present disclosure described above, components included in the present disclosure are expressed in the singular or plural form, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in the plural form may be composed of singular elements, or components expressed in the singular form may be composed of plural elements.

[0339] While the detailed description of the disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be defined not only by the scope of the claims described below, but also by equivalents thereof.

Claims

1. In a method performed in a first MME (Mobility Management Entity) in a wireless communication system, A step of receiving an UL (Uplink) NAS (Non-Access-Stratum) Transport message including a MO (Mobile Oriented) SMS (short message service) from a user equipment (UE); When there is no connection to the feeder link, a step of transmitting a DL (downlink) NAS Transport message including information indicating whether the MO SMS has been received to the UE; and When the above feeder link is connected, the step of transmitting the MO SMS to the second MME is included. A method, characterized in that the first MME and the second MME are separated.

2. In paragraph 1, The above first MME is located on a satellite, and A method, characterized in that the second MME is located in a ground base station.

3. In paragraph 1, A method characterized in that it further includes a step of buffering the MO SMS transmission for a predetermined time when there is no connection to the feeder link.

4. In paragraph 1, A method characterized in that it further includes a step of storing the MO SMS when there is no connection of the feeder link.

5. In a method performed in a user equipment (UE) in a wireless communication system, A step of transmitting an UL (Uplink) NAS (Non-Access-Stratum) Transport message including a MO (Mobile Oriented) SMS (short message service) to a first MME (Mobility Management Entity); and In the case where there is no connection to the feeder link, a step of receiving a DL (downlink) NAS Transport message including information indicating whether the MO SMS has been received from the first MME is included. When the above feeder link is connected, the MO SMS is transmitted from the first MME to the second MME, and A method, characterized in that the first MME and the second MME are separated.

6. In paragraph 5, The above first MME is located on a satellite, and A method, characterized in that the second MME is located in a ground base station.

7. In paragraph 5, A method characterized in that, when there is no connection to the feeder link, the MO SMS transmission is buffered for a predetermined amount of time.

8. In paragraph 5, A method characterized in that the MO SMS is stored when there is no connection to the feeder link.

9. In the first MME (Mobility Management Entity) in a wireless communication system, A transceiver capable of transmitting and receiving at least one signal; and Including a control unit coupled with the above transmitter and receiver, The above control unit: Receive an UL (Uplink) NAS (Non-Access-Stratum) Transport message containing a MO (Mobile Oriented) SMS (short message service) from a user equipment (UE), If there is no connection to the feeder link, a DL (downlink) NAS Transport message including information indicating whether the MO SMS has been received is transmitted to the UE, and / if the feeder link is connected, the MO SMS is transmitted to the second MME. A first MME, characterized in that the first MME and the second MME are separated.

10. In paragraph 9, The above first MME is located on a satellite, and The first MME, characterized in that the second MME is located at a ground base station.

11. In paragraph 9, A first MME, characterized in that it is further configured to buffer the MO SMS transmission for a predetermined time when there is no connection to the feeder link.

12. In paragraph 9, A first MME, characterized in that it is further configured to store the MO SMS when there is no connection to the feeder link.

13. In a wireless communication system, in a user equipment (UE), A transceiver capable of transmitting and receiving at least one signal; and Including a control unit coupled with the above transmitter and receiver, The above control unit: As the first MME (Mobility Management Entity), it transmits an UL (Uplink) NAS (Non-Access-Stratum) Transport message containing a MO (Mobile Oriented) SMS (short message service), and When there is no connection to the feeder link, it is configured to receive a DL (downlink) NAS Transport message including information indicating whether the MO SMS has been received from the first MME, When the above feeder link is connected, the MO SMS is transmitted from the first MME to the second MME, and A user device, characterized in that the first MME and the second MME are separated.

14. In paragraph 13, The above first MME is located on a satellite, and A user device, characterized in that the second MME is located in a ground base station.

15. In paragraph 13, If there is no connection to the above feeder link, The above MO SMS transmission is buffered for a predetermined amount of time, and A user device characterized in that the above MO SMS is stored.

Images