Method and apparatus for controlling network access using non-access stratum message in wireless communication system

Abstract

The present disclosure relates to a method and apparatus for controlling network access using a non-access stratum (NAS) message in a wireless communication system. A method performed by a UE in a wireless communication system according to an embodiment of the present disclosure may comprise the steps of: transmitting, through a first base station of a first RAT, a first registration request message to a first network entity for managing the mobility of the UE; receiving, from the first network entity through the first base station, a registration accept message including information related to access to a second RAT for which previous access of the UE has been rejected, in response to the transmission of the first registration request message; and transmitting, through a second base station of the second RAT, a second registration request message to a second network entity for managing the mobility of the UE on the basis of the information related to access to the second RAT.

Description

Method and device for controlling network access using connectionless layer messages in a wireless communication system

[0001] The present disclosure relates to a device and method for controlling network operation 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 a wireless communication system, when network congestion occurs or the user equipment (UE) subscription information changes and the UE cannot use a specific network (e.g., a radio access technology (RAT) such as an LTE network or an NR network), according to the current 3GPP standard definition, the UE reattempts to connect to the network multiple times (e.g., 5 times). In addition, after the UE retries, the network may re-execute the authentication procedure for the UE's network connection, which results in a high signaling load on the network. Therefore, a method is required to resolve the signaling overhead caused by the multiple retries for the UE's network connection and to further optimize network operation.

[0009] The present disclosure provides a method and device for efficiently controlling network access using a non-access stratum (NAS) message in a wireless communication system.

[0010] Additionally, the present disclosure provides a method and device for efficiently processing NAS messages for network access control of a UE in a wireless communication system.

[0011] In a wireless communication system according to an embodiment of the present disclosure, a UE comprises: at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; And at least one memory communicatively coupled to said at least one processor and storing instructions executable individually or in combination by said at least one processor, said instructions causing the UE to transmit, via said at least one transceiver, a first registration request message to a first network entity managing mobility of the UE via a first base station of a first radio access technology (RAT), and in response to transmission of said first registration request message, receive, via said at least one transceiver, a registration acceptance message from the first network entity via the first base station, the registration acceptance message including access-related information to a second RAT to which previous access of the UE was denied, and transmit, via said at least one transceiver, a second registration request message to a second network entity managing mobility of the UE via a second base station of the second RAT based on said access-related information to the second RAT.

[0012] In one embodiment, the access-related information to the second RAT may include at least one of information about at least one disabled RAT that was disabled for access to the UE and is now or will be enabled, and information about at least one enabled RAT that is registered or available for use by the UE.

[0013] In one embodiment, the access-related information to the second RAT further includes timer information required to confirm activation of all or part of the at least one disabled RAT, and the timer information may include at least one timer set for all or part of the at least one disabled RAT.

[0014] In one embodiment, the second RAT is one of the at least one disabled RAT, and the instructions executable individually or in combination by the at least one processor may cause the UE to determine that the second RAT is switched to an enabled RAT when a timer for the second RAT among the at least one timer expires, and to transmit the second registration request message after the timer for the second RAT expires.

[0015] In one embodiment, the instructions executable individually or in combination by the at least one processor may cause the UE to select the second RAT from among the at least one disabled RAT according to a determined priority.

[0016] In one embodiment, the first network entity and the second network entity may be the same or different network entities depending on the type of RAT, and the first network entity and the second network entity may be either an access and mobility management function (AMF) or a mobility management entity (MME), respectively.

[0017] A method performed by a UE in a wireless communication system according to an embodiment of the present disclosure may include: transmitting a first registration request message to a first network entity managing mobility of the UE through a first base station of a first RAT; receiving, in response to transmitting the first registration request message, a registration acceptance message from the first network entity through the first base station, the registration acceptance message including access-related information for a second RAT to which previous access of the UE was denied; and transmitting, based on the access-related information for the second RAT, a second registration request message to a second network entity managing mobility of the UE through a second base station of the second RAT.

[0018] In a wireless communication system according to an embodiment of the present disclosure, a network entity for managing mobility of a UE comprises at least one transceiver, at least one processor communicatively coupled to the at least one transceiver, and at least one memory communicatively coupled to the at least one processor and storing instructions executable individually or in combination by the at least one processor, wherein the instructions cause the network entity to receive, via the at least one transceiver, a registration request message from the UE via a first base station of a first RAT, and in response to receiving the first registration request message, transmit, via the at least one transceiver, a registration acceptance message to the UE via the first base station, the registration acceptance message including information regarding access to a second RAT to which previous access of the UE was denied.

[0019] FIG. 1 is a diagram illustrating an example of a network structure for a wireless communication system to which the present disclosure applies;

[0020] FIG. 2 is a flowchart illustrating a procedure for performing communication using NAS messages in a wireless communication system according to an embodiment of the present disclosure.

[0021] FIG. 3 is a flowchart illustrating a procedure for performing communication using NAS messages in a wireless communication system according to one embodiment of the present disclosure;

[0022] FIG. 4 is a flowchart illustrating a procedure for performing communication using NAS messages in a wireless communication system according to one embodiment of the present disclosure.

[0023] FIG. 5 is a diagram showing the configuration of a terminal according to one embodiment of the present disclosure, and

[0024] FIG. 6 is a diagram showing the configuration of a network entity according to one embodiment of the present disclosure.

[0025] 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.

[0026] 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.

[0027] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described in detail below 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 solely 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 invention, and the present disclosure is defined only by the scope of the claims. Like reference numerals designate like elements throughout the specification.

