Method and device for supporting terminal movement in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method performed by a terminal in a wireless communication system may comprise the steps of: receiving, from an access and mobility management function (AMF) entity associated with a first radio access technology (RAT), a detach request message including at least one of information indicating that the first RAT is disabled, information indicating that a second RAT is available, and timer information associated with re-registration based on the first RAT; performing an operation of registering in a network on the basis of the second RAT; transmitting a registration request message to the AMF entity; and receiving a registration accept message from the AMF entity.

Description

Method and device for supporting terminal movement in a wireless communication system

[0001] The present disclosure relates to a method and device for supporting terminal mobility when a terminal moves in a wireless 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 wireless interface architecture / protocols is in progress for technologies such as intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) that 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 random access (2-step RACH for NR) that simplifies random access procedures. Standardization is also in progress for system architecture / services such as 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal.

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will 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 one embodiment of the present disclosure, a method performed by a terminal in a wireless communication system may include the steps of: receiving a detach request message from an access and mobility management function (AMF) entity associated with a first radio access technology (RAT), the detach request message including at least one of information indicating that the first RAT is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT; performing an operation of registering with a network based on the second RAT; transmitting a registration request message to the AMF entity; and receiving a registration accept message from the AMF entity.

[0009] In one embodiment of the present disclosure, the method performed by a terminal in a wireless communication system may further include a step of starting a timer based on the timer information. In one embodiment of the present disclosure, the step of transmitting a registration request message to the AMF entity may include a step of transmitting the registration request message to the AMF entity based on the expiration of the timer.

[0010] In one embodiment of the present disclosure, the registration request message may include information indicating activation of the first RAT.

[0011] In one embodiment of the present disclosure, the registration acceptance message may include information indicating that registration based on the first RAT is possible.

[0012] In one embodiment of the present disclosure, a method performed by an access and mobility management function (AMF) entity in a wireless communication system may include the steps of: transmitting a detach request message to a terminal, the detach request message including at least one of information indicating that a first radio access technology (RAT) is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT; receiving a registration request message from the terminal registered in a network based on the second RAT; and transmitting a registration accept message to the terminal.

[0013] In one embodiment of the present disclosure, the step of receiving a registration request message from the terminal may include the step of receiving the registration request message from the terminal starting a timer based on the timer information, based on the expiration of the timer.

[0014] In one embodiment of the present disclosure, the registration request message may include information indicating activation of the first RAT.

[0015] In one embodiment of the present disclosure, the registration acceptance message may include information indicating that registration based on the first RAT is possible.

[0016] In one embodiment of the present disclosure, a terminal in a wireless communication system may include at least one transceiver; at least one processor connected to the at least one transceiver; and a memory connected to the at least one processor and storing instructions. In one embodiment of the present disclosure, when the at least one processor executes the instructions, the terminal may receive a detach request message from an access and mobility management function (AMF) entity associated with a first radio access technology (RAT), the detach request message including at least one of information indicating that the first RAT is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT, perform an operation of registering with a network based on the second RAT, transmit a registration request message to the AMF entity, and receive a registration acceptance message from the AMF entity.

[0017] In one embodiment of the present disclosure, when the at least one processor executes the instruction, the terminal can start a timer based on the timer information, and transmit the registration request message to the AMF entity based on expiration of the timer.

[0018] In one embodiment of the present disclosure, the registration request message may include information indicating activation of the first RAT.

[0019] In one embodiment of the present disclosure, the registration acceptance message may include information indicating that registration based on the first RAT is possible.

[0020] In one embodiment of the present disclosure, an access and mobility management function (AMF) entity in a wireless communication system may include at least one transceiver; at least one processor connected to the at least one transceiver; and a memory connected to the at least one processor and storing instructions. In one embodiment of the present disclosure, when the at least one processor executes the instructions, the AMF entity may transmit a detach request message to a terminal, the detach request message including at least one of information indicating that a first radio access technology (RAT) is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT, receive a registration request message from the terminal registered in a network based on the second RAT, and transmit a registration acceptance message to the terminal.

[0021] In one embodiment of the present disclosure, the at least one processor executes the instruction so that the AMF entity can receive the registration request message from the terminal that starts a timer based on the timer information, based on the expiration of the timer.

[0022] In one embodiment of the present disclosure, the registration request message may include information indicating activation of the first RAT. In one embodiment of the present disclosure, the registration acceptance message may include information indicating that registration based on the first RAT is possible.

[0023] In a given area, a large number of terminals can degrade the Quality of Service (QoS) or cause network congestion. Furthermore, this can result in service outages or excessive signaling load until the terminal selects a different network. According to one embodiment of the present disclosure, a method can be provided that efficiently supports terminal mobility while resolving service outages or signaling overload.

[0024] FIG. 1 illustrates an embodiment of a terminal and network environment for supporting terminal mobility in a 5G network according to one embodiment of the present disclosure.

[0025] FIG. 2 is a flowchart illustrating a procedure for supporting terminal mobility in a 5G network according to one embodiment of the present disclosure.

[0026] FIG. 3 is a flowchart illustrating a procedure for supporting terminal mobility in a 5G network according to one embodiment of the present disclosure.

[0027] FIG. 4 is a flowchart illustrating a procedure for supporting terminal mobility in a 5G network according to one embodiment of the present disclosure.

