Method and apparatus for selecting access and mobility management functions in a mobile communication system

Abstract

To provide a method and a device for appropriately searching for a network node that provides a service desired by a user terminal (UE, User Equipment) when a user performs initial connection with a 5G network in a 5G mobile communication system.SOLUTION: In a communication system, a base station receives, from a user terminal, a message including at least one of first information to identify an AMF (access and mobility management function) and second information to identify a service type requested from the user terminal, selects an AMF set based on at least one of the first information and the second information, and selects the AMF with the selected AMF set.SELECTED DRAWING: Figure 16

Description

Technical Field

[0001] The present invention generally relates to a method and apparatus for selecting an AMF (access and mobility management function).

Background Art

[0002] In order to meet the needs for wireless data traffic, which has been on the increase trend since the commercialization of the 4G communication system, efforts are being made to develop an improved 5G communication system or a pre-5G communication system. For this reason, the 5G communication system or the pre-5G communication system is called a communication system after the 4G network (Beyond 4G Network) or a system after the LTE system (PostLTE).

[0003] In order to achieve a high data transmission rate, the 5G communication system is considered to be implemented in a millimeter wave (mmWave) band (such as a 60 giga (60 GHz) band).

[0004] In order to mitigate the path loss of radio waves and increase the transmission distance of radio waves in the millimeter wave band, beamforming, massive multiple-input multiple-output (massive MIMO), full-dimensional multiple-input multiple-output (Full Dimensional MIMO: FD-MIMO), array antenna, analog beam-forming, and large scale antenna technologies are being discussed in the 5G communication system.

[0005] In addition, for the improvement of the system network, in the 5G communication system, technologies such as evolved small cells, advanced small cells, cloud radio access network (cloudRAN), ultra-dense network, Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation are being developed.

[0006] In addition to this, in the 5G system, FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), which are advanced coding modulation (ACM) methods, and FBMC (Filter Bank Multi Carrier), NOMA (nonorthogonal multiple access), and SCMA (sparse code multiple access), which are advanced connection technologies, are being developed.

[0007] On the other hand, the Internet is evolving from a human-centered connection network where humans generate and consume information to an IoT (Internet of Things) network that exchanges and processes information between distributed components such as things.

[0008] IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology and other technologies through connection to cloud servers and the like, is also emerging.

[0009] To implement the IoT, technical elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required. Recently, technologies such as sensor networks, Machine to Machine (M2M), and Machine Type Communication (MTC) for connecting things have been studied.

[0010] In the IoT environment, intelligent IT (Internet Technology) services can be provided that collect and analyze data generated by connected things to create new value for human life. The IoT can be applied to fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services through the integration and combination of existing IT (information technology) technologies and various industries.

[0011] In this regard, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor networks, Machine to Machine (M2M), and Machine Type Communication (MTC) are being implemented by 5G communication technologies through techniques such as beamforming, MIMO, and array antennas.

[0012] The application of cloud radio access network (cloud RAN) as the aforementioned big data processing technology can also be regarded as an example of the integration of 5G technology and IoT technology.

[0013] As 5G communication technology develops, there is a need for a method to provide efficient services in the 5G mobile communication environment by quickly searching for a network that provides the services desired by the user terminal when the user initially connects to the 5G network. Summary of the Invention

Problems to be Solved by the Invention

[0014] Therefore, the present invention is made to solve the above-described problems and / or disadvantages and provide at least the advantages described below.

[0015] An object of the present invention is to propose a method for appropriately searching for a network node that provides a service desired by a user terminal (UE, User Equipment) when the user initially connects to a 5G network in a 5G mobile communication system. For this purpose, detailed proposed techniques are to propose a method for managing network deployment information and a method for transmitting an initial connection request message.

[0016] Also, even when modifying the service provided to the user terminal after the initial connection, the network node that provides the service can be searched in a similar manner.

[0017] Another object of the present invention is to propose a method for separately managing Mobility Restriction Areas for each Network Slice used by a terminal in allocating and managing Mobility Restriction Areas for service control based on the mobility of the terminal. A mobile communication operator can configure different Network Slices for different services provided to a terminal, and can provide different Mobility Restriction Areas for each of the Network Slices. Further, an operation is proposed in which the terminal requests a data service in consideration of the Mobility Restriction Area allocated for each Network Slice, or the Mobility Restriction Area is considered when establishing a session for the terminal with respect to the Network Slice in the Core Network of the 5G system. Further, when the terminal is using several Network Slices, an operation is proposed in which the Network Slices capable of establishing a session at the current location of the terminal are identified based on the Mobility Restriction Area, and a session is established.

[0018] Another object of the present invention is, in a situation where a terminal capable of non-3gpp access and 3gpp access is connected to the 5G network via one access and connects to the 5G network via another access later, to effectively select an AMF for the access to be connected later. In the case of non-3gpp access, as a method for this, in the case of non-3gpp access, in accordance with the relationship between the PLMN that serves the N3IWF and the PLMN that the terminal accesses in the case of 3gpp access, when the selection of the AMF is incorrect, problems such as unnecessary complication of the routing of NAS signaling occur. Therefore, a solution for selecting an appropriate AMF is proposed.

[0019] In addition, another object of the present invention is that according to the existing LTE network configuration, when the base station selects the MME, it uses the GUMMEI, which is the ID of the MME that assigned the GUTI to the terminal, as routing information to select the MME. Furthermore, since the MME that assigned the GUTI for this purpose must continue to hold the context information of the terminal, there can be a problem that the selection of the MME has a high correlation (stickiness or persistence) with the UE's information and it becomes difficult to perform network management such as network updates on the MME and the like. In the present invention, a solution for reducing the correlation (stickiness or persistence) with the UE's information is introduced.

[0020] The object of the present invention is not limited to the above object. That is, other objects not mentioned can be clearly understood by those skilled in the art from the following description starting from the present disclosure.

Means for Solving the Problems

[0021] A method for a base station in a wireless communication system according to an embodiment of the present invention includes receiving, from a terminal, a message including at least one of first information for identifying an AMF (access and mobility management function) and second information for identifying a service type requested from the terminal; selecting an AMF set based on at least one of the first information and the second information; and selecting an AMF from the selected AMF set.

[0022] According to an embodiment, the step of selecting the AMF from the selected AMF set may include selecting the AMF from the AMF set based on at least one of the availability of the AMF and load balancing among the AMFs in the AMF set.

[0023] According to an embodiment, the first information may include an AMF set identifier and an AMF identifier.

[0024] According to an embodiment, the base station may include a radio access network and a non-3GPP inter-working function (N3IWF).

[0025] According to an embodiment, the method may further include transmitting, to the terminal, third information for identifying the selected AMF.

[0026] A method of a terminal in a wireless communication system according to another embodiment of the present invention includes transmitting, to a first base station, a first message including at least one of first information for identifying an access and mobility management function (AMF) and second information for identifying a service type requested from the terminal, and receiving, from the AMF, a second message for the first message, wherein the AMF is selected in an AMF set, and the AMF set can be selected based on at least one of availability of the AMF and load balancing among AMFs in the AMF set.

[0027] According to an embodiment, the AMF can be selected in the AMF set based on at least one of availability of the AMF and load balancing among AMFs in the AMF set.

[0028] According to an embodiment, the first information may include an AMF set identifier and an AMF identifier.

[0029] According to an embodiment, the first base station may include a radio access network and a non-3GPP inter-working function (N3IWF).

[0030] According to an embodiment, the method may further include receiving, from the first base station, third information for identifying the selected AMF; determining whether a first PLMN (public land mobile network) of a first access network including the first base station is the same as a second PLMN of a second access network including the second base station; and when the first PLMN is the same as the second PLMN, transmitting, to the second base station, a second message including the third information for identifying the selected AMF.

[0031] A base station according to another embodiment of the present invention may include a transceiver and a control unit connected to the transceiver. The control unit is configured to receive, from a terminal, a message including at least one of first information for identifying an AMF (access and mobility management function) and second information for identifying a service type requested from the terminal, select an AMF set based on at least one of the first information and the second information, and control to select an AMF from the selected AMF set.

[0032] A terminal according to another embodiment of the present invention may include a transceiver and a control unit connected to the transceiver. The control unit is configured to transmit, to a first base station, a first message including at least one of first information for identifying an AMF (access and mobility management function) and second information for identifying a service type requested from the terminal, and receive, from the AMF, a second message in response to the first message. The AMF is selected from an AMF set, and the AMF set can be selected based on at least one of the first information and the second information.

Advantages of the Invention

[0033] According to an embodiment of the present invention, a method for managing and using network deployment information in a wireless communication system is disclosed. Further, a method for searching for a network node that provides a service desired by a user terminal based on the network deployment information is disclosed. Through this, efficient services can be provided in a 5G mobile communication environment.

[0034] According to another embodiment of the present invention, a mobile network operator can allocate different Mobility Restriction Areas for each Network Slice to provide specific services to terminals. According to the present invention, a terminal can determine a Network Slice in which a session can be established and data can be transmitted and received at the current location among several Network Slices it is using, from the Mobility Restriction Area, and control the session connection. According to the present invention, the 5G Core Network can determine, from the Mobility Restriction Area, a Network Slice in which a terminal can establish a session and perform data transmission and reception at the current location, based on the operation by the Service request transmitted by the terminal, and operate accordingly.

[0035] According to still another embodiment of the present invention, through the present invention, when necessary for a terminal with respect to 3gpp and non-3gpp access, by selecting the same AMF or another AMF, the routing of NAS messages and data transmission can be made more efficient. Further, according to still another embodiment of the present invention, by removing the association (stickiness or persistence) with the UE information during the process of selecting the AMF, network management such as virtualization of the AMF-related network and reduction / expansion of AMF facilities becomes easier.

[0036] The above and other aspects, features, and advantages of any embodiment of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0037]

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Embodiments for Carrying Out the Invention

[0038] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed herein and can be embodied in various forms.

[0039] It should be noted that the same components in the accompanying drawings are denoted by the same reference numerals as much as possible. In addition, detailed descriptions of known functions and configurations that may obscure the gist of the present invention are omitted.

[0040] Furthermore, in specifically describing embodiments of the present invention, the main target is an Advanced E-UTRA (evolved universal terrestrial radio access) (also referred to as LTE-A (long term evolution-advanced)) system that supports carrier aggregation (CA). However, the main gist of the present invention can be applied with a slight modification within the scope without significantly departing from the scope of the present invention to other communication systems having a similar technical background and channel form, which would be possible by the judgment of those with technical knowledge skilled in the technical field of the present invention. For example, the main gist of the present invention can also be applied to a multicarrier HSPA (high speed packet access) system that supports carrier aggregation.

[0041] In this specification, when describing the embodiments, descriptions of content that is well known in the technical field to which the present invention belongs and is not directly related to the present invention are omitted. This is to clearly and more precisely convey the gist of the present invention by omitting unnecessary explanations.

[0042] For the same reason, in the accompanying drawings, some components are exaggerated, omitted, or shown schematically. Also, the sizes of the components do not fully reflect the actual sizes. The same reference numerals are assigned to the same or corresponding components in each drawing.

[0043] The advantages, features, and the methods for achieving them of the present invention will become clear by referring to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be embodied in various different forms. Merely, these embodiments are provided to complete the disclosure of the present invention and fully inform those with ordinary knowledge in the technical field to which the present invention belongs of the scope of the invention. The present invention is only defined by the scope of the claims. The same reference signs throughout the specification refer to the same components.

[0044] At this time, it will be understood that the combination of each block of the process flowchart and the drawing of the flowchart can be performed by computer program instructions. These computer program instructions can be loaded onto the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions performed via the processor of the computer or other programmable data processing equipment will generate means for performing the functions described in the flowchart blocks. These computer program instructions can also be stored in a computer-usable or computer-readable memory that can be oriented to a computer or other programmable data processing equipment to embody functions in a specific manner, so that the instructions stored in the computer-usable or computer-readable memory can also produce a manufactured item that includes instruction means for performing the functions described in the flowchart blocks. Since the computer program instructions can also be loaded onto a computer or other programmable data processing equipment, a series of operational steps are performed on the computer or other programmable data processing equipment, and the instructions executed by the computer to generate a process for performing the computer or other programmable data processing equipment can also provide steps for performing the functions described in the flowchart blocks.

[0045] Also, each block can represent a module, a segment, or a portion of code that includes one or more executable instructions for performing a specified logical function. It should also be noted that in some alternative embodiments, the functions recited in the blocks can occur out of order. For example, two blocks shown in succession can in fact be performed substantially simultaneously, or the blocks can sometimes be performed in reverse order depending on the functions involved.

[0046] At this time, the term '~ unit' used in this embodiment means software or hardware components such as FPGA and ASIC, and what role does the '~ unit' play. However, the '~ unit' is not limited to meaning software or hardware. The '~ unit' can also be configured to be in a storage medium that can be addressed, or can be configured to cause one or more processors to execute. Therefore, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, and processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided among the components and the '~ unit' can be combined with a smaller number of components and '~ units' or further separated by additional components and '~ units'. In addition, the components and the '~ unit' can also be implemented to cause one or more CPUs in a device or a security multimedia card to execute.

[0047] <First Embodiment> In describing this first embodiment, terms such as slice, service, network slice, network service, application slice, application service, etc. can be used interchangeably.

[0048] FIG. 1 shows an initial configuration of a mobile communication network and an initial connection structure of a user terminal. RAN 102 corresponding to the first node in the radio section may be connected to the node of CN 105 regardless of whether the terminal (or UE) 101 is connected. For example, in FIG. 1, RAN 102 is connected to CCNF (Common Core Network Function(s)) 1 and CCNF2, respectively. CCNF is a representative network function of CN (Core Network) connected to RAN, and it may be one network function or a set of several network functions. When the terminal 101 requests an initial connection to the mobile communication network (e.g., initial attach request or initial access request), RAN 102 that has received the request transmits the message to an appropriate CCNF. For example, in FIG. 1, RAN 102 that has received an initial connection request message from the terminal transmits the message to CCNF1, and a connection between the terminal (UE) 101 and CCNF1 is set up through an approval procedure. The detailed procedure will be described with reference to FIG. 8.

[0049] The CCNF to which the initial connection request message of the terminal 101 is transmitted checks whether the CCNF is a node that can provide the service desired by the terminal. For this purpose, three pieces of information are used and are diagrammatically represented in FIG. 2. The CCNF checks and verifies whether it is a node that can provide the service desired by the terminal based on the UE request information included in the initial connection request message of the terminal 101, the UE subscription information stored in the database 210 of the mobile communication network, and the policy information of the mobile communication network operator (for example, local policy or operator policy or PLMN policy). The operator policy information can be stored and used by the CCNF or received from another network function (for example, policy control function 212) that stores the user policy. The UE request information can include the type of network slice (service) desired by the user, the type of application slice (service), the service provider that provides the slice (service), the priority of each slice (service), and the location information of the user. If there are several services desired by the user, it can include one value representing this. This representative value is stored in the terminal 101, RAN 102, and core network 105, and the RAN 102 and core network 105 can interpret which service the one value transmitted by the terminal 102 corresponds to. This one value can be pre-configured in the terminal 101 or can be received and used by the terminal 101 after connecting to the network. At this time, the user request information may be information explicitly input by the user (for example, the service desired by the user), or may be information automatically included by the protocol design (for example, tracking area or cellid information indicating the location information of the user).UE access information can include the network slice (service) type that the user terminal can use, the application slice (service) type that terminal 101 can use, the slice (service) provider that provides the service, the slice (service) type that terminal 101 must use, the area (region) where each slice (service) type can be provided, the area (region) where each slice (service) type should not be provided, and the priority order of each slice (service). The CCNF determines the final service to be provided to terminal 101 based on three pieces of information. The final slice (service) provided by the network to the confirmed terminal may or may not be the same as the terminal request slice (service) included in the initial connection request message sent by terminal 101.

[0050] After the CCNF that has received the initial connection request message verifies whether it is an appropriate node that can provide services to the terminal, if the CCNF is determined to be appropriate, it sends an initial connection request commitment message (for example, initial attach response or initial access response) to terminal 101. The initial connection request commitment message can include information about what the final service information provided to terminal 101 confirmed by the network is. Terminal 101 that has received the message knows that the network connection request of terminal 101 has been well processed and knows what services it can use from now on. If the CCNF is not appropriate, it must search for other appropriate CCNFs that can provide services to terminal 101. There are two ways to search for other CCNFs, and Figures 3 and 4 schematize each method.

[0051] In order for a CCNF to search for other CCNFs, it must know what services each of the other CCNFs provides. Figure 3 shows a way in which there are many CCNFs in the network and each CCNF exchanges information directly with each other to know the functional information provided by each CCNF. At this time, the connection between each CCNF may be a direct connection or a direct connection through other network functions. If the function provided by a specific CCNF is changed, it must notify other CCNFs. That is, if CCNF2 starts providing service 3 in addition to services 1 and 2, this information must be notified to CCNF1, CCNF3, and CCNF4, which are the surrounding CCNFs connected to CCNF2, respectively. The CCNFs that receive the information update the surrounding CCNF information they manage respectively. The method of notifying the information can be either sending a message or using the event-subscription method. For example, if CCNF1, which has received the initial connection message of the user terminal, determines that it is not a compliant CCNF that can support the final service provided to the terminal through the verification process in Figure 2, it can determine based on other CCNF information managed by CCNF1 that CCNF2 can support the said final service.

[0052] On the one hand, as shown in FIG. 4, instead of the method where each CCNF directly exchanges information, it is a method of registering each provided function with a central server. For example, CCNF1, CCNF2, CCNF3, and CCNF4 each register their provided functions with a central server (for example, NRF, Network Function Repository (450)). When using this method, CCNF does not need to know the functions of the surrounding CCNF. To explain the process of searching for other CCNF, if CCNF1 that has received the initial connection message of the user terminal 101 determines through the verification process in FIG. 2 that it is not a compatible CCNF that can support the final service provided to the terminal 101, it asks the NRF450 what the compatible CCNF that can support the final service is. Based on the information of the registered CCNF, the NRF450 determines that CCNF2 is a compatible node and provides the information of CCNF2 to CCNF1.

[0053] Through the above process, it becomes necessary to search for an appropriate CCNF that can provide the final service, and CCNF1 must transmit the initial connection request message received from the terminal to CCNF2. There are three possible ways to transmit, and each method is schematized in FIGS. 5, 6, and 7.

[0054] FIG. 5 shows a method in which CCNF1 transmits the request message of the terminal 101 to CCNF2 via the RAN102. CCNF1 sends a redirection request message to the RAN102. The redirection request message includes the information of CCNF2 and can include the first request message (for example, initial attach request) received by the terminal 101. The RAN102 that has received the redirection message 530 uses the CCNF2 information to transmit the initial request message of the terminal to CCNF2. The CCNF2 that has received the message processes the message and sends a response message (for example, initial attach response) 540 to the terminal 101.

[0055] FIG. 6 shows a method in which CCNF1 directly sends a message to CCNF2. CCNF1 sends a redirection request message 630 to CCNF2. The redirection message includes the terminating point information (e.g., NG2 signaling ID) of RAN102 connected to terminal 101 and can include the first request message received by terminal 101. After receiving the message, CCNF2 processes the message and uses the terminating point information of RAN102 to send a response message 640 to terminal 101 at that location.

[0056] FIG. 7 shows a method in which CCNF1 directly sends a message to CCNF2, similar to FIG. 6. The difference from FIG. 6 is that when CCNF2 sends a response message 740, it is sent via CCNF1. The redirection request message 730 sent by CCNF1 to CCNF2 includes the first request message received by terminal 101. After receiving the message, CCNF2 processes the message and sends a response message 740 to CCNF1. At this time, it can include the terminating point information for CCNF2 to communicate with RAN102 in the future. After receiving the response message 740, CCNF1 transmits the message to RAN102. At this time, the terminating point information 750 for CCNF2 to communicate with RAN102 in the future can also be transmitted together. RAN102 transmits the response message 740 to terminal 101 and can establish a connection 750 with CCNF2 using the CCNF2 terminating point information.

[0057] That is, CCNF1 transmits a message to CCNF2 using any one of the three methods shown in FIGS. 5, 6, and 7. FIG. 8 schematizes the overall procedure of the embodiments described so far. At step 810, when the user terminal 701 makes a minimum connection to the network, it sends an initial connection request message. The initial connection request message includes information such as the service type (NSSAI) desired by the terminal 801. The RAN 802 that receives the message selects an appropriate CCNF1 based on the NSSAI information at step 820 and transmits the message. For example, this process is described in the description of FIG. 1. At step 830, CCNF1 authenticates whether the terminal 801 is a terminal that can connect to the PLMN. If the authentication is successful, it authenticates what services the terminal can use. Furthermore, the final provided service is determined based on the service information requested by the terminal 801, the subscription information, and the operator policy information. For example, this process is described in the description of FIG. 2. CCNF1 determines whether it can provide the final provided service. If it can provide it, CCNF1 sends an initial attach response to the RAN and skips steps 850 to 870. The initial attach response can include AcceptedNSSAI, which is the final provided service information. However, if CCNF1 is a node that cannot provide the final provided service (840), it must search for a CCNF that can provide the final provided service (850). For example, the search method can be determined based on the information that CCNF1 has (similar to that illustrated in FIG. 3), or it can be determined by using the NRF method (similar to that illustrated in FIG. 4). When the method of FIG. 3 is used, CCNF1 itself determines whether it is an appropriate CCNF, and there is no additional message flow. However, when the method of FIG. 4 is used, a specific message flow schematized in FIG. 9 is shown. Referring to FIG. 9, at steps 910, 913, and 915, each CCNF registers its service providing capability with the central server NRF905 in advance. The NRF905 stores and manages the information (profile) of each CCNF.If the CCNF's capability changes, it sends an update message to the NRF905 to keep the capability information managed by the NRF905 up-to-date. At step 920, CCNF1 sends an NF (network function) request message to the NR905F. The NR request message contains the required functions of the CCNF that CCNF1 wishes to discover. The NRF905 searches for the CCNF desired by CCNF1 based on the CCNF profile information (in this embodiment, CCNF2) and includes this information in the NF response and sends it (950). The NF information can be the address of the node (e.g., IP (internet protocol) address or URL (uniform resource locator) information), the address of a group of nodes of the same type having the capability (e.g., the IP address or URL information representing the group), or the group ID. CCNF1 can store the information sent to the NRF905 for a certain period and reuse it until the value of the information expires. That is, when the same type of node information with the same capability is required, the stored information can be used without further asking the NRF905. Further, steps 930 and 940, and steps 960 and 970 can occur optionally. Step 930 is a process of further confirming whether CCNF2 can provide the service before the NRF905 responds to CCNF1 (step 950). The message at step 930 can be transmitted including the requested capability. Or the NRF905 can ask about what capabilities there are without including the requested capability. In response to the query, CCNF2 can send a message at step 940 including the capability information it has, or including the presence or absence of the capability requested at step 930. Step 960 is to notify CCNF2 by the NRF905 that CCNF1 can also connect. The message at step 960 can include CCNF1 information and a token for authentication.For this purpose, the token information can be included in 950 steps. CCNF1 can send a message including the token when connecting to the subsequent CCNF2. Then, CCNF2 can authenticate that CCNF1 is an authenticated node and a node that may provide services compared with the token information previously received by NRF905, and then communicate.

[0058] Referring to FIG. 8, there are three possible methods for message redirection corresponding to the 860 stage, and each method was described in FIGS. 5, 6, and 7. FIG. 10 schematizes the detailed message flow. Group A in FIG. 10 is the reroute method through the RAN described in FIG. 5. The value included in the 1011 stage of Group A in FIG. 10 contains information on CCNF2, which is the node to which RAN1002 must reroute the message. The CCNF2 information may be the address or id of CCNF2, or may be the address or identifier of the group to which CCNF2 belongs. Based on this information, RAN1002 searches for CCNF2 connected to RAN1002 and reroutes the message. When the NSSAI received from the terminal is changed at the 830 stage of FIG. 8, the changed NSSAI can be included. Furthermore, when performing the 830 stage of FIG. 8, security information indicating that the terminal has been authenticated can also be included in the 1011 stage. Additionally, terminal information, subscriber information, etc. can be included. RAN1002 sends the message to CCNF2 at the 1012 stage. If security information is included, CCNF2 may confirm that the terminal has been pre-authenticated and may not perform additional authentication. CCNF2 receives the terminal request message (NAS request, 1012 stage), processes it, and if necessary, includes NAS response in the message sent to RAN1002 at the 1013 stage and sends it to the RAN. For example, the 1013 stage corresponds to the 870 stage of FIG. 8. In the case of FIG. 8, NAS response is the initial attach response. Group B in FIG. 10 corresponds to FIG. 6. At the 1021 stage, CCNF1 immediately sends a reroute message to CCNF2. The reroute message at the 1021 stage can include the terminating point information of RAN1002. Furthermore, when the NSSAI received from the terminal is changed at the 830 stage of FIG. 8, the changed NSSAI can be included. For example, the 1021 stage corresponds to the 870 stage of FIG. 8. Group C in FIG. 10 corresponds to FIG. 7. When the NSSAI received from the terminal is changed at the 830 stage of FIG. 8, the changed NSSAI can be included in the message at the 1031 stage.CCNF2, which received the reroute message at stage 1032, sends a response to CCNF1, and at stage 1033, CCNF1 forwards it to RAN1002. In the case of group C in Figure 10, the 870 stage in Figure 8 does not occur.

[0059] At the initial connection of the terminal, RAN1002 searches for an appropriate CCNF based on the information provided by the terminal. If RAN1002 searches for an incorrect CCNF, it means that the routing information stored in RAN1002 is incorrect and the information needs to be updated. The necessary information for RAN information update can be included in stage 1011 of Figure 10. Or it can be included in stage 1013 of Figure 10. Or it can be included in stage 1022 of (B) in Figure 10. Or it can be included in stages 1032 and 1033 of Figure 10 and transmitted to RAN1002. Or the CCNF can send a message separately from the flow described so far to the RAN. The information is the mapping of the NSSAI, which is the information requested by the terminal, and the ID of the CCNF that supports the NSSAI, or the mapping information of the NSSAI and the CCNF group ID. RAN1002, which received the information, updates the corresponding routing table it manages.

[0060] On one hand, the terminal (UE) is connected to the RAN (Radio Access Network) and then connected to the device that performs the Mobility Management Function of the 5G core network device. In the present invention, this device can be replaced by the CCNF (Common Control Network Function), and the CCNF performs the roles of Mobility Management and terminal authentication. In the present invention, this will be referred to as the AMF (Access and Mobility management Function). This can refer to a Function or device that is responsible for both the access of the RAN and the Mobility management of the terminal. The CCNF is a comprehensive concept of network function or device that includes the AMF. The AMF or the CCNF including it serves to route session-related messages for the terminal to the SMF (Session Management Function). The CCNF is connected to the SMF, and the SMF is connected to the UPF (UserPlaneFunction) to allocate the user plane resources provided to the terminal and establish a tunnel for transmitting data between the base station and the UPF. Referring to the AMF in the present invention can mean the core network device that provides Mobility Management for the terminal, that is, the device that receives the NAS messages of the terminal having the CCNF or other names. For convenience, in the present invention, it is referred to as the AMF (Access Mobility management Function). The Networksliceinstance means one service provided by the network, which consists of the CCNF, the SM, and the UPF. For example, when a mobile communication operator supports a broadband communication service, a network service that satisfies the requirements for broadband communication is defined and composed of the Network SliceInstance to provide the service. When a mobile communication operator supports an IoT service, a network service that satisfies the requirements for the IoT service is defined and composed of the IoT Network Slice Instance to provide the service.

[0061] 4G means the fourth-generation mobile communication, which is composed of the Radio Access Network technology called LTE and the core network technology called EPC (Evolved Packet Core). 5G means the fifth-generation mobile communication. The Radio Access Network technology of 5G is called NG-RAN (Next Generation RAN), and the core network technology is called 5G System Core.

[0062] Mobility Restriction Area means a set of area information composed of an allowed area where a session can be established and data can be exchanged depending on the position of the terminal, a non-allowed area where a session cannot be established and only control signaling is possible, and a forbidden area where all mobile communication services are impossible.

[0063] Mobile network operators can configure different Network Slices for different services provided to terminals, and can provide different Mobility Restriction Areas for different Network Slices. For example, a mobile network operator providing Mobile Broadband services and IoT services can provide the two services by configuring them from different Network Slices respectively. The mobile network operator can restrict the terminal to receive services in a wide area through the Mobility Restriction Area for Mobile Broadband, and can apply the Mobility Restriction Area so that the terminal can receive data transmission and reception services in a specific area for IoT.

[0064] <Second Embodiment> In specifically describing the second embodiment, terms for identifying connection nodes (nodes) used, terms for referring to network entities, terms for referring to messages, terms for referring to interfaces between network entities, terms for referring to various identification information, etc. are exemplified for convenience of explanation. Therefore, the present invention is not limited to the terms described later, and other terms that refer to objects having equivalent technical meanings can be used.

[0065] Hereinafter, for convenience of explanation, the present invention uses terms and names defined in the standards for 5G systems. However, the present invention is not limited by the above terms and names, and can be similarly applied to systems based on other standards. Also, non-3gpp access can be similarly applied to other accesses excluding access through 5G including access through WiFi.

[0066] FIG. 11 shows an example of a cellular network structure using a common AMF when the PLMN of 3gpp access and the PLMN of N3IWF are the same when a terminal according to an embodiment of the present invention is connected via 3gpp access and non-3gpp access.

[0067] Referring to FIG. 11, when the terminal (or UE) 1101 connects to the 5G core network via 3gpp access, that is, 5GRAN 1102, and at the same time the terminal 1101 connects to the 5G core network via non-3gpp access 1103, if the N3IWF 1104 selected by the terminal 1101 for this purpose is in the same PLMN as 3gpp access, the situation regarding how to select the same common AMF 1105 will be described later.

[0068] Here, N3IWF1104 is defined as 5G core network equipment for the smooth interworking of non-3GPP access1103 and the 5G core network. It is also called ngPDG as an entity responsible for forwarding NAS messages or data transmitted and received via non-3GPP access1103.

[0069] Figure 12 shows an example of a cellular network structure in which different AMFs are used when the terminal according to the embodiment of the present invention is connected via 3GPP access and non-3GPP access, and the PLMN of 3GPP access is different from the PLMN of N3IWF.

[0070] Referring to Figure 12, when the terminal (or UE) 1201 is connected to the 5G core network via 3GPP access, that is, 5GRAN1202, and at the same time the terminal 1201 is connected to the 5G core network via non-3GPP access1203, the situation of how to select the AMF will be described later, taking as an example the case where different AMFs (1205, 1206) are selected when the N3IWF1204 selected by the terminal 1201 is in a different PLMN from 3GPP access, that is, 5GRAN1202.

[0071] Figure 13 shows the process of selecting an AMF when a terminal connected to 3GPP access connects to the 5G network via non-3GPP access according to the embodiment of the present invention.

[0072] Referring to FIG. 13, when the terminal 1301 successfully registers with the 5G network, a temporary UE ID for the terminal 1301 is assigned from the serving AMF 1303 (step 1311). Here, the temporary UE ID is composed of a temporary value assigned by the AMF to the terminal 1301 together with part or all of the information of the PLMN accessed by the terminal 1301, or the ID of the AMF group to which the serving AMF 1303 belongs, or the ID of the serving AMF 1303. The temporary UE ID corresponds to the GUTI (globally unique temporary identity) in the case of the LTE system. The terminal 1301 can also include the network capability at the connected AMF 1303 together with the temporary UE ID. The network capability can also include information on the service type provided by the AMF 1303.

[0073] When the terminal 1301 that has registered with the 5G network through 3gpp access finds a non-3gpp access such as WiFi (step 1313) and attempts to connect to the 5G network via the non-3gpp access, the terminal 1301 discovers and selects the N3IWF 1302 (step 1314). The method by which the terminal 1301 discovers and selects the N3IWF 1302 can use the same method as the method for the terminal to select the ePDG in the case of the LTE system (see TS23.402).

[0074] Compare the PLMN selected in 3GPP access at step 1315 with the PLMN to which the N3IWF selected above belongs. When the PLMNs are the same as each other, the terminal 1301 sets the routing information, which is the information for the N3IWF 1302 to select an AMF, to the temporary UE ID assigned at the previous 3GPP registration step or a part of the temporary UE ID. For example, a part of the temporary UE ID can include a part or all of the PLMN ID, or the ID of the group of AMFs to which the serving AMF 1303 belongs, or the ID of the serving AMF.

[0075] On the other hand, when the PLMN selected in 3GPP access and the PLMN to which the selected N3IWF belongs are different from each other, no value is set in the routing information, or a null value is set (step 1316).

[0076] The terminal 1301 transmits the routing information generated at step 1316 to the N3IWF 1302 together with a registration request message for attachment (step 1317). Using the received routing information, the N3IWF 1302 selects an AMF 1304 (step 1318). The registration request message can include the temporary UE ID received via 3GPP access. Further, the registration request message can also include an indication indicating that the temporary UE ID is assigned from the AMF currently connected via 3GPP access or notifying that there has already been a registration through another access.

[0077] When N3IWF1302 selects an AMF for non-3GPP access and the ID of the serving AMF1303 is included in the routing information, it selects the serving AMF1303.

[0078] On the other hand, when the ID of the AMF group to which the serving AMF1303 belongs is included in the routing information without the ID of the serving AMF1303, and a different AMF1304 from the serving AMF1303 is selected through selection of an AMF for non-3GPP access, the selected AMF searches for the ID of the serving AMF1303 with reference to the temporary UE ID included in the terminal's registration request message, and then can redirect the registration request message with the serving AMF1303 so that the same common AMF is selected.

[0079] When there is not enough information to search for the ID of the serving AMF1303 in the routing information, a default AMF can also be selected. At this time, the default AMF can search for the ID of the serving AMF1303 with reference to the temporary UE ID included in the terminal's registration request message if necessary, and then redirect the registration request message with the serving AMF1303 so that the same common AMF is selected.

[0080] After that, the registration process for the terminal's non-3GPP access is performed through the selected AMF.

[0081] FIG. 14 shows the process of selecting an AMF when a terminal connected to 3GPP access according to another embodiment of the present invention connects to a 5G network via non-3GPP access.

[0082] Referring to FIG. 14, when the terminal 1401 successfully registers with the 5G network, a temporary UE ID for the terminal is assigned from the serving AMF 1403 (step 1411). Here, the temporary UE ID is composed of a temporary value assigned by the AMF 1403 to the terminal together with part or all of the information of the PLMN accessed by the terminal 1401, the ID of the group of the AMF to which the serving AMF 1403 belongs, or the ID of the serving AMF 1403. The temporary UE ID corresponds to the GUTI in the case of the LTE system. The terminal 1401 can also include the network capability at the connected AMF 1403 together with the temporary UE ID. The network capability can also include information on the service type provided by the AMF 1403.

[0083] When the terminal 1401 that has registered with the 5G network through 3GPP access finds non-3GPP access such as WiFi (step 1413) and attempts to connect to the 5G network via non-3GPP access, the terminal discovers and selects the N3IWF 1402 (step 1414). The method by which the terminal 1401 discovers and selects the N3IWF 1402 can use the same method as the method for the terminal to select the ePDG in the case of the LTE system (see TS23.402).

[0084] Compare the PLMN selected via 3GPP access with the PLMN to which the selected N3IWF belongs (step 1415a). Further, the terminal 1401 determines whether the serving AMF 1403 supports the service type that the terminal 1401 intends to request via non-3GPP access based on the network capability information received at the 1411 step (step 1415b).

[0085] If the PLMNs are identical to each other and the serving AMF 1403 supports the service type that the terminal 1401 intends to request via non-3GPP access, the terminal 1401 sets the routing information, which is the information for the N3IWF 1402 to select an AMF, with the temporary UE ID assigned at the previous 3GPP registration step or a part of the temporary UE ID. For example, a part of the temporary UE ID may include a part or all of the PLMN ID, the ID of the group of the AMF to which the serving AMF 1403 belongs, or the ID of the serving AMF.

[0086] On the other hand, if the PLMN selected via 3GPP access and the PLMN to which the selected N3IWF 1402 belongs are different from each other, or if the serving AMF 1403 does not support the service type that the terminal 1401 intends to request via non-3GPP access, set the service type that is intended to be requested via non-3GPP access with the routing information (1416).

[0087] The terminal 1401 sends the routing information generated in the 1416 stage to the N3IWF (1402) together with a registration request message for attachment (stage 1417). Using the received routing information, the N3IWF 1402 selects the AMF 1404 (stage 1418). The registration request message can include a temporary UE ID received via 3gpp access. Further, it can also include an indication for indicating that the temporary UE ID has been assigned from the AMF to which the terminal is currently connected via 3gpp access, or for notifying that there has already been a registration through another access.

[0088] When selecting an AMF for non-3gpp access, if the ID of the serving AMF 1403 is included in the routing information, the N3IWF 1402 selects the serving AMF 1403.

[0089] On the other hand, when the ID of the AMF group to which the serving AMF 1403 belongs is included in the routing information without the ID of the serving AMF 1403, and a different AMF 1404 from the serving AMF 1403 is selected through selection of an AMF for non-3gpp access, the selected AMF can search for the ID of the serving AMF 1403 with reference to the temporary UE ID included in the registration request message of the terminal 1401, and then redirect the registration request message to the serving AMF 1403 so that the same common AMF is selected.

[0090] When the service type to be requested via non-3GPP access is included in the routing information, an appropriate AMF that can serve the service type separately from the serving AMF 1403 of 3GPP access can also be selected.

[0091] Thereafter, the registration process through the non-3GPP access of the terminal 1401 is performed via the selected AMF.

[0092] FIG. 15 shows the process of selecting an AMF when a terminal connected to non-3GPP access connects to a 5G network via 3GPP access according to an embodiment of the present invention.

[0093] Referring to FIG. 15, when the terminal 1501 successfully registers with the 5G network via non-3GPP access, a temporary UE ID for the terminal 1501 is assigned from the serving AMF 1503 (step 1511). Here, the temporary UE ID is composed of a temporary value assigned by the AMF 1503 to the terminal 1501 together with part or all of the PLMN information of the serving AMF 1503 accessed by the terminal 1501, the ID of the group of AMFs to which the serving AMF 1503 belongs, or the ID of the serving AMF 1503. The temporary UE ID corresponds to the GUTI in the case of the LTE system. The terminal 1501 can also include the network capability at the connected AMF 1503 together with the temporary UE ID. The network capability can also include information on the service type that can be provided by the AMF 1503.

[0094] The terminal 1501 registered in the 5G network through non-3GPP access enters the 3GPP coverage (step 1513), and selects a PLMN (step 1514) to connect to the 5G network via 3GPP access.

[0095] Compare the PLMN of the N3IWF selected by non-3GPP access with the PLMN selected for 3GPP access (step 1515). If the PLMNs are the same, the terminal 1501 sets the routing information, which is the information for the RAN 1502 to select the AMF, to the temporary UE ID or a part of the temporary UE ID assigned in the previous non-3GPP registration stage. For example, a part of the temporary UE ID can include part or all of the PLMN ID, or the ID of the group of AMFs to which the serving AMF 1503 belongs, or the ID of the serving AMF.

[0096] On the other hand, if the PLMN selected for 3GPP access is different from the PLMN to which the selected N3IWF for non-3GPP access belongs, no value or a null value is set in the routing information (step 1516).

[0097] The terminal 1501 transmits the routing information generated in the 1516 stage to the RAN 1502 together with a registration request message for attachment (stage 1517), and the RAN 1502 selects the AMF 1504 using the received routing information (stage 1518). The registration request message may include a temporary UE ID received via non-3GPP access. Further, it may also include an indication for indicating that the temporary UE ID has been assigned from the AMF to which the terminal is currently connected via non-3GPP access, or for notifying that there has already been a registration through another access.

[0098] When the RAN 1502 selects an AMF for 3GPP access and the ID of the serving AMF 1503 is included in the routing information, it selects the serving AMF.

[0099] On the other hand, when the ID of the AMF group to which the serving AMF 1503 belongs is included in the routing information without the ID of the serving AMF 1503, and a different AMF 1504 is selected via selection of an AMF for 3GPP access, the selected AMF 1504 searches for the ID of the serving AMF 1503 with reference to the temporary UE ID included in the registration request message of the terminal, and then can redirect the registration request message to the serving AMF 1503 so that the same common AMF is selected.

[0100] If there is not enough information in the routing information to search for the ID of the serving AMF 1503, the default AMF can also be selected. At this time, the default AMF can search for the ID of the serving AMF 1503 with reference to the temporary UE ID included in the terminal's registration request message if necessary, and then redirect the registration request message with the serving AMF 1503 so that the same common AMF can be selected.

[0101] After that, the registration process through the 3GPP access of the terminal is performed via the selected AMF.

[0102] FIG. 16 shows the process of selecting an AMF when a terminal connected to non-3GPP access connects to a 5G network via 3GPP access according to another embodiment of the present invention.

[0103] Referring to FIG. 16, when the terminal 1601 successfully registers with the 5G network via non-3GPP access, a temporary UE ID for the terminal 1601 is assigned from the serving AMF 1603 (step 1611). Here, the temporary UE ID is composed of a temporary value assigned by the AMF 1603 to the terminal 1601 together with part or all of the PLMN information of the serving AMF 1603 accessed by the terminal 1601, or the ID of the AMF group to which the serving AMF 1603 belongs, or the ID of the serving AMF 1603. The temporary UE ID corresponds to the GUTI in the case of the LTE system. The terminal 1601 can also include the network capability at the connected AMF 1603 together with the temporary UE ID. The network capability can also include information on the service type that can be provided by the AMF 1603.

[0104] On the other hand, when the terminal 1601 that has registered with the 5G network via non-3GPP access enters the 3GPP coverage (step 1613) and selects a PLMN for connecting to the 5G network via 3GPP access (step 1614).

[0105] At this time, the PLMN of the N3IWF selected by non-3GPP access is compared with the PLMN selected for 3GPP access (step 1615a).

[0106] Also, the terminal 1601 determines whether the serving AMF 1603 supports the service type that the terminal 1601 intends to request via 3GPP access through the network capability information received at the 1611 step (step 1615b).

[0107] When the PLMNs are the same as each other and the serving AMF 1603 supports the service type that the terminal 1603 attempts to request via 3GPP access, the terminal 1601 sets the routing information, which is the information for the RAN 1602 to select an AMF, to the temporary UE ID assigned at the previous non-3GPP registration stage or a part of the temporary UE ID (stage 1616). For example, a part of the temporary UE ID can include some or all of the PLMN ID, or the ID of the group of AMFs to which the serving AMF 1603 belongs, or the ID of the serving AMF.

[0108] On the other hand, when the PLMN selected by 3GPP access and the PLMN to which the N3IWF selected for non-3GPP access belongs are different from each other, or when the serving AMF 1603 does not support the service type that the terminal 1601 attempts to request via 3GPP access, the service type that attempts to be requested via 3GPP access is set with the routing information (stage 1616).

[0109] The terminal 1601 transmits the routing information generated at the stage 1616 to the RAN 1602 together with a registration request message for attachment (stage 1617), and the RAN 1602 selects the AMF 1604 using the received routing information (stage 1618). The registration request message can include the temporary UE ID received via non-3GPP access. Further, the registration request message can also include an indication for indicating that the temporary UE ID is assigned from the AMF to which the terminal is currently connected via non-3GPP access or for notifying that there has already been a registration through another access.

[0110] When RAN1602 selects an AMF for 3GPP access, if the ID of the serving AMF1603 is included in the routing information, the serving AMF1603 shall be selected.

[0111] On the other hand, when the ID of the AMF group to which the serving AMF1603 belongs is included in the routing information without the ID of the serving AMF1603, and a different AMF1604 from the serving AMF1603 is selected via selection of an AMF for 3GPP access, the selected AMF1604 shall search for the ID of the serving AMF1603 with reference to the temporary UE ID included in the terminal's registration request message, and then redirect the registration request message with the serving AMF1603 so that the same common AMF can be selected.

[0112] When the service type to be requested via 3GPP access is included in the routing information, it is also possible to select an appropriate AMF that can service the service type separately from the serving AMF1603 for non-3GPP access.

[0113] Thereafter, perform the registration process for the terminal's 3GPP access via the selected AMF.

[0114] <Embodiment 3> Terms for identifying connection nodes (nodes) used in specifically describing the third embodiment, terms for referring to network entities, terms for referring to messages, terms for referring to interfaces between network entities, terms for referring to various identification information, etc. are exemplified for convenience of explanation. Therefore, the present invention is not limited to the terms described later, and other terms that refer to objects having equivalent technical meanings can be used.

[0115] Hereinafter, for convenience of explanation, the present invention uses terms and names defined by the standards for 5G systems. However, the present invention is not limited by the above terms and names, and can be similarly applied to systems based on other standards.

[0116] FIG. 17 shows an example of the network structure between a (R)AN node and an AMF according to an embodiment of the present invention. Here, the (R)AN node corresponds to a RAN node, i.e., a base station, in the case of 3gpp access, and corresponds to an N3IWF in the case of non-3gpp access.

[0117] In particular, FIG. 17 relates to a method for the RAN node to select an appropriate AMF for forwarding the initial NAS message when a terminal connects to a 5G network in a mobile communication network and transmits an initial NAS message such as a registration request message. Further, FIG. 17 relates to a network configuration solution for removing the stickiness or persistence between the terminal and the AMF in the process of selecting the AMF.

[0118] Referring to FIG. 17, the AMFs (AMF1-9) generate AMF groups (AMFgroup1-3) for terminals capable of the same service according to the types of service types that each can serve. Each AMF group has an AMG group database (DB) that stores information such as UE context, such as UE status, handled by all AMFs belonging to the AMF group. And the (R)AN node 1702 has a connection preconfigured with the AMF of each AMF group (for example, a concept such as an S1-MME (mobility management entity) connection in the EPC (evolved packet core) network). All AMFs in the AMF group have a connection with the same (R)AN node 1702.

[0119] Each AMF records in the database of the AMF group, including the status of the terminal 1701, when the context of the UE1701 is added, updated, or deleted.

[0120] In the process of setting up a PDU (packet data unit) session, the AMF selects an appropriate SMF, and the SMF selects an appropriate UPF to generate a tunnel between the (R)AN node 1702 and the UPF for transmitting data.

[0121] FIG. 18 shows the process by which the (R)AN node selects an appropriate AMF when the terminal transmits an initial NAS message according to an embodiment of the present invention.

[0122] Referring to FIG. 18, the terminal 1801 generates an initial NAS message (step 1811) to connect to the 5G core network. The initial NAS message corresponds to, for example, an attach request message for registration, a TAU (tracking area update) request message, a registration request message, a service request message, etc. The terminal 1801 can include routing information in the generated initial NAS message so that the (R) AN node 1802 can send it with an appropriate AMF.

[0123] In step 1812, when the terminal 1801 is pre-registered in the current area (for example, a TAI (tracking area identifier) list), all or a part of the temporary UE ID assigned by the AMF in the previous registration process, for example, a part or all of the PLMN ID, AMF group ID, or AMF ID, is used as the routing information. If the terminal 1801 is not pre-registered in the current area (for example, a TAI list), the terminal 1801 can also set the service type desired by the terminal 1801 as the routing information.

[0124] The terminal 1801 transmits the initial NAS message together with the routing information to the (R) AN node 1802 (step 1813). The (R) AN node 1802 means the RAN, that is, the base station in the case of 3GPP access, and means the N3IWF in the case of non-3GPP access.

[0125] The (R)AN node 1802 determines whether the received routing information is a temporary UE ID or part of a temporary UE ID (step 1814). If so, it extracts the AMF group ID from the routing information. On the other hand, if not, it selects the AMF group associated with the requesting service types requested by the terminal 1801 to obtain the AMF group ID. If there is no AMF group that supports all the requesting service types, it is also possible to select, as a second best option, an AMF group that supports some of the service types or select the default AMF group (step 1815). The (R)AN node 1802 selects an appropriate AMF by referring to the location information of the terminal 1801 or the load information between the AMFs in the selected AMF group (step 1816), and transmits the initial NAS message using the selected AMF (step 1817). When the initial NAS message contains a temporary UE ID, the AMF 1803 requests and receives the UE context from the AMF group database 1804. At step 1818, the UE context request message can convey both the temporary UE ID and information regarding the purpose for which it is used. In response at step 1819, the AMF group database 1804 transmits the UE context information including the status of the terminal 1801 to the AMF 1803. The UE context information can include information for terminal authentication.

[0126] Based on the received UE context, the AMF 1803 processes the initial NAS message (at stage 1820), and if necessary, the processing result can be transmitted to the terminal 1801 (at stage 1821). Further, when the UE context and UE status are changed during the processing of the initial NAS message, the AMF group database 1804 is notified of the updated information (at stages 1822, 1823, and 1824).

[0127] Figure 19 shows the process by which the SMF selects the AMF to send paging to a terminal in the IDLE mode according to an embodiment of the present invention.

[0128] Referring to Figure 19, after the terminal has successfully registered with the 5G network and enters the idle mode (at stage 1911), when downlink data arrives at the UPF 1901 (at stage 1912), the UPF 1901 sends a downlink data notification message to the SMF 1902 to notify the terminal that data has arrived (at stage 1913). The downlink data notification may also include some or all of the PDU session ID or UE ID. The UE ID can be a pre-assigned temporary UE ID or the terminal's permanent ID, such as IMSI information, etc.

[0129] The SMF 1902 that has received the downlink data notification checks whether there is a connection with the AMF for the terminal (at stage 1914). If there is no connection, the SMF 1902 selects the AMF group ID from the temporary UE ID of the terminal it has, and selects one of the AMFs belonging to the selected AMF group ID (at stage 1915). However, if there is a connection, the AMF having the connection is selected.

[0130] The selected AMF1 (1903) can be notified by the SMF1902 sending a paging request message that downlink data has occurred for the terminal (step 1916). At this time, the paging request message can also include the PDU session ID where the downlink data has arrived in addition to the temporary UE ID.

[0131] The AMF1 (1903) that has received the paging request message requests and receives the UE context corresponding to the temporary UE ID from the AMF group database 1904 (steps 1917, 1918). At this time, the AMF1 (1903) notifies the UE context request message that it is for paging for the PDU session in addition to the temporary UE ID together with the PDU session ID, so that the AMF group database 1904 can update the UE status together with the UE context (steps 1917, 1919).

[0132] The AMF1 (1903) that has received the UE context performs UE paging via the RAN (step 1920). The terminal that has received the UE paging transmits an initial NAS message via the method provided in FIG. 18, and an appropriate AMF2 (1905) receives the initial NAS message (step 1921), and requests and receives the UE context from the AMF group database 1904 using the temporary UE ID included in the initial NAS message (steps 1922 and 1923). The AMF2 (1905) recognizes from the AMF group database 1904 the UE status together with the UE context, that is, the situation that paging for the PDU session is in progress, and sets up a tunnel for transmitting the downlink data pending for the PDU session and forwards the data (step 1924). Of course, the change in UE status due to this is notified by the AMF to the AMF group database and the UE context is updated when paging ends and it is switched to the connected mode.

[0133] FIG. 20 is a drawing showing the configuration of a terminal according to an embodiment of the present invention.

[0134] Referring to FIG. 20, a terminal according to an embodiment of the present invention can include a transmission / reception unit 2010 and a control unit 2020 that controls the overall operation of the terminal. And the transmission / reception unit 2010 can include a transmission unit 2013 and a reception unit 2015.

[0135] The transmission / reception unit 2010 can transmit and receive signals to and from other network entities via the transmission unit 2013 and the reception unit 2015.

[0136] The control unit 2020 can control the terminal to perform the operation of any one of the above-described embodiments. For example, the control unit 2020 can transmit a first message including at least one of first information for identifying the AMF and second information of the service type requested by the terminal to the first base station, and can receive a second message from the AMF as a response to the first message.

[0137] On the other hand, the control unit 2020 and the transceiver unit 2010 do not necessarily have to be embodied as separate modules, and of course, they can be embodied as one component in a form such as a single chip. And the control unit 2020 and the transceiver unit 2010 can be electrically connected. And, for example, the control unit 2020 may be a circuit, an application-specific circuit, or at least one processor. Further, the operation of the terminal can be realized by providing a memory device storing the program code in any component within the terminal.

[0138] Furthermore, the terminal according to an embodiment of the present invention may further include a storage unit 2030. The storage unit 2030 can store at least one of the information transmitted and received via the transceiver unit 2010 and / or the information generated via the control unit 2010.

[0139] FIG. 21 is a drawing showing the configuration of a base station according to an embodiment of the present invention.

[0140] Referring to FIG. 21, a base station according to an embodiment of the present invention may include a transceiver unit 2110 and a control unit 2120 that controls the overall operation of the base station. And the transceiver unit 2110 may include a transmitter 2113 and a receiver 2115.

[0141] The transceiver unit 2110 can transmit and receive signals to and from other network entities via the transmitter 2113 and the receiver 2115.

[0142] The control unit 2120 can control the base station to perform the operation of any one of the above-described embodiments. For example, the control unit 2120 receives a first message including at least one of first information for identifying the AMF from the terminal and second information of a service type requested by the terminal, selects an AMF set based on the first information and the second information, and can select an AMF with the selected AMF set.

[0143] On the other hand, the control unit 2120 and the transceiver unit 2110 do not necessarily have to be implemented as separate modules, and of course, they can be implemented as one component in a form such as a single chip. And the control unit 2120 and the transceiver unit 2110 can be electrically connected. And, for example, the control unit 2120 may be a circuit, an application-specific circuit, or at least one processor. Furthermore, the operation of the base station can be realized by providing a memory device storing the program code in any component within the base station.

[0144] Furthermore, the base station according to an embodiment of the present invention may further include a storage unit 2130. The storage unit 2130 can store at least one of the information transmitted and received via the transceiver unit 2110 and / or the information generated via the control unit 2120. For example, the storage unit 2130 can store at least one of the information transmitted and received via the transceiver unit 2110 and / or the information generated via the control unit 2110.

[0145] FIG. 22 is a drawing showing the configuration of an AMF according to an embodiment of the present invention.

[0146] Referring to FIG. 22, an AMF according to an embodiment of the present invention can include a transceiver unit 2210 and a control unit 2220 that controls the overall operation of the AMF. And the transceiver unit 2210 can include a transmitter unit 2213 and a receiver unit 2215.

[0147] The transceiver unit 2210 can transmit and receive signals to and from other network entities via the transmitter unit 2213 and the receiver unit 2215.

[0148] The control unit 2220 can control the AMF to perform any one of the operations of the above-described embodiments. For example, the control unit 2220 can determine to reroute a request message received from a terminal including information of a service requested by the terminal, select another AMF that supports the service requested by the terminal, and transmit the request message to the selected other AMF.

[0149] On the other hand, the control unit 2220 and the transceiver unit 2210 do not necessarily have to be implemented as separate modules, and of course, they can be implemented as one component in a form such as a single chip.

[0150] And the control unit 2220 and the transceiver unit 2210 can be electrically connected. And, for example, the control unit 2220 can be a circuit, an application-specific circuit, or at least one processor. Further, the operation of the AMF can be realized by providing a memory device storing the program code in any component within the AMF.

[0151] Furthermore, the AMF according to an embodiment of the present invention may further include a storage unit 2230. The storage unit 2230 can store at least one of the information transmitted and received via the transmission / reception unit 2210 and / or the information generated via the control unit 2220. For example, the storage unit 2230 can store at least one of the information transmitted and received via the transmission / reception unit 2210 and / or the information generated via the control unit 2210.

[0152] In the specific embodiments of the present invention described above, the components included in the invention are represented in singular or plural by the presented specific embodiments. However, the singular or plural expressions are selected for convenience of explanation to suit the presented situation, and the present invention is not limited to singular or plural components. Even if the components are expressed in plural, they can be composed of a single one, or even if the components are expressed in singular, they can be composed of a plurality.

[0153] On the other hand, the embodiments of the present invention disclosed in this specification and the drawings are only presented as specific examples to easily explain the description content of the present invention and assist in understanding the present invention, and are not intended to limit the scope of the present invention. That is, it is obvious to those having ordinary knowledge in the technical field to which the present invention belongs that other modifications based on the technical idea of the present invention are feasible. Also, the respective embodiments can be operated in combination with each other if necessary. For example, a part of the embodiments of the present invention can be combined with each other so that the base station and the terminal can be operated. Furthermore, although the embodiments are presented based on the NR system, other modifications based on the technical idea of the embodiments may also be feasible for other systems such as FDD or TDD LTE systems.

[0154] Furthermore, although the preferred embodiments of the present invention are disclosed in the present specification and the drawings, and specific terms are used, these are only used in a general sense to easily explain the description of the present invention and assist in understanding the invention, and are not intended to limit the scope of the present invention. It is obvious to those having ordinary knowledge in the technical field to which the present invention pertains that other variations can be implemented based on the technical idea of the present invention in addition to the embodiments disclosed herein.

Explanation of Signs

[0155] 101 Terminal 105 Network 210 Database 212 Policy Control Function 450 Repository 530 Redirection Message 540 Response Message 630 Redirection Request Message 640 Response Message 730 Redirection Request Message 740 Response Message 801 Terminal 1101 Terminal 1201 Terminal 1301 Terminal 1401 Terminal 1501 Terminal 1601 Terminal 1801 Terminal 2010 Transceiver 2013 Transmitter 2015 Receiver 2020 Control Unit 2030 Memory Unit 2110 Transceiver 2113 Transmitter 2115 Receiver 2120 Control Unit 2130 Memory Unit 2210 Transceiver 2213 Transmitter 2215 Receiver 2220 Control Unit 2230 Memory Unit

Claims

1. A method performed by a terminal in a wireless communication system, comprising: receiving, from an AMF (access and mobility management function), a first message including first information for identifying the AMF and the terminal, wherein the first message includes the first information assigned based on a successful registration for a first connection; determining whether a PLMN (public land mobile network) associated with a second connection is the same as a PLMN associated with the first connection; when the PLMN associated with the second connection is the same as the PLMN associated with the first connection, transmitting, to a connection network entity for the second connection, a second message including second information for identifying the AMF and requesting registration for the second connection; the second information includes at least a part of the first information; the second information includes an AMF set identifier for the AMF and an AMF identifier for the AMF; the first connection includes a 3GPP (3rd generation partnership project) connection, and the second connection includes a non-3GPP connection.

2. the first information includes a GUTI (globally unique temporary identifier); the second information includes at least a part of the GUTI; The method according to claim 1, wherein the second information identifies the AMF used by the connection network entity for the second connection.

3. The method according to claim 1, wherein the connection network entity is a wireless connection network entity or an N3IWF (non-3rd generation partnership project (3gpp) inter-working function).

4. The method according to claim 1, further comprising: when a PLMN associated with the second connection is not the same as a PLMN associated with the first connection, transmitting the second message not including the second information to the connection network entity for the second connection.

5. A method performed by a connection network entity of a first connection in a wireless communication system, comprising: when a PLMN (public land mobile network) associated with the first connection is the same as a PLMN associated with the second connection, receiving, from a terminal, a registration request message for the first connection and a message including first information for identifying an AMF (access and mobility management function); selecting the AMF based on the first information. The first information includes at least a part of second information. The first information includes an AMF set identifier for the AMF and an AMF identifier for the AMF. The second information identifies the AMF and the terminal. The second connection includes a 3gpp (3rd generation partnership project) connection, and the first connection includes a non-3gpp connection.

6. The second information includes a GUTI (globally unique temporary identifier). The first information includes at least a part of the GUTI. The method according to claim 5, characterized in that the second information is assigned based on a successful registration for the second connection. **Claim 7** The method according to claim 5, characterized in that the connection network entity is a wireless connection network entity or an N3IWF (non-3rd generation partnership project (3gpp) inter-working function). **Claim 8** The method according to claim 5, characterized by including the step of receiving, from the terminal, the message not including the first information when a PLMN associated with the second connection is not the same as a PLMN associated with the first connection. **Claim 9** A terminal of a wireless communication system, including a transceiver, and a control unit, wherein the control unit receives, from an AMF (access and mobility management function), a first message including first information for identifying the AMF and the terminal, the first information being assigned based on a successful registration for a first connection, determines whether a PLMN (public land mobile network) associated with the second connection is the same as a PLMN associated with the first connection, when the PLMN associated with the second connection is the same as the PLMN associated with the first connection, controls to transmit, to a connection network entity for the second connection, a second message including second information for identifying the AMF and requesting registration for the second connection, wherein the second information includes at least a part of the first information, and the second information includes an AMF set identifier for the AMF and an AMF identifier for the AMF. The terminal is characterized in that the first connection includes a 3GPP (3rd Generation Partnership Project) connection, and the second connection includes a non-3GPP connection.

10. The first information includes a GUTI (globally unique temporary identifier), The second information includes at least a part of the GUTI, The terminal according to claim 9, wherein the second information identifies the AMF used by the connection network entity for the second connection.

11. The terminal according to claim 9, wherein the connection network entity is a radio connection network entity or an N3IWF (non-3rd Generation Partnership Project (3GPP) inter-working function).

12. The control unit, The terminal according to claim 9, wherein when a PLMN (public land mobile network) associated with the second connection is not the same as a PLMN associated with the first connection, the control unit controls to transmit the second message not including the second information to the connection network entity for the second connection.

13. A connection network entity of a first connection of a radio communication system, including a transceiver unit and a control unit, wherein the control unit, when a PLMN (public land mobile network) associated with the first connection is the same as a PLMN associated with the second connection, receives, from a terminal, a registration request message for the first connection and a message including first information for identifying an AMF (access and mobility management function), and controls to select the AMF based on the first information. The first information includes at least a part of the second information The first information includes an AMF set identifier for the AMF and an AMF identifier for the AMF, The second information identifies the AMF and the terminal, The second connection includes a 3GPP (3rd Generation Partnership Project) connection, and the first connection includes a non-3GPP connection, characterized as a connection network entity.

14. The second information includes a GUTI (globally unique temporary identifier), The first information includes at least a part of the GUTI, The second information is assigned based on a successful registration for the second connection, characterized as the connection network entity according to claim 13.

15. The connection network entity is a radio connection network entity or an N3IWF (non-3rd Generation Partnership Project (3GPP) inter-working function), characterized as the connection network entity according to claim 13.

16. The control unit, When the PLMN associated with the second connection is not the same as the PLMN associated with the first connection, controls to receive from the terminal the message that does not include the first information, characterized as the connection network entity according to claim 13.

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