Method and apparatus for improving service reliability in a wireless communication system

Abstract

Provided is a method performed by a first session management function (SMF) of providing continuous service to a user equipment (UE), comprising: identifying, by the first SMF, that a SMF change operation is triggered; sending, to an access and mobility management function (AMF), a message indicating a state change of a packet data unit (PDU) session of the UE in order to request a procedure of changing the SMF; receiving, from a second SMF as a target SMF, a context request message requesting a context of the UE; and sending a context request response message to the second SMF.

Description

[0001] Cross-references to related applications

[0002] This application is based on Korean Patent Application No. 10-2019-0068265, filed with the Korean Intellectual Property Office on June 10, 2019, and claims priority to that application pursuant to 35 U.SC §119, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to methods for managing context in a mobile communication system. Background Technology

[0004] To meet the growing demand for wireless data traffic following the commercialization of fourth-generation (4G) communication systems, efforts have been made to develop improved fifth-generation (5G) communication systems, or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are referred to as super-4G network communication systems or post-Long Term Evolution (LTE) systems.

[0005] To achieve high data transmission rates, 5G communication systems are being considered for implementation in millimeter-wave (mmW) bands (e.g., the 60 GHz band). To reduce radio wave propagation path loss and increase propagation distance within the millimeter-wave band, discussions are underway regarding technologies such as beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO in 5G communication systems.

[0006] In addition, to improve the network of the system, the development of technologies such as Evolved Small Cell, Advanced Small Cell, Cloud Radio Access Network (Cloud RAN), Ultra-Dense Network, Device-to-Device Communication (D2D), Wireless Backhaul, Mobile Network, Cooperative Communication, Coordinated Multipoint Communication (CoMP), and Interference Cancellation is underway in 5G communication systems.

[0007] Furthermore, in 5G communication systems, the development of advanced coding and modulation (ACM) schemes, such as hybrid frequency shift keying and orthogonal amplitude modulation (FQAM) and sliding window superposition coding (SWSC), and enhanced network access schemes, such as filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), or sparse coded multiple access (SCMA), are underway.

[0008] Compared to existing 4G communication systems, 5G communication systems consider resources for a variety of services. For example, the most representative services may include enhanced mobile broadband (eMBB) communication services, ultra-reliable low-latency communication (URLLC) services, massive machine-type communication (mMTC) services, and evolved multimedia broadcast / multicast services (eMBMS). Furthermore, a system providing URLLC services can be called an URLLC system, and a system providing eMBB services can be called an eMBB system. Additionally, the terms "service" and "system" are used interchangeably.

[0009] URLLC service is a newly considered service in 5G systems. Unlike existing 4G systems, it requires extremely high reliability compared to other services (e.g., a packet error rate of approximately 10%). -5 The conditions for URLLC services include low latency (e.g., approximately 0.5 msec). To meet these stringent conditions, URLLC services may require shorter Transmission Time Intervals (TTIs) than eMBB services, and various operational methods for using URLLC services should be considered.

[0010] The internet is evolving from a human-centric network (through which people generate and consume information) to an Internet of Things (IoT) network (distributed components, such as things, through which they send or receive information and process it). The Internet of Things (IoE) technology is emerging, where big data processing technologies are combined with IoT technologies through connections to cloud servers or similar devices. Realizing the IoT requires technological elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology. Therefore, sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC) for connecting things are under investigation.

[0011] In the IoT environment, intelligent Internet of Things (IoT) services can be provided to collect and analyze data generated by connected things, creating new value in people's lives. By integrating and combining existing information technology (IT) with various industries, IoT is applicable to various fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart appliances, and advanced healthcare.

[0012] Therefore, various attempts are underway to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, M2M communication, or MTC are being implemented using 5G communication technologies such as beamforming, MIMO, or array antennas. The application of cloud RNA as a big data processing technology can also be considered an example of the integration of 5G and IoT technologies.

[0013] Meanwhile, with the development of various IT technologies, network devices have evolved into virtualized network functions (NFs) through the application of virtualization technology. Virtualized NFs can be implemented as service units (SWs) free from physical limitations, and therefore can be installed / operated in several types of clouds or data centers (DCs). In particular, NFs can be freely scaled up / down (adjusted) or started / deactivated according to service requirements, system capacity, and network load. Summary of the Invention

[0014] It provides structures and communication methods for exchanging or storing user data (context) processed by network functions (NF) to improve communication efficiency and customer service quality in 5G systems.