[0028] FIG. 5 is a diagram showing the configuration of a terminal according to one embodiment of the present disclosure.

[0029] FIG. 6 is a diagram illustrating a configuration of a network entity according to one embodiment of the present disclosure.

[0030] FIG. 7 is a flowchart illustrating an example of a method performed by a terminal in a wireless communication system according to one embodiment of the present disclosure.

[0031] FIG. 8 is a flowchart illustrating an example of a method performed by an AMF entity in a wireless communication system according to one embodiment of the present disclosure.

[0032] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. In describing the embodiments, descriptions of technical details that are well-known in the technical field to which the present disclosure pertains and are not directly related to the present disclosure will be omitted. This is to avoid obscuring the gist of the present disclosure by omitting unnecessary explanations and to convey the gist more clearly.

[0033] 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. In each drawing, identical or corresponding components are assigned the same or different reference numbers.

[0034] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present disclosure is complete and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Like reference numerals designate like elements throughout the specification. In addition, when describing the present disclosure, if a specific description of a related function or configuration is determined to unnecessarily obscure the gist of the present disclosure, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of the functions of the present disclosure, and these may vary depending on the intention or custom of the user or operator. Therefore, their definitions should be made based on the contents throughout the specification.

[0035] In the present disclosure, it will be appreciated that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed based on computer program instructions. These computer program instructions can be selectively installed in at least one processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by any one or any combination of at least one processor of the computer or other programmable data processing equipment create 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 an article of manufacture that includes 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).

[0036] 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.

[0037] The term '~ unit' used in the embodiments of the present disclosure means a software or hardware component such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), and the '~ unit' performs certain roles. However, terms including '~ unit' are not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Thus, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, the components and '~parts' may be implemented to play one or more central processing units (CPUs) within the device or secure multimedia card. Also, in an embodiment, the '~parts' may include one or more processors.

[0038] As described above, it should be noted that the blocks and combinations of flowcharts described in the present disclosure may be implemented by one or more computer programs containing instructions. One or more computer programs may be stored entirely in a single memory device, or one or more computer programs may be divided and stored in different portions across multiple memory devices.

[0039] Additionally, any / any function or operation described in the present disclosure may be processed by a single processor or a combination of processors. The single processor or the combination of processors may include circuitry that performs processing, such as an application processor (AP, e.g., a central processing unit (CPU)), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a Wi-Fi chip, a Bluetooth® chip, a global positioning system (GPS) chip, a near-field communication (NFC) chip, a connectivity chip, a sensor controller, a touch controller, a fingerprint sensor controller, a display driver integrated circuit (IC), an audio codec (CODEC) chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a microprocessor unit (MPU), a system on a chip (SoC), an IC, or similar circuitry.

[0040] It should also be noted that the various embodiments in the claims and description of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0041] Such software may be stored on a non-transitory computer-readable storage medium. The non-transitory computer-readable storage medium stores one or more computer programs (software modules), wherein the one or more computer programs include computer-executable instructions that, when executed alone or collectively by one or more processors of an electronic device, cause the electronic device to perform a method according to the present disclosure.

[0042] The software may be stored in a temporary or non-transitory storage device, for example, in the form of a read-only memory (ROM) (whether erasable or rewritable), a random access memory (RAM), a memory chip, a device, or an integrated circuit (IC). The software may also be stored in an optically or magnetically readable medium, for example, a compact disc (CD), a digital versatile disc (DVD), a magnetic disk, or a magnetic tape. It should be understood that the storage device and the storage medium are examples of non-transitory machine-readable storage media suitable for storing a program for implementing various embodiments of the present disclosure. Accordingly, various embodiments of the present disclosure may provide a program comprising code for implementing a device or method according to any one of the claims of the present specification, and a non-transitory machine-readable storage medium storing such a program.

[0043] In the present disclosure, determining the priority between A and B may be referred to in various ways, such as selecting a higher priority according to a predetermined priority rule and performing an action corresponding to it, or omitting or dropping an action for a lower priority.

[0044] Hereinafter, 'A or B' described in the present disclosure may be understood as 'A and / or B', which may be understood to include 'A', or 'B', or 'A and B'.

[0045] Additionally, 'at least one of A, B, and C' described in the present disclosure may be understood to include 'A', or 'B', or 'C', or 'any combination of A, B, and C'.

[0046] Additionally, 'at least one of A, B, or C' described in the present disclosure may be understood to include 'A', or 'B', or 'C', or 'any combination of A, B, and C'.

[0047] Additionally, 'A / B' described in the present disclosure may be understood as 'A and / or B', which may be understood to include 'A', or 'B', or 'A and B'.

[0048] Additionally, 'A, B' described in the present disclosure may be understood as 'A and / or B', which may be understood to include 'A', or 'B', or 'A and B'.

[0049] Additionally, 'A and B' described in the present disclosure may be understood as 'A and / or B', which may be understood to include 'A', or 'B', or 'A and B'.

[0050] In addition, it can be understood that the 'case where conditions A and B are satisfied' described in the present disclosure is not necessarily limited to the case where both conditions A and B are satisfied, but may include the case where each of conditions A or B is satisfied, the case where both conditions A and B are satisfied, or the case where one or more additional conditions are satisfied together.

