WO2025150955A1 - Method and apparatus for supporting multiple nr accesses in same network - Google Patents

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. The present invention relates to a method and an apparatus for providing multiple 3GPP accesses to a wireless terminal.

Description

Method and device for supporting multiple NR accesses in the same network

The present invention relates to a wireless communication network, and more particularly, to a method and device for providing multiple accesses to a wireless terminal with a 3GPP 5GS (5G system). In particular, the present invention relates to a method and device for providing multiple 3GPP accesses to a wireless terminal.

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 (Above 6GHz), called millimeter wave (㎜Wave), such as 28GHz and 39GHz. In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz (THz) band (for example, 3 THz band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and ultra-low latency that is reduced to one-tenth.

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). The technology includes beamforming and massive MIMO to reduce 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 sub-carrier 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, L2 pre-processing, and support for specific services. Standardization has been made on network slicing, which provides specialized, dedicated networks.

Currently, discussions are underway on improving and enhancing the initial 5G mobile communication technology in consideration of the services that the 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to assist in driving decisions of autonomous vehicles and increase user convenience based on the vehicle's own location and status information transmitted by the vehicle, 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.

In addition, standardization of wireless interface architecture/protocols for technologies such as the Industrial Internet of Things (IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) to provide nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step RACH for NR to simplify random access procedures is also in progress, and standardization of system architecture/services for 5G baseline architecture (e.g., Service-based Architecture: SBA, Service-based Interface: SBI) 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 is also in progress.

When such 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, which will require enhanced functions and performance of 5G mobile communication systems and integrated operation of connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity using extended reality (XR), artificial intelligence (AI), and machine learning (ML) to efficiently support augmented reality (AR), virtual reality (VR), and mixed reality (MR), AI service support, metaverse service support, and drone communications.

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 antennas, and large scale antennas, metamaterial-based lenses and antennas to improve coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve frequency efficiency and system network of 6G mobile communication technology, satellite, and AI (Artificial Intelligence) from the design stage and AI-based communication technology that implements end-to-end AI support functions to realize system optimization, and services with complexity that exceeds the limits of terminal computing capabilities that are realized by utilizing ultra-high-performance communication and computing resources. It could serve as a basis for the development of next-generation distributed computing technologies.

In order for a wireless communication network, more specifically, a 3GPP 5GS (5G system), to provide multiple 3GPP accesses to a wireless terminal, a method for selecting multiple 3GPP access networks can be used. In some cases, the multiple 3GPP access networks may belong to multiple PLMNs (public land mobile networks). An embodiment of the present invention provides a method for a wireless terminal to access the multiple 3GPP access networks and receive data services when the multiple 3GPP access networks belong to one PLMN.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

According to an embodiment of the present invention for solving the above problems, a method performed by a terminal of a wireless communication system comprises the steps of: transmitting a first message associated with registration in a first access network for applying dual steer to a first access network entity; receiving a second message including information of a first access and mobility management function (AMF) selected by the first access network entity in response to the first message; storing information indicating that the first AMF has been selected for registration in the first access network in dual steer information; transmitting a third message associated with registration in a second access network for applying the dual steer to a second access network entity; receiving a fourth message including information of the second AMF selected by the second access network entity in response to the third message; And a step of storing information indicating that the second AMF has been selected for registration with the second access network in the dual steer information, wherein the first AMF and the second AMF may be the same AMF or different AMFs.

In some embodiments, the first message may include at least one of a first terminal identifier used by the terminal to access the first access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use via the first access network.

In some embodiments, the third message may include at least one of a second terminal identifier used by the terminal to access the second access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use via the first access network.

In accordance with an embodiment, the method comprises the steps of: transmitting a fifth message requesting establishment of a first protocol data unit (PDU) session to the first access network to the first AMF through the first access network entity; receiving, from a first SMF selected by the first AMF, a sixth message accepting establishment of the first PDU session and including information of the first SMF in response to the fifth message; storing, in the dual steer information, information indicating that the first SMF has been selected for establishment of the first PDU session; transmitting a seventh message requesting establishment of a second PDU session to the second access network to the second AMF through the second access network entity; receiving, from a second SMF selected by the second AMF, a seventh message accepting establishment of the second PDU session and including information of the second SMF in response to the seventh message; And a step of storing information indicating that the second SMF is selected for establishing the second PDU session in the dual steer information, wherein the first SMF and the second SMF may be the same SMF or different SMFs.

In some embodiments, the fifth message may include at least one of a first terminal identifier used by the terminal to access the first access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use via the first access network.

In some embodiments, the seventh message may include at least one of a second terminal identifier used by the terminal to access the second access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use via the first access network.

In addition, according to an embodiment of the present invention for solving the above-described problem, a method performed by a first AMF (access and mobility management function) of a wireless communication system comprises the steps of: receiving a first message associated with registration of a terminal with a first access network for application of dual steer from the terminal through a first access network entity; if the terminal supports the dual steer and the first AMF supports the dual steer, transmitting a second message including information of the first AMF to the terminal through the first access network entity in response to the first message; storing information indicating that the first AMF has been selected for registration with the first access network in dual steer information; receiving a third message associated with registration of the terminal with a second access network for application of the dual steer from the terminal through a second access network entity; If the terminal supports the dual steer and the first AMF supports the dual steer, the method may further include: transmitting a fourth message including information of the first AMF to the terminal through a second access network entity in response to the third message; and storing information indicating that the first AMF has been selected for registration with the second access network in the dual steer information.

According to an embodiment, the method may further include a step of determining whether the terminal supports the dual steer based on subscription information of the terminal received from a UDM (unified data management); and a step of determining whether the first AMF supports the dual steer based on policy information received from a PCF (policy control function).

In an embodiment, the method may further include: transmitting the third message to a second AMF that supports registration with the second access network when the first AMF does not support registration with the second access network for application of the dual steer of the terminal; receiving information indicating that the second AMF has been selected for registration with the second access network from the second AMF or a unified data management (UDM); and storing information indicating that the second AMF has been selected for registration with the second access network in the dual steer information.

According to an embodiment, the method comprises the steps of: receiving a fifth message requesting establishment of a first PDU (protocol data unit) session to the first access network from the terminal through the first access network entity; selecting a first SMF based on at least one of the fifth message and a context of the first AMF; transmitting a sixth message requesting establishment of the first PDU session to the first SMF; receiving a seventh message from the first SMF in response to the sixth message, accepting establishment of the first PDU session; transmitting an eighth message accepting establishment of the first PDU session and including information of the first SMF to the terminal through the first access network entity in response to the fifth message; storing information indicating that the first SMF has been selected for establishment of the first PDU session in the dual steer information; The method further comprises the steps of: receiving a ninth message requesting establishment of a second PDU session to the second access network from the terminal via the second access network entity; selecting a second SMF based on at least one of the ninth message and a context of the first AMF; transmitting a tenth message requesting establishment of the second PDU session to the second SMF; receiving an eleventh message from the second SMF in response to the tenth message, accepting establishment of the second PDU session; transmitting a twelfth message accepting establishment of the second PDU session and including information of the second SMF in response to the ninth message, to the terminal via the second access network entity; and storing information indicating that the second SMF is selected for establishment of the second PDU session, in the dual steer information, wherein the first SMF and the second SMF may be the same SMF or different SMFs.

In addition, according to one embodiment of the present invention to solve the above problems, a terminal of a wireless communication system comprises: a transceiver; And a control unit connected to the transceiver, transmitting a first message associated with registration in a first access network for application of dual steer to a first access network entity, receiving a second message including information of the first AMF (access and mobility management function) selected by the first access network entity in response to the first message, storing information indicating that the first AMF is selected for registration in the first access network in the dual steer information, transmitting a third message associated with registration in a second access network for application of the dual steer to a second access network entity, receiving a fourth message including information of the second AMF selected by the second access network entity in response to the third message, and storing information indicating that the second AMF is selected for registration in the second access network in the dual steer information, wherein the first AMF and the second AMF may be the same AMF or different AMFs. It could be AMF.

In addition, according to one embodiment of the present invention to solve the above problems, a first AMF (access and mobility management function) of a wireless communication system comprises: a transceiver; And connected to the transceiver, receiving a first message associated with registration with a first access network for application of dual steer of the terminal from the terminal through the first access network entity, if the terminal supports the dual steer and the first AMF supports the dual steer, transmitting a second message including information of the first AMF to the terminal through the first access network entity in response to the first message, storing information indicating that the first AMF has been selected for registration with the first access network in dual steer information, receiving a third message associated with registration with a second access network for application of the dual steer of the terminal from the terminal through the second access network entity, if the terminal supports the dual steer and the first AMF supports the dual steer, transmitting a fourth message including information of the first AMF to the terminal through the second access network entity in response to the third message, and The control unit may include information indicating that the first AMF has been selected for registration with the network, stored in the dual steer information.

According to one embodiment of the present invention, it becomes possible for a 3GPP 5GS (5G system) to provide a multiple access-based network service that provides multiple 3GPP accesses belonging to one PLMN to a wireless terminal.

The effects obtainable from the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present disclosure pertains from the description below.

FIG. 1 illustrates an example of a multi-access network applying dual steer according to one embodiment of the present invention.

FIG. 2 illustrates an example of AMF selection and SMF selection issues in a multi-access network applying dual steer according to an embodiment of the present invention.

FIG. 3 illustrates an example of an outline of AMF selection and SMF selection methods in a multi-access network applying dual steer according to an embodiment of the present invention.

FIG. 4a and FIG. 4b illustrate an example of a method for selecting the same AMF by utilizing DS Info in AN to support dual steer in a single PLMN according to an embodiment of the present invention.

FIG. 5a and FIG. 5b illustrate an example of a method for selecting the same AMF through an AMF reselection process to support dual steer in a single PLMN according to an embodiment of the present invention.

FIGS. 6A and 6B illustrate an example of a method for selecting the same SMF when using the same AMF to support dual steer in a single PLMN according to an embodiment of the present invention.

FIGS. 7a and 7b illustrate an example of a method for selecting a different SMF when using the same AMF to support dual steer in a single PLMN according to an embodiment of the present invention.

FIGS. 8A and 8B illustrate an example of a method for selecting a different AMF to support dual steer in a single PLMN according to an embodiment of the present invention.

FIGS. 9a and 9b illustrate an example of a method for selecting the same SMF when using different AMFs to support dual steer in a single PLMN according to an embodiment of the present invention.

FIGS. 10A and 10B illustrate an example of a method for selecting different SMFs when using different AMFs to support dual steer in a single PLMN according to an embodiment of the present invention.

Figure 11 is a drawing showing the configuration of a terminal according to an embodiment of the present invention.

FIG. 12 is a diagram showing the configuration of a base station or network entity according to an embodiment of the present invention.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the attached drawings. In the following description of the present invention, if it is judged that a specific description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of the functions in the present invention, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification.

In describing the embodiments in this specification, descriptions of technical contents that are well known in the technical field to which the present disclosure belongs and are not directly related to the present disclosure are omitted. This is to convey the gist of the present disclosure more clearly without obscuring it by omitting unnecessary explanations.

For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically illustrated. In addition, the size of each component does not entirely reflect the actual size. The same or corresponding components in each drawing are given the same reference numbers.

The advantages and features of the present disclosure, and the methods for achieving them, will become apparent by referring 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, and the embodiments are provided only to make the disclosure of the present disclosure complete and to fully inform a person skilled in the art to which the present disclosure belongs of the scope of the disclosure, and the present disclosure is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In addition, when explaining the present disclosure, if it is judged that a specific description of a related function or configuration may unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted. In addition, the terms described below are terms defined in consideration of the functions in the present disclosure, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification.

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 invention is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

In describing embodiments of the present disclosure, the main target is New Radio (NR), which is a wireless access network, and the core network, packet core 5G System, or 5G Core Network, or NG Core (Next Generation Core) specified by 3GPP (3rd Generation Partnership Project), a mobile communication standard standardization organization, 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 will be possible at the discretion of a person skilled in the technical field of the present disclosure. For the convenience of the following description, the present invention uses terms and names defined in the standards of 5GS (5G system) and NR (new radio), LTE or similar systems, which are the latest standards defined by the 3GPP organization among the currently existing communication standards. However, the present invention is not limited by the above terms and names, and can be equally applied to wireless communication networks conforming to other standards. In particular, the present invention can be applied to 3GPP 5GS/NR (5th generation mobile communication standard).

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 wireless access unit, a base station controller, or a node on a network. The terminal may include a UE (User Equipment), an MS (Mobile Station), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, downlink (DL) refers to a wireless transmission path of a signal that a base station transmits to a terminal, and uplink (UL) refers to a wireless transmission path of a signal that a terminal transmits to a base station.

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. These computer program instructions can be loaded onto a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flow diagram block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can be directed to 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 an instruction means for performing the functions described in the flow diagram block(s). Since the computer program instructions may be installed on a computer or other programmable data processing apparatus, a series of operational steps may be performed on the computer or other programmable data processing apparatus to produce a computer-executable process, so that the instructions executing the computer or other programmable data processing apparatus may also provide steps for executing the functions described in the flowchart block(s).

Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a particular logical function(s). It should also be noted that in some alternative implementation examples, the functions mentioned in the blocks may occur out of order. For example, two blocks shown in succession may in fact be performed substantially concurrently, or the blocks may sometimes be performed in reverse order, depending on the functionality they perform.

Here, the term '~ part' used in the present 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 in an addressable storage medium and may be configured to reproduce one or more processors. Accordingly, as an example, the '~ part' includes components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and '~ parts' may be combined into a smaller number of components and '~ parts' or further separated into additional components and '~ parts'. In addition, the components and '~parts' may be implemented to play one or more central processing units (CPUs) within the device or the secure multimedia card. Also, in the embodiment, the '~part' may include one or more processors.

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 (㎜Wave), 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 delay time that is reduced by one-tenth.

In the early stages of 5G mobile communication technology, the goal was to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), including 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.