[0028] At this time, it will be understood that each block of the processing flow diagrams and combinations of the flow diagrams can be performed by computer program instructions.

[0029] 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.

[0030] 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.

[0031] In this disclosure, phrases such as "A / B", "A or B", "A and / or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" can each include any one of the items listed together in that phrase, or all possible combinations thereof. Terms such as "first", "second", or "first" or "second" may be used merely to distinguish the corresponding component from other corresponding components and do not limit the corresponding components in any other respect (e.g., importance or order).

[0032] The terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, and terms referring to various identification information are provided as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0033] For convenience of explanation, this disclosure uses terms and names defined in the 3GPP NR (New Radio) standard, or terms and names modified from the same. However, this disclosure is not limited to the terms and names described above, and can be equally applied to systems conforming to other standards.

[0034] In the present disclosure, a base station (BS) is a network entity that performs resource allocation for a terminal and can communicate with the terminal via a wireless network, and may be at least one of an eNode B, a Node B, a gNB, a RAN (Radio Access Network), an AN (Access Network), a RAN node, an IAB (Integrated Access / Backhaul) node, a wireless access unit, a base station controller, a node on a network, or a TRP (Transmission Reception Point). A terminal (UE) may be at least one of a terminal, a MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In addition, in the present disclosure, eNB may be used interchangeably with gNB for convenience of description. That is, a base station described as an eNB may represent a gNB. In the present disclosure, the term terminal may represent various wireless communication devices as well as mobile phones, NB-IoT devices, and sensors.

[0035] 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.

[0036] In 5G or NR systems, the Access and Mobility Management Function (AMF), which is the management entity that manages the mobility of the UE, and the Session Management Function (SMF), which is the entity that manages the session, have separate structures. Accordingly, unlike in 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 into the AMF and SMF, which changed the communication method and communication management method between the UE and the network entity.

[0037] In 5G or NR systems, mobility management for non-3GPP access is performed via the Non-3GPP Inter-Working Function (N3IWF) and AMF, while session management is performed via the SMF. Security-related information, a crucial element in mobility management, can also be processed through the AMF.

[0038] As described above, in LTE systems, the MME is responsible for both mobility management and session management. 5G or NR systems can support a non-standalone architecture (NSA), which utilizes these LTE system network entities to perform communications.

[0039] In the present disclosure, network technology may refer to standard specifications defined by the International Telecommunication Union (ITU) or 3GPP (e.g., TS 23.501, TS 23.502, TS 23.503, etc.), and components included in the network structure of FIG. 1 described below may mean physical entities, or may mean software performing individual functions or hardware combined with software. Reference numerals shown as N1, N2, N3, ..., Nxx, etc. in the drawings represent known interfaces between NFs in a 5G core network (CN).

[0040] FIG. 1 is a diagram illustrating an example of a network structure for a wireless communication system to which the present disclosure applies. The structure of FIG. 1 illustrates a 5G system.

[0041] Referring to FIG. 1, a 5G system may include a 5GC (5G core network), base stations (RANs) (103, 103-3, 103-5), and UEs (101, 101-3, 101-5: 101). In the example of FIG. 1, a UE (101) is illustrated as attempting to connect to different base stations (RANs) (103, 103-3, 103-5) at a given location as the UE (101) moves in the network. However, the embodiments of the present disclosure, which will be described below, may be applied to various communication environments in which a UE (101) attempts to connect to a network through an available RAT, whether the UE (101) moves or does not move.

[0042] The above 5GC may include network functions (NF, Network Functions) such as a UPF (User Plane Function, 131) that is connected to a data network (DN) (not shown) and performs a data transmission role, a SMF (Session Management Function, 121) that manages sessions, an AMF (Access and Mobility Management Function, 111) that manages the mobility of a UE (101), a UDM (User Data Management, 151) that provides data management functions such as subscription information and / or policy control information, a PCF (Policy Control Function, 161) that provides a network operator's policy control function, an AUSF (Authentication Server Function) (141) that performs authentication of network entity(ies) in a 5G system, an AAA (Authentication, Authorization, Accounting) (171) that is an authentication server in the network, and an OAM (Operations, Administration and Maintenance) (191) that provides a function to respond to network failures by identifying failures such as defects, abnormalities, and malfunctions that may occur in the network and notifying the network operator. Additionally, the AF (Application Function) (181) can provide application services by communicating with the 5GC through the NEF (Network Exposure Function) (not shown) that transmits or receives events occurring in the 5G system and supported capabilities to the outside.

[0043] In addition, in FIG. 1, the AMF (111) is a network entity for managing access and mobility of the UE (101). For example, the AMF (111) can perform network functions such as registration, connection, reachability, mobility management, access confirmation, authentication, and mobility event generation of the UE (101). The SMF (121) can perform a management function for the PDU session of the UE (101). For example, the SMF (121) can perform network functions such as session establishment, modification, and release, session management function through tunnel maintenance between the UPF (131) and the base station (RAN) (103, 103-3, 130-5), IP (Internet Protocol) address allocation and management function of the UE (101), and user plane selection and control. The UPF (131) may perform a data processing function to transfer data transmitted by the UE (101) to an external network, DN (not shown), or to transfer data received from the DN to the UE (101). In addition, the UPF (131) may perform network functions such as performing an anchor role between radio access technologies (RATs), providing a connection between a PDU session and an AF (181), packet routing and forwarding, packet inspection, applying a user plane policy, creating a traffic usage report, buffering, etc. The PCF (161) may manage operator policy information for providing a service in a 5G system, and the UDM (151) may perform functions such as generating authentication information for 3GPP security, managing a list of NFs supporting the UE (101), and managing subscription information.