[0051] Additionally, throughout this specification, ordinal terms such as "first," "second," "third," and the like (and modifiers thereof) are used solely to distinguish between various instances, occurrences, configurations, messages, stages, or aspects of elements, operations, or information, as described below. Unless the context clearly requires otherwise, the use of such ordinal terms does not require that the elements, operations, or information distinguished by them be structurally, numerically, or inherently different. For example, "a first signal" and "a second signal" may represent instances of the same signal transmitted at different times, may represent signals containing the same core information albeit with some modifications, or may represent signals having different content or characteristics depending on the specific context. Similarly, "a first value" and "a second value" may represent measurements or applications of the same magnitude in different circumstances, or may represent different magnitudes. Such interpretation should be determined by the specific technical context, functions and relationships described in the relevant portions of the specification and claims.

[0052] Furthermore, although terms such as "first" and "second" described in this disclosure are used to refer to various elements such as information, objects, actions, and sequences, they are not intended to limit such elements to a specific order. These terms may be understood to be used merely to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0053] Additionally, it may be understood that the terms "first~" and "second~" described in this disclosure may refer to the same or different elements. For example, if the elements are information, the first information and the second information may both be information, and in some cases, they may be the same information or different information.

[0054] In addition, the expressions "if" and "in case that" described in the present disclosure or claims may be interpreted to mean "when or upon," "in response to," or "based on," or "according to," depending on the context, and these expressions may be used interchangeably. In addition, in addition to these expressions, other expressions having substantially the same meaning may be used interchangeably, within the scope that does not impair the technical features of the present disclosure.

[0055] Additionally, the term "not perform" as used in this disclosure or claims may be understood to mean omitting or skipping a step, depending on the context. Such terms may be replaced with other terms having the same or substantially similar meaning.

[0056] Additionally, "transmitting a message including A and B" as described herein may be interpreted to include both (i) cases where A and B are transmitted in a single message, as well as (ii) cases where A and B are transmitted individually via multiple messages (e.g., transmitting a first message including A and a second message including B). This interpretation may also apply when a message including two or more items, such as A, B, and C, is transmitted together or individually.

[0057] Additionally, 'sending a message containing A and sending a message containing B' can also be interpreted as sending a single message containing A and B.

[0058] In the specific embodiments of the present disclosure described below, terms or components included in the disclosure will be expressed in the singular or plural, 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 may be composed of singular elements, or components expressed in the singular may be composed of plural elements.

[0059] The drawings or flowcharts described below illustrate exemplary methods that may be implemented according to the principles of the present disclosure, and various modifications may be made to the methods depicted in the flowcharts of the present disclosure. For example, although depicted as a series of steps, various steps in each drawing or flowchart may overlap, occur in parallel, occur in different orders, or occur multiple times. In other instances, any step may be omitted or replaced with another step.

[0060] The methods and devices proposed in the embodiments of the present disclosure are not limited to each embodiment, and may be utilized as a combination of one or more embodiments, all or part of the embodiments proposed in the disclosure. Accordingly, the embodiments of the present disclosure may be applied with some modifications within a scope that does not significantly deviate from the scope of the present disclosure, as determined by a person skilled in the art.

[0061] In this case, even if any wording is mentioned in different embodiments, if the concepts correspond, they may be used interchangeably, combined, or substituted. For example, for identical or corresponding concepts, even if one embodiment uses the expression "A" and another embodiment uses the expression "B," these may be understood interchangeably, substituted, or combined.

[0062] In the following description, terms used to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc. are examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used. In addition, the terms may be replaced with terms defined in the 3rd generation partnership project (3GPP) Technical Specifications (TS), if appropriate.

[0063] Hereinafter, the base station 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, a BS (base station), a radio access unit, a base station controller, or a node on a network. In addition, the base station of the present disclosure may include a structure that is split into a central unit (CU) and a distributed unit (DU). In this structure, the CU is responsible for the upper layers of the control and user planes, and the DU is responsible for radio resource processing of the lower layers. The embodiments of the present disclosure can be equally applied to a 5G base station structure in which functions are separated into the CU and DU.

[0064] The terminal may include a UE (user equipment), MS (mobile station), cellular phone, smartphone, computer, or multimedia system capable of performing communication functions.

[0065] In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station.

[0066] In addition, although the fifth generation mobile communication system (5G, new radio, NR) and the sixth generation mobile communication system (6G) may be described below as examples, the 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 new evolved mobile communication systems developed after 5G and 6G. In addition, the present disclosure may be applied to other communication systems (e.g., Wi-Fi 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.

[0067] In the following description, the terms "physical channel" and "signal" may be used interchangeably with data or control signals. For example, while PDSCH (physical downlink shared channel) refers to a physical channel through which data is transmitted, PDSCH may also be used to refer to data. That is, in the present disclosure, the expression "transmitting a physical channel" may be interpreted equivalently to the expression "transmitting data or a signal through a physical channel."

[0068] In the following description of the present disclosure, upper layer signaling may be signaling corresponding to at least one or a combination of one or more of MIB (master information block), SIB (system information block), SIB M (M=1, 2, …), RRC (radio resource control), MAC (medium access control) CE (control element), NAS (non-access stratum) signaling, or application layer messages. The RRC signaling may also be referred to as L3 signaling (layer 3 signaling).