[0015] Other aspects will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of the embodiments described herein.

[0016] According to embodiments of this disclosure, a method for providing continuous service to a user equipment (UE) performed by a first session management function (SMF) includes: identifying an SMF change operation triggered by the first SMF; sending a message to an access and mobility management function (AMF) indicating a change in the state of a packet data unit (PDU) session of the UE in order to request a process for changing the SMF; receiving a context request message from a second SMF, which is the target SMF, requesting the UE's context; and sending a context request response message to the second SMF.

[0017] SMF change operations can be triggered in response to an Operations, Administration and Maintenance (OAM) request, and the OAM request may include identification information of the second SMF.

[0018] The method may further include: sending a message to the AMF requesting notification of information about a change in the UE's state; and receiving a notification message from the AMF indicating a change in the UE's state.

[0019] Messages indicating a change in the state of a UE's PDU session may include at least one of the identification information of a second SMF, a context identifier (ID), or the UE's ID information.

[0020] The context request response message may include the context of the UE requested by the second AMF, and the context may include information about the User Plane Function (UPF) to be selected by the second SMF.

[0021] According to embodiments of this disclosure, a method for providing continuous service to a user equipment (UE) performed by an access and mobility management function (AMF) includes: receiving a message from a first session management function (SMF) indicating a change in the state of a packet data unit (PDU) session of the UE in order to request a process of changing the SMF; selecting a second SMF as the target SMF; sending a request message to the second SMF requesting the creation of a new session; and receiving a response message from the second SMF to the request message requesting the creation of a new session.

[0022] The selection of the second SMF can be performed by the AMF or through the Service Communication Agent (SCP).

[0023] The method may further include: receiving a message from a first SMF requesting notification of information about a change in the state of the UE; monitoring the change in the state of the UE; and sending a notification message to the first SMF indicating the change in the state of the UE based on the monitoring results.

[0024] The message indicating a state change of the UE's PDU session may include at least one of the identification information of the second SMF, the context identifier (ID), or the UE's ID information, and the identification information of the second SMF may include SMF set identification information.

[0025] The second SMF can be registered in the Unified Data Management (UDM).

[0026] According to embodiments of this disclosure, a first session management function (SMF) for providing continuous service to a user equipment (UE) includes: a transceiver; and a processor coupled to the transceiver, the processor being configured to: recognize an SMF change operation triggered by the first SMF; send a message to the access and mobility management function (AMF) indicating a state change of the UE's packet data unit (PDU) session to request a change of SMF; receive a context request message from a second SMF, which is the target SMF, requesting the UE's context; and send a context request response message to the second SMF.

[0027] SMF change operations can be triggered in response to an Operations, Administration and Maintenance (OAM) request, and the OAM request may include identification information of the second SMF.

[0028] The processor can be further configured to send a message to the AMF requesting notification of information about a change in the UE's state, and to receive a notification message from the AMF indicating a change in the UE's state.

[0029] Messages indicating a change in the state of a UE's PDU session may include at least one of the identification information of a second SMF, a context identifier (ID), or the UE's ID information.

[0030] The context request response message may include the context of the UE requesting the second SMF, and the context may include information about the User Plane Function (UPF) to be selected by the second SMF.

[0031] According to embodiments of this disclosure, an access and mobility management function (AMF) for providing continuous service to a user equipment (UE) includes: a transceiver; and a processor coupled to the transceiver, the processor being configured to: receive from a first session management function (SMF) a message indicating a change in the state of a packet data unit (PDU) session of the UE, so as to request a process for changing the SMF; select a second SMF as the target SMF; send a request message to the second SMF requesting the creation of a new session; and receive from the second SMF a response message to the request message requesting the creation of a new session.

[0032] The selection of the second SMF can be performed by the AMF or through the Service Communication Agent (SCP).

[0033] The processor can be further configured to receive a message from the first SMF requesting notification of information about a change in the UE's state; monitor the change in the UE's state; and, based on the monitoring results, send a notification message to the first SMF indicating the change in the UE's state.