[0044] In addition, the AUSF (141) and AAA (171) may provide a function for authentication of network entities in the example of Fig. 1. The UE (101) may access the 5G core network through the base station (103). Meanwhile, in order to support a case where the UE (101) communicates through a base station (RAN or AP (access point)) (104) for non-3GPP access, the 5GC may include an N3IWF (N3 interworking function) (not shown). When using non-3GPP access for network access of UE (101), session management for UE (101) can be controlled through signaling among UE (101), base station (104) for non-3GPP access, N3IWF, and SMF (121), and mobility management for UE (101) can be controlled through signaling among UE (101), base station (104) for non-3GPP access, N3IWF, and AMF (111).

[0045] In the 5G system, the network entities that perform mobility management and session management are separated into the AMF (111) and the SMF (121). Meanwhile, the 5G system is being considered for a stand-alone (SA) deployment structure that performs communication only with the network entities of the 5G system, and a non-stand-alone (NSA) deployment structure that performs communication using the network entities of the 4G system and the network entities of the 5G system together.

[0046] Although the example of FIG. 1 illustrates a 5G system using the SA structure, the embodiments of the present disclosure, which will be described below, can also be applied to a 5G system using the NSA structure. In addition, when the UE (101) communicates with the network, access control is performed by the eNB of the LTE system, and the core network can be deployed in a form in which network entities of the 5G system are used. In this case, mobility management between the UE (101) and the AMF (111) and session management between the UE (101) and the SMF (121) can be performed by transmitting and receiving NAS messages in the NAS (Non Access Stratum) layer, which is layer 3, as illustrated in the embodiments of FIGS. 2 to 4. In the embodiments of FIGS. 2 to 4, the terms base station and (5G) RAN can be used interchangeably.

[0047] FIG. 2 is a flowchart illustrating a procedure for performing communication using NAS messages in a wireless communication system according to an embodiment of the present disclosure. The example of FIG. 2 illustrates an example of a procedure for disabling an RAT that cannot be used by a UE (101) in a 5G system. The RAT may include, for example, at least one of an NR network (i.e., a 5G network), an LTE network (i.e., a 4G network), and a non-3GPP network defined in the 3GPP standard. In the example of FIG. 2, in the case of RAT access via an LTE network (i.e., a 4G network), the AMF (111) may be an MME (Mobility Management Entity) (not shown), and in the embodiments of FIGS. 3 and 4 described below, a registration procedure may be performed between the UE (101) and the AMF (111) / MME depending on the type of RAT to which the UE (101) accesses.

[0048] Referring to FIG. 2, when a UE (101) attempts to register with a network through a base station (5G RAN, 4G RAN, or AP for non-3GPP access) in process 201, it may transmit a registration request message to AMF (111). For convenience of explanation, the example of FIG. 2 exemplifies a 5G RAN (103, 103-3) as the base station, but the base station is not limited to a 5G RAN (103, 103-3).

[0049] In process 202, if the AMF (111) rejects the network registration of the UE (101) due to reasons such as network congestion or a problem in the operator's network, an attempt to access the network through a RAT that the UE (101) cannot use, a network status, the terminal capability of the UE (101), subscription information (change / restriction) of the UE (101), or any other reason, the AMF (111) may transmit a registration reject message to the UE (101) through the base station (103). The registration reject message may include at least one of the following parameters (information). The parameters (information) may perform the following roles.

[0050] - AMF (111) may transmit a registration reject message to UE (101) in response to a registration request message received when UE (101) attempts to register with a network, and may include at least one of information on a registerable / usable RAT (i.e., possible RAT information) (possible-RAT-info) and information on a disabled RAT (i.e., disabled RAT information) (disable-RAT-info) in the registration reject message.

[0051] - Or, as an example, a base station (103) that has received a registration request message from a UE (101) may provide information on a RAT that failed to establish a path when the UE (101) transmitted the registration request message to the AMF (111) through the base station (103), and the AMF (111) may store the corresponding RAT information in disabled RAT information and transmit a registration reject message including the disabled RAT information to the UE (101) through the base station (103).

[0052] - Or, in one embodiment, when a registration request of a UE (101) through a path via a network (RAN) (e.g., a path via an NR network, an LTE network, or a non-3GPP network defined in the 3GPP standard) fails, the AMF (111) that confirms the failure of the registration request through the path can store the RAN for which the registration request failed in the disabled RAT information and transmit a registration reject message including the disabled RAT information to the UE (101) through the base station (103).

[0053] In step 203, the UE (101) can confirm / store the information received via the registration reject message. The confirmed / stored information may include at least one of information on RATs that are available for registration / use for the UE (101) (possible-RAT-info) and information on RATs that are disabled for the UE (101) (disable-RAT-info). The confirmed / stored information may be used to change the network (RAT) that the UE (101) attempts to connect to to a different RAT and perform a registration procedure for network connection.

[0054] UE (101) may attempt network registration by changing the transmission path of a message (e.g., NAS message, etc.) to be transmitted to AMF (111) to the corresponding available (possible) RAT based on the registered / available RAT information (possible-RAT-info) among the above-mentioned confirmed / stored information.

[0055] Afterwards, when the UE (101) attempts network registration by changing the RAT for network access based on the possible RAT information confirmed in the above process 203, the UE (101) can transmit a registration request message to the AMF (111) through the base station (103-3) of the changed RAT in process 204.

[0056] In process 205, when AMF (111) accepts network registration of UE (101), AMF (111) transmits a registration accept message to UE (101) through the base station (103-3). The registration accept message may include RAT information (possible-RAT-info) that the UE (101) can register / use.

[0057] A UE (101) that has successfully registered with the network in process 206 transmits a PDU session establishment request message to the SMF (121) through the base station (103-3) of the RAT available to the UE (101).

[0058] In process 207, the SMF (121) that accepted the PDU session establishment for the UE (101) transmits a PDU session establishment accept message to the UE (101) through the base station (103-3).

[0059] FIG. 3 is a flowchart illustrating a procedure for performing communication using NAS messages in a wireless communication system according to one embodiment of the present disclosure. The example of FIG. 3 illustrates an example of a procedure for enabling a disabled RAT that cannot be used by a UE (101) using a timer. The RAT may include, for example, at least one of an NR network (i.e., a 5G network), an LTE network (i.e., a 4G network), and a non-3GPP network defined in the 3GPP standard.

[0060] Referring to FIG. 3, when a UE (101) attempts to register with a network through a base station (5G RAN, 4G RAN, or AP for non-3GPP access) in process 301, it may transmit a registration request message to the AMF (111). For convenience of explanation, the example of FIG. 3 exemplifies a 5G RAN (103, 103-3) as the base station, but the base station is not limited to a 5G RAN (103, 103-3).

[0061] In process 302, if AMF (111) rejects network registration of UE (101) due to network access attempt through RAT that UE (101) cannot use, network status, terminal capability of UE (101), subscription information (change / restriction) of UE (101), or any other reason, AMF (111) may transmit a registration reject message to UE (101) through base station (103). The registration reject message may include at least one of the following parameters (information). The parameters (information) may perform the following roles.

[0062] - AMF (111) may transmit a registration reject message to UE (101) in response to a registration request message received when UE (101) attempts to register with the network if registration of the UE (101) fails.

[0063] - When AMF (111) transmits the registration reject message to UE (101), the registration reject message may include at least one of information on a registered / usable RAT (i.e., possible RAT information) (possible-RAT-info), information on a disabled RAT (i.e., disabled RAT information) (disable-RAT-info), and timer information required to activate a disabled RAT.

[0064] - Or, as an example, a base station (103) that has received a registration request message from a UE (101) may provide information on a RAT that failed to establish a path when the UE (101) transmitted the registration request message to the AMF (111) through the base station (103), and the AMF (111) may store the corresponding RAT information in disabled RAT information and transmit a registration reject message including the disabled RAT information to the UE (101) through the base station (103).

[0065] - Or, in one embodiment, when a registration request of a UE (101) through a path via a network (RAN) (e.g., a path via an NR network, an LTE network, or a non-3GPP network defined in the 3GPP standard) fails, the AMF (111) that confirms the failure of the registration request through the path can store the RAN for which the registration request failed in the disabled RAT information and transmit a registration reject message including the disabled RAT information to the UE (101) through the base station (103).

[0066] - The UE (101) may receive at least one of disabled RAT information (disable-RAT-info), registered / available RAT information (possible-RAT-info), and timer-for-active information for activating the RAT (i.e., information about a timer for enabling the UE (101) to use the RAT) from the network (e.g., AMF) through the registration reject message. In an optional embodiment, at least one of the disable RAT information, registered / available RAT information, and timer-for-active information may be provided to the UE (101) through the base station (103).

[0067] - The UE (101) that has received information about the above timer (timer-for-active) can set a timer time equal to the timer (timer-for-active) for the UE (101) on the UE side, and after the time has elapsed / expired, can (re)transmit a registration request message to the network of the RAT disabled for the UE (101). In one embodiment, since the disabled RAT is no longer a disabled RAT for the UE (101) (i.e., becomes an available RAT) when the time equal to the timer (timer-for-active) has elapsed, the UE (101) can also transmit a registration request message to the network of the RAT using the RAT information (disable-RAT-info) after the timer (timer-for-active) has expired. In an optional embodiment, the disabled RAT information (disable-RAT-info) may include a list of at least one disabled RAT for the UE (101), and a timer for activating the RAT (timer-for-active) may be individually set for each of the at least one disabled RAT for the UE (101), or may be set commonly for the at least one disabled RAT, or may be selectively set for some RATs among the at least one disabled RAT.

[0068] -Or, UE (101) can transmit a registration request message again to AMF (111) through the possible RAT based on the information (possible-RAT-info) about the registered / available RAT received through the registration reject message.

[0069] In one embodiment, the network (e.g., at least one of AMF (111) and RAN (103)) may also operate a timer (which may be set identically to the timer-for-active) for reactivating a disabled RAT for the UE (101) on the network side. In other words, if the timer (timer-for-active) required for activating a disabled RAT on the UE side is referred to as the first timer, the network side may also operate a second timer to check the same timer time as the first timer.

[0070] In step 303, the UE (101) can confirm / store information received through a registration reject message. The confirmed / stored information may include at least one of information on RATs that can be registered / used for the UE (101) (possible-RAT-info), information on RATs that are disabled for the UE (101) (disable-RAT-info), and information on a timer (timer-for-active) required to activate a disabled RAT for the UE (101). The confirmed / stored information may be used to change the network (RAT) that the UE (101) attempts to connect to to another RAT and perform a registration procedure for network connection.

[0071] And, the UE (101) may attempt to register the transmission path of a message (e.g., NAS message, etc.) to be transmitted to AMF (111) with the available RAT based on the registered / available RAT information (possible-RAT-info) among the above-mentioned confirmed / stored information.

[0072] In one embodiment, the UE (101) starts the timer based on timer information (timer-for-active) required to activate the disabled RAT received / confirmed through the registration reject message, and when the timer expires, the UE (101) can transmit a registration request message to the AMF (111) through the activated RAT. The UE (101) can transmit the registration request message through the RAT selected by expiring the timer among at least one RAT confirmed in the information about the disabled RAT (disable-RAT-info).

[0073] In one embodiment, when UE (101) attempts network registration by changing RAT for network access based on information (possible-RAT-info) about registered / available RAT confirmed in step 303, UE (101) may transmit a registration request message to AMF (111) through base station (103-3) of changed RAT in step 304. In the example of FIG. 3, only one AMF (111) is illustrated for convenience of explanation, but the registration request message may be transmitted to AMF (111) or MME (not illustrated) depending on the type of RAT (e.g., NR network or LTE network) to which UE (101) transmits the registration request message.

[0074] In process 305, if AMF (111) accepts network registration of UE (101), AMF (111) transmits a registration accept message to UE (101) through the base station (103-3). The registration accept message may include RAT information (possible-RAT info) that the UE (101) can register / use.

[0075] A UE (101) that has successfully registered with the network in process 306 transmits a PDU session establishment request message to the SMF (121) through the base station (103-3) of the RAT available to the UE (101).

[0076] In process 307, the SMF (121) that accepted the PDU session establishment for the UE (101) transmits a PDU session establishment accept message to the UE (101) through the base station (103-3).

[0077] In one embodiment, when the UE (101) confirms that the disabled RAT, for example, the base station (103) in this embodiment, has become active by the expiration of the timer-for-active timer, and performs registration with the network (AMF (111)) in the process after step 307, the UE (101) may transmit a registration request message to the AMF (111) via the base station (5G-RAN, 103-3). This is an example of receiving information about the activation of the disabled RAT in the UE (101) and timer information, and performing a registration procedure with the network (AMF (111)) using the received information.

[0078] FIG. 4 is a flowchart illustrating a procedure for performing communication using NAS messages in a wireless communication system according to an embodiment of the present disclosure. The example of FIG. 4 illustrates an example of a procedure for enabling a disabled RAT that cannot be used by a UE (101) using information on a disabled and then activated RAT. The RAT may include, for example, at least one of an NR network (i.e., a 5G network), an LTE network (i.e., a 4G network), and a non-3GPP network defined in the 3GPP standard. For convenience of explanation, the example of FIG. 4 exemplifies a 5G RAN (103, 103-3), but the RAN may be any one of a 5G RAN, an LTE RAN, and an AP.

[0079] The embodiment of FIG. 4 shows an example in which AMF (111) controls network access of the UE (101) by executing and controlling a timer required to activate the disabled RAT for the UE (101).

[0080] The embodiment of Fig. 4 can be performed in various cases (case1, case2 or case3) as follows.

[0081] For example, in case 1, it is assumed that the UE (101) attempted to register with the 5G RAN (103-3) before process 401, or that it previously accessed the 5G RAN (103-3) and knows that the RAT of the 5G RAN (103-3) is disabled. In one embodiment, the UE (101) can receive information related to the activation of the RAT of the 5G RAN (103-3) from the 5G RAN (103), which is the current serving network of the UE (101).

[0082] As an example, in case 2, UE (101) attempts to register with AMF (111) through 5G RAN (103-3), but the corresponding RAT of 5G RAN (103-3) is disabled, and since the registered / available RAT (possible RAT) of UE (101) is the RAT of 5G RAN (103), the registration procedure with AMF (111) may be performed through the corresponding RAT of 5G RAN (103).

[0083] Or, in case 3 as an example, the UE (101) can know that the RAN is activated through a timer (timer-for-RAN-activated). For example, a) UE (101) attempts to register with AMF (111) through 5G RAN (103-3) and then the corresponding RAT of 5G RAN (103-3) is disabled, b) since the possible RAT is the RAT of 5G RAN (103), AMF registration is attempted through the corresponding RAT of 5G RAN (103), and c) information indicating that the RAT of 5G RAN (103-3) previously connected during registration has been activated is received from AMF (111), or after previously receiving information about the timer (timer-for-RAN-activated), the received timer (timer-for-RAN-activated) is started and when it expires, it can be confirmed that the RAT of 5G RAN (103-3) has been activated.

[0084] Therefore, in this embodiment, it is assumed that the RAT of the 5G RAN (103-3) for the UE (101) was a disabled RAT, but the timer for the RAT managed by the AMF (111) required to activate the disabled RAT has expired, and thus network access through the 5G RAN (103-3) is possible. According to this assumption, in the process 401, the UE (101) can use the activated RAT of the 5G RAN (103-3), as the 5G RAN (103-3), which was a disabled RAT in the previous network access attempt, is activated. In the process 404 described below, the UE (101) can transmit a registration request message to the AMF (111) through the activated RAT of the 5G RAN (103-3).

[0085] In step 402, if the AMF (111) accepts the network registration of the UE (101), it can transmit a registration accept message to the UE (101) via the base station (103). The registration accept message can include at least one of the following parameters (information). The parameters (information) can perform the following roles. The parameters (information) included in the registration accept message in step 402 can be referred to as access-related information for the RAT to which the UE (101) was previously denied access.

[0086] In one embodiment, when transmitting the registration accept message to the UE (101), the AMF (111) may transmit to the UE (101) at least information about the RAT that can be registered / used (i.e., possible RAT information) (possible-RAT-info), information about the disabled RAT that was previously disabled (i.e., the RAT to which the previous access of the UE (101) was denied), and timer information required to activate the previously disabled RAT.

[0087] Or, as an example, the AMF (111) may transmit information about the RAT that was previously disabled and then activated / to be activated, i.e., activation information of the disabled RAT (activated-disable-RAT-info), through the registration accept message to the UE (101). The UE (101) that has confirmed / received the activation information of the disabled RAT (activated-disable-RAT-info) may store the information in step 403 and transmit the registration request message to the AMF (111) through the corresponding RAT (e.g., the RAT that was previously disabled and then activated) of the 5G RAN (103-3).

[0088] - In addition, as an embodiment, the UE (101) may receive at least one of information on a previously disabled disabled RAT, information on a registerable / available RAT, and timer information required to activate the disabled RAT from the network (e.g., AMF) through the registration accept message. The timer information may use the timer (timer-for-active) described in the embodiment of FIG. 3 to enable the UE (101) to use the corresponding RAT. As an optional embodiment, at least one of information on a previously disabled disabled RAT, information on a registerable / available RAT, and information on a timer (timer-for-active) required to activate the disabled RAT may be provided to the UE (101) through the base station (103).

[0089] - The UE (101) that has received the above timer (timer-for-active) information sets a timer time equal to the timer (timer-for-active) on the UE side, and after the time has elapsed / expired, the UE (101) can transmit a registration request message to the network of the RAT previously disabled for the UE (101). In one embodiment, when the time of the timer (timer-for-active), i.e. the time equal to the timer time, has elapsed, the RAT previously disabled for the UE (101) is no longer a disabled RAT (i.e., becomes an available RAT), and thus the UE (101) can transmit a registration request message to the network of the RAT previously disabled based on the timer (timer-for-active) information required to activate (active) the disabled RAT.

[0090] -Or, as another example, the UE (101) may transmit a registration request message back to the AMF (111) through the possible RAT based on the information (possible-RAT-info) about the registered / available RAT received through the registration accept message.

[0091] In one embodiment, the network (e.g., at least one of AMF (111) and RAN (103)) may also operate a timer (which may be set to be the same as the timer-for-active) for reactivating a disabled RAT for the UE (101) on the network side. In other words, if the timer (timer-for-active) required for activating a disabled RAT on the UE side is referred to as the first timer, the network side may also operate a second timer to check the same timer time as the first timer.

[0092] In the embodiment of FIG. 4, the UE (101) and / or the network (e.g., at least one of AMF (111), RAN (103)) may use at least one of the timers (timer-for-RAN-activated) and the timer (timer-for-active) described above to check for activation of a disabled RAT that was previously disabled as in the embodiments described above when the timer expires, and transmit a registration request message to the network of the RAT.

[0093] In the 403 process, the UE (101) can confirm / store the information received through the registration accept message. The confirmed / stored information may include at least one of activation information of a previously disabled RAT for the UE (101) (activated-disable-RAT-info), information on a RAT that can be registered / used for the UE (101) (possible-RAT-info), and timer information required to confirm activation of a disabled RAT. The timer information may utilize various timers provided from the network, such as the aforementioned timer (timer-for-RAN-activated) and timer (timer-for-active). The following operation exemplifies a case where the timer (timer-for-active) is used. The confirmed / stored information may be used to change the network (RAT) that the UE (101) attempts to connect to to another RAT and perform a network connection, i.e., a registration procedure.

[0094] And, the UE (101) may attempt network registration by changing the transmission path of a message (e.g., NAS message, etc.) to be transmitted to AMF (111) through the RAT to the activated / possible RAT based on the activation information (activated-disable-RAT-info) of the previously disabled RAT or the information on the registered / available RAT (possible RAT).

[0095] In one embodiment, UE (101) starts the timer based on timer information (timer-for-active) required to activate the disabled RAT received / confirmed through the registration accept message, and when the timer expires, UE (101) can transmit a registration request message to AMF (111) through the activated RAT.

[0096] Alternatively, as an example, the UE (101) may receive information on a previously disabled and then activated RAT, i.e., activated-disable-RAT-info information, from the AMF (111) and store the information. The UE (101) that has received the activated-disable-RAT-info information may transmit a registration request message to the AMF (111) through the base station (103-3) of the previously disabled and then activated RAT.

[0097] As described above, in the present disclosure, in process 404, the UE (101) can transmit a registration request message to the AMF (111) through the base station (103-3) of the RAT that was disabled and then activated. The RAT that was previously disabled and then activated may be a RAT that the UE (101) prefers when accessing a network or has a high priority when accessing a network. Although the UE (101) received a registration accept message through the base station (103) in process 402, the UE (101) can transmit a registration request message to the AMF (111) again through the base station (103-3) of the RAT that was previously disabled and then activated in order to access the network through the preferred RAT or the RAT that has a high priority when accessing the network. In the example of FIG. 4, only one AMF (111) is illustrated for convenience of explanation, but the registration request message may be transmitted to the AMF (111) or the MME (not illustrated) depending on the type of RAT (e.g., NR network or LTE network) to which the UE (101) transmits the registration request message. That is, the network entity (AMF or MME) that manages mobility that receives the registration request message from the UE (101) in the above-mentioned 401 process and the network entity (AMF or MME) that manages mobility that receives the registration request message from the UE (101) in the above-mentioned 404 process may be the same or different.

[0098] In one embodiment, in the process 404, the UE (101) may transmit a registration request message to the AMF (111) through the base station (103-3) of the corresponding RAT based on the information (possible-RAT-info) about the registered / available RAT (possible RAT). In one embodiment, in the process 404, the UE (101) may transmit a registration request message to the AMF (111) through the base station (103-3) of the corresponding RAT based on the activation information (activated-disable-RAT-info) of the previously disabled RAT. Here, the activation information (activated-disable-RAT-info) of the previously disabled RAT may include a list of at least one RAT (activated-disable-RAT) that was previously disabled and then activated for the UE (101).

[0099] In the 405 process, if the AMF (111) accepts the network registration of the UE (101), the AMF (111) transmits a registration accept message to the UE (101) through the base station (103-3). The registration accept message may include RAT information (possible-RAT info) that the UE (101) can register / use.

[0100] The UE (101) that has successfully registered with the network in process 406 transmits a PDU session establishment request message to the SMF (121) through the base station (103-3).

[0101] In process 407, the SMF (121) that has accepted the PDU session establishment for the UE (101) transmits a PDU session establishment accept message to the UE (101) through the base station (103-3).

[0102] According to the embodiments of the present disclosure described above, it is possible to efficiently support the registration procedure of a UE in a network environment where multiple RATs are available or unavailable to the UE or multiple RATs that can be selectively used based on a timer exist / are mixed.

[0103] FIG. 5 is a diagram showing the configuration of a UE according to one embodiment of the present disclosure.

[0104] As illustrated in FIG. 5, the UE of the present disclosure may include a transceiver (510), a memory (520), and a processor (530). The processor (530), the transceiver (510), and the memory (520) of the UE may operate according to the aforementioned UE communication method. However, the components of the UE are not limited to the examples described above. For example, the UE may include more or fewer components than the aforementioned components. In addition, the processor (530), the transceiver (510), and the memory (520) may be implemented in the form of a single chip.

[0105] The transceiver (510) is a general term for the UE's receiving unit and transmitting unit, 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 a 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.

[0106] Additionally, the transceiver (510) may include a wired or wireless transceiver and may include various configurations for transmitting and receiving signals.

[0107] Additionally, 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.

[0108] Additionally, the transceiver (510) can receive a communication signal and output it to the processor (530), and transmit the signal output from the processor (530) to a network entity via a wired or wireless network.

[0109] The memory (520) can store programs and data necessary for the operation of the UE. In addition, the memory (520) can store control information or data included in signals acquired from the UE. 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.

[0110] The processor (530) may control a series of processes so that the UE can operate according to at least one of the embodiments of the present disclosure described above in FIGS. 1 to 4. 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 / or an application processor (AP) that controls upper layers such as application programs.

[0111] In a wireless communication system according to an embodiment of the present disclosure, a UE includes at least one transceiver (510), at least one processor (530) communicatively coupled to the at least one transceiver (510), and at least one memory (520) communicatively coupled to the at least one processor (530) and storing instructions executable individually or in combination by the at least one processor (530), the instructions causing the UE to transmit, via the at least one transceiver (510), a first registration request message to a first network entity managing mobility of the UE via a first base station of a first RAT, and in response to transmission of the first registration request message, receive, via the at least one transceiver (510), from the first network entity via the first base station, a registration acceptance message including information related to access to a second RAT to which the UE's previous access was denied, and send, via the at least one transceiver (510), a registration acceptance message to the second RAT. Based on the above access-related information to the RAT, a second registration request message may be caused to be transmitted to a second network entity managing the mobility of the UE via a second base station of the second RAT.

[0112] In one embodiment, the access-related information to the second RAT may include at least one of information about at least one disabled RAT that was disabled for access to the UE and is now or will be enabled, and information about at least one enabled RAT that is registered or available for use by the UE.

[0113] In one embodiment, the access-related information to the second RAT further includes timer information required to confirm activation of all or part of the at least one disabled RAT, and the timer information may include at least one timer set for all or part of the at least one disabled RAT.

[0114] In one embodiment, the second RAT is one of the at least one disabled RAT, and the instructions executable individually or in combination by the at least one processor (530) may cause the UE to determine that the second RAT is switched to an activated RAT when a timer for the second RAT among the at least one timer expires, and to transmit the second registration request message after the timer for the second RAT expires.

[0115] In one embodiment, the instructions executable individually or in combination by the at least one processor (530) may cause the UE to select the second RAT from among the at least one disabled RAT according to a determined priority.

[0116] In one embodiment, the first network entity and the second network entity may be the same or different network entities depending on the type of RAT, and the first network entity and the second network entity may be either an AMF or an MME, respectively.

[0117] FIG. 6 is a diagram illustrating a configuration of a network entity according to one embodiment of the present disclosure.

[0118] As illustrated in FIG. 6, a network entity of the present disclosure may include a transceiver (610), a memory (620), and a processor (630). 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. The network entity of FIG. 6 may be one of the network functions (NFs), such as the AMF, SMF, PCF, NEF (Network Exposure Function), UDM, and UPF described above. Additionally, the network entity of FIG. 6 may be a base station.

[0119] 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 UE 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 / wireless transceivers and may include various configurations for transmitting and receiving signals.

[0120] Additionally, 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.

[0121] Additionally, the transceiver (610) can receive a communication signal and output it to the processor, and transmit the signal output from the processor to a UE or network entity via a wired or wireless network.

[0122] 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.

[0123] The processor (630) may control a series of processes so that a network entity can operate according to at least one of the embodiments of the present disclosure described in FIGS. 1 to 4 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] In a wireless communication system according to an embodiment of the present disclosure, a network entity for managing mobility of a UE comprises at least one transceiver (610), at least one processor (630) communicatively coupled to the at least one transceiver (610), and at least one memory (620) communicatively coupled to the at least one processor (630) and storing instructions executable individually or in combination by the at least one processor (630), wherein the instructions cause the network entity to receive, via the at least one transceiver (610), a registration request message from the UE via a first base station of a first RAT, and in response to receiving the first registration request message, transmit, via the at least one transceiver (610), to the UE via the first base station, a registration acceptance message including information related to access to a second RAT to which previous access of the UE was denied.

[0128] In the specific embodiments of the present disclosure described above, components included in the 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.

[0129] 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 wireless communication system, in UE (user equipment), At least one transmitter / receiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions executable individually or in combination by said at least one processor, said instructions causing said UE to: Transmitting a first registration request message to a first network entity managing mobility of the UE via a first base station of a first RAT (radio access technology) through at least one transceiver; In response to transmission of the first registration request message, receiving, through the at least one transceiver, from the first network entity via the first base station, a registration acceptance message including access-related information for a second RAT to which the UE's previous access was denied, and A UE that causes a second registration request message to be transmitted to a second network entity managing mobility of the UE via a second base station of the second RAT, based on the access-related information to the second RAT, through the at least one transceiver.

2. In paragraph 1, The above access-related information to the second RAT is: Information about at least one disabled RAT that was disabled for the UE and is now or will be enabled; and A UE comprising at least one piece of information about at least one possible RAT that is registered or available for use by the UE.

3. In paragraph 2, The above access-related information to the second RAT is: A UE further comprising timer information required to confirm activation of all or part of the at least one disabled RAT, wherein the timer information includes at least one timer set for all or part of the at least one disabled RAT.

4. In paragraph 3, The second RAT is one of the at least one disabled RAT, The instructions executable individually or in combination by the at least one processor cause the UE to: If the timer for the second RAT among the at least one timer has expired, it is confirmed that the second RAT is switched to an activated RAT, and A UE causing the second registration request message to be transmitted after the timer for the second RAT expires.

5. In paragraph 2, The instructions executable individually or in combination by the at least one processor cause the UE to: A UE causing the second RAT to be selected according to a predetermined priority from among the at least one disabled RAT.

6. In paragraph 1, The above first network entity and the above second network entity are the same or different network entities depending on the type of RAT. The first network entity and the second network entity are each a UE, which is either an access and mobility management function (AMF) or a mobility management entity (MME).

7. In a method performed by a UE (user equipment) in a wireless communication system, A process of transmitting a first registration request message to a first network entity managing mobility of the UE through a first base station of a first RAT (radio access technology); In response to the transmission of the first registration request message, a process of receiving, from the first network entity through the first base station, a registration acceptance message including access-related information for a second RAT to which the UE's previous access was denied; and A method comprising the step of transmitting a second registration request message to a second network entity managing mobility of the UE through a second base station of the second RAT based on the access-related information to the second RAT.

8. In paragraph 7, The above access-related information to the second RAT is: Information about at least one disabled RAT that was disabled for the UE and is now or will be enabled; and A method comprising at least one piece of information about at least one possible RAT that is registered or available for use by the UE.

9. In paragraph 8, The above access-related information to the second RAT is: A method further comprising timer information necessary for confirming activation of all or part of the at least one disabled RAT, wherein the timer information includes at least one timer set for all or part of the at least one disabled RAT.

10. In paragraph 9, The second RAT is one of the at least one disabled RAT, If the timer for the second RAT among the at least one timer has expired, the UE confirms that the second RAT has been switched to an activated RAT, A method in which the UE transmits the second registration request message after the timer for the second RAT expires.

11. In paragraph 2, A method in which the second RAT is a RAT selected from among the at least one disabled RAT according to a set priority.

12. In paragraph 7, The above first network entity and the above second network entity are the same or different network entities depending on the type of RAT. A method in which the first network entity and the second network entity are each one of an access and mobility management function (AMF) and a mobility management entity (MME).

13. In a network entity that manages the mobility of UE (user equipment) in a wireless communication system, At least one transmitter / receiver; At least one processor communicatively coupled to said at least one transceiver; and At least one memory communicatively coupled to said at least one processor and storing instructions executable individually or in combination by said at least one processor, said instructions causing said network entity to: Receive a registration request message from the UE via the first base station of the first RAT (radio access technology) through at least one transceiver, and A network entity that, in response to receiving the first registration request message, causes the UE to transmit, via the first base station, a registration acceptance message containing access-related information for a second RAT to which the UE's previous access was denied, through the at least one transceiver.

14. In paragraph 13, The above access-related information to the second RAT is: Information about at least one disabled RAT that was disabled for the UE and is now or will be enabled; and A network entity that contains at least one piece of information about at least one possible RAT that is registered or available for use by the UE.

15. In paragraph 14, The above access-related information to the second RAT is: A network entity further comprising timer information required to confirm activation of all or part of the at least one disabled RAT, wherein the timer information includes at least one timer set for all or part of the at least one disabled RAT.

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