[0069] In addition, L1 signaling may be signaling corresponding to at least one or a combination of one or more signaling methods using a physical layer channel or signaling of PDCCH (physical downlink control channel), DCI (downlink control information), UE-specific DCI, group common DCI, common DCI, scheduling DCI (e.g., DCI used for the purpose of scheduling downlink or uplink data), non-scheduling DCI (e.g., DCI not for the purpose of scheduling downlink or uplink data), physical uplink control channel (PUCCH), or uplink control information (UCI). The L1 signaling may also be referred to as physical layer signaling.

[0070] Hereinafter, the expression that information can be configured from a base station in the present disclosure or claims may mean that a terminal receives the information from the base station through physical layer signaling or upper layer signaling, depending on the context, and such expression may be replaced with other terms having the same or substantially similar meaning.

[0071] The operating principle of the present disclosure is described in detail with reference to the attached drawings below.

[0072] To meet the growing demand for wireless data traffic following the commercialization of 4G communication systems, efforts are being made to develop improved 5G or pre-5G communication systems. For this reason, 5G or pre-5G communication systems are also referred to as "Beyond 4G Network" or "Post-LTE" systems. The 5G communication system specified by 3GPP is called the New Radio (NR) system. To achieve high data rates, 5G communication systems are being considered for implementation in ultra-high frequency (mmWave) bands (e.g., the 60 GHz band). To mitigate the path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, and large-scale antenna technologies have been discussed and applied to NR systems in 5G communication systems.In addition, to improve the network of the system, technologies such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, moving networks, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation are being developed in 5G communication systems. In addition, advanced coding modulation (ACM) methods such as Hybrid FSK and QAM Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), and advanced access technologies such as Filter Bank Multi Carrier (FBMC), Non-Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA) are being developed in 5G systems.

[0073] For the convenience of explanation below, this disclosure uses terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP) LTE standard, or terms and names modified therefrom. However, this disclosure is not limited to the above-described terms and names, and can be equally applied to systems conforming to other standards. In this disclosure, eNB may be used interchangeably with gNB for the convenience of explanation. That is, a base station described as an eNB may represent a gNB. In this disclosure, the term "terminal" may refer to various wireless communication devices, including mobile phones, NB-IoT devices, and sensors.

[0074] That is, in specifically explaining the embodiments of the present disclosure, the communication standards specified by 3GPP will be the main target, but the main gist of the present disclosure can be applied to other communication systems with similar technical backgrounds with slight modifications within a range that does not significantly deviate from the scope of the present disclosure, and this can be done at the discretion of a person skilled in the technical field of the present disclosure.

[0075] In 5G or NR systems, the Access and Mobility Management Function (AMF), which is the management entity that manages the mobility of terminals, and the Session Management Function (SMF), which is the entity that manages sessions, are separated. Accordingly, unlike in 4G LTE communication systems, where the Mobility Management Entity (MME) performed both mobility management and session management, in 5G or NR systems, the entities that perform mobility management and session management are separated, which has changed the communication method and communication management method between terminals and network entities.

[0076] In 5G or NR systems, mobility management for non-3GPP access is performed through the Non-3GPP Inter-Working Function (N3IWF) and AMF, while session management is performed through the SMF. Furthermore, security-related information, a crucial element in mobility management, is also processed through the AMF.

[0077] As described above, in 4G LTE systems, the MME is responsible for both mobility management and session management. 5G or NR systems can support a non-standalone architecture that utilizes these network entities from the 4G LTE system to perform communications.

[0078] The present disclosure relates to a method for supporting terminal mobility when a terminal moves in a wireless communication system. Conventional techniques do not limit resource usage for user equipment (UE) in roaming areas, which can result in degraded quality of service or network congestion due to roaming users. Furthermore, this can result in service outages or excessive signaling load until the UE selects a different network. One embodiment of the present disclosure relates to a method for supporting terminal mobility when a terminal moves while resolving such service outages and signaling overload.

[0079] In one embodiment of the present disclosure, a method can be provided to efficiently support terminal mobility while resolving service outages and signaling overload when the terminal moves. For example, a large number of terminals in a certain area can degrade the quality of service or cause network congestion. Furthermore, this can result in service outages or excessive signaling load until the terminal selects a different network. According to one embodiment of the present disclosure, the problems of terminals not receiving service or signaling overhead can be resolved.

[0080] FIG. 1 illustrates a first embodiment of a terminal and a network environment for communication with improved communication performance in a 5G network according to one embodiment of the present disclosure.

[0081] Referring to FIG. 1, a 5G or NR core network may be composed of network functions (NFs) such as a User Plane Function (UPF, 131), a Session Management Function (SMF, 121), an Access and Mobility Management Function (AMF, 111), a 5G Radio Access Network (RAN, 103), a User Data Management (UDM, 151), and a Policy Control Function (PCF, 161). In addition, for authentication of these entities, entities such as an Authentication Server Function (AUSF, 141) and an authentication, authorization, and accounting (AAA, 171) may be included. A User Equipment (UE, Terminal) may access a 5G core network through a base station (5G RAN, Radio Access Network, base station, BS, 103). Meanwhile, for cases where UE communicates via non-3GPP access, N3IWF (N3 interworking function) exists, and in case of non-3GPP access, session management is controlled by UE, non-3GPP access, N3IWF, and SMF, and mobility management can be controlled by UE, non-3GPP access, N3IWF, and AMF.