In order to increase transmission speed, increase transmission stability, and reduce transmission delay time, a wireless communication network, more specifically, 3GPP 5GS (5G system), can provide multiple accesses. Previously, there was a way to use only one 3GPP access and additionally use non-3GPP access to provide multiple accesses to terminals, but the coverage of non-3GPP access may be relatively more restricted than that of 3GPP access. In addition, 3GPP accesses actually come in several types. They can be divided into PLMN (public land mobile network) and NPN (non-public network), and can be divided into sub-6GHz band and higher mmWave band depending on the supported frequency, and can be divided into TN (terrestrial network) and NPN (non-terrestrial network). TN and NTN can also be further categorized into EUTRA (evolved UMTS terrestrial radio access network), NR (new radio), LEO (low earth orbit), GEO (geostationary orbit), etc., depending on the RAT (radio access technology). Therefore, a single wireless terminal can use multiple different types of 3GPP accesses simultaneously. In other words, 3GPP 5GS (5G system) can provide multiple 3GPP accesses to wireless terminals. To support this, a method for selecting networks for multiple 3GPP accesses is required.

FIG. 1 illustrates an example of a multi-access network applying dual steer according to one embodiment of the present invention.

Referring to FIG. 1, in order to increase transmission speed, increase transmission stability, and reduce transmission delay time, a wireless communication network, more specifically, 3GPP 5GS, may use one 3GPP access and additionally use another 3GPP access to provide multiple accesses to a terminal. At this time, as shown in FIG. 1 (a), multiple 3GPP accesses (e.g., 3GPP access network 1, 3GPP access network 2) may be provided to one terminal (e.g., DS (dual steer) terminal, DS device, DS supported terminal) through a CN (core network) (e.g., AMF (access and mobility management function), SMF (session management function), UPF (user plane function), PCF (policy control function), UDM (unified data management), etc.) of a single PLMN to provide a data service. Alternatively, as in (b) of Fig. 1, multiple 3GPP accesses may be provided to a single terminal by using multiple PLMN CNs (e.g., AMF1, AMF2, SMF1, SMF2, UPF1, UPF2, PCF1, PCF2, etc.) to provide data services. The DS terminal may refer to a terminal that supports the DS service. And the DS service may be used interchangeably with a multiple access network service. The DS service may refer to a service provided through multiple accesses (multiple access networks), and the multiple accesses may refer to 3GPP accesses.

FIG. 2 illustrates an example of AMF selection and SMF selection issues in a multi-access network applying dual steer (DS) in one PLMN according to an embodiment of the present invention.

Referring to Fig. 2, data services can be provided by providing multiple 3GPP accesses to one terminal using CNs of multiple PLMNs as in (b) of Fig. 2. In this case, it can be expected that different AMFs (e.g., AMF1, AMF2) will be selected to provide services.

Figure 2 (a) illustrates a case where, when providing a data service by providing multiple 3GPP accesses to a single terminal through the CN of a single PLMN, the same AMF (e.g., AMF1) is selected as in Figure 1 (a) to provide the service. To this end, a terminal applying dual steer can perform the following operations.

A. DS (dual steer) applied terminal can access the first access network (AN1) (first access network) and perform the registration process up to the AMF of the CN. At this time, the issue is how AN1 selects the AMF that provides the multi-access network service.

B. The DS application terminal can establish a PDU (protocol data unit) session to receive data services by connecting to the CN's SMF through the first access network (AN1). At this time, the issue is how the AMF (AMF1) selected in step A selects the SMF that provides the multi-access network service.

C. The DS application terminal can perform the registration process to the CN's AMF through the second access network (AN2) (second access network). At this time, the issue is how AN2 selects the AMF that provides the multi-access network service. In particular, the AMF1 selected in step A should be selected in the same manner.

D. The DS application terminal can connect to the SMF of the CN through the second access network (AN2) and set up a PDU session to receive data service. At this time, the issue is how the AMF (AMF1) selected in step C will select the SMF that provides the multi-access network service. At this time, the same SMF (SMF1) selected in step B may be selected, or a different SMF (SMF2) may be selected. In addition to how the SMF will be selected, the issue is how the PDU session (PDU session 1) set in step B and the PDU session (PDU session 2) set in step D support data service steering, switching, or even simultaneous transmission for each service through the selected SMF.

Figure 2 (b) illustrates a case where, when providing a data service by providing multiple 3GPP accesses to a single terminal through the CN of a single PLMN, different AMFs are selected to provide the service, as in Figure 1 (b). To this end, a terminal applying dual steer can perform the following operations.

A. DS application terminal can access the first access network (AN1) and perform the registration process to the CN's AMF (e.g., AMF1). At this time, the issue is how AN1 selects the AMF that provides the multi-access network service.

B. The DS application terminal can establish a PDU session to receive data service by connecting to the CN's SMF (e.g., SMF1) through the first access network (AN1). At this time, the issue is how the AMF (AMF1) selected in step A selects the SMF that provides the multi-access network service.

C. The DS application terminal can perform the registration process to the CN's AMF (for example, AMF2) through the second access network (AN2). At this time, the issue is how AN2 selects the AMF that provides the multi-access network service. In particular, AMF2, which is different from AMF1 selected in step A, may need to be selected.

D. The DS application terminal can connect to the SMF (for example, SMF2) of the CN through the second access network (AN2) and set up a PDU session to receive data service. At this time, the issue is how the AMF (AMF2) selected in step C will select the SMF that provides the multi-access network service. At this time, the same SMF (SMF1) selected in step B may be selected, or a different SMF (SMF2) may be selected. In addition to how the SMF will be selected, the issue is how the PDU session (PDU session1) set in step B and the PDU session (PDU session2) set in step D can support data service steering, switching, or even simultaneous transmission for each service through the selected SMF.

FIG. 3 illustrates an example of an outline of AMF selection and SMF selection methods in a multi-access network applying dual steer according to an embodiment of the present invention.

Referring to FIG. 3, at step 310, a terminal supporting dual steer can provide (input) information including dual steer information (Info) to the registration process or PDU session setup process.

* Terminal input information may include at least one of the following information: terminal identification information (e.g., SUPI (subscription permanent identifier) (User ID)), AT (access type), RAT (radio access technology), dual steer Info, slice information (e.g., requested S-NSSAIs (single network slice selection assistance information)), etc.

- AT(access type): 3GPP, non-3GPP

- RAT (radio access technology): NR(-TN), NR-NTN, EUTRA

· TN: terrestrial network

· NTN: non-terrestrial network

- Dual steer Info: SUPI1, AN1, AT1, RAT1, PLMN1, AMF1, SMF1, PDU session ID1,

SUPI2, AN2, AT1, RAT1, PLMN2, AMF2, SMF2, PDU session ID2

At step 320, when selecting an AMF, the access network can select the same AMF for each AN by referring to the input of the terminal. Depending on the embodiment, the access network may have difficulty selecting the same AMF or may have to intentionally select different AMFs. For example, when the access network selects an AMF, the following factors may be considered.

* Same AMF cases: AN1 and AN2 have the same RAT or similar coverage/signaling characteristics.

- AN1: NR-TN1, AN2: NR-TN2

- AN1: NR-NTN1, AN2: NR-NTN2

* Different AMFs cases: cases where they have different RATs or different coverage/signaling characteristics.

- AN1: NR-TN1 (Cell ID list1,...), AN2: NR-NTN1 (Cell ID list2,...)

- AN1: NR-TN1 (Cell ID list1,...), AN2: NR-TN2 (Cell ID list2,...)

When an identical AMF is selected, the AMF may consider the following when selecting an SMF:

* SMF selection based on

- AMF context (including DS Info)

- UDM data, NRF (network repository function), UE input, configuration

When different AMFs are selected, each AMF may consider the following when selecting an SMF:

* SMF selection based on

- UDM data (SMF ID of AN1 PDU session stored in DS Info, etc.)

- Inter-AMF signaling (AN1 transmits SMF ID of AN1's PDU session to AN2)

- NRF, UE input, configuration

Specifically, in a single PLMN case, to support dual steer, the 5G system can operate as follows.

1. AMF selection results in the same AMF (method of utilizing the common AMF context when selecting/linking SMF for each 3GPP access network of UE (terminal) in dual steer)

A. RAN selects AMF based on

- UE input (DS Info, DS capability (Cap, ability), DS indication (indicator), requested S-NSSAIs, etc.)

· DS Info: SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1, SUPI2, AN2, PLMN2, AMF2, SMF2, PDU session ID2

- AN configuration

- UDM subscription data (DS support), reselect

- AM policy (selects the same AMF), reselect

- NSSF(network slice selection function)(supported slice info), reselect

B. SMF selection results in the same SMF (P-SMF): AMF selects SMF based on

- AMF context (In case of secondary PDU session request)

- UE input (DS Info, DS Cap, DS indication, DNN (data network name)/S-NSSAI, etc.)

- UDM subscription data (DS support), reselect

- SM policy (selects the same SMF), reselect

C. SMF selection results in different SMFs (P-SMF): AMF selects SMF based on

- UE Input (DS Info, DS Cap, DS indication, DNN/S-NSSAI, etc.)

- UDM subscription data (DS support), reselect

- SM policy (selects the same SMF), reselect

- AMF context to SMFs for inter-SMF signaling (when setting up PDU session of AN2)

2. AMF selection results in the different AMFs (How to use inter-AMF signaling when selecting/connecting SMFs for each 3GPP access network of the UE in dual steer)

A. RAN selects AMF Based on

- UE input (DS Info, DS Cap, DS indication)

- AN configuration

- UDM subscription data (DS support), reselect

- AM policy (selects the same AMF), reselect

-NSSF(supported slice info), reselect

B. SMF selection results in the same SMF (P-SMF): AMF selects SMF based on

- Inter-AMF signaling (In case of secondary PDU session request)

- UE input (DS Info, DS Cap, DS indication, DNN/S-NSSAI, etc.)

- UDM subscription data (DS support), reselect

- SM policy (selects the same SMF), reselect

C. SMF selection results in different SMFs (P-SMF): AMF selects SMF based on

- UE input (DS Info, DS Cap, DS indication, DNN/S-NSSAI, etc.)

- UDM subscription data (DS support), reselect

- SM policy (selects the same SMF), reselect

- Inter-AMF signaling to SMFs for inter-SMF signaling (when setting up PDU session of AN2)

FIG. 4 illustrates an example of a method for selecting the same AMF by utilizing DS Info in AN to support dual steer in a single PLMN according to an embodiment of the present invention.

Referring to FIG. 4, in step 410, a DS-supporting terminal (dual steer device) (401) may transmit a registration request message or a TA (tracking area) update request message to AN1 (first access network, first access network entity) (402). The AN1 (402) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI1, DS Cap1, DS Ind1 (indication 1), DS Info1 (information 1), PLMN1, AN1, Requested NS (network slice) IDs, Cell ID1, etc. SUPI1 is a User ID used by the DS-supporting terminal (401) to access AN1 (402), and is information that is pre-registered in UDM (408) so as to have a common profile with SUPI2. DS Cap1 is a function of the terminal (401) indicating whether the terminal (401) supports the dual steer function. DS Ind1 is information indicating whether the terminal (401) intends to use an application for DS. DS Info1 is information related to the dual steer function of the terminal (401) and may include at least one of the contents of the following [Table 1].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 N/A N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A N/A N/A N/A N/A N/A

At step 410, DS Info1 that the terminal (401) has and transmits to AN1 (402) may include SUPI1, AN1, and PLMN1. In this case, since selection of AMF, SMF, etc. has not been made yet, DS info1 may not include information such as AMF, SMF, and PDU session ID. In the drawing, exemplary DS information stored in the terminal is expressed in bold letters. In addition, in the case of DS information in the drawing that is not expressed in bold letters, it is an exemplary DS information that can be DS information and the DS information is not stored with the corresponding content. For example, in the case of a part written as SUPI2, AN2, PLMN2, AMF2, SMF2, PDU session ID2 in the drawing, if a PDU session is established later, it may be stored as SUPI2, AN2, PLMN1, AMF1, SMF1, PDU session ID2, etc.

In addition, the Requested NS (network slice) IDs represent the IDs of the network slices that the terminal (401) wishes to use by connecting to the corresponding AN1 (402). Cell ID1 is base station information when the terminal (401) connects through AN1 (402), and therefore, can also be utilized as location information of the terminal (401) based on AN1 (402).

At step 415, AN1 (402) can select AMF. At this time, AN1 (402) can select the same AMF as in (a) of Fig. 2. At this time, AN1 (402) can utilize input information of terminal (401) as in 1.A described in the embodiment related to Fig. 3. At this time, AN1 (402) can consider SUPI1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, Requested NS IDs, Cell ID1, etc. when selecting AMF.

At step 420, AN1 (402) can transmit the registration or TA update request message received at step 410 to AMF1 (first AMF) (405), which is the AMF selected (selected) at step 415. At this time, the request message can include at least one of SUPI1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, Requested NS IDs, Cell ID1, etc. In addition, the request message can additionally include AT1 and RAT1 information.

At step 425, AMF1 (405) can receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (408), update it, and request to be notified of future changes (subscription). The subscription data received by AMF1 (405) can include DS support information. DS support is information including whether the corresponding SUPI (SUPI1) supports DS. If DS support is not supported, even if a terminal (401) capable of supporting DS with DS Cap1 sends a registration or TA update request with the intention of supporting DS with DS Ind1, AMF1 (405) can reject the registration or TA update request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (401), AMF1 (405) may send a response including an error cause to the terminal (401) or AN1 (402) by writing the reason why it is not supported in the DS support information.

At step 430, AMF1 (405) may receive access and mobility related policy data (policy request and policy response) through signaling with PCF1 (407), update it, and request notification if there is a change in the future. The policy data received by AMF1 (405) may include information on whether the same AMF is supported for the DS. Whether the same AMF is supported for the DS is information that includes (indicates) whether the corresponding PLMN1 or AMF1 (405) will use the same AMF for the DS for the terminal (401) of the corresponding SUPI.

At step 435, AMF1 (405) can perform a policy update. Then, AMF1 (405) can check the policy information and, if the current AMF1 (405) cannot support the DS service through the same AMF, can start the AMF reselection process.

At step 440, AMF1 (405) can transmit a registration/TA update response message to the DS supporting terminal (401) via AN1 (402). At this time, the response message can include additional information such as policy update, AMF reselection, etc.

At step 445, if necessary, a UE policy update process can be performed between the terminal (401) and PCF1 (407). In addition, an AMF reselection process can be performed if necessary, and after another AMF is selected other than the previously selected AMF1 (405), steps 410 to 440 can be performed again. When registration/TA update is completed, the terminal (401), AN1 (402), and AMF1 (405) can store DS Info, and UDM (408) can record the DS Info and information of AMF1 (405). At this time, the DS Info to be stored can be as shown in the following [Table 2].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A N/A N/A N/A N/A N/A

When step 445 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1.

At step 450, the DS-supporting terminal can transmit a registration or TA update request message to AN2 (second access network, second access network entity) (403). The AN2 (403) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, Requested NS IDs, Cell ID2, etc. SUPI2 is a User ID used by the DS-supporting terminal (401) to access AN2 (403) and is information that is pre-registered in the UDM (408) so that it has a common profile with SUPI1. DS Cap2 indicates a function of the terminal (401) whether the terminal (401) supports the dual steer function. DS Ind2 is information that indicates whether the terminal (401) intends to use a DS application. DS Info2 is information related to the dual steer function of this terminal (401) and may include at least one of the contents of [Table 3] below.

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 N/A N/A N/A

At step 450, the DS Info2 that the terminal (401) has and transmits to AN2 (403) may include SUPI2, AN2, and PLMN1. In this case, since selection of AMF, SMF, etc. has not yet been made in the registration procedure to AN2 (403), information such as AMF, SMF, and PDU session ID may not be included in DS Info2. In addition, DS Info2 may include SUPI1, AN1, PLMN1, and AMF1 information that are stored in the registration procedure to AN1 (402).

In addition, Requested NS IDs represent the IDs of the network slices that the terminal (401) wishes to use by connecting to the corresponding AN2 (403). Cell ID2 is base station information when the terminal (401) connects through AN2 (403), and therefore, can also be utilized as location information of the terminal (401) based on AN2 (403).

At step 455, AN2 (403) can select AMF. At this time, AN2 (403) can select the same AMF as in (a) of Fig. 2. At this time, AN2 can utilize input information of terminal (401) as in 1.A described in the embodiment related to Fig. 3. At this time, AN2 (403) can consider SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, Requested NS IDs, Cell ID2, etc. when selecting AMF.

At step 460, AN2 (403) can transmit the registration or TA update request message received at step 450 to AMF1 (405), which is the AMF selected at step 455. At this time, the request message can include at least one of SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN2, AN2, Requested NS IDs, Cell ID2, etc.

At step 465, AMF1 (405) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (408), update it, and request to be notified of any changes in the future. The subscription data received by AMF1 (405) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI2) supports DS. If DS support is not supported, even though a terminal (401) capable of supporting DS with DS Cap2 sends a registration or TA update request with the intention of supporting DS with DS Ind2, AMF1 (405) may reject the registration or TA update request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (401), AMF1 (405) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (401) or AN2 (403).

At step 470, AMF1 (405) may receive access and mobility related policy data (policy request and policy response) through signaling with PCF1 (407), update it, and request notification if there is a change in the future. The policy data received by AMF1 (405) may include information on whether the same AMF for the DS is supported. Whether the same AMF for the DS is supported is information that includes (indicates) whether the corresponding PLMN1 or AMF1 (405) will use the same AMF for the DS for the terminal (401) of the corresponding SUPI (SUPI2).

At step 475, AMF1 (405) can perform a policy update. Then, AMF1 (405) can check the policy information and, if the current AMF1 (405) cannot support the DS service through the same AMF, can start the AMF re-selection process.

At step 480, AMF1 (405) can transmit a registration/TA update response message to the DS supporting terminal (401) via AN2 (403). At this time, the response message can include additional information such as policy update, AMF reselection, etc.

At step 485, if necessary, a UE policy update process can be performed between the terminal (401) and PCF1 (407). In addition, an AMF reselection process can be performed if necessary, and after another AMF is selected other than the previously selected AMF1 (405), steps 450 to 480 can be performed again. When registration/TA update is completed, the terminal (401), AN2 (403), and AMF1 (405) can store DS Info, and UDM (408) can record the DS Info and information of AMF1 (405). At this time, the DS Info to be stored can be as shown in the following [Table 4].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF1 N/A N/A

When step 485 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SUPI2, AN2, PLMN1, AMF1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1, and AMF1 is selected when connecting to AN2 belonging to PLMN1 while requesting DS support with SUPI2.

FIG. 5 illustrates an example of a method for selecting the same AMF through an AMF reselection process to support dual steer in a single PLMN according to an embodiment of the present invention.

Referring to FIG. 5, in step 510, the DS-supporting terminal (501) may transmit a registration or TA update request message to AN1 (502). The AN1 (502) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, Requested NS IDs, Cell ID1, etc. SUPI1 is a User ID used by the DS-supporting terminal (501) to access AN1 (502) and is information that is pre-registered in the UDM (508) so that it has a common profile with SUPI2. DS Cap1 indicates a function of the terminal (501) whether the terminal (501) supports the dual steer function. DS Ind1 is information that indicates whether the terminal (501) intends to use a DS application. DS Info1 is information related to the dual steer function of this terminal (501) and may include at least one of the contents of [Table 5] below.

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 N/A N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A N/A N/A N/A N/A N/A

At step 510, DS Info1 that the terminal (501) has and transmits to AN1 (502) may include SUPI1, AN1, and PLMN1. That is, since selection of AMF, SMF, etc. has not yet been made, DS info1 may not include information such as AMF, SMF, and PDU session ID.

In addition, Requested NS IDs represent the IDs of the network slices that the terminal (501) wishes to use by connecting to the corresponding AN1 (502). Cell ID1 is base station information when the terminal (501) connects through AN1 (502), and therefore, can also be utilized as location information of the terminal (501) based on AN1 (502).

At step 515, AN1 (502) can select an AMF. At this time, AN1 (502) can select the same AMF as in (a) of FIG. 2 or can select a different AMF as in (b) of FIG. 2. At this time, AN1 (502) can utilize input information of terminal (501) as in 1.A or 2.A described in the embodiment related to FIG. 3. At this time, AN1 (502) can consider SUPI1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, Requested NS IDs, Cell ID1, etc. when selecting an AMF.

At step 520, AN1 (502) can transmit the registration or TA update request message received at step 510 to AMF1 (505), which is the AMF selected at step 515. At this time, the request message can include at least one of SUPI1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, Requested NS IDs, Cell ID1, etc. In addition, the request message can additionally include AT1 and RAT1 information.

At step 525, AMF1 (505) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (508), update it, and request to be notified of any changes in the future. The subscription data received by AMF1 (505) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI1) supports DS. If DS support is not supported, even though a terminal (501) capable of supporting DS with DS Cap1 sends a registration or TA update request with the intention of supporting DS with DS Ind1, AMF1 (505) may reject the registration or TA update request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (501), AMF1 (505) may send a response including an error cause to the terminal (501) or AN1 (502) by writing the reason that it is not supported in the DS support information.

At step 530, AMF1 (505) may receive access and mobility related policy data (policy request and policy response) through signaling with PCF1 (507), update it, and request notification if there is a change in the future. The policy data received by AMF1 (505) may include information on whether the same AMF for the DS is supported. The same AMF for the DS is information that includes (indicates) whether the corresponding PLMN1 or AMF1 (505) will use the same AMF for the DS for the terminal (501) of the corresponding SUPI.

At step 535, AMF1 (505) can perform a policy update. Then, AMF1 (505) can check the policy information and, if the current AMF1 (505) cannot support the DS service through the same AMF, can start the AMF reselection process.

At step 540, AMF1 (505) can transmit a registration/TA update response message to the DS supporting terminal (501) via AN1 (502). At this time, the response message can include additional information such as policy update, AMF reselection, etc.

At step 545, if necessary, a UE policy update process can be performed between the terminal (501) and PCF1 (507). In addition, an AMF reselection process can be performed if necessary, and after another AMF is selected other than the previously selected AMF1 (505), steps 510 to 540 can be performed again. When registration/TA update is completed, the terminal (501), AN1 (502), and AMF1 (505) can store DS Info, and UDM (508) can record the DS Info and information of AMF1 (505). At this time, the DS Info to be stored can be as shown in the following [Table 6].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A N/A N/A N/A N/A N/A

When step 545 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1.

At step 550, the DS-supporting terminal (501) can transmit a registration or TA update request message to AN2 (503). The AN2 (503) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, Requested NS IDs, Cell ID2, etc. SUPI2 is a User ID used by the DS-supporting terminal (501) to access AN2 (503) and is information that is pre-registered in the UDM (508) so that it has a common profile with SUPI1. DS Cap2 indicates a function of the terminal (501) to determine whether the terminal (501) supports the dual steer function. DS Ind2 is information that indicates whether the terminal (501) intends to use a DS application. DS Info2 is information related to the dual steer function of this terminal (501) and may include at least one of the contents of [Table 7] below.

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 N/A N/A N/A

At step 550, DS Info2 that the terminal (501) has and transmits to AN2 (503) may include SUPI2, AN2, and PLMN1. That is, since selection of AMF, SMF, etc. has not yet been made in the registration procedure to AN2 (503), information such as AMF, SMF, and PDU session ID may not be included in DS Info2. In addition, DS Info2 may include SUPI1, AN1, PLMN1, and AMF1 information that are stored in the registration procedure to AN1 (502).

In addition, Requested NS IDs represent the IDs of the network slices that the terminal (501) wishes to use by connecting to the corresponding AN2 (503). Cell ID2 is base station information when the terminal (501) connects through AN2 (503), and therefore, can also be utilized as location information of the terminal (501) based on AN2 (503).

At step 555, AN2 (503) can select AMF. At this time, AN2 (503) can select AMF (AMF2) (509) different from AMF (AMF1) (505) selected by AN1 (502) as shown in (b) of FIG. 2. At this time, AN2 (503) can utilize input information of terminal (501) as described in 2.A in the embodiment related to FIG. 3. At this time, AN2 (503) can consider SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, Requested NS IDs, Cell ID2, etc. when selecting AMF.

At step 560, AN2 (503) can transmit the registration or TA Update request message received at step 550 to AMF2 (509), which is the AMF selected (selected) at step 555. At this time, the request message can include at least one of SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN2, AN2, Requested NS IDs, Cell ID2, etc.

At step 565, AMF2 (509) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (508), update it, and request to be notified of any changes in the future. The subscription data received by AMF2 (509) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI2) supports DS. If DS support is not supported, even though a terminal (501) capable of supporting DS with DS Cap2 sends a registration or TA update request with the intention of supporting DS with DS Ind2, AMF2 (509) may reject the registration or TA update request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (501), AMF2 (509) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (501) or AN2 (503).

At step 570, AMF2 (509) may receive access and mobility related policy data (policy request and policy response) through signaling with PCF1 (507), update it, and request notification if there is a change in the future. The policy data received by AMF2 (509) may include information on whether the same AMF for the DS is supported. The same AMF for the DS is information that includes (indicates) whether the corresponding PLMN1 or AMF2 (509) will use the same AMF for the DS for the terminal (501) of the corresponding SUPI (SUPI2).

At step 575, AMF2 (509) can perform a policy update. Then, AMF2 (509) can check the policy information and, if the current AMF2 (509) cannot support the DS service through the same AMF, can start the AMF reselection process or the AMF relocation process.

At step 577, AMF2 (509) may perform an AMF reallocation process. Depending on the embodiment, AMF2 (509) may directly route a registration or TA update request message to AMF1 (505), or AMF2 (509) may route a registration or TA update request message to AMF1 (505) via AN2 (503). If step 577 is performed, step 585 may be performed instead of step 580.

At step 580, AMF2 (509) can transmit a registration/TA update response message to the DS supporting terminal (501) via AN2 (503). At this time, the response message can include additional information of AMF reselection. In addition, the response message can include additional information of policy update.

At step 585, AMF1 (505) can transmit a registration/TA update response message to the DS supporting terminal (501) via AN2 (503). At this time, the response message can include additional information of AMF reselection. In addition, the response message can include additional information of policy update. If step 585 is performed, step 580 is not performed.

At step 590, if necessary, an AMF reselection process may be performed, and after another AMF, AMF1 (505), is selected in addition to the previously selected AMF2 (509), the preceding steps 550 to 580 may be performed again. For example, this may be the case when the registration request to AN1 (502) and the registration request to AN2 (503) are performed simultaneously, resulting in the selection of different AMFs. If steps 577 and 585 are performed, the AMF reselection process may not be performed.

And, if necessary, a UE policy update process can be performed between the terminal (501) and PCF1 (507). When registration/TA update is completed, the terminal (501), AN2 (503), and AMF1 (505) store DS Info, and UDM (508) records the DS Info and information of AMF1 (505). At this time, the DS Info to be stored can be as shown in the following [Table 8].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF1 N/A N/A

When step 590 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SUPI2, AN2, PLMN1, AMF1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1, and AMF1 is selected when connecting to AN2 belonging to PLMN1 while requesting DS support with SUPI2.

FIG. 6 illustrates an example of a method for selecting the same SMF when using the same AMF to support dual steer in a single PLMN according to an embodiment of the present invention.

In this embodiment, the same SMF is selected when the target DNN/S-NSSAI is the same. And, when the target DNN/S-NSSAI is different, the same SMF may not be selected.

Referring to FIG. 6, at step 610, the DS-supporting terminal (601) can transmit a PDU (protocol data unit) session establishment request message to AMF1 (605) via AN1 (602). The AN1 (602) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI1, PDU session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSA, etc. SUPI1 is a User ID used by the DS-supporting terminal (601) to access AN1 (602), and is information that is pre-registered in UDM (608) so that it has a common profile with SUPI2. PDU session ID1 is an identifier assigned to a PDU session generated based on the corresponding SUPI, SUPI1. DS Cap1 is a function of the terminal (601) indicating whether the terminal (601) supports the dual steer function. DS Ind1 is information indicating whether the terminal (601) intends to use an application for DS. DS Info1 is information related to the dual steer function of the terminal (601) and may include at least one of the contents of the following [Table 9].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A or SUPI2 N/A or AN2 N/A or PLMN1 N/A or AMF1 N/A N/A

At step 610, DS Info1 that the terminal (601) has and transmits to AMF1 (605) may include SUPI1, AN1, PLMN1, AMF1, and PDU session ID1. In this case, since the terminal (601) requests establishment for a PDU session corresponding to PDU session ID1 and SMF selection has not yet been performed, DS info1 may not include information such as SMF. In addition, DS Info1 may include SUPI2, AN2, PLMN1, and AMF1 information that are stored in the registration procedure with AN2 (603).

In addition, DNN/S-NSSAI indicates the ID of the network slice that the terminal (601) wishes to use by connecting to the corresponding AN1 (602) and the data network name to be used in the network slice.

At step 615, AMF1 (605) can select SMF. At this time, AMF1 (605) can utilize input information of terminal (601) and context within AMF (605) as described in 1.B in the embodiment related to Fig. 3. At this time, AMF1 (605) can consider SUPI1, PDU Session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, Cell ID1, etc. when selecting SMF.

At step 620, AMF1 (605) can transmit the PDU session establishment request message received at step 610 to SMF1 (603), which is the SMF selected (selected) at step 615. At this time, the request message can include at least one of SUPI1, PDU session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, Cell ID1, etc.

At step 625, SMF1 (606) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (608), update it, and request to be notified of any changes in the future. The subscription data received by SMF1 (606) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI1) supports DS. If DS support is not supported, even though a terminal (601) capable of supporting DS with DS Cap1 sends a PDU session establishment request with the intention of supporting DS with DS Ind1, SMF1 (606) may reject the PDU session establishment request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (601), SMF1 (606) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (601), AN1 (602), or AMF1 (605).

At step 630, SMF1 (606) may receive (policy request and policy response) session management related policy data through signaling with PCF1 (607), update it, and request notification if there is a change in the future. The policy data received by SMF1 (606) may include information on whether the same SMF for the DS is supported. Whether the same SMF for the DS is supported is information that includes (indicates) whether the corresponding PLMN1 or SMF1 (606) will use the same SMF for the DS for the terminal (601) of the corresponding SUPI (SUPI1).

At step 635, SMF1 (606) can perform a policy update. Then, SMF1 (606) can check the policy information and, if the current SMF1 (606) cannot support the DS service through the same SMF, can start the SMF reselection process.

At step 640, SMF1 (606) can transfer (send) a PDU session establishment response message (e.g., a PDU session establishment accept message) to AMF1 (605). At this time, the response message can include additional information such as policy update and SMF reselection.

At step 643, if SMF reselection was requested at step 640, AMF1 (605) can select SMF again. At step 643, SMF1 (606) can select UPF (604) and perform N4 protocol signaling (UPF N4 setup) to set up a path to UPF (604) via terminal (601) and AN1 (602) of SUPI1 for PDU session 1. After that, SMF1 (606) can store PDU session ID1, DS Info, etc.

At step 645, AMF1 (605) can transmit the PDU session establishment response message received at step 640 or additionally updated at step 643 to the DS supporting terminal (601) via AN1 (602). At this time, the response message can include additional information such as policy update and SMF reselection.

At step 650, if necessary, a UE policy update process can be performed between the terminal (601) and PCF1 (607). In addition, an SMF reselection process can be performed if necessary, and after another SMF is selected other than the previously selected SMF1 (606), steps 610 to 645 can be performed again. When PDU session establishment is completed, the terminal (601), AN1 (602), AMF1 (605), and SMF1 (606) can store DS Info, and UDM (608) can record the DS Info and information of SMF1 (606). At this time, the DS Info to be stored can be as shown in the following [Table 10].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A or SUPI2 N/A or AN2 N/A or PLMN1 N/A or AMF1 N/A N/A

If step 650 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1, and SMF1 is selected for establishing a PDU session corresponding to PDU session ID1. DS Info may include SUPI2, AN2, PLMN1, AMF1 information stored in the registration procedure with AN2 (603).

At step 655, the DS-supporting terminal (601) can transmit a PDU session establishment request message to AMF1 (605) via AN2 (603). The AN2 (603) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc. SUPI2 is a User ID used by the DS-supporting terminal (601) to access AN2 (603) and is information that is registered in advance in the UDM (608) so that it has a common profile with SUPI1. PDU session ID2 is an identifier assigned to a PDU session generated based on the corresponding SUPI, SUPI2. DS Cap2 indicates a function of the terminal, indicating whether the terminal (601) supports the dual steer function. DS Ind2 is information indicating whether this terminal (601) intends to use an application for DS. DS Info2 is information related to the dual steer function of this terminal (601) and may include at least one of the contents of the following [Table 11].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF1 N/A PDU Session ID2

At step 655, DS Info2 that the terminal (601) has and transmits to AMF1 (605) may include SUPI2, AN2, PLMN1, AMF1, and PDU session ID2. In this case, since the terminal (601) requests establishment for a PDU session corresponding to PDU session ID2 and SMF selection has not yet been performed, DS info2 may not include information such as SMF. In addition, DS Info2 may include SUPI1, AN1, PLMN1, AMF1, SMF1, and PDU session ID1 information that are stored in the PDU session establishment procedure to AN1 (602).

In addition, DNN/S-NSSAI indicates the ID of the network slice that the terminal (601) wishes to use by connecting to the corresponding AN2 (603) and the data network name to be used in the network slice.

At step 660, AMF1 (605) can select SMF. At this time, AMF1 (605) can utilize input information of terminal (601) and context within AMF (605) as described in 1.B in the embodiment related to Fig. 3. At this time, AMF1 (605) can consider SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc. when selecting SMF.

At step 665, AMF1 (605) can transmit the PDU session establishment request message received at step 655 to SMF1 (606), which is the SMF selected (selected) at step 660. At this time, the request message can include at least one of SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc.

At step 670, SMF1 (606) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (608), update it, and request to be notified of any changes in the future. The subscription data received by SMF1 (606) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI2) supports DS. If DS support is not supported, even though a terminal (601) capable of supporting DS with DS Cap2 sends a PDU session establishment request with the intention of supporting DS with DS Ind2, SMF1 (606) may reject the PDU session establishment request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (601), SMF1 (606) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (601), AN2 (603), or AMF1 (605).

At step 675, SMF1 (606) may receive (policy request and policy response) session management related policy data through signaling with PCF1 (607), update it, and request notification if there is a change in the future. The policy data received by SMF1 (606) may include information on whether the same SMF for the DS is supported. Whether the same SMF for the DS is supported is information that includes (indicates) whether the corresponding PLMN1 or SMF1 (606) will use the same SMF for the DS for the terminal (601) of the corresponding SUPI (SUPI2).

At step 680, SMF1 (606) can perform a policy update. Then, SMF1 (606) can check the policy information and, if the current SMF1 (606) cannot support the DS service through the same SMF, can start the SMF reselection process.

At step 685, SMF1 (606) can transfer (send) a PDU session establishment response message (e.g., PDU session establishment accept message) to AMF1 (605). At this time, the response message can include additional information such as policy update, SMF reselection, etc.

At step 687, if SMF reselection was requested at step 685, AMF1 (605) can select SMF again. At step 687, SMF1 (606) can select UPF (604) and perform N4 protocol signaling (UPF N4 setup) to set up a path to UPF (604) via terminal (601) and AN2 (603) of SUPI2 for PDU session 2. After that, SMF1 (606) can store PDU session ID2, DS Info, etc.

At step 690, AMF1 (605) can transmit the PDU session establishment response message received at step 685 or additionally updated at step 687 to the DS supporting terminal (601) via AN2 (603). At this time, the response message can include additional information such as policy update and SMF reselection.

In step 695, if necessary, a UE policy update process can be performed between the terminal (601) and PCF1 (607). In addition, an SMF reselection process can be performed if necessary, and after another SMF is selected other than the previously selected SMF1 (606), steps 655 to 690 can be performed again. For example, this may be the case when the PDU session request to AN1 (602) and the PDU session request to AN2 (603) are performed simultaneously and different SMFs are selected.

When PDU session establishment is completed, terminal (601), AN2 (603), AMF1 (605), and SMF1 (606) can store DS Info, and UDM (608) can record DS Info and information of SMF1 (606). At this time, the DS Info to be stored can be as shown in the following [Table 12].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF1 SMF1 PDU Session ID2

If step 695 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1, SUPI2, AN2, PLMN1, AMF1, SMF1, PDU session ID2 as illustrated. For example, DS info may include information that when requesting DS support with SUPI1 and connecting to AN1 belonging to PLMN1, AMF1 is selected and SMF1 is selected for PDU session establishment corresponding to PDU session ID1, and when requesting DS support with SUPI2 and connecting to AN2 belonging to PLMN1, AMF1 is selected and SMF1 is selected for PDU session establishment corresponding to PDU session ID2.

FIG. 7 illustrates an example of a method for selecting a different SMF when using the same AMF to support dual steer in a single PLMN according to an embodiment of the present invention.

In this embodiment, it is required when the target DNN/S-NSSAI is the same, and may not be used when the target DNN/S-NSSAI is different.

Referring to FIG. 7, in step 710, the DS-supporting terminal (701) can transmit a PDU session establishment request message to AMF1 (705) via AN1 (702). The AN1 (702) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI1, PDU session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, etc. SUPI1 is a User ID used by the DS-supporting terminal (701) to access AN1 (702) and is information that is pre-registered in UDM (708) so that it has a common profile with SUPI2. PDU session ID1 is an identifier assigned to a PDU session generated based on the corresponding SUPI, SUPI1. DS Cap1 indicates a function of the terminal (701) whether the terminal supports the dual steer function. DS Ind1 is information indicating whether this terminal (701) intends to use an application for DS. DS Info1 is information related to the dual steer function of this terminal (701) and may include at least one of the contents of the following [Table 13].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A or SUPI2 N/A or AN2 N/A or PLMN1 N/A or AMF1 N/A N/A

At step 710, DS Info1 that the terminal (701) has and transmits to AMF1 (705) may include SUPI1, AN1, PLMN1, AMF1, and PDU session ID1. In this case, since the terminal (701) requests establishment for a PDU session corresponding to PDU session ID1 and SMF selection has not yet been performed, information such as SMF may not be included in DS info1. In addition, DS Info1 may include SUPI2, AN2, PLMN1, and AMF1 information that are stored in the registration procedure with AN2 (703).

In addition, DNN/S-NSSAI indicates the ID of the network slice that the terminal (701) wishes to use by connecting to the corresponding AN1 (702) and the data network name to be used in the network slice.

At step 715, AMF1 (705) can select SMF. At this time, AMF1 (705) can utilize input information of terminal (701) and context within AMF (705) as described in 1.B or 1.C in the embodiment related to Fig. 3. At this time, AMF1 (705) can consider SUPI1, PDU Session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, Cell ID1, etc. when selecting SMF.

At step 720, AMF1 (705) can transmit the PDU session establishment request message received at step 710 to SMF1 (706), which is the SMF selected (selected) at step 715. At this time, the request message can include at least one of SUPI1, PDU session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, Cell ID1, etc.

At step 725, SMF1 (706) may receive subscription data (subscription data request and response), update it, and request to be notified of any changes in the future through signaling with UDM (or UDR) (708). The subscription data received by SMF1 (706) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI1) supports DS. If DS support is not supported, even though a terminal (701) capable of supporting DS with DS Cap1 sends a PDU session establishment request with the intention of supporting DS with DS Ind1, SMF1 (706) may reject the PDU session establishment request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (701), SMF1 (706) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (701), AN1 (702), or AMF1 (705).

At step 727, SMF1 (706) may receive (policy request and policy response) session management related policy data through signaling with PCF1 (707), update it, and request notification if there is a change in the future. The policy data received by SMF1 (706) may include information on whether the same SMF for the DS is supported. Whether the same SMF for the DS is supported is information that includes (indicates) whether the corresponding PLMN1 or SMF1 (706) will use the same SMF for the DS for the terminal (701) of the corresponding SUPI (SUPI1).

At step 730, SMF1 (706) can perform a policy update. Then, SMF1 (706) can check the policy information and, if the current SMF1 (706) cannot support the DS service through the same SMF, can start the SMF reselection process.

At step 735, SMF1 (706) can transfer (send) a PDU session establishment response message (e.g., PDU session establishment accept message) to AMF1 (705). At this time, the response message can include additional information such as policy update, SMF reselection, etc.

At step 737, if SMF reselection was requested at step 735, AMF1 (705) can select SMF again. At step 737, SMF1 (706) can select UPF (704) and perform N4 protocol signaling (UPF N4 setup) to set up a path to UPF (704) via terminal (701) and AN1 (702) of SUPI1 for PDU session 1. After that, SMF1 (706) can store PDU session ID1, DS Info, etc.

At step 740, AMF1 (705) can transmit the PDU session establishment response message received at step 735 or additionally updated at step 737 to the DS supporting terminal (701) via AN1 (702). At this time, the response message can include additional information such as policy update and SMF reselection.

In step 745, if necessary, a UE policy update process can be performed between the terminal (701) and PCF1 (707). In addition, if necessary, an SMF reselection process can be performed, and after another SMF is selected other than the previously selected SMF1 (706), steps 710 to 740 can be performed again. When PDU session establishment is completed, the terminal (701), AN1 (702), AMF1 (705), and SMF1 (706) can store DS Info, and UDM (708) can record the DS Info and information of SMF1 (706). At this time, the DS Info to be stored can be as shown in the following [Table 14].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A or SUPI2 N/A or AN2 N/A or PLMN1 N/A or AMF1 N/A N/A

If step 745 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1, and SMF1 is selected for establishing a PDU session corresponding to PDU session ID1. In addition, DS Info may include SUPI2, AN2, PLMN1, AMF1 information stored in the registration procedure with AN2 (703).

At step 750, the DS-supporting terminal (701) can transmit a PDU session establishment request message to AMF1 (705) via AN2 (703). The AN2 (703) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc. SUPI2 is a User ID used by the DS-supporting terminal (701) to access AN2 (703) and is information that is pre-registered in UDM (708) so that it has a common profile with SUPI1. PDU session ID2 is an identifier assigned to a PDU session generated based on the corresponding SUPI, SUPI2. DS Cap2 indicates a function of the terminal (701) whether the terminal supports the dual steer function. DS Ind2 is information indicating whether this terminal (701) intends to use an application for DS. DS Info2 is information related to the dual steer function of this terminal (701) and may include at least one of the contents of the following [Table 15].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF1 N/A PDU Session ID2

At step 750, DS Info2 that the terminal (701) has and transmits to AMF1 (705) may include SUPI2, AN2, PLMN1, AMF1, and PDU session ID2. In this case, since the terminal (701) requests establishment for a PDU session corresponding to PDU session ID2 and SMF selection has not yet been performed, DS info2 may not include information such as SMF. In addition, DS Info2 may include SUPI1, AN1, PLMN1, AMF1, SMF1, and PDU session ID1 information that are stored in the PDU session establishment procedure to AN1 (702).

In addition, DNN/S-NSSAI indicates the ID of the network slice that the terminal (701) wishes to use by connecting to the corresponding AN2 (703) and the data network name to be used in the network slice.

At step 755, AMF1 (705) can select SMF. At this time, AMF1 (705) can utilize input information of terminal (701) and context within AMF (705) as described in 1.C in the embodiment related to FIG. 3. At this time, AMF1 (705) can consider SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc. when selecting SMF.

At step 760, AMF1 (705) can transmit the PDU session establishment request message received at step 750 to SMF2 (709), which is the SMF selected (selected) at step 755. At this time, the request message can include at least one of SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc.

At step 765, SMF2 (709) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (708), update it, and request to be notified of any changes in the future. The subscription data received by SMF2 (709) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI2) supports DS. If DS support is not supported, even though a terminal (701) capable of supporting DS with DS Cap2 sends a PDU session establishment request with the intention of supporting DS with DS Ind2, SMF2 (709) may reject the PDU session establishment request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (701), SMF2 (709) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (701), AN2 (703), or AMF1 (705).

At step 767, SMF2 (709) may receive (policy request and policy response) session management related policy data through signaling with PCF1 (707), update it, and request notification if there is a change in the future. The policy data received by SMF2 (709) may include information on whether the same SMF for the DS is supported. The same SMF for the DS is information that includes (indicates) whether the corresponding PLMN1 or SMF2 (709) will use the same SMF for the DS for the terminal (701) of the corresponding SUPI (SUPI2).

At step 770, SMF2 (709) can perform a policy update. Then, SMF2 (709) can check the policy information and, if the current SMF2 (709) cannot support the DS service through the same SMF, can start the SMF reselection process.

At step 775, SMF2 (709) can transfer (send) a PDU session establishment response message (e.g., PDU session establishment accept message) to AMF1 (705). At this time, the response message can include additional information such as policy update, SMF reselection, etc.

At step 777, if SMF reselection was requested at step 775, AMF1 (705) can select SMF again. At step 777, SMF2 (709) can select UPF (704) and perform N4 protocol signaling (UPF N4 setup) to set up a path to UPF (704) via terminal (701) and AN2 (703) of SUPI2 for PDU session 2. After that, SMF2 (709) can store PDU session ID2, DS Info, etc.

At step 780, AMF1 (705) can transmit the PDU session establishment response message received at step 775 or additionally updated at step 777 to the DS supporting terminal (701) via AN2 (703). At this time, the response message can include additional information such as policy update and SMF reselection.

At step 785, if necessary, a UE policy update process can be performed between the terminal (701) and PCF1 (707). In addition, an SMF reselection process can be performed if necessary, and after another SMF is selected other than the previously selected SMF2 (709), steps 750 to 780 can be performed again. When PDU session establishment is completed, the terminal (701), AN2 (703), AMF1 (705), and SMF2 (709) can store DS Info, and UDM (708) can record the DS Info and information of SMF2 (709). At this time, the DS Info to be stored can be as shown in the following [Table 16].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF1 SMF2 PDU Session ID2

If step 785 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1, SUPI2, AN2, PLMN1, AMF1, SMF2, PDU session ID2 as illustrated. For example, DS info may include information that when requesting DS support with SUPI1 and connecting to AN1 belonging to PLMN1, AMF1 is selected and SMF1 is selected for PDU session establishment corresponding to PDU session ID1, and when requesting DS support with SUPI2 and connecting to AN2 belonging to PLMN1, AMF1 is selected and SMF2 is selected for PDU session establishment corresponding to PDU session ID2.

According to an embodiment, at step 790, AMF1 (705) may send SMF1 (706) a PDU session update request for PDU session 1 or an information notification to update PDU session related context. The PDU session update request or the information notification to update PDU session related context may include at least one of PDU session ID2, SMF2 and PDU session ID1, SMF1. DS Info. Upon receiving this, SMF1 (706) updates DS Info, recognizes that PDU session 2 using AN2 (703) related to PDU session 1 using AN1 (702) has been created, and may perform data steering, switching, or simultaneous data transmission for each service in the two PDU sessions according to each status change.

According to an embodiment, at step 795, UDM (708) may send SMF1 (706) a PDU session update request for PDU session 1 or an information notification to update PDU session related context. The PDU session update request or the information notification to update PDU session related context may include at least one of PDU session ID2, SMF2 and PDU session ID1, SMF1. DS Info. Upon receiving this, SMF1 (706) updates DS Info, recognizes that PDU session 2 using AN2 (703) associated with PDU session 1 using AN1 (702) has been created, and may perform data steering, switching, or simultaneous data transmission for each service in the two PDU sessions according to each status change.

According to an embodiment, at step 797, SMF2 (709) may send SMF1 (706) a PDU session update request for PDU session1 or an information notification to update PDU session related context. The PDU session update request or the information notification to update PDU session related context may include at least one of PDU session ID2, SMF2 and PDU session ID1, SMF1. DS Info. Upon receiving this, SMF1 (706) updates DS Info, recognizes that PDU session 2 using AN2 (703) associated with PDU session 1 using AN1 (702) has been created, and may perform data steering, switching, or simultaneous data transmission for each service in the two PDU sessions according to each status change.

FIG. 8 illustrates an example of a method for selecting a different AMF to support dual steer in a single PLMN according to an embodiment of the present invention.

Referring to FIG. 8, in step 810, the DS-supporting terminal (801) may transmit a registration or TA update request message to AN1 (802). The AN1 (802) may be a base station, but is not limited thereto. At this time, the request message may include SUPI1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, Requested NS IDs, Cell ID1, etc. SUPI1 is a User ID used by the DS-supporting terminal (801) to access AN1 (802), and is information that is pre-registered in the UDM (808) so that it has a common profile with SUPI2. DS Cap1 indicates a function of the terminal (801) to determine whether the terminal (801) supports the dual steer function. DS Ind1 is information that indicates whether the terminal (801) intends to use a DS application. DS Info1 is information related to the dual steer function of this terminal (801) and may include at least one of the contents of [Table 17] below.

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 N/A N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A N/A N/A N/A N/A N/A

At step 810, DS Info1 that the terminal (801) has and transmits to AN1 (802) may include SUPI1, AN1, and PLMN1. That is, since selection of AMF, SMF, etc. has not yet been made, DS info1 may not include information such as AMF, SMF, and PDU session ID.

In addition, Requested NS IDs represent the IDs of the network slices that the terminal (801) wishes to use by connecting to the corresponding AN1 (802). Cell ID1 is base station information when the terminal (801) connects through AN1 (802), and therefore, can also be utilized as location information of the terminal (801) based on AN1 (802).

At step 815, AN1 (802) can select an AMF. At this time, AN1 (802) can select a different AMF as shown in Fig. 2(b). At this time, AN1 (802) can utilize input information of terminal (801) as described in 2.A in the embodiment related to Fig. 3. At this time, AN1 (802) can consider SUPI1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, Requested NS IDs, Cell ID1, etc. when selecting an AMF.

At step 820, AN1 (802) can transmit the registration or TA update request message received at step 810 to AMF1 (805), which is the AMF selected (selected) at step 815. At this time, the request message can include at least one of SUPI1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, Requested NS IDs, Cell ID1, etc.

At step 825, AMF1 (805) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (808), update it, and request to be notified of any changes in the future. The subscription data received by AMF1 (805) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI1) supports DS. If DS support is not supported, even though a terminal (801) capable of supporting DS with DS Cap1 sends a registration or TA update request with the intention of supporting DS with DS Ind1, AMF1 (805) may reject the registration or TA update request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (801), AMF1 (805) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (801) or AN1 (802).

At step 830, AMF1 (805) may receive access and mobility related policy data (policy request and policy response) through signaling with PCF1 (807), update it, and request notification if there is a change in the future. The policy data received by AMF1 (805) may include information on whether the same AMF for the DS is supported. The same AMF for the DS is information that includes (indicates) whether the PLMN1 or AMF1 (805) will use the same AMF for the DS for the terminal of the SUPI.

At step 835, AMF1 (805) can perform a policy update. Then, AMF1 (805) can check the policy information and, if the current AMF1 (805) cannot support the DS service through the same AMF, can start the AMF re-selection process.

At step 840, AMF1 (805) can transmit a registration/TA update response message to the DS supporting terminal (801) via AN1 (802). At this time, the response message can include additional information such as policy update, AMF reselection, etc.

At step 845, if necessary, a UE policy update process can be performed between the terminal (801) and PCF1 (807). In addition, an AMF reselection process can be performed if necessary, and after another AMF is selected other than the previously selected AMF1 (805), steps 810 to 840 can be performed again. When registration/TA update is completed, the terminal (801), AN1 (802), and AMF1 (805) can store DS Info, and UDM (808) can record the DS Info and information of AMF1 (805). At this time, the DS Info to be stored can be as shown in the following [Table 18].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A N/A N/A N/A N/A N/A

When step 845 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1.

At step 850, the DS-supporting terminal (801) can transmit a registration or TA update request message to AN2 (803). The AN2 (803) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, Requested NS IDs, Cell ID2, etc. SUPI2 is a User ID used by the DS-supporting terminal (801) to access AN2 (803) and is information pre-registered in the UDM to have a common profile with SUPI1. DS Cap2 indicates a function of the terminal (801) to determine whether the terminal (801) supports the dual steer function. DS Ind2 is information indicating whether the terminal (801) intends to use a DS application. DS Info2 is information related to the dual steer function of this terminal (801) and may include at least one of the contents of [Table 19] below.

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 N/A N/A N/A

At step 850, DS Info2 that the terminal (801) has and transmits to AN2 (803) may include SUPI2, AN2, and PLMN1. That is, since selection of AMF, SMF, etc. has not yet been made in the registration procedure to AN2 (803), information such as AMF, SMF, and PDU session ID may not be included in DS Info2. In addition, DS Info2 may include SUPI1, AN1, PLMN1, and AMF1 information that are stored in the registration procedure to AN1 (802).

In addition, Requested NS IDs represent the IDs of the network slices that the terminal (801) wishes to use by connecting to the corresponding AN2 (803). Cell ID2 is base station information when the terminal (801) connects through AN2 (803), and therefore, can also be utilized as location information of the terminal (801) based on AN2 (803).

At step 855, AN2 (803) can select AMF. At this time, AN2 (803) can select AMF (AMF2) (809) different from AMF (AMF1) (805) selected by AN1 (802) as shown in Fig. 2(b). At this time, AN2 (803) can utilize input information of terminal (801) as described in 2.A in the embodiment related to Fig. 3. At this time, AN2 (803) can consider SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, Requested NS IDs, Cell ID2, etc. when selecting AMF.

At step 860, AN2 (803) can transmit the registration or TA update request message received at step 850 to AMF2 (809), which is the AMF selected at step 855. At this time, the request message can include at least one of SUPI2, DS Cap2, DS Ind2, DS Info2, PLMN2, AN2, Requested NS IDs, Cell ID2, etc.

At step 865, AMF2 (809) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (808), update it, and request to be notified of any changes in the future. The subscription data received by AMF2 (809) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI2) supports DS. If DS support is not supported, even though a terminal (801) capable of supporting DS with DS Cap2 sends a registration or TA update request with the intention of supporting DS with DS Ind2, AMF2 (809) may reject the registration or TA update request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (801), AMF2 (809) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (801) or AN2 (803).

At step 870, AMF2 (809) may receive access and mobility related policy data (policy request and policy response) through signaling with PCF1 (807), update it, and request notification if there is a change in the future. The policy data received by AMF2 (809) may include information on whether the same AMF for the DS is supported. The same AMF for the DS is information that includes (indicates) whether the corresponding PLMN1 or AMF2 (809) will use the same AMF for the DS for the terminal (801) of the corresponding SUPI (SUPI2).

At step 875, AMF2 (809) can perform a policy update. Then, AMF2 (809) can check the policy information and, if the current AMF2 (809) cannot support the DS service through the same AMF, can start the AMF re-selection process.

At step 880, AMF2 (809) can transmit a registration/TA update response message to the DS-supporting terminal (801) via AN2 (803). At this time, the response message can include additional information such as policy update or AMF reselection.

At step 885, if necessary, an AMF reselection process is performed so that another AMF, AMF1 (805), is selected in addition to the previously selected AMF2 (809), and then steps 850 to 880 may be performed again. In addition, if necessary, a UE policy update process may be performed between the terminal (801) and PCF1 (807). When registration/TA update is completed, the terminal (801), AN2 (803), and AMF2 (809) may store DS Info, and the UDM (808) may record the DS Info and information of AMF2 (809). At this time, the DS Info to be stored may be as shown in the following [Table 20].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A N/A SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF2 N/A N/A

When step 885 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SUPI2, AN2, PLMN1, AMF2 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1, and AMF2 is selected when connecting to AN2 belonging to PLMN1 while requesting DS support with SUPI2.

According to an embodiment, at step 890, AMF2 (809) may notify AMF1 (805) of the DS Info update associated with SUPI1. Upon receiving this, AMF1 (805) may update the DS Info associated with its SUPI1.

According to an embodiment, at step 895, UDM (808) may notify AMF1 (805) of the DS Info update associated with SUPI1. Upon receiving this, AMF1 (805) may update its DS Info associated with SUPI1.

FIG. 9 illustrates an example of a method for selecting the same SMF when using different AMFs to support dual steer in a single PLMN according to an embodiment of the present invention.

In this embodiment, the same SMF is selected when the target DNN/S-NSSAI is the same. And, when the target DNN/S-NSSAI is different, the same SMF may not be selected.

Referring to FIG. 9, in step 910, the DS-supporting terminal (901) can transmit a PDU session establishment request message to AMF1 (905) via AN1 (902). The AN1 (902) may be a base station, but is not limited thereto. At this time, the PDU session establishment request message may include at least one of SUPI1, PDU session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, etc. SUPI1 is a User ID used by the DS-supporting terminal (901) to access AN1 (902) and is information that is pre-registered in UDM (908) so that it has a common profile with SUPI2. PDU session ID1 is an identifier assigned to a PDU session generated based on the corresponding SUPI, SUPI1. DS Cap1 indicates a function of the terminal, indicating whether the terminal (901) supports the dual steer function. DS Ind1 is information indicating whether this terminal (901) intends to use an application for DS. DS Info1 is information related to the dual steer function of this terminal (901) and may include at least one of the contents of the following [Table 21].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A or SUPI2 N/A or AN2 N/A or PLMN1 N/A or AMF2 N/A N/A

At step 910, DS Info1 that the terminal (901) has and transmits to AMF1 (905) may include SUPI1, AN1, PLMN1, AMF1, and PDU session ID1. In this case, since the terminal (701) requests establishment for the PDU session corresponding to PDU session ID1 and SMF selection has not yet been performed, DS info1 may not include information such as SMF. In addition, DS Info1 may include SUPI2, AN2, PLMN1, and AMF2 information that are stored in the registration procedure with AN2 (903).

In addition, DNN/S-NSSAI indicates the ID of the network slice that the terminal (901) wishes to use by connecting to the corresponding AN1 (902) and the data network name to be used in the network slice.

At step 915, AMF1 (905) can select SMF. At this time, AMF1 (905) can utilize input information of terminal (901) and context within AMF (905) as described in 1.B in the embodiment related to Fig. 3. At this time, AMF1 (905) can consider SUPI1, PDU Session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, Cell ID1, etc. when selecting SMF.

At step 920, AMF1 (905) can transmit the PDU session establishment request message received at step 910 to SMF1 (906), which is the SMF selected (selected) at step 915. At this time, the request message can include at least one of SUPI1, PDU session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, Cell ID1, etc.

At step 925, SMF1 (906) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (908), update it, and request to be notified of any changes in the future. The subscription data received by SMF1 (906) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI1) supports DS. If DS support is not supported, even though a terminal (901) capable of supporting DS with DS Cap1 sends a PDU session establishment request with the intention of supporting DS with DS Ind1, SMF1 (906) may reject the PDU session establishment request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (901), SMF1 (906) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (901), AN1 (902), or AMF1 (905).

At step 927, SMF1 (906) may receive (policy request and policy response) session management related policy data through signaling with PCF1 (907), update it, and request notification if there is a change in the future. The policy data received by SMF1 (906) may include information on whether the same SMF is supported for the DS. The same SMF is information that includes (indicates) whether the corresponding PLMN1 or SMF1 (906) will use the same SMF for the DS for the terminal (901) of the corresponding SUPI (SUPI1).

At step 930, SMF1 (906) can perform a policy update. Then, SMF1 (906) can check the policy information and, if the current SMF1 (906) cannot support the DS service through the same SMF, can start the SMF reselection process.

At step 935, SMF1 (906) can transfer (send) a PDU session establishment response message (e.g., PDU session establishment accept message) to AMF1 (905). At this time, the response message can include additional information such as policy update, SMF reselection, etc.

At step 937, if SMF reselection was requested at step 935, AMF1 (905) can select SMF again. At step 937, SMF1 (906) can select UPF (904) and perform N4 protocol signaling (UPF N4 setup) to set up a path from SUPI1 terminal (901) to AN1 (902) to UPF (904) for PDU session 1. After that, SMF1 (906) can store PDU session ID1, DS Info, etc.

At step 940, AMF1 (905) can transmit the PDU session establishment response message received at step 935 or additionally updated at step 937 to the DS supporting terminal (901) via AN1 (902). At this time, the response message can include additional information such as policy update and SMF reselection.

At step 945, if necessary, a UE policy update process can be performed between the terminal (901) and PCF1 (907). In addition, an SMF reselection process can be performed if necessary, and after another SMF is selected other than the previously selected SMF1 (906), steps 910 to 940 can be performed again. When PDU session establishment is completed, the terminal (901), AN1 (902), AMF1 (905), and SMF1 (906) can store DS Info, and UDM (908) can record the DS Info and information of SMF1 (906). At this time, the DS Info to be stored can be as shown in the following [Table 22].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A or SUPI2 N/A or AN2 N/A or PLMN1 N/A or AMF2 N/A N/A

If step 945 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1, and SMF1 is selected for PDU session establishment corresponding to PDU session ID1. In addition, DS Info may include SUPI2, AN2, PLMN1, AMF2 information stored in the registration procedure with AN2 (903).

At step 950, the DS-supporting terminal (901) can transmit a PDU session establishment request message to AMF2 (909) via AN2 (903). The AN2 (703) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc. SUPI2 is a User ID used by the DS-supporting terminal (901) to access AN2 (903) and is information that is registered in advance in the UDM (908) so that it has a common profile with SUPI1. PDU session ID2 is an identifier assigned to a PDU session generated based on the corresponding SUPI, SUPI2. DS Cap2 indicates a function of the terminal, indicating whether the terminal (901) supports the dual steer function. DS Ind2 is information indicating whether this terminal (901) intends to use an application for DS. DS Info2 is information related to the dual steer function of this terminal (901) and may include at least one of the contents of the following [Table 23].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF2 N/A PDU Session ID2

At step 950, DS Info2 that the terminal (901) has and transmits to AMF2 (909) may include SUPI2, AN2, PLMN1, AMF2, and PDU session ID2. In this case, since the terminal (901) requests establishment for a PDU session corresponding to PDU session ID2 and SMF selection has not yet been performed, DS info2 may not include information such as SMF. In addition, DS Info2 may include SUPI1, AN1, PLMN1, AMF1, SMF1, and PDU session ID1 information that are stored in the PDU session establishment procedure to AN1 (902).

In addition, DNN/S-NSSAI indicates the ID of the network slice that the terminal (901) wishes to use by connecting to the corresponding AN2 (903) and the data network name to be used in the network slice.

At step 955, AMF2 (909) can select SMF. At this time, AMF2 (909) can utilize input information of terminal (901) and context within AMF (909) as described in 2.B in the embodiment related to Fig. 3. At this time, AMF2 (909) can consider SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc. when selecting SMF.

At step 960, AMF2 (909) can transmit the PDU session establishment request message received at step 950 to SMF1 (906), which is the SMF selected (selected) at step 955. At this time, the request message can include at least one of SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc.

At step 963, SMF1 (906) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (908), update it, and request to be notified of any changes in the future. The subscription data received by SMF1 (906) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI2) supports DS. If DS support is not supported, even though a terminal (901) capable of supporting DS with DS Cap2 sends a PDU session establishment request with the intention of supporting DS with DS Ind2, SMF1 (906) may reject the PDU session establishment request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (901), SMF1 (906) may send a response including an error cause by writing the reason that it is not supported in the DS support information to the terminal (901), AN2 (903), or AMF2 (909).

At step 965, SMF1 (906) may receive (policy request and policy response) session management related policy data through signaling with PCF1 (907), update it, and request notification if there is a change in the future. The policy data received by SMF1 (906) may include information on whether the same SMF for the DS is supported. The same SMF for the DS is information that includes (indicates) whether the corresponding PLMN1 or SMF1 (906) will use the same SMF for the DS for the terminal (901) of the corresponding SUPI (SUPI2).

At step 967, SMF1 (906) can perform a policy update. Then, SMF1 (906) can check the policy information and, if the current SMF1 (906) cannot support the DS service through the same SMF, can start the SMF reselection process.

At step 970, SMF1 (906) can transfer (send) a PDU session establishment response message (e.g., PDU session establishment accept message) to AMF2 (909). At this time, the response message can include additional information such as policy update, SMF reselection, etc.

At step 975, if SMF reselection was requested at step 970, AMF2 (909) can select SMF again. At step 975, SMF1 (906) can select UPF (904) and perform N4 protocol signaling (UPF N4 setup) to set up a path from SUPI2 terminal (901) to AN2 (903) to UPF (904) for PDU session 2. After that, SMF1 (906) can store PDU session ID2, DS Info, etc.

At step 980, AMF2 (909) can transmit the PDU session establishment response message received at step 970 or additionally updated at step 975 to the DS supporting terminal (901) via AN2 (903). At this time, the response message can include additional information such as policy update and SMF reselection.

At step 985, if necessary, a UE policy update process can be performed between the terminal (901) and PCF1 (907). In addition, an SMF reselection process can be performed if necessary, and after another SMF is selected other than the previously selected SMF1 (906), steps 950 to 980 can be performed again. When PDU session establishment is completed, the terminal (901), AN2 (903), AMF2 (909), and SMF1 (906) can store DS Info, and UDM (908) can record the DS Info and information of SMF1 (906). At this time, the DS Info to be stored can be as shown in the following [Table 23].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF2 SMF1 PDU Session ID2

If step 985 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1, SUPI2, AN2, PLMN1, AMF2, SMF1, PDU session ID2 as illustrated. For example, DS info may include information that when requesting DS support with SUPI1 and connecting to AN1 belonging to PLMN1, AMF1 is selected and SMF1 is selected for PDU session establishment corresponding to PDU session ID1, and that when requesting DS support with SUPI2 and connecting to AN2 belonging to PLMN1, AMF2 is selected and SMF1 is selected for PDU session establishment corresponding to PDU session ID2.

According to an embodiment, at step 990, AMF2 (909) may send SMF1 (906) a PDU session update request for PDU session 1 or an information notification to update PDU session related context. The PDU session update request or the information notification to update PDU session related context may include at least one of PDU session ID2, SMF2 and PDU session ID1, SMF1. DS Info. Upon receiving this, SMF1 (906) updates DS Info, recognizes that PDU session 2 using AN2 (903) related to PDU session 1 using AN1 (902) has been created, and may perform data steering, switching, or simultaneous data transmission for each service in the two PDU sessions according to each status change.

According to an embodiment, at step 995, UDM (908) may send SMF1 (906) a PDU session update request for PDU session 1 or an information notification to update PDU session related context. The PDU session update request or the information notification to update PDU session related context may include at least one of PDU session ID2, SMF2 and PDU session ID1, SMF1. DS Info. Upon receiving this, SMF1 (906) updates DS Info, recognizes that PDU session 2 using AN2 (903) related to PDU session 1 using AN1 (902) has been created, and may perform data steering, switching, or simultaneous data transmission for each service in the two PDU sessions according to each status change.

FIG. 10 illustrates an example of a method for selecting a different SMF when using a different AMF to support dual steer in a single PLMN according to an embodiment of the present invention.

In this embodiment, it is required when the target DNN/S-NSSAI is the same, and may not be used when the target DNN/S-NSSAI is different.

Referring to FIG. 10, in step 1010, a DS-supporting terminal (1001) can transmit a PDU session establishment request message to AMF1 (1005) via AN1 (1002). The AN1 (1002) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI1, PDU session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, etc. SUPI1 is a User ID used by the DS-supporting terminal (1001) to access AN1 (1002) and is information that is pre-registered in UDM (1008) so that it has a common profile with SUPI2. PDU session ID1 is an identifier assigned to a PDU session generated based on the corresponding SUPI, SUPI1. DS Cap1 indicates whether the terminal (1001) supports the dual steer function. DS Ind1 is information indicating whether this terminal (1001) intends to use an application for DS. DS Info1 is information related to the dual steer function of this terminal (1001) and may include at least one of the contents of the following [Table 25].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 N/A PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A or SUPI2 N/A or AN2 N/A or PLMN1 N/A or AMF2 N/A N/A

At step 1010, DS Info1 that the terminal (1001) has and transmits to AMF1 (1005) may include SUPI1, AN1, PLMN1, AMF1, and PDU session ID1. In this case, since the terminal (1001) requests establishment for a PDU session corresponding to PDU session ID1 and SMF selection has not yet been performed, DS info1 may not include information such as SMF. In addition, DS Info1 may include SUPI2, AN2, PLMN1, and AMF2 information that are stored in the registration procedure with AN2 (1003).

In addition, DNN/S-NSSAI indicates the ID of the network slice that the terminal (1001) wishes to use by connecting to the corresponding AN1 (1002) and the data network name to be used in the network slice.

At step 1015, AMF1 (1005) can select SMF. At this time, AMF1 (1005) can utilize input information of terminal (1001) and context within AMF (1005) as described in 1.C in the embodiment related to Fig. 3. At this time, AMF1 (1005) can consider SUPI1, PDU Session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, Cell ID1, etc. when selecting SMF.

At step 1020, AMF1 (1005) can transmit the PDU session establishment request message received at step 1010 to SMF1 (1006), which is the SMF selected (selected) at step 1015. At this time, the request message can include at least one of SUPI1, PDU session ID1, DS Cap1, DS Ind1, DS Info1, PLMN1, AN1, DNN/S-NSSAI, Cell ID1, etc.

At step 1025, SMF1 (1006) may receive subscription data through signaling with UDM (or UDR) (1008), update it, and request notification of future changes. The subscription data received by SMF1 (1006) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI1) supports DS. If DS support is not supported, a terminal (1001) capable of supporting DS with DS Cap1 may send a PDU session establishment request with the intention of supporting DS with DS Ind1, but SMF1 (1006) may reject the PDU session establishment request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (1001), SMF1 (1006) may send a response including an error cause to the terminal (1001) or AN1 (1002) or AMF1 (1005) by writing the reason why it is not supported in the DS support information.

At step 1027, SMF1 (1006) may receive (policy request and policy response) session management related policy data through signaling with PCF1 (1007), update it, and request notification if there is a change in the future. The policy data received by SMF1 (1006) may include information on whether the same SMF for the DS is supported. The same SMF for the DS is information that includes (indicates) whether the corresponding PLMN1 or SMF1 (1006) will use the same SMF for the DS for the terminal (1001) of the corresponding SUPI (SUPI1).

At step 1030, SMF1 (1006) can perform a policy update. Then, SMF1 (1006) can check the policy information and, if the current SMF1 (1006) cannot support the DS service through the same SMF, can start the SMF reselection process.

At step 1035, SMF1 (1006) can transfer (send) a PDU session establishment response message (e.g., PDU session establishment accept message) to AMF1 (1005). At this time, the response message can include additional information such as policy update, SMF reselection, etc.

At step 1037, if SMF reselection was requested at step 1035, AMF1 (1005) can select SMF again. At step 1037, SMF1 (1006) can select UPF (1004) and perform N4 protocol signaling (UPF N4 setup) to set up a path to UPF (1004) through terminal (1001) and AN1 (1002) of SUPI1 for PDU session 1. After that, SMF1 (1006) stores PDU session ID1, DS Info, etc.

At step 1040, AMF1 (1005) can transmit the PDU session establishment response message received at step 1035 or additionally updated at step 1037 to the DS supporting terminal (1001) via AN1 (1002). At this time, the response message can include additional information such as policy update and SMF reselection.

At step 1045, if necessary, a UE policy update process can be performed between the terminal (1001) and PCF1 (1007). In addition, an SMF reselection process can be performed if necessary, and after another SMF is selected other than the previously selected SMF1 (1006), steps 1010 to 1040 can be performed again. When PDU session establishment is completed, the terminal (1001), AN1 (1002), AMF1 (1005), and SMF1 (1006) can store DS Info, and UDM (1008) can record the DS Info and information of SMF1 (1006). At this time, the DS Info to be stored can be as shown in the following [Table 26].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 N/A or SUPI2 N/A or AN2 N/A or PLMN1 N/A or AMF2 N/A N/A

If step 1045 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1 as illustrated. For example, DS info may include information that AMF1 is selected when connecting to AN1 belonging to PLMN1 while requesting DS support with SUPI1, and SMF1 is selected for PDU session establishment corresponding to PDU session ID1. In addition, DS Info may include SUPI2, AN2, PLMN1, AMF2 information stored in the registration procedure with AN2 (1003).

According to an embodiment, at step 1047, UDM (1008) may inform AMF2 (1009) of information related to PDU session establishment corresponding to PDU session ID1 (inform, notify). The information related to the PDU session establishment may include SMF1 (1006), PDU session ID1, DS Info., etc. Upon receiving this, AMF2 (1009) may recognize that PDU session 1 using AN1 (1002) is created in association with SMF1 (1006).

According to an embodiment, at step 1047, AMF1 (1005) may inform AMF2 (1009) of information related to PDU session establishment corresponding to PDU session ID1 (inform, notify). The information related to the PDU session establishment may include SMF1 (1006), PDU session ID1, DS Info., etc. Upon receiving this, AMF2 (1009) may recognize that PDU session 1 using AN1 (1002) is created in association with SMF1 (1006).

At step 1050, the DS-supporting terminal (1001) can transmit a PDU session establishment request message to AMF2 (1009) via AN2 (1003). The AN2 (1003) may be a base station, but is not limited thereto. At this time, the request message may include at least one of SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc. SUPI2 is a User ID used by the DS-supporting terminal (1001) to access AN2 (1003) and is information that is registered in advance in the UDM (1008) so that it has a common profile with SUPI1. PDU session ID2 is an identifier assigned to a PDU session generated based on the corresponding SUPI, SUPI2. DS Cap2 indicates a function of the terminal (1001) whether the terminal supports the dual steer function. DS Ind2 is information indicating whether this terminal (1001) intends to use an application for DS. DS Info2 is information related to the dual steer function of this terminal (1001) and may include at least one of the contents of the following [Table 27].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF2 N/A PDU Session ID2

At step 1050, DS Info2 that the terminal (1001) has and transmits to AMF2 (1009) may include SUPI2, AN2, PLMN1, AMF2, and PDU session ID2. In this case, since the terminal (1001) requests establishment for a PDU session corresponding to PDU session ID2 and SMF selection has not yet been performed, DS info2 may not include information such as SMF. In addition, DS Info2 may include SUPI1, AN1, PLMN1, AMF1, SMF1, and PDU session ID1 information that are stored in the PDU session establishment procedure to AN1 (1002).

In addition, DNN/S-NSSAI indicates the ID of the network slice that the terminal (1001) wishes to use by connecting to the corresponding AN2 (1002) and the data network name to be used in the network slice.

At step 1055, AMF2 (1009) can select SMF. At this time, input information of terminal (1001) and context within AMF (1009) can be utilized as in 2.C described in the embodiment related to FIG. 3. At this time, AMF2 (1009) can consider SUPI2, PDU session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc. when selecting SMF. In this case, AMF2 (1009) can select SMF1 (1006) or select SMF2 (1000) which is different from SMF1 (1006).

At step 1060, AMF2 (1009) can transmit the PDU session establishment request message received at step 1050 to SMF2 (1000) different from the SMF selected (selected) at step 1055 (if SMF1 (1006) is selected at step 1055) or to SMF2 (1000) selected (selected) at step 1055 (if SMF2 (1000) is selected at step 1055). At this time, the request message can include at least one of SUPI2, PDU Session ID2, DS Cap2, DS Ind2, DS Info2, PLMN1, AN2, DNN/S-NSSAI, Cell ID2, etc.

At step 1063, SMF2 (1000) may receive subscription data (subscription data request and response) through signaling with UDM (or UDR) (1008), update it, and request to be notified of any changes in the future. The subscription data received by SMF2 (1000) may include DS support information. DS support is information including whether the corresponding SUPI (SUPI2) supports DS. If DS support is not supported, a terminal (1001) capable of supporting DS with DS Cap2 may send a PDU session establishment request with the intention of supporting DS with DS Ind2, but SMF2 (1000) may reject the PDU session establishment request on the grounds that it does not support DS. Depending on the embodiment, instead of sending a rejection message to the terminal (1001), SMF2 (1000) may send a response including an error cause to the terminal (1001), AN2 (1003), or AMF2 (1009) by writing the reason why it is not supported in the DS support information.

At step 1065, SMF2 (1000) may receive policy data related to session management through signaling with PCF1 (1007) (policy request and policy response), update it, and request notification if there is a change in the future. The policy data received by SMF2 (1000) may include information on whether the same SMF for the DS is supported. The same SMF for the DS is information on whether the PLMN1 or SMF2 (1000) will use the same SMF for the DS for the terminal (1001) of the SUPI (SUPI2).

At step 1067, SMF2 (1000) can perform a policy update. Then, SMF2 (1000) can check the policy information and, if the current SMF2 (1000) cannot support the DS service through the same SMF, can start the SMF reselection process.

At step 1070, SMF2 (1000) can transfer (send) a PDU session establishment response message (e.g., PDU session establishment accept message) to AMF2 (1009). At this time, the response message can include additional information such as policy update, SMF reselection, etc.

At step 1075, if SMF reselection was requested at step 1070, AMF2 (1009) can select SMF again. At step 1075, SMF2 (1000) can select UPF (1004) and perform N4 protocol signaling (UPF N4 setup) to set up a path from SUPI2 terminal (1001) to AN2 (1003) to UPF (1004) for PDU session 2. After that, SMF2 (1000) can store PDU session ID2, DS Info, etc.

At step 1080, AMF2 (1009) can transmit the PDU session establishment response message received at step 1070 or additionally updated at step 1075 to the DS supporting terminal (1001) via AN2 (1002). At this time, the response message can include additional information such as policy update and SMF reselection.

In step 1085, if necessary, a UE policy update process can be performed between the terminal (1001) and PCF1 (1007). In addition, an SMF reselection process can be performed if necessary, and after another SMF is selected other than the previously selected SMF2 (1000), steps 1050 to 1080 can be performed again. When PDU session establishment is completed, the terminal (1001), AN2 (1003), AMF2 (1009), and SMF2 (1000) can store DS Info, and UDM (1008) can record the DS Info and information of SMF2 (1000). At this time, the DS Info to be stored can be as shown in the following [Table 28].

DS Info SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI1 AN1 PLMN1 AMF1 SMF1 PDU Session ID1 SUPI2 AN2 PLMN2 AMF2 SMF2 PDU Session ID2 SUPI2 AN2 PLMN1 AMF2 SMF2 PDU Session ID2

If step 1085 is performed, DS info may include SUPI1, AN1, PLMN1, AMF1, SMF1, PDU session ID1, SUPI2, AN2, PLMN1, AMF2, SMF2, PDU session ID2 as illustrated. For example, DS info may include information that when requesting DS support with SUPI1 and connecting to AN1 belonging to PLMN1, AMF1 is selected and SMF1 is selected for PDU session establishment corresponding to PDU session ID1, and that when requesting DS support with SUPI2 and connecting to AN2 belonging to PLMN1, AMF2 is selected and SMF2 is selected for PDU session establishment corresponding to PDU session ID2.

According to an embodiment, at step 1090, AMF2 (1009) may send a PDU session update request for PDU session 1 or an information notification to SMF1 (1006) to update PDU session related context. The PDU session update request or the information notification to update PDU session related context may include PDU session ID2, SMF2 and PDU session ID1, SMF1. DS Info. Upon receiving this, SMF1 (1006) updates DS Info, recognizes that PDU session 2 using AN2 (1003) related to PDU session 1 using AN1 (1002) has been created, and may perform data steering, switching, or simultaneous data transmission for each service in the two PDU sessions according to each status change.

According to an embodiment, at step 1095, UDM (1008) may send SMF1 (1006) a PDU session update request for PDU session1 or an information notification to update PDU session related context. The PDU session update request or the information notification to update PDU session related context may include PDU session ID2, SMF2 and PDU session ID1, SMF1. DS Info. Upon receiving this, SMF1 (1006) updates DS Info, recognizes that PDU session 2 using AN2 (1003) related to PDU session 1 using AN1 (1002) has been created, and may perform data steering, switching, or simultaneous data transmission for each service in the two PDU sessions according to each status change.

According to an embodiment, at step 1097, SMF2 (1000) may send SMF1 (1006) a PDU session update request for PDU session1 or an information notification to update PDU session related context. The PDU session update request or the information notification to update PDU session related context may include PDU session ID2, SMF2 and PDU session ID1, SMF1. DS Info. Upon receiving this, SMF1 (1006) updates DS Info, recognizes that PDU session 2 using AN2 (1003) related to PDU session 1 using AN1 (1002) has been created, and may perform data steering, switching, or simultaneous data transmission for each service in the two PDU sessions according to each status change.

FIG. 11 is a drawing showing the configuration of a terminal according to an embodiment of the present disclosure.

Referring to FIG. 11, a terminal according to an embodiment of the present disclosure may include a processor (control unit) (1120) that controls the overall operation of the terminal, a transceiver unit (1100) including a transmitter and a receiver, and a memory (910). Of course, the present invention is not limited to the above example, and the terminal may include more or fewer components than those illustrated in FIG. 11.

According to one embodiment of the present disclosure, the transceiver (1100) can transmit and receive signals with network entities or other terminals. The signals transmitted and received with the network entities can include control information and data. In addition, the transceiver (1100) can receive signals through a wireless channel and output them to the processor (1120), and transmit the signals output from the processor (1120) through the wireless channel.

According to one embodiment of the present disclosure, the processor (1120) can control the terminal to perform any one of the operations of the embodiments described above. Meanwhile, the processor (1120), the memory (1110), and the transceiver (1100) do not necessarily have to be implemented as separate modules, and of course, they can be implemented as a single component in the form of a single chip. In addition, the processor (1120) and the transceiver (1100) can be electrically connected. In addition, the processor (1120) can be an AP (Application Processor), a CP (Communication Processor), a circuit, an application-specific circuit, or at least one processor.

According to one embodiment of the present disclosure, the memory (1110) can store data such as a basic program for the operation of the terminal, an application program, and setting information. In particular, the memory (1110) provides the stored data upon request of the processor (1120). The memory (1110) 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. In addition, there can be a plurality of memories (1110). In addition, the processor (1120) can perform the above-described embodiments based on a program for performing the above-described embodiments of the present disclosure stored in the memory (1110).

FIG. 12 is a diagram showing the configuration of a base station or network entity according to an embodiment of the present invention.

Referring to FIG. 12, a network entity according to an embodiment of the present disclosure may include a processor (control unit) (1220) that controls the overall operation of the network entity, a transceiver unit (1200) including a transmitter and a receiver, and a memory (1210). Of course, the present invention is not limited to the above example, and the network entity may include more or fewer components than the configuration illustrated in FIG. 12.

According to one embodiment of the present disclosure, the transceiver (1200) can transmit and receive signals with at least one of other network entities or terminals. The signals transmitted and received with at least one of other network entities or terminals can include control information and data.

According to one embodiment of the present disclosure, the processor (1220) can control a network entity to perform any one of the operations of the embodiments described above. Meanwhile, the processor (1220), the memory (1210), and the transceiver (1200) do not necessarily have to be implemented as separate modules, and of course, they can be implemented as a single component in the form of a single chip. In addition, the processor (1220) and the transceiver (1200) can be electrically connected. In addition, the processor (1220) can be an AP (Application Processor), a CP (Communication Processor), a circuit, an application-specific circuit, or at least one processor.

According to one embodiment of the present disclosure, the memory (1210) can store data such as a basic program, an application program, and setting information for the operation of a network entity. In particular, the memory (1210) provides the stored data upon a request of the processor (1220). The memory (1210) 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. In addition, the memory (1210) can be plural. In addition, the processor (1220) can perform the above-described embodiments based on a program for performing the above-described embodiments of the present disclosure stored in the memory (1210).

The above network entity can be any one of a base station, AMF, SMF, UPF, PCF, UDM, UDR, NEF, NRF, AF, NSSF, NWDAF, NSACF, AUSF, DN, EASDF, NSSAAF, AN, etc.

It should be noted that the above-described configuration diagram, example diagram of control/data signal transmission method, example diagram of operation procedure, and configuration diagram are not intended to limit the scope of the present disclosure. That is, not all components, entities, or steps of operations described in the embodiments of the present disclosure should be construed as essential components for implementing the disclosure, and the disclosure may be implemented within a scope that does not harm the essence of the disclosure even if only some components are included. In addition, each embodiment may be combined and operated with each other as needed. For example, some of the methods proposed in the present disclosure may be combined with each other to operate a network entity and a terminal.

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

The operations of the terminal, base station, or network entity described above can be realized by providing a memory device storing the corresponding program code in any component within the base station or terminal device. That is, the control unit of the base station or terminal device can execute the operations described above by reading and executing the program code stored in the memory device by a processor or CPU (Central Processing Unit).

The various components, modules, etc. of the entity, base station or terminal device described in this specification may be operated using hardware circuits, for example, logic circuits based on complementary metal oxide semiconductors, firmware, software and/or a combination of hardware and firmware and/or software embedded in a machine-readable medium. For example, various electrical structures and methods may be implemented using electrical circuits such as transistors, logic gates, and application-specific semiconductors.

In the case of software implementation, 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 in an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present invention.

These programs (software modules, software) may be stored in a random access memory, a non-volatile memory including a flash memory, a ROM (Read Only Memory), an Electrically Erasable Programmable Read Only Memory (EEPROM), a magnetic disc storage device, a Compact Disc-ROM (CD-ROM), a Digital Versatile Discs (DVDs) or other forms of optical storage devices, a magnetic cassette. Or, they may be stored in a memory composed of a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

Additionally, the program may be stored in an attachable storage device that is accessible via a communication network such as the Internet, an Intranet, a Local Area Network (LAN), a Wide LAN (WLAN), or a Storage Area Network (SAN), or a combination thereof. The storage device may be connected to the device performing an embodiment of the present invention via an external port. Additionally, a separate storage device on the communication network may be connected to the device performing an embodiment of the present invention.

In the specific embodiments of the present invention described above, the components included in the invention are expressed in the singular or plural form according to the specific embodiments presented. However, the singular or plural expressions are selected appropriately for the presented situation for the convenience of explanation, and the present invention is not limited to the singular or plural components, and even if a component is expressed in the plural form, it may be composed of the singular form, or even if a component is expressed in the singular form, it may be composed of the plural form.

Meanwhile, although specific embodiments have been described in the detailed description of the present invention, it is to be understood that various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the claims described below but also by the equivalents of the scope of the claims. In other words, it will be apparent to those skilled in the art that other modifications based on the technical idea of the present disclosure are possible. In addition, each of the above embodiments may be combined and operated as needed. For example, some of the methods proposed in the present disclosure may be combined and operated by a base station and a terminal. In addition, although the above embodiments have been presented based on a 5G, NR system, other modifications based on the technical idea of the above embodiments may be implemented in other systems such as LTE, LTE-A, and LTE-A-Pro systems.

Meanwhile, although the detailed description of the present disclosure has described specific embodiments, it is obvious that various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the claims described below, but also by equivalents of the scope of the claims.

Claims (15)

In a method performed by a terminal of a wireless communication system, A step of transmitting a first message associated with registration with a first access network for application of dual steer to a first access network entity; A step of receiving a second message including information of the first AMF in response to the first message from a first AMF (access and mobility management function) selected by the first access network entity; A step of storing information indicating that the first AMF has been selected for registration with the first access network in the dual steer information; A step of transmitting a third message associated with registration with a second access network for application of the above dual steer to the second access network entity; receiving a fourth message including information of the second AMF in response to the third message from the second AMF selected by the second access network entity; and A step of storing information indicating that the second AMF has been selected for registration with the second access network in the dual steer information, A method characterized in that the first AMF and the second AMF are the same AMF or different AMFs. In the first paragraph, The first message includes at least one of a first terminal identifier used by the terminal to access the first access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use through the first access network. A method according to claim 1, wherein the third message comprises at least one of a second terminal identifier used by the terminal to access the second access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use via the first access network. In the first paragraph, A step of transmitting a fifth message requesting establishment of a first PDU (protocol data unit) session to the first access network to the first AMF through the first access network entity; A step of receiving, in response to the fifth message, a sixth message from the first SMF selected by the first AMF, accepting establishment of the first PDU session and including information of the first SMF; A step of storing information indicating that the first SMF is selected for establishing the first PDU session in the dual steer information; A step of transmitting a seventh message requesting establishment of a second PDU session to the second access network to the second AMF through the second access network entity; A step of receiving a seventh message from a second SMF selected by the second AMF, in response to the seventh message, accepting establishment of the second PDU session and including information of the second SMF; and Including a step of storing information indicating that the second SMF is selected for establishing the second PDU session in the dual steer information, A method characterized in that the first SMF and the second SMF are the same SMF or different SMFs. In the third paragraph, The fifth message includes at least one of a first terminal identifier used by the terminal to access the first access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use through the first access network. A method according to claim 7, wherein the seventh message comprises at least one of a second terminal identifier used by the terminal to access the second access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use via the first access network. A method performed by a first AMF (access and mobility management function) of a wireless communication system, A step of receiving a first message from a terminal through a first access network entity, the first message being associated with registration with a first access network for application of dual steer of the terminal; A step of transmitting a second message including information of the first AMF to the terminal through a first access network entity in response to the first message, when the terminal supports the dual steer and the first AMF supports the dual steer; A step of storing information indicating that the first AMF has been selected for registration with the first access network in the dual steer information; A step of receiving a third message from the terminal through a second access network entity, the third message associated with registration with the second access network for application of the dual steering of the terminal; If the terminal supports the dual steer and the first AMF supports the dual steer, a step of transmitting a fourth message including information of the first AMF to the terminal through a second access network entity in response to the third message; A method comprising the step of storing information in the dual steer information indicating that the first AMF has been selected for registration with the second access network. In clause 5, A step of determining whether the terminal supports the dual steering based on the subscription information of the terminal received from UDM (unified data management); and A method characterized by further comprising a step of determining whether the first AMF supports the dual steer based on policy information received from a policy control function (PCF). In clause 5, A step of transmitting the third message to a second AMF that supports registration with the second access network when the first AMF does not support registration with the second access network for application of the dual steering of the terminal; A step of receiving information from the second AMF or UDM (unified data management) indicating that the second AMF has been selected for registration with the second access network; and A method characterized by further comprising the step of storing, in the dual steer information, information indicating that the second AMF has been selected for registration with the second access network. In clause 5, A step of receiving a fifth message from the terminal through the first access network entity, the fifth message requesting establishment of a first PDU (protocol data unit) session to the first access network; A step of selecting a first SMF based on at least one of the context of the fifth message and the first AMF; A step of transmitting a 6th message requesting establishment of the first PDU session to the first SMF; In response to the sixth message, receiving a seventh message from the first SMF, accepting establishment of the first PDU session; In response to the fifth message, a step of accepting establishment of the first PDU session and transmitting an eighth message including information of the first SMF to the terminal through the first access network entity; A step of storing information indicating that the first SMF is selected for establishing the first PDU session in the dual steer information; A step of receiving a ninth message from the terminal through the second access network entity, the message requesting establishment of a second PDU session to the second access network; A step of selecting a second SMF based on at least one of the contexts of the ninth message and the first AMF; A step of transmitting a 10th message requesting establishment of the second PDU session to the second SMF; In response to the 10th message, receiving an 11th message from the 2nd SMF, accepting establishment of the 2nd PDU session; In response to the 9th message, a step of accepting establishment of the 2nd PDU session and transmitting a 12th message including information of the 2nd SMF to the terminal through the 2nd access network entity; and Further comprising a step of storing information indicating that the second SMF is selected for establishing the second PDU session in the dual steer information, A method characterized in that the first SMF and the second SMF are the same SMF or different SMFs. In a terminal of a wireless communication system, Transmitter and receiver; and Connected to the above transmitter and receiver, Transmitting a first message associated with registration with a first access network for application of dual steer to a first access network entity, Receive a second message including information of the first AMF in response to the first message from a first AMF (access and mobility management function) selected by the first access network entity, Store information indicating that the first AMF has been selected for registration with the first access network in the dual steer information, Transmitting a third message to the second access network entity in connection with registration with the second access network for application of the above dual steer, Receive a fourth message including information of the second AMF in response to the third message from the second AMF selected by the second access network entity, A control unit for storing information indicating that the second AMF has been selected for registration with the second access network in the dual steer information, A terminal characterized in that the first AMF and the second AMF are the same AMF or different AMFs. In Article 9, The first message includes at least one of a first terminal identifier used by the terminal to access the first access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use through the first access network. A terminal characterized in that the third message includes at least one of a second terminal identifier used by the terminal to access the second access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use through the first access network. In the 9th paragraph, the control unit, Transmitting a fifth message requesting establishment of a first PDU (protocol data unit) session to the first access network to the first AMF through the first access network entity; Receive a sixth message from the first SMF selected by the first AMF, in response to the fifth message, accepting establishment of the first PDU session and including information of the first SMF; Information indicating that the first SMF is selected for establishing the first PDU session is stored in the dual steer information, Transmitting a seventh message requesting establishment of a second PDU session to the second access network to the second AMF through the second access network entity; Receive a seventh message from the second SMF selected by the second AMF, in response to the seventh message, accepting establishment of the second PDU session and including information of the second SMF; Information indicating that the second SMF is selected for establishing the second PDU session is stored in the dual steer information, A terminal characterized in that the first SMF and the second SMF are the same SMF or different SMFs. In Article 11, The fifth message includes at least one of a first terminal identifier used by the terminal to access the first access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use through the first access network. A terminal characterized in that the seventh message includes at least one of a second terminal identifier used by the terminal to access the second access network, information indicating whether the terminal supports the dual steer, information indicating that the terminal requests the dual steer, the dual steer information, or information of a slice that the terminal wants to use through the first access network. In the first AMF (access and mobility management function) of a wireless communication system, Transmitter and receiver; and Connected to the above transmitter and receiver, Receiving a first message associated with registration with a first access network for application of dual steer of the terminal from the terminal through the first access network entity, If the terminal supports the dual steer and the first AMF supports the dual steer, in response to the first message, a second message including information of the first AMF is transmitted to the terminal through the first access network entity, Store information indicating that the first AMF has been selected for registration with the first access network in the dual steer information, Receiving a third message from the terminal through the second access network entity, associated with registration with the second access network for application of the dual steering of the terminal; If the terminal supports the dual steer and the first AMF supports the dual steer, a fourth message including information of the first AMF is transmitted to the terminal through the second access network entity in response to the third message, A first AMF characterized by including a control unit that stores information indicating that the first AMF has been selected for registration with the second access network in the dual steer information. In the 13th paragraph, the control unit, Based on the subscription information of the terminal received from UDM (unified data management), it is determined whether the terminal supports the dual steering, Based on the policy information received from the PCF (policy control function), it is determined whether the first AMF supports the dual steering, The above control unit, If the first AMF does not support registration of the terminal with the second access network for application of the dual steering, the third message is transmitted to the second AMF that supports registration with the second access network. Receiving information indicating that the second AMF has been selected for registration with the second access network from the second AMF or UDM (unified data management), A first AMF characterized in that it stores information indicating that the second AMF has been selected for registration with the second access network in the dual steer information. In the 13th paragraph, the control unit, Receiving a fifth message requesting establishment of a first PDU (protocol data unit) session to the first access network from the terminal through the first access network entity, Selecting a first SMF based on at least one of the contexts of the fifth message and the first AMF, Transmitting a 6th message requesting establishment of the above 1st PDU session to the 1st SMF, In response to the sixth message, a seventh message is received from the first SMF, accepting establishment of the first PDU session; In response to the fifth message, the establishment of the first PDU session is accepted, and an eighth message including information of the first SMF is transmitted to the terminal through the first access network entity, Information indicating that the first SMF is selected for establishing the first PDU session is stored in the dual steer information, Receiving a ninth message requesting establishment of a second PDU session to the second access network from the terminal through the second access network entity, Selecting a second SMF based on at least one of the contexts of the ninth message and the first AMF, Transmitting a 10th message requesting establishment of the second PDU session to the second SMF, In response to the above 10th message, an 11th message is received from the 2nd SMF, accepting establishment of the 2nd PDU session; In response to the 9th message, the establishment of the 2nd PDU session is accepted, and a 12th message including information of the 2nd SMF is transmitted to the terminal through the 2nd access network entity, Information indicating that the second SMF is selected for establishing the second PDU session is stored in the dual steer information, A first AMF, characterized in that the first SMF and the second SMF are the same SMF or different SMFs.