Method and apparatus for supporting roaming service traffic routing in mobile communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method performed by an access and mobility management function (AMF) in a communication system includes receiving a registration request message from a user equipment (UE); receiving subscription information for session management function (SMF) selection from a unified data management (UDM), the subscription information including an identifier (ID) of a target public land mobile network (PLMN) for traffic routing; and selecting an SMF for traffic routing in the target PLMN based on the ID of the target PLMN included in the subscription information.

Description

Technical Field

[0001] This invention relates to mobile communication systems. More specifically, this disclosure relates to methods and apparatus for supporting roaming service routing in mobile communication systems. Background Technology

[0002] 5G mobile communication technology defines a wide frequency band, enabling high transmission rates and new services. It can be implemented not only in "sub-6GHz" bands such as 3.5GHz, but also in "above 6GHz" bands, including 28GHz and 39GHz, known as mmWave (millimeter waves). Furthermore, 6G mobile communication technology (referred to as "super 5G systems") is being considered in terahertz bands (e.g., the 95GHz to 3THz band) to achieve transmission rates fifty times faster than 5G and ultra-low latency one-tenth that of 5G.

[0003] At the outset of 5G mobile communication technology development, in order to support services and meet performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC), standardization is underway for beamforming and massive multiple-input multiple-output (MIMO) to mitigate radio wave path loss and increase millimeter-wave transmission distance; dynamic operation to support parameter sets (e.g., operating multiple subcarrier spacings) and time slot formats for efficient utilization of millimeter-wave resources; initial access technologies to support multi-beam transmission and broadband; the definition and operation of BWP (bandwidth portion); new channel coding methods such as LDPC (low-density parity-check) codes for large-volume data transmission and polar codes for highly reliable transmission of control information; L2 preprocessing; and network slicing for providing dedicated networks for specific services.

[0004] Currently, considering the services supported by 5G mobile communication technology, there are discussions about improvements and performance enhancements to the initial 5G mobile communication technology, and there is already physical layer standardization for technologies such as: V2X (Vehicle-to-Everything) for assisting autonomous vehicle driving determination based on information about the location and status of vehicles transmitted by vehicles and for enhancing user convenience; NR-U (New Radio Unlicensed) for system operation aimed at complying with various regulatory requirements in unlicensed frequency bands; NR UE power saving; NTN (Non-Terrestrial Network) for providing coverage in areas where communication with terrestrial networks is unavailable, as UE-satellite direct communication; and positioning.

[0005] Furthermore, standardization is ongoing for air interface architectures / protocols related to technologies such as the Industrial Internet of Things (IIoT) for supporting new services through interoperability and convergence with other industries, IAB (Integrated Access and Backhaul) for providing nodes for network service area extension by supporting wireless backhaul and access links in an integrated manner, mobility enhancements including conditional handover and DAPS (Dual Active Stack) handover, and two-step random access (two-step RACH for NR) for simplifying the random access process. Standardization is also underway for 5G baseline architectures (e.g., service-based architectures or service-based interfaces) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, as well as system architectures / services for Mobile Edge Computing (MEC) based on UE location reception services.

[0006] With the commercialization of 5G mobile communication systems, the already exponentially growing number of connected devices will connect to communication networks, and the enhanced functionality and performance of 5G mobile communication systems, as well as the integrated operation of connected devices, are expected to be necessary. To this end, new research is planned related to: Extended Reality (XR) for effectively supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality), etc.; 5G performance improvements and complexity reduction through the utilization of Artificial Intelligence (AI) and Machine Learning (ML); AI service support; Metaverse service support; and drone communication.

[0007] Furthermore, this development of 5G mobile communication systems will serve as the foundation for not only the development of new waveforms for providing terahertz band coverage for 6G mobile communication technologies, multi-antenna transmission technologies (such as full-dimensional MIMO (FD-MIMO), array antennas, and massive MIMO), metamaterial-based lenses and antennas for improving terahertz band signal coverage, high-dimensional spatial multiplexing technologies using OAM (orbital angular momentum), and RIS (reconfigurable smart surfaces), but also the development of: full-duplex technologies for improving the frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technologies for system optimization by leveraging satellites and AI (artificial intelligence) from the design phase and internalizing end-to-end AI support capabilities, and next-generation distributed computing technologies for providing services at a level of complexity exceeding the operational capabilities of UEs by utilizing ultra-high-performance communication and computing resources.

[0008] The above information is presented as background information only to aid in understanding this disclosure. No determination or assertion is made regarding whether any of the above content can be used as prior art with respect to this disclosure. Summary of the Invention

[0009] Technical issues

[0010] When a home network operator operates multiple public terrestrial mobile networks (PLMNs) (e.g., when multiple PLMN identifiers (IDs) are used), there is a need to support methods for selecting a PLMN to handle roaming for a specific subscriber and for specifying home network functions.

[0011] In addition, a method is needed to support routing services of roaming UEs to the core network of another country operated by the home network operator or the core network of a partner of the home network operator.

[0012] Solution to the problem

[0013] According to an aspect of this disclosure, a method is provided performed by an Access and Mobility Management Function (AMF) in a communication system. The method includes receiving a registration request message from a User Equipment (UE), receiving subscription information from a Unified Data Management (UDM) for selecting a Session Management Function (SMF), the subscription information including an identifier (ID) of a target Public Land Mobile Network (PLMN) for service routing, and selecting an SMF in the target PLMN for service routing based on the ID of the target PLMN included in the subscription information.

[0014] According to another aspect of this disclosure, a method is provided performed by a Visited Network Repository Function (v-NRF) in a communication system. The method includes receiving a first Network Function (NF) Discovery Request message from an AMF for SMF selection, the message including the ID of a target PLMN for traffic routing; sending a second NF Discovery Request message including the ID of the target PLMN to a Home Network Repository Function (h-NRF); receiving a first NF Discovery Request Response message from the h-NRF including information about SMFs in the target PLMN for traffic routing; and sending a second NF Discovery Request Response message to the AMF including information about SMFs in the target PLMN for traffic routing.

[0015] According to another aspect of this disclosure, a method performed by an h-NRF in a communication system is provided. The method includes receiving from a v-NRF a first NF discovery request message including the ID of a target PLMN for service routing, identifying a service routing SMF in the target PLMN based on the target PLMN's ID, and sending to the v-NRF a first NF discovery request response message including information about the service routing SMF in the target PLMN.

[0016] According to another aspect of this disclosure, an AMF (Automatic Management Function) in a communication system is provided. The AMF includes a transceiver and a controller coupled to the transceiver and configured to receive a registration request message from a UE, receive subscription information for SMF selection from a UDM (User Device), the subscription information including the ID of a target PLMN for service routing, and select an SMF for service routing in the target PLMN based on the ID of the target PLMN included in the subscription information.

[0017] According to another aspect of this disclosure, a v-NRF in a communication system is provided. The v-NRF includes a transceiver and a controller coupled to the transceiver and configured to receive, from an AMF, a first NF discovery request message for SMF selection, the first NF discovery request message including the ID of a target PLMN for service routing; send a second NF discovery request message including the ID of the target PLMN to an h-NRF; receive from the h-NRF a first NF discovery request response message including information about SMFs for service routing in the target PLMN; and send a second NF discovery request response message including information about SMFs for service routing in the target PLMN to the AMF.

[0018] According to another aspect of this disclosure, an h-NRF in a communication system is provided. The h-NRF includes a transceiver and a controller, the controller being coupled to the transceiver and configured to receive from a v-NRF a first NF discovery request message including the ID of a target PLMN for service routing, identify a service routing SMF in the target PLMN based on the target PLMN ID, and send a first NF discovery request response message to the v-NRF including information about the service routing SMF in the target PLMN.

[0019] According to another aspect of this disclosure, one or more non-transitory computer-readable storage media are provided, storing one or more computer programs including computer-executable instructions that, when executed individually or jointly by one or more processors of an Access and Mobility Management Function (AMF) in a communication system, cause the AMF in the communication system to perform operations. These operations include: receiving a registration request message from a User Equipment (UE); receiving subscription information from a Unified Data Management (UDM) for selecting a Session Management Function (SMF), the subscription information including an identifier (ID) of a target Public Land Mobile Network (PLMN) for service routing; and selecting an SMF in the target PLMN for service routing based on the ID of the target PLMN included in the subscription information.

[0020] Beneficial effects of the invention

[0021] The aspects of this disclosure will at least address the aforementioned problems and / or disadvantages, and provide at least the following advantages. Therefore, one aspect of this disclosure is to provide a method for transmitting service traffic of a roaming UE to a specific home network.

[0022] Additional aspects will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practicing the embodiments presented.

[0023] Other aspects, advantages, and salient features of this disclosure will become clear to those skilled in the art from the following detailed description of various embodiments disclosed in conjunction with the accompanying drawings. Attached Figure Description

[0024] The above and other aspects, features and advantages of certain embodiments of this disclosure will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0025] Figure 1A The structure of a 5G system supporting Home Routing (HR) roaming service according to an embodiment of the present disclosure is shown;

[0026] Figure 1B The structure of a 5G system supporting Local Loosening (LBO) roaming service according to an embodiment of the present disclosure is shown;

[0027] Figure 2 This illustrates an embodiment of the present disclosure of routing the service traffic of a roaming UE to a managed environment of the home network.

[0028] Figure 3 This is a sequence diagram illustrating a method for selecting a roaming route target network or an alternative home route PLMN for a roaming UE according to an embodiment of the present disclosure;

[0029] Figure 4A This is a sequence diagram illustrating a method for selecting a roaming route target network or an alternative home route PLMN for a roaming UE according to various embodiments of the present disclosure;

[0030] Figure 4B This is a sequence diagram illustrating a method for selecting a roaming route target network or an alternative home route PLMN for a roaming UE according to various embodiments of the present disclosure;

[0031] Figure 5 This is a sequence diagram illustrating a method for selecting a roaming route target SMF for a roaming UE according to embodiments of the present disclosure; and

[0032] Figure 6 The structure of NF according to an embodiment of the present disclosure is shown.

[0033] Throughout the accompanying drawings, it should be noted that the same reference numerals are used to depict the same or similar elements, features, and structures. Detailed Implementation

[0034] The following description with reference to the accompanying drawings has proven helpful in fully understanding the various embodiments of this disclosure as defined by the claims and their equivalents. It includes various specific details to aid understanding, but these are considered exemplary only. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of this disclosure. Additionally, for clarity and brevity, descriptions of well-known functions and structures may be omitted.

[0035] The terms and words used in the following description and claims are not limited to their literal meaning, but are used by the inventors only to enable a clear and consistent understanding of this disclosure. Therefore, it should be apparent to those skilled in the art that the following description of various embodiments of this disclosure is for illustrative purposes only and is not intended to limit the scope of this disclosure as defined by the appended claims and their equivalents.

[0036] It should be understood that, unless the context clearly specifies otherwise, the singular forms “a,” “an,” and “the” include plural indicators. Thus, for example, a reference to “a component surface” includes a reference to one or more such surfaces.

[0037] In describing the embodiments in this specification, descriptions relating to technical content known in the art and not directly related to this disclosure will be omitted. This omission of unnecessary descriptions is intended to prevent obscuring the main ideas of this disclosure and to convey them more clearly.

[0038] For the same reason, some elements may be exaggerated, omitted, or shown schematically in the accompanying drawings. Furthermore, the size of each element does not perfectly reflect its actual size. In the various drawings, the same or corresponding elements have the same reference numerals.

[0039] The advantages and features of this disclosure, as well as methods for implementing them, will become clear from the embodiments described in detail below with reference to the accompanying drawings. However, this disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose this disclosure and to inform those skilled in the art of its scope, and this disclosure is limited only by the scope of the appended claims. Throughout the specification, the same or similar reference numerals indicate the same or similar elements.

[0040] It should be understood that each box in a flowchart illustration, and combinations of boxes in a flowchart illustration, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create parts for implementing the functions specified in one or more flowchart boxes. These computer program instructions can also be stored in a computer-usable or computer-readable storage medium that can instruct the computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-usable or computer-readable storage medium produce an article of writing comprising instruction parts that implement the functions specified in one or more flowchart boxes. The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus, thereby producing a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide operations for implementing the functions specified in the flowchart boxes.

[0041] Each box in a flowchart can represent a module, segment, or section of code, which includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in the boxes may occur out of order. For example, depending on the functions involved, two boxes shown consecutively may actually execute substantially simultaneously, or these boxes may sometimes execute in reverse order.

[0042] As used in embodiments of this disclosure, "cell" refers to a software or hardware element that performs a predetermined function, such as a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC). However, "cell" is not always limited to software or hardware. A "cell" may be configured to be stored in addressable storage media or to run one or more processors. A "cell" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and parameters. Elements and functions provided by a "cell" may be combined into a smaller number of elements or "cells," or divided into a larger number of elements or "cells." Furthermore, elements and "cells" may be implemented as one or more CPUs within a playback device or secure multimedia card.

[0043] This disclosure provides an apparatus and method for providing interoperability of network slices (or network slicing) in a wireless communication system. Specifically, this disclosure will describe a 5G network system architecture for providing network slicing functionality in a wireless communication system and techniques for interoperability between EPS network systems.

[0044] In the following description, for ease of description, terms referring to signals, channels, control information, network entities, and device elements are used illustratively. Therefore, this disclosure is not limited to the terms described below, and other terms with equivalent technical meanings may be used.

[0045] Various embodiments of this disclosure will be described using terminology found in some communication standards (e.g., the 3rd Generation Partnership Project (3GPP)), but these are for illustrative purposes only. The various embodiments of this disclosure can be readily applied to other communication systems with modifications.

[0046] The operating principles of this disclosure will be described in detail below with reference to the accompanying drawings. The terminology described below is defined in consideration of the functions in this disclosure. They may vary depending on the user, the user's intention, or habits; therefore, the definition of the terminology should be based on the entire contents of this specification.

[0047] For ease of description, terms referring to network entities or network functions and entities of edge computing systems, terms referring to messages, terms referring to identification information, etc., are used illustratively. Therefore, this disclosure is not limited to the terms described below, and other terms referring to subjects with equivalent technical meanings may also be used.

[0048] In the following description, for ease of description, the terms and names defined in the 5G system standards will be used to describe this disclosure, but this disclosure is not limited by these terms and names and can be applied in the same way to systems conforming to other standards.

[0049] It should be understood that the boxes in each flowchart and the combination of flowcharts can be executed by one or more computer programs that include computer-executable instructions. The entirety of one or more computer programs can be stored in a single memory device, or one or more computer programs can be divided into different parts stored in multiple different memory devices.

[0050] Any function or operation described herein can be processed by a processor or a combination of processors. A processor or a combination of processors is circuitry that performs processing and includes circuitry such as an application processor (AP, e.g., a central processing unit (CPU)), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a Wi-Fi chip, a Bluetooth™ chip, a Global Positioning System (GPS) chip, a Near Field Communication (NFC) chip, a connectivity chip, a sensor controller, a touch controller, a fingerprint sensor controller, a display driver integrated circuit (IC), an audio codec chip, a Universal Serial Bus (USB) controller, a camera controller, an image processing IC, a microprocessor unit (MPU), a system-on-a-chip (SoC), an IC, etc.

[0051] Figure 1A and Figure 1B The structures of 5G systems supporting HR roaming services and LBO roaming services according to various embodiments of the present disclosure are shown.

[0052] A 5G system architecture that supports roaming can include various network functions (NFs), and Figure 1A and Figure 1B Examples shown include, for example, Access and Mobility Management Function (AMF), Session Management Function (SMF), Policy Control Function (PCF), Unified Data Management (UDM), Data Network (DN) or Edge Data Network (a local portion of the DN (or a local DN, where a local access data network is possible), User Plane Function (UPF), Application Function (AF), (Radio) Access Network ((R)AN), and User Equipment (UE).

[0053] Roaming in a 5G system allows users to move out of the service area of ​​their home network (or home public land mobile network (H-PLMN)) and then connect to a visited network (or visited public land mobile network (V-PLMN)) to continuously access mobile services. In an embodiment, Figure 1A This illustrates a Home Route (HR) roaming scenario. In HR roaming, even if the UE is located in the visited network, the user's data path can be configured from the visited network to the home network, and can be routed to the data network through the home network. In HR roaming, the home network can control the user's services and data, and can also simplify billing and policy control. Meanwhile, Figure 1B This illustrates a Locally Borrowed (LBO) roaming scenario. In LBO roaming, user data can be directly routed from the visited network to the data network without having to retransmit the data through the home network.

[0054] Each NF can support the following functions:

[0055] -AMF provides access and mobility management functions at the UE level, and a UE can basically connect to one AMF.

[0056] -DN can refer to, for example, operator services, internet access, or third-party services. A DN can transmit downlink protocol data units (PDUs) or receive PDUs transmitted from a UE from a UPF. The local portion of a DN can refer to a data network that, as part of the DN, enables local access and has short data transmission paths. Alternatively, the local portion of a DN can refer to a DN in which edge application servers supporting edge computing services are configured.

[0057] - A PCF can provide the ability to receive information about packet flows from an application server and determine policies such as mobility management and session management. Specifically, a PCF can support the following functions: support a single policy framework for controlling network operations; provide policy rules that allow control plane functions (e.g., AMF, SMF, etc.) to enforce policy rules; and implement a front-end for accessing subscription information related to policy decisions in the Unified Data Repository (UDR). A PCF belonging to an H-PLMN can be referred to as a Home PCF (H-PCF), and a PCF belonging to a V-PLMN can be referred to as a Visited PCF (V-PCF).

[0058] - The SMF provides session management functionality. If a UE has multiple sessions, each session can be managed by a different SMF. The SMF belonging to the H-PLMN can be called the Home SMF (H-SMF), and the SMF belonging to the V-PLMN can be called the Visited SMF (V-SMF).

[0059] -UDM can store user subscription data, policy data, etc.

[0060] - The UPF can transmit downlink PDUs received from the DN to the UE via the (R)AN, and can also transmit uplink PDUs received from the UE to the DN via the (R)AN. An uplink classifier (ULCL) can refer to a UPF that has the function of classifying and transmitting uplink data. A local UPF (L-UPF) can act as an anchor point (PDU session anchor) for sessions sent to the local portion of the DN.

[0061] AF can provide service-related or application-related information to NF service customers. Through AF, NF service customers can subscribe to regular notifications and / or notifications related to subscribed event sensing, or unsubscribe.

[0062] Figure 2This illustration demonstrates an embodiment of the present disclosure of routing the service traffic of a roaming UE to a managed environment of the home network.

[0063] Figure 2 An example of a scenario is shown in which a home network is selected to provide roaming services to a roaming UE and the NF of the selected home network is selected.

[0064] Figure 2 The left side illustrates a scenario where the home network operator of a currently roaming UE operates multiple PLMNs within a country (within the borders of the subscriber's home country). In an embodiment, home network operator A can operate multiple PLMNs identified by PLMNs A-1 to A-3. For example, PLMNs can be divided and operated by region. In this case, home network operator A can delegate the management of home routing PDU sessions for roaming UEs registered in VPLMNs to PLMNs selected from PLMNs A-1 to A-3. Specifically, a connection to a V-SMF can be made by selecting an H-SMF set in a PLMN ID other than the PLMN ID specified in the UE's identifier (e.g., PLMN A-1) (e.g., PLMN A-2). In such an example, in this disclosure, the PLMN identified by the PLMN ID included in the UE's identifier can be referred to as the existing home network, and the roaming routing target network other than the PLMN that can be identified by the UE's identifier can be referred to as the roaming routing target PLMN or the alternative home routing PLMN. Figure 2 On the left, PLMN A-1 can correspond to the existing home network, and PLMN A-2 or PLMN A-3 can correspond to the roaming route target PLMN or the alternative home route PLMN.

[0065] In another embodiment, Figure 2 The right side illustrates a scenario where a home routing session is created by a PLMN operated by a partner operator of the roaming UE's existing home network. In this example, the home routing session may connect to a PLMN set up to a country adjacent to the country the UE is currently roaming in, rather than a PLMN that can be identified by information included in the UE's identifier (i.e., the PLMN that provides communication services in the roaming UE's home country (the home PLMN)). In this case, the operator of the PLMN (set up in an adjacent country) that is selected as the roaming routing target PLMN can be the same as the home network operator, or it can be a partner operator with a service level agreement.

[0066] Figure 3This is a sequence diagram illustrating a method for selecting a roaming route target network or an alternative home route PLMN for a roaming UE according to an embodiment of the present disclosure.

[0067] refer to Figure 3 The UDM can store and manage Home Routing Permission (SDB HR) information based on subscription data. The UDM may have such information configured for it by the Operations, Administration and Maintenance (OAM) server or the Operations and Maintenance (AF). The UDM can provide SDB HR permission information to the AMF or SMF. SDB HR permission information stored in the UDM can be configured for each PLMN ID. In the example, SDB HR permission information can be configured for each PLMN ID of a VPLMN to indicate whether SDB HR is allowed for that specific VPLMN. Additionally, information about the roaming route target PLMN (or alternative HR PLMN) that can be selected when SDR HR is allowed can be included in the SDB HR permission information, or it can be linked to a separately stored and corresponding SDB HR permission information. Furthermore, SDB HR permission information can be configured for each individual UE / subscriber, or for a specific UE group. If SDB HR permission information is configured for a UE group, then SDB HR permission information corresponding to a UE group ID that can be used to identify the UE group may already be configured. Furthermore, the UDM can store SDB HR authorization information that differs from the SDB HR permission information and can provide it to the SMF. The SDB HR authorization information can be provided to the SMF in the roaming routing target PLMN, and can imply that an SDR HR has been authorized for the corresponding UE and the requested PDU session.

[0068] In an embodiment, upon receiving a registration request from a roaming UE, the AMF can obtain SDB HR permission information from the UDM. The AMF can receive SDB HR permission information and roaming route target PLMN (or alternative HR PLMN) information (e.g., identifier, etc.) from the UDM, and this information can be used for H-SMF search and selection upon receiving a PDU session establishment request from the UE. For example, if the AMF has already received a PDU session establishment request from the UE, and if the AMF has already received at least one of SDB HR permission information and roaming route target PLMN (or alternative HR PLMN) information from the UDM, the AMF can perform home SMF selection by using a roaming route target PLMN ID other than the HPLMN ID that can be identified by the UE's SUPI. Furthermore, the AMF can select a V-SMF that supports SDR HR and can connect to the roaming route target PLMN.

[0069] Next, a detailed process relating to the above embodiments will be described. Although optional steps are included in the following description for ease of description, not all of the operations described below must be performed, and some operations may be omitted, depending on various system configurations and scenarios.

[0070] In Operation 301, a roaming UE can send a registration request to the AMF of the VPLMN.

[0071] In Operation 302, AMF, AUSF, and UDF can perform the authentication process for the UE.

[0072] In Operation 303, the AMF can select a UDM to obtain the UE's subscriber information. The AMF can use the PLMN ID information included in the UE's identifier to select the UDM.

[0073] In operation 304, the AMF can register AMF information as UE context information in the UDM.

[0074] In Operation 305, the AMF can obtain the UE's subscriber information from the UDM. The AMF can obtain at least one of SDB HR permission information and roaming route target PLMN (or alternative HR PLMN) information from the UDM. The SDB HR permission information may include information about whether SDB HR is permitted for the corresponding UE. Additionally, the SDB HR permission information can be configured for each VPLMN ID, Data Network Name (DNN), and / or Single Network Slice Selection Auxiliary Information (S-NSSAI). The SDB HR permission information can be stored in the UDM along with the roaming route target PLMN (or alternative HR PLMN) ID. The roaming route target PLMN (or alternative HR PLMN) ID can indicate the target PLMN (other than the PLMN included in the UE's identifier) ​​that can be used to create a session for the roaming UE via SDB HR. Such information can be stored within the SMF selection information in the UDM and can also be provided to the AMF.

[0075] In Operation 306, the UE can register with the AMF and then send a PDU session establishment request message to the AMF.

[0076] In operation 307, upon receiving a PDU session establishment request message from a roaming UE, the AMF may perform SMF (V-SMF and / or H-SMF) selection. The AMF may perform SMF selection by considering at least one of the SDB HR allowance information or roaming route target PLMN (or alternative HR PLMN) information received from the UDM in a previous operation and locally configured SDB HR allowance information.

[0077] For example, upon receiving an SDB HR allowance message, the AMF can select the roaming route target PLMN (or alternatively, the HRPLMN) ID as the SDR HR target PLMN, and can select the SMF set in the selected roaming route target PLMN as the H-SMF. This may mean that the AMF selects the PLMN that can be identified by subscriber information from the UDM, rather than the PLMN that can be identified from the roaming UE's identifier, as the home network. Additionally, this may mean that when the AMF performs an H-SMF selection operation, the AMF considers the PLMN ID received from the UDM rather than the PLMN ID included in the UE identifier when performing the H-SMF search and selection.

[0078] In addition, the AMF can select an SMF that supports SDR HR and can connect to an SMF set in the roaming route target PLMN as a V-SMF.

[0079] In operation 308, the AMF may send a message for a PDU session creation request (Nsmf_PDUSession_Create SM context request) to the V-SMF selected in the previous operation, and may configure and provide it with information about the roaming route target SMF selected as the H-SMF. For example, the AMF may provide the V-SMF with at least one of the following: roaming route target SMF information, roaming route target PLMN ID, SDB home route request indicator, and UE identifier information.

[0080] In Operation 309, the V-SMF may send a PDU session creation request message (PDUSession_Create request) to the roaming route destination SMF. The PDU session creation request message may include information received from the AMF in a previous operation. For example, the V-SMF may send a PDU session creation request message to the H-SMF that includes an SDB home route request indicator.

[0081] In Operation 310, the Roaming Routing Target SMF can function as an H-SMF. To obtain UE subscriber information, the Roaming Routing Target SMF can be configured to reside in a UDM located within the home PLMN identifiable by the UE's identifier, rather than in a PLMN where the Roaming Routing Target SMF is configured, and can request and retrieve the UE's subscriber information. The Roaming Routing Target SMF can receive SDB HR authorization information and / or subscriber information including the target PLMN ID from the UDM. Upon receiving the SDB HR authorization information, the Roaming Routing Target SMF knows that an SDR HR has been authorized for the corresponding PDU session.

[0082] In Operation 311, the roaming route target SMF can be configured as an H-SMF to perform UP path configuration.

[0083] In operation 312, the roaming route target SMF can send a PDU session creation response message (PDUSession_Create response) to the V-SMF, which includes UP path configuration information and / or information indicating that the SDB HR session can be successfully created.

[0084] In operation 313, the V-SMF can send a message to the AMF indicating that a PDU session has been successfully created to the roaming route target PLMN (Nsmf_PDUSession_Create SM context response).

[0085] In operation 314, the AMF can send a PDU session establishment response message to the UE to indicate the successful creation of the PDU session.

[0086] Figure 4A and Figure 4B This is a sequence diagram illustrating a method for selecting a roaming route target network or an alternative home route PLMN for a roaming UE according to various embodiments of the present disclosure.

[0087] Although optional steps are included in the following description for ease of description, not all of the operations described below must be performed, and some operations may be omitted, depending on the various configurations and scenarios on the system.

[0088] refer to Figure 4A In Operation 401, a roaming UE can send a registration request to the VPLMN's AMF.

[0089] In Operation 402, AMF, AUSF, and UDF can perform the authentication process for the UE.

[0090] In Operation 403, the AMF can select a UDM to obtain the UE's subscriber information. The AMF can use the PLMN ID information included in the UE's identifier to select a UDM.

[0091] In Operation 404, the AMF can register AMF information as UE context information in the UDM.

[0092] In operation 405, the AMF can obtain the UE's subscriber information from the UDM. The AMF can obtain at least one of SDB HR permission information and roaming route target PLMN (or alternative HR PLMN) information from the UDM. The SDB HR permission information may include information about whether SDB HR is permitted for the corresponding UE. Additionally, the SDB HR permission information can be configured for each VPLMN ID, DNN, and / or S-NSSAI. The SDB HR permission information can be stored in the UDM along with the roaming route target PLMN (or alternative HR PLMN) ID. In an embodiment, the roaming route target PLMN (or alternative HR PLMN) ID may indicate the target PLMN (a PLMN other than the PLMN included in the UE's identifier) ​​that can be used to create a session for the roaming UE via SDB HR. Such information can be stored within the SMF selection information in the UDM and can also be provided to the AMF.

[0093] In Operation 406, the UE can register with the AMF and then send a PDU session establishment request message to the AMF.

[0094] In operation 407, upon receiving a PDU session establishment request message from a roaming UE, the AMF may perform SMF (V-SMF and / or H-SMF) selection. The AMF may perform SMF selection by considering at least one of the SDB HR allowance information or roaming route target PLMN (or alternative HR PLMN) information received from the UDM in a previous operation and locally configured SDB HR allowance information.

[0095] Upon receiving the SDB HR allowance information, the AMF can select the roaming route target PLMN (or the alternative HR PLMN) ID as the SDR HR target PLMN, and can select the SMF set in the selected roaming route target PLMN as the H-SMF. This may mean that the AMF selects the PLMN that can be identified by the subscriber information from the UDM, rather than the PLMN that can be identified from the roaming UE's identifier, as the home network. Additionally, this may mean that when the AMF performs the H-SMF selection operation, the AMF considers the PLMN ID received from the UDM rather than the PLMN ID included in the UE identifier when performing the H-SMF search and selection.

[0096] AMF can be selected as a V-SMF that supports SDR HR and can connect to an SMF set in the roaming route destination PLMN.

[0097] In operation 408, the AMF may send a message for a PDU session creation request (Nsmf_PDUSession_Create SM context request) to the V-SMF selected in the previous operation, and may configure and provide it with information about the roaming route target SMF selected as the H-SMF. For example, the AMF may provide the V-SMF with at least one of the following: roaming route target SMF information, roaming route target PLMN ID, SDB home route request indicator, and UE identifier information.

[0098] refer to Figure 4B In operation 409, the V-SMF may send a PDU session creation request message (PDUSession_Create request) to the SMF (H-SMF1) of the HPLMN that can be identified from the UE identifier. The PDU session creation request message may include information received from the AMF in previous operations. For example, the V-SMF may send a PDU session creation request message to H-SMF1 that includes an SDB home route request indicator.

[0099] In operation 410, H-SMF1 can receive SDB HR authorization information from the UDM. Upon receiving the SDB HR authorization information, H-SMF1 knows that an SDR HR has been authorized for the corresponding PDU session. H-SMF1 can receive the SDB HR authorization information and roaming route target PLMN information (identifier) ​​from the UDM together.

[0100] In operation 411, H-SMF1 may trigger the H-SMF reselection process when it receives at least one of the SDB HR authorization information and roaming route target PLMN information (identifier) ​​in a previous operation.

[0101] In operation 412, if the H-SMF reselection process has been triggered in a previous operation, H-SMF1 may send a PDU session creation response message (PDUSession_Create response) to V-SMF, which includes at least one of the following: SDB HR authorization information, roaming route target PLMN information (identifier), and H-SMF reselection indicator.

[0102] In operation 413, the V-SMF can provide the information received from H-SMF1 to the AMF and can send it a message requesting H-SMF reselection (Nsmf_PDUSession_Create SM context response).

[0103] In operation 414, the AMF can perform roaming route target SMF selection based on information received from the V-SMF, can provide roaming route target SMF information to the V-SMF, and can perform PDU session creation operations. This can be done as follows: Figure 3 Perform the PDU session creation operation as described in operations 408 to 414.

[0104] In Operation 415, the roaming route target SMF can be configured as an H-SMF (H-SMF2) to perform UP path configuration.

[0105] In operation 416, the AMF can send a PDU session establishment response message to the UE to indicate the successful creation of the PDU session.

[0106] Figure 5 This is a sequence diagram illustrating a method for selecting a roaming routing target SMF for a roaming UE according to an embodiment of the present disclosure.

[0107] exist Figure 5 In the embodiments described above, reference will be made to Figure 3 , Figure 4A and Figure 4B The detailed process of the AMF (vAMF) selecting the roaming route target SMF in the described embodiment is described.

[0108] Although optional steps are included in the following description for ease of description, not all of the operations described below must be performed, and some operations may be omitted, depending on the various configurations and scenarios on the system.

[0109] refer to Figure 5 In Operation 501, an AMF (also referred to as the AMF of the VPLMN to which the UE is roaming, the AMF to which the UE has registered, or the AMF to which the UE can send a PDU session establishment request message) may send an NF discovery request to a visited NRF (vNRF) that is a Network Repository Function (NRF) in the VPLMN. The NF discovery request may include at least one of the following: Home Routing Support Function (SDB HR capability) based on subscription data, the roaming route target PLMN ID, and UE identifier information.

[0110] In operation 502, the vNRF can specify the home NRF (hNRF) as an NRF in the HPLMN by using the HPLMN ID information included in the UE identifier information, and can send an NF discovery request. The NF discovery request message may include information received from the AMF in previous operations and / or the vPLMN ID.

[0111] In Operation 503a-1, the hNRF can select information (identifier and address) about the roaming route target SMF set in the roaming route target PLMN, and can send a response message to the vNRF for the NF discovery request, which includes the roaming route target SMF information.

[0112] In Operation 503a-2, the vNRF can send a response message to the NF discovery request to the AMF, which includes the roaming route target SMF information received from the hNRF.

[0113] If the hNRF does not store information about the network capabilities of the roaming route target PLMN, then operations 503a-1 and 503a-2 above can be omitted, and operations 503b-1 through 303b-4 can be performed.

[0114] In Operation 503b-1, the hNRF can send an NF discovery request to the NRF located in the roaming route destination PLMN, either based on operator policies configured in the hNRF or without storing information about network functions configured in the roaming route destination PLMN. In an embodiment, the message sent from the hNRF to the NRF of the roaming route destination PLMN may include at least one of the following: VPLMN ID, HPLMN ID, UE identifier, and Home Routing Support Function (SDB HR capability) information based on subscription data.

[0115] In Operation 503b-2, the NRF of a roaming route destination PLMN can send a response message to the hNRF in response to an NF discovery request. The response message may include roaming route destination SMF information.

[0116] In Operation 503b-3, the hNRF can send a response message to the vNRF in response to an NF discovery request, which includes SMF information received from the NRF of the roaming route target PLMN.

[0117] In Operation 503b-4, the vNRF can send a response message to the NF discovery request to the AMF, which includes the roaming route target SMF information received from the hNRF.

[0118] The AMF can map the roaming route target SMF information received from the vNRF to the HPLMN ID and / or the roaming route target PLMN ID, and then store it. Upon receiving a PDU session establishment request from a roaming UE, the AMF can provide the V-SMF with information about the roaming route target SMF.

[0119] Figure 6 The structure of NF according to an embodiment of the present disclosure is shown.

[0120] refer to Figure 6 The NF may include a transceiver 610, a controller 620, and a memory 630. The NF may refer to an AMF, SMF, PCF, UPF, AF, UDM, NRF, etc. The transceiver 610, controller 620, and memory 630 of the NF can operate according to at least one or a combination of methods corresponding to the above embodiments. The controller may be defined as a circuit, an application-specific integrated circuit, or at least one processor.

[0121] Transceiver 610 can send / receive signals with other network entities. Transceiver 610 can send control messages and / or subscription information to other NFs, and can receive control messages and / or subscription information from other NFs.

[0122] In embodiments, controller 620 may control the overall operation of the NF according to embodiments presented in this disclosure. For example, controller 620 may control the signal flow between various blocks to perform operations according to the flowchart described above. Specifically, according to embodiments of this disclosure, controller 620 may control a series of operations for selecting a roaming route target network or an alternative home route PLMN for a roaming UE.

[0123] The memory 630 can store at least one of the information sent / received by the transceiver 610 and the information generated by the controller 620.

[0124] While this disclosure has been shown and described with reference to various embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of this disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by an access and mobility management function (AMF) in a communication system, the method comprising: receiving a registration request message from a user equipment (UE); receiving subscription information for session management function (SMF) selection from a unified data management (UDM), the subscription information including an identifier (ID) of a target public land mobile network (PLMN) for traffic routing; and selecting an SMF in the target PLMN for traffic routing based on the ID of the target PLMN included in the subscription information.

2. The method of claim 1, wherein, The selecting an SMF in the target PLMN for traffic routing comprises: sending a network function (NF) discovery request message for SMF selection to a visited network repository function (v-NRF), the network function (NF) discovery request message including the ID of the target PLMN; and receiving a NF discovery response message from the v-NRF, the NF discovery response message including information about the SMF in the target PLMN for traffic routing.

3. The method of claim 1, wherein, The subscription information is associated with each single network slice selection assistance information (S-NSSAI) or each data network name (DNN). 4.The method of claim 1, further comprising: sending the information about the SMF in the target PLMN for traffic routing to the SMF in the visited PLMN. 5.A method performed by a visited network repository function (v-NRF) in a communication system, the method comprising: receiving a first network function (NF) discovery request message for session management function (SMF) selection from an access and mobility management function (AMF), the first network function (NF) discovery request message including an identifier (ID) of a target public land mobile network (PLMN) for traffic routing; sending a second NF discovery request message including the ID of the target PLMN to a home network repository function (h-NRF); receiving a first NF discovery request response message from the h-NRF, the first NF discovery request response message including information about the SMF in the target PLMN for traffic routing; and sending a second NF discovery request response message to the AMF, the second NF discovery request response message including the information about the SMF in the target PLMN for traffic routing.

6. The method of claim 5, wherein, The h-NRF is identified based on identifier information of a user equipment (UE). 7.A method performed by a home network repository function (h-NRF) in a communication system, the method comprising: receiving a first network function (NF) discovery request message from a visited network repository function (v-NRF), the first network function (NF) discovery request message including an identifier (ID) of a target public land mobile network (PLMN) for traffic routing; identifying an SMF in the target PLMN for traffic routing based on the ID of the target PLMN; and sending a first NF discovery request response message to the v-NRF, the first NF discovery request response message including information about the SMF in the target PLMN for traffic routing.

8. The method of claim 7, wherein, Identifying the SMF in the target PLMN for traffic routing includes: sending, to a NRF in the target PLMN, a second NF discovery request based on a configuration in the h-NRF; and receiving, from the NRF in the target PLMN, a second NF discovery request response message including information about the SMF in the target PLMN for traffic routing.

9. An Access and Mobility Management Function (AMF) in a communication system, the AMF comprising: a transceiver; and a controller coupled with the transceiver and configured to: receive, from a User Equipment (UE), a registration request message, receive, from a Unified Data Management (UDM), subscription information for Session Management Function (SMF) selection, the subscription information including an identifier (ID) of a target Public Land Mobile Network (PLMN) for traffic routing, and select the SMF in the target PLMN for traffic routing based on the ID of the target PLMN included in the subscription information.

10. The AMF of claim 9, wherein, To select the SMF in the target PLMN for traffic routing, the controller is configured to: send, to a visited network repository function (v-NRF), a network function (NF) discovery request message for SMF selection, the network function (NF) discovery request message including the ID of the target PLMN; and receive, from the v-NRF, a NF discovery response message including information about the SMF in the target PLMN for traffic routing.

11. The AMF of claim 9, wherein, The subscription information is associated with each single network slice selection assistance information (S-NSSAI) or each data network name (DNN), and wherein the controller is further configured to send, to the SMF in the visited PLMN, the information about the SMF in the target PLMN for traffic routing.

12. A visited network repository function (v-NRF) in a communication system, the v-NRF comprising: a transceiver; and a controller coupled with the transceiver and configured to: receive, from an Access and Mobility Management Function (AMF), a first network function (NF) discovery request message for Session Management Function (SMF) selection, the first network function (NF) discovery request message including an identifier (ID) of a target Public Land Mobile Network (PLMN) for traffic routing, send, to a home network repository function (h-NRF), a second NF discovery request message including the ID of the target PLMN, receive, from the h-NRF, a first NF discovery request response message including information about the SMF in the target PLMN for traffic routing, and send, to the AMF, a second NF discovery request response message including the information about the SMF in the target PLMN for traffic routing.

13. The v-NRF of claim 12, wherein, The h-NRF is identified based on identifier information of a User Equipment (UE).

14. A home network repository function (h-NRF) in a communication system, the h-NRF comprising: a transceiver; and a controller coupled with the transceiver and configured to: receive, from a visited network repository function (v-NRF), a first network function (NF) discovery request message for Session Management Function (SMF) selection, the first network function (NF) discovery request message including an identifier (ID) of a target Public Land Mobile Network (PLMN) for traffic routing, send, to a User Equipment (UE), a registration request response message including the ID of the target PLMN for traffic routing, and select the SMF in the target PLMN for traffic routing based on the ID of the target PLMN included in the first NF discovery request message. receive, from a visited network repository function (v-NRF), a first network function (NF) discovery request message including an identifier (ID) of a target public land mobile network (PLMN) for traffic routing, identify, based on the ID of the target PLMN, an SMF in the target PLMN for traffic routing, and send, to the v-NRF, a first NF discovery request response message including information about the SMF in the target PLMN for traffic routing.

15. The h-NRF of claim 14, wherein, To identify the SMF in the target PLMN for traffic routing, the controller is configured to: send, to an NRF in the target PLMN, a second NF discovery request based on a configuration in the h-NRF; and receive, from the NRF in the target PLMN, a second NF discovery request response message including information about the SMF in the target PLMN for traffic routing.

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