[0082] In a 5G or NR system, entities that perform mobility management and session management are separated into AMF (111) and SMF (121). Meanwhile, a stand-alone deployment structure that performs communication only with 5G or NR entities and a non-stand-alone deployment structure that uses 4G entities and 5G or NR entities together are being considered for the 5G or NR system.

[0083] As illustrated in Figure 1, a deployment in which control is performed by the eNB when the UE communicates with the network and a 5G entity of the core network is used may be possible. In this case, mobility management between the UE and the AMF and session management between the UE and the SMF may be performed in the NAS (Non Access Stratum) layer, which is layer 3.

[0084] The communication network on which the present disclosure is based assumes a 5G or 4G LTE network, but if the same concept can be applied to other systems within a range that can be understood by a person having ordinary technical skills, one or more embodiments of the present disclosure can be applied to other systems as well.

[0085] Referring to Figure 1, a terminal can roam from one network to another. A method for supporting terminal movement while preventing service interruption or overhead is described with reference to the following diagram.

[0086] Referring to FIG. 1, a UE can move from a home network, network A, to a visited network, region B or C. Furthermore, the UE can register in a network with an AMF (111-3) in the visited network, and then change the radio network to register in AMF (111-5). Alternatively, the UE can register in a 5G network with an AMF (113-3) in the visited network, and then change the RAT to attach to a 4G network. Specific examples will be described with reference to FIGS. 2 to 4.

[0087] FIG. 2 is a flowchart illustrating a communication procedure for supporting terminal mobility in a 5G network according to one embodiment of the present disclosure.

[0088] FIG. 2 is a diagram illustrating an embodiment in which, in order to prevent a terminal from being unable to receive a service or from incurring overhead, a network transmits to a UE the information necessary for connecting to another RAT / network, etc., so that the terminal can connect to another RAT / network, and the UE changes the network using the information and connects.

[0089] Referring to FIG. 2, a UE can attach from a home network to a visited network. In one embodiment of the present disclosure, the UE can attach from a visited network to a 4G network, C network, based on information received from a home network, A network.

[0090] In one embodiment of the present disclosure, referring to FIG. 2, a UE may attempt to register from a visited network to a 5G network, but may change the RAT and attach to a 4G network. For example, a UE may register from a visited network to a 5G network with an AMF (113-3) and then change the RAT to attach to a 4G network.

[0091] At step 201, the UE may send a registration request message to AMF.

[0092] At step 205, the AMF may send a registration reject message to the UE.

[0093] At this time, the network can transmit to the UE information on available RATs, information on disabled RATs, and Change-RAT information to change the RAT and connect.

[0094] For example, the information transmitted may include:

[0095] - disable-RAT information may be transmitted. For example, disable-RAT information may indicate that the RAT is disabled and cannot be used.

[0096] - Possible RAT information may be transmitted. For example, possible RAT information may be information indicating that the UE can register using the corresponding RAT.

[0097] - Change-RAT information may be transmitted. In one embodiment, the change-RAT information may include information indicating a change in RAT. In one embodiment, the change-RAT information may include information on the RAT to which the UE must change and attach or register.

[0098] At step 211, the UE may store the information.

[0099] For example, the information stored may include:

[0100] - disable-RAT information may be stored. For example, disable-RAT information may indicate that the RAT is disabled and cannot be used.

[0101] - Possible RAT information may be stored. For example, possible RAT information may be information indicating that the UE can register using the corresponding RAT.

[0102] - Change-RAT information may be stored. In one embodiment, the change-RAT information may include information indicating a change in RAT. In one embodiment, the change-RAT information may include information on the RAT to which the UE must change and attach or register.

[0103] If registration fails, the UE can change the network to perform registration or attachment. For example, the UE can use this information to change the RAT / network and attempt connection.

[0104] For example, a UE may attempt to connect by changing the network from a 5G network to a 4G network.

[0105] In the following, an example may be described in which a UE attempts to connect by changing the network from a 5G to a 4G network.

[0106] At step 212, the UE may send an attach request message to the MME.

[0107] At step 213, the UE may send an attach accept message to the MME.

[0108] For example, the information transmitted may include:

[0109] - Possible RAT information may be transmitted. For example, possible RAT information may be information indicating that the UE can register using the corresponding RAT.

[0110] FIG. 3 is a flowchart illustrating a communication procedure for supporting terminal mobility in a 5G network according to one embodiment of the present disclosure.

[0111] According to one embodiment of the present disclosure, a network transmits information available to a terminal while forcibly detaching the terminal in order to limit resources used by the terminal or to limit resources of the terminal when the subscription of the terminal is changed, and the terminal can register in an available RAT after detaching from the network.

[0112] Referring to FIG. 3, a UE can register from a home network to a visited network. In one embodiment of the present disclosure, the UE can register from a visited network to a 5G network, network B, based on information received from a home network, network A.

[0113] In one embodiment of the present disclosure, referring to FIG. 3, a UE can register from a visited network to another visited network. For example, a UE may attempt to register in a 5G network but change the RAT to register in a different 5G network. A UE may also register in a network with an AMF (111-3) in a visited network and then change the radio network to register in an AMF (111-5).

[0114] Figure 3 can show an example in which information about a disabled RAT is transmitted through a detach request, and registration with another RAT is performed because registration with the RAT is not possible.

[0115] In step 301, the UE may send a registration request message to AMF.

[0116] At step 305, the AMF may send a registration accept message to the UE.

[0117] At step 311, the UE may send a PDU session establishment request message to the AMF.

[0118] At step 313, the AMF may send a PDU session establishment accept message to the UE.

[0119] At step 321, the AMF may make a decision. For example, the AMF may decide whether to detach the UE.

[0120] At step 331, the AMF may send a detach request message to the UE.

[0121] The network may limit the resources used by the terminal, or may forcibly detach the terminal to limit the terminal's resources when the terminal's subscription changes.

[0122] The network can send information such as disabled RAT information and available RAT information to the terminal when detaching the terminal.

[0123] For example, the information transmitted may include:

[0124] - disable-RAT information may be transmitted. For example, disable-RAT information may include information that the RAT is disabled and cannot be used.

[0125] - Possible RAT information may be transmitted. For example, the possible RAT information may include information indicating that the UE can register using the corresponding RAT.

[0126] At step 335, the UE may send a detach accept message to AMF.

[0127] At step 351, the UE stores the information.

[0128] For example, the information stored at this time may include:

[0129] - disable-RAT information may be stored. For example, disable-RAT information may include information that the RAT is disabled and cannot be used.

[0130] - Possible RAT information may be stored. For example, the possible RAT information may include information indicating that the UE can register using the corresponding RAT.

[0131] After the UE detaches from the network, it can register with the network using the information of the registerable RAT.

[0132] For example, a UE may attempt to register to a registerable network using possible RAT information.

[0133] In one embodiment of the present disclosure, the UE may then select and connect to another 5G RAT.

[0134] To this end, at step 361, the UE may send a registration request message to the AMF.

[0135] At this time, the UE can attempt registration with the AMF via the RAT using possible RAT information by sending a registration request message.

[0136] At step 363, the AMF may send a registration accept message to the UE.

[0137] For example, the information transmitted at this time may include:

[0138] - Possible RAT information may be transmitted. For example, the possible RAT information may include information indicating that the UE can register using the corresponding RAT.

[0139] FIG. 4 is a flowchart illustrating a communication procedure for supporting terminal mobility in a 5G network according to one embodiment of the present disclosure.

[0140] According to one embodiment of the present disclosure, a network may transmit information available to a terminal while forcibly detaching the terminal in order to limit the resources used by the terminal or to limit the resources of the terminal when the subscription of the terminal is changed.

[0141] At this time, according to one embodiment, the network may transmit to the terminal timer information that the disabled RAT is activated so that the terminal can register.

[0142] Afterwards, the terminal can detach from the network and register with an available RAT. In one embodiment, if the terminal can connect to the RAT after a certain period of time, the terminal can set an active timer to connect to the RAT.

[0143] Referring to FIG. 4, a UE can register from a home network to a visited network. In one embodiment of the present disclosure, the UE can register from a visited network to a 5G network, network B, based on information received from a home network, network A.

[0144] In one embodiment of the present disclosure, referring to FIG. 4, a UE can register from a visited network to another visited network. For example, a UE may attempt to register in a 5G network but change the RAT to register in a different 5G network. A UE may also register in a network with an AMF (111-3) in a visited network and then change the radio network to register in an AMF (111-5).

[0145] FIG. 4 illustrates an embodiment in which information about a disabled RAT is transmitted via a detach request, and registration with another RAT is performed as registration with the RAT is not possible. FIG. 4 also illustrates an embodiment in which registration is performed through the activated RAT when a previously disabled RAT becomes active.

[0146] At step 401, the UE may send a registration request message to AMF.

[0147] At step 405, the AMF may send a registration accept message to the UE.

[0148] At step 411, the UE may send a PDU session establishment request message to the AMF.

[0149] At step 413, the AMF may send a PDU session establishment accept message to the UE.

[0150] At step 421, the AMF may make a decision. For example, the AMF may decide whether to detach the UE.

[0151] At step 431, the AMF may send a detach request message to the UE.

[0152] The network may forcibly detach a terminal to limit the resources used by the terminal, or to limit the terminal's resources when the terminal's subscription changes.

[0153] In one embodiment, if the terminal is able to connect to the network or the RAT after a certain period of time, the network may set a timer to allow the terminal to connect.

[0154] In one embodiment, the network may transmit to the terminal information such as information on a disabled RAT when detaching the terminal, information on an available RAT, a timer for allowing the terminal to connect to the network, or information on an active timer for enabling registration when the RAT is activated.

[0155] For example, the information transmitted at this time may include:

[0156] - Disable-RAT information may be transmitted. For example, disable-RAT information may include information that the RAT is disabled and cannot be used.

[0157] - Possible RAT information may be transmitted. For example, the possible RAT information may include information indicating that the UE can register using the corresponding RAT.

[0158] - Timer-active information may be transmitted. For example, this information may include a timer value that the UE sets to enable re-registration through a disabled RAT with that information.

[0159] At step 433, the timer of timer-active can be started.

[0160] At step 435, the UE may send a detach accept message to AMF.

[0161] Afterwards, the UE can register with AMF using a different RAT.

[0162] To this end, at step 461, the UE may send a registration request message to the AMF.

[0163] At this time, the UE can attempt registration with the AMF via the RAT using possible RAT information by sending a registration request message.

[0164] At step 463, the AMF may send a registration accept message to the UE.

[0165] For example, the information transmitted at this time may include:

[0166] - Possible RAT information may be transmitted. For example, the possible RAT information may include information indicating that the UE can register using the corresponding RAT.

[0167] Afterwards, the value of the timer started in step 433 may expire and the timer may stop. In one embodiment, in step 471, the value of the timer-active timer of the UE may expire and the timer may stop.

[0168] In one embodiment of the present disclosure, after the expiration of a timer indicating that UE connection is possible (e.g., the network is active) for the network or RAT from which the UE was detached, the UE may connect to the RAT that has become accessible. At this time, the UE may transmit an activated indicator to the network to notify that the UE connection to the network or RAT has become active. Alternatively or additionally, the UE may attempt to register to a registerable network using possible RAT information.

[0169] At step 481, the UE may send a registration request message to the AMF.

[0170] For example, the UE can use the possible RAT information to attempt registration with the AMF via that RAT.

[0171] For example, at this time, the registration request message may contain the following information:

[0172] - Activated-disable-RAT information may be transmitted. For example, along with Activated-disable-RAT information, activated information (e.g., an activated indicator) indicating that the RAT has been activated may be transmitted.

[0173] At step 483, the AMF may send a registration accept message to the UE.

[0174] For example, the information transmitted at this time may include:

[0175] - Possible RAT information may be transmitted. For example, the possible RAT information may include information indicating that the UE can register using the corresponding RAT.

[0176] FIG. 5 is a diagram showing the configuration of a terminal according to one embodiment of the present disclosure.

[0177] As illustrated in FIG. 5, the terminal of the present disclosure may include a transceiver (510), a memory (520), and a processor (530). As illustrated in FIG. 5, the processor (530) may be connected to the transceiver (510) or the memory (520). The processor (530), the transceiver (510), and the memory (520) of the terminal may operate according to the communication method of the terminal described above. However, the components of the terminal are not limited to the examples described above. For example, the terminal may include more or fewer components than the components described above. In addition, the processor (530), the transceiver (510), and the memory (520) may be implemented in the form of a single chip.

[0178] The transceiver (510) is a general term for the terminal's receiver and transmitter, and can transmit and receive signals with a base station or network entity. The signals transmitted and received with the base station may include control information and data. To this end, the transceiver (510) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-converts the received signal. However, this is only one embodiment of the transceiver (510), and the components of the transceiver (510) are not limited to the RF transmitter and RF receiver.

[0179] Additionally, the transceiver (510) may include a wired or wireless transceiver and may include various configurations for transmitting and receiving signals.

[0180] In addition, the transceiver (510) can receive a signal through a wireless channel and output it to the processor (530), and transmit the signal output from the processor (530) through the wireless channel.

[0181] In addition, the transceiver (510) can receive a communication signal and output it to the processor, and transmit the signal output from the processor to a network entity via a wired or wireless network.

[0182] The memory (520) can store programs and data necessary for the operation of the terminal. In addition, the memory (520) can store control information or data included in signals obtained from the terminal. The memory (520) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD.

[0183] The processor (530) can control a series of processes so that the terminal can operate according to the embodiments of the present disclosure described above. The processor (530) may include at least one processor. For example, the processor (530) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs.

[0184] FIG. 6 is a diagram illustrating a configuration of a network entity according to one embodiment of the present disclosure.

[0185] As illustrated in FIG. 6, a network entity of the present disclosure may include a transceiver (610), a memory (620), and a processor (630). As illustrated in FIG. 6, the processor (630) may be connected to the transceiver (610) or the memory (620). The processor (630), the transceiver (610), and the memory (620) of the network entity may operate according to the communication method of the network entity described above. However, the components of the network entity are not limited to the examples described above. For example, the network entity may include more or fewer components than the components described above. In addition, the processor (630), the transceiver (610), and the memory (620) may be implemented in the form of a single chip. A network entity may include network functions (NF) such as the Access and Mobility Management Function (AMF), Session Management Function (SMF), Policy and Charging Function (PCF), Network Exposure Function (NEF), Unified Data Management (UDM), and User Plane Function (UPF) described above. It may also include a base station.

[0186] The transceiver (610) is a general term for the receiving unit and the transmitting unit of a network entity, and can transmit and receive signals with a terminal or other network entities. At this time, the transmitted and received signals may include control information and data. To this end, the transceiver (610) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-converts the received signal. However, this is only one embodiment of the transceiver (610), and the components of the transceiver (610) are not limited to the RF transmitter and RF receiver. The transceiver (610) may include wired and wireless transceivers, and may include various configurations for transmitting and receiving signals.

[0187] In addition, the transceiver (610) can receive a signal through a communication channel (e.g., a wireless channel) and output the signal to the processor (630), and transmit the signal output from the processor (630) through the communication channel.

[0188] In addition, the transceiver (610) can receive a communication signal and output it to the processor, and transmit the signal output from the processor to a terminal or network entity via a wired or wireless network.

[0189] The memory (620) can store programs and data required for the operation of the network entity. In addition, the memory (620) can store control information or data included in signals acquired from the network entity. The memory (620) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD.

[0190] The processor (630) may control a series of processes to enable a network entity to operate according to the embodiments of the present disclosure described above. The processor (630) may include at least one processor. 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.

[0191] FIG. 7 is a flowchart illustrating an example of a method performed by a terminal in a wireless communication system according to one embodiment of the present disclosure.

[0192] In step 710, the terminal may receive a detach request message from an access and mobility management function (AMF) entity associated with a first radio access technology (RAT), the detach request message including at least one of information indicating that the first RAT is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT.

[0193] In step 720, the terminal may perform an operation of registering with the network based on the second RAT.

[0194] In step 730, the terminal may transmit a registration request message to the AMF entity. In one embodiment of the present disclosure, the terminal may start a timer based on timer information. In one embodiment of the present disclosure, the terminal may transmit a registration request message to the AMF entity based on the expiration of the timer. In one embodiment of the present disclosure, the registration request message may include information indicating the activation of the first RAT.

[0195] In step 740, the terminal may receive a registration accept message from the AMF entity. In one embodiment of the present disclosure, the registration accept message may include information indicating that first RAT-based registration is possible.

[0196] FIG. 8 is a flowchart illustrating an example of a method performed by an AMF entity in a wireless communication system according to one embodiment of the present disclosure.

[0197] In step 810, the AMF entity may transmit a detach request message to the terminal, the detach request message including at least one of information indicating that the first radio access technology (RAT) is disabled, information indicating that the second RAT is available, or timer information associated with first RAT-based re-registration.

[0198] In step 820, the AMF entity may receive a registration request message from a terminal registered in the network based on the second RAT. In one embodiment of the present disclosure, the AMF entity may receive the registration request message from a terminal that starts a timer based on timer information, based on the expiration of the timer. In one embodiment of the present disclosure, the registration request message may include information indicating the activation of the first RAT.

[0199] In step 830, the AMF entity may transmit a registration accept message to the terminal. In one embodiment of the present disclosure, the registration accept message may include information indicating that first RAT-based registration is possible.

[0200] 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 include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of the present disclosure.

[0201] These programs (software modules, software) may be stored in random access memory, non-volatile memory including 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 memories formed by a combination of some or all of these. In addition, each configuration memory may include multiple copies.

[0202] 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 area network (WAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device performing 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 performing an embodiment of the present disclosure.

[0203] In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed singularly or plurally, 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 plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

[0204] While the detailed description of this disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this 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 by a terminal in a wireless communication system, A step of receiving a detach request message from an access and mobility management function (AMF) entity associated with a first radio access technology (RAT), the detach request message including at least one of information indicating that the first RAT is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT; A step of performing an operation of registering to a network based on the above second RAT; a step of sending a registration request message to the above AMF entity; and A method comprising the step of receiving a registration accept message from the AMF entity.

2. In paragraph 1, Further comprising a step of starting a timer based on the above timer information, The step of sending a registration request message to the above AMF entity is: A method comprising the step of transmitting the registration request message to the AMF entity based on the expiration of the timer.

3. In paragraph 1, A method wherein the registration request message includes information indicating activation of the first RAT.

4. In paragraph 1, A method wherein the registration acceptance message includes information indicating that registration based on the first RAT is possible.

5. In a method performed by an AMF (access and mobility management function) entity in a wireless communication system, A step of transmitting a detach request message to a terminal, the detach request message including at least one of information indicating that a first radio access technology (RAT) is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT; A step of receiving a registration request message from the terminal registered in the network based on the second RAT; and A method comprising the step of transmitting a registration acceptance message to the terminal.

6. In paragraph 5, The step of receiving a registration request message from the above terminal is: A method comprising the step of receiving the registration request message from the terminal starting a timer based on the timer information, based on the expiration of the timer.

7. In paragraph 5, A method wherein the registration request message includes information indicating activation of the first RAT.

8. In paragraph 5, A method wherein the registration acceptance message includes information indicating that registration based on the first RAT is possible.

9. In a terminal in a wireless communication system, At least one transceiver; At least one processor connected to at least one transceiver; and A memory connected to at least one processor and storing instructions, The terminal, by the at least one processor executing the instruction, Receive a detach request message from an access and mobility management function (AMF) entity associated with a first radio access technology (RAT), the detach request message including at least one of information indicating that the first RAT is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT; Performs an operation to register on the network based on the above second RAT, Send a registration request message to the above AMF entity, A terminal that receives a registration acceptance message from the above AMF entity.

10. In paragraph 9, The terminal, by the at least one processor executing the instruction, Start the timer based on the above timer information, A terminal that transmits the registration request message to the AMF entity based on the expiration of the timer.

11. In paragraph 9, The terminal, wherein the registration request message includes information indicating activation of the first RAT.

12. In paragraph 9, The terminal, wherein the registration acceptance message includes information indicating that registration based on the first RAT is possible.

13. In the AMF (access and mobility management function) entity in a wireless communication system, At least one transceiver; At least one processor connected to at least one transceiver; and A memory connected to at least one processor and storing instructions, The AMF entity, by the at least one processor executing the instruction, Transmitting a detach request message to a terminal, the detach request message including at least one of information indicating that a first radio access technology (RAT) is disabled, information indicating that a second RAT is available, or timer information associated with re-registration based on the first RAT; Receive a registration request message from the terminal registered in the network based on the second RAT, An AMF entity that sends a registration acceptance message to the above terminal.

14. In paragraph 13, The AMF entity, by the at least one processor executing the instruction, An AMF entity that receives the registration request message from the terminal that starts the timer based on the timer information, based on the expiration of the timer.

15. In paragraph 13, The above registration request message includes information indicating activation of the first RAT, The above registration acceptance message is an AMF entity that includes information indicating that registration based on the first RAT is possible.

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