[0034] The message indicating a state change of the UE's PDU session may include at least one of the identification information of the second SMF, the context identifier (ID), or the UE's ID information, and the identification information of the second SMF may include SMF set identification information.

[0035] The second SMF can be registered in the Unified Data Management (UDM).

[0036] Before proceeding with the detailed description of the embodiments below, it may be advantageous to define certain words and phrases used throughout this patent document: the terms “comprising” and “including” and their derivatives refer to unrestricted inclusion; the term “or” is inclusive and means “and / or”; the phrases “related to” and “in connection with” and their derivatives can mean including, being contained within, being interconnected with, containing, being included in, being connected or combined with, communicating with, cooperating with, interspersed, juxtaposed, being close to, being related to, having, having the nature of, and so on; and the term “controller” refers to any device, system or part thereof that controls at least one operation, which may be implemented in hardware, firmware or software, or at least some combination of both. It should be noted that the functionality associated with any particular controller can be centralized or distributed, whether local or remote.

[0037] Furthermore, the various functions described below can be implemented or supported by one or more computer programs, each consisting of computer-readable program code embedded in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, procedures, functions, objects, classes, instances, associated data, or portions thereof suitable for implementation in appropriate computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code, and executable code. The term "computer-readable medium" includes any type of media accessible to a computer, such as read-only memory (ROM), random access memory (RAM), hard disk drive, optical disc (CD), digital video disc (DVD), or any other type of storage. "Non-transitory" computer-readable media does not include wired, wireless, optical, or other communication links that transmit temporary electronic or other signals. Non-transitory computer-readable media includes media that can permanently store data and media that can store and later rewrite data, such as rewritable optical discs or erasable storage devices.

[0038] This patent document provides definitions of certain words and phrases, which should be understood by those skilled in the art as applicable in many, if not most, cases to the use of the words and phrases defined therein and in the future. Attached Figure Description

[0039] The above-described aspects, features, and advantages of certain embodiments of the present disclosure, as well as other aspects, features, and advantages, will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein:

[0040] Figure 1 This illustrates a fifth-generation (5G) system architecture based on a service-based architecture (SBA) according to embodiments of the present disclosure;

[0041] Figure 2 This illustrates a network function (NF) configuration and context management structure according to an embodiment of the present disclosure;

[0042] Figure 3 This illustrates an example of the operation of a 5G system including a user equipment (UE), a base station, and a core, according to embodiments of the present disclosure.

[0043] Figure 4 This is a flowchart illustrating a method for processing a service according to an embodiment of the present disclosure, which can maintain the service without conflict when changes to the NF are required during the service period.

[0044] Figure 5This is a flowchart illustrating a method for processing a service according to an embodiment of the present disclosure, which is able to maintain the service without conflict when changes are needed in the NF during the service period;

[0045] Figure 6 This is a flowchart illustrating a method for selecting an NF (Network Function) taking into account network conditions according to an embodiment of the present disclosure;

[0046] Figure 7 This is a flowchart illustrating a method for moving the context of an NF by reducing the duration of a UE state change according to an embodiment of the present disclosure;

[0047] Figure 8 This is a flowchart illustrating a method for performing an NF change by triggering a state change of a UE according to an embodiment of the present disclosure;

[0048] Figure 9 This is a flowchart illustrating a method for exchanging information related to an NF as a backup NF according to an embodiment of the present disclosure;

[0049] Figure 10 This is a block diagram illustrating a network entity according to an embodiment of the present disclosure; and

[0050] Figure 11 This is a block diagram illustrating a UE according to an embodiment of the present disclosure. Detailed Implementation

[0051] The appendix discussed below Figures 1 to 11 The various embodiments described in this patent document to illustrate the principles of this disclosure are for illustrative purposes only and should not be construed as limiting the scope of this disclosure in any way. Those skilled in the art will recognize that the principles of this disclosure can be implemented in any suitably arranged system or apparatus.

[0052] The operating principles of this disclosure will now be described more fully with reference to the accompanying drawings. In describing this disclosure, detailed descriptions of known functions or configurations may be omitted where it is deemed that such detailed descriptions might unnecessarily obscure the essence of this disclosure. Furthermore, the terminology used herein is defined with reference to the functions described in this disclosure and may have different meanings depending on the intent, conventions, etc., of the user or operator. Therefore, the terminology should be defined in accordance with the description throughout the specification.

[0053] For the same reason, some elements in the accompanying drawings are enlarged, omitted, or shown schematically. Furthermore, the actual size of each element does not need to be shown in the drawings. In the accompanying drawings, identical or corresponding elements are indicated by the same reference numerals.

[0054] The advantages and features of this disclosure, as well as methods for achieving these advantages and features, will become more apparent from the following detailed description of relevant embodiments with reference to the accompanying drawings. However, this disclosure may be implemented in many different forms and should not be construed as being limited to the embodiments described herein; rather, these embodiments are provided to make the disclosure more thorough and complete, and to fully express the principles of the disclosure to those skilled in the art. The scope of this disclosure is defined only in the claims. Throughout the specification, similar reference numerals or characters refer to similar elements.

[0055] It is understood that each block and combination of blocks in a flowchart can be implemented using computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus to cause the instructions, which execute via the processor of the computer or other programmable data processing apparatus, to generate methods for performing the functions specified in the flowchart blocks. These computer program instructions can also be stored in a computer-usable or computer-readable memory that instructs the computer or other programmable data processing apparatus to operate in a particular manner, causing the instructions stored in the computer-usable or computer-readable memory to produce a product including instruction methods for performing the functions specified in the flowchart blocks. 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 data processing apparatus to produce a computer-executable process, such that the instructions, which execute on the computer or other programmable data processing apparatus, provide steps for implementing the functions specified in the flowchart blocks.

[0056] Furthermore, each block can represent a module, segment, or portion of code that includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions recorded in a block may not appear in the current order. For example, depending on the functions involved, two blocks displayed consecutively may actually execute substantially concurrently, or these blocks may sometimes be executed in reverse order.

[0057] As used herein, the term "unit" or "device" refers to a software element or hardware element, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), that performs a certain function. However, the term "unit" or "device" is not limited to software or hardware. The term "unit" or "device" may be configured to be contained in addressable storage media or to replicate one or more processors. Thus, the term "unit" or "device" may, for example, include object-oriented software components, class components, and task components, as well as processes, functions, attributes, programs, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables, etc. The functionality provided by components and "units" or "devices" may be combined into a smaller number of components and "units" or "devices," or may be further separated into other components and "units" or "devices." Furthermore, components and "units" or "devices" may be used to operate one or more central processing units (CPUs) in a device or secure multimedia card. According to embodiments of this disclosure, a "unit" or "device" may include one or more processors.

[0058] In this specification, the expression "at least one of a, b or c" means only a, only b, only c, both a and b, both a and c, both b and c, both a, b and c, or variations thereof.

[0059] Examples of terminals can include user equipment (UE), mobile workstation (MS), mobile phone, smartphone, computer, multimedia system capable of performing communication functions, and so on.

[0060] In this disclosure, the controller may also be referred to as a processor.

[0061] Throughout the specification, a layer (or layer device) may also be referred to as an entity.

[0062] Specifically, this disclosure applies to the 3rd Generation Partnership Project (3GPP) New Radio (NR) (the fifth-generation (5G) mobile communication standard). This disclosure applies to smart systems based on 5G communication technology and Internet of Things (IoT) related technologies (such as smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail businesses, and security and security-related services). In this disclosure, for ease of interpretation, eNB and gNB are used interchangeably. In other words, a base station described as eNB can also represent a gNB. Furthermore, the term "terminal" can refer to mobile phones, NB-IoT devices, sensors, and other wireless communication devices.

[0063] As described below, for ease of explanation, examples are given of terms representing access nodes, network entities or network functions (NFs), messages, interfaces between network entities, various types of identification information, and so on. Therefore, this disclosure is not limited to the terms described below, and other terms representing objects with equivalent technical significance may also be used. An NF can be a network entity.

[0064] For ease of description, this disclosure uses the terms and names defined in the 3GPP Long Term Evolution (LTE) standard and the 5G standard. However, this disclosure is not limited to these terms and names, but is equally applicable to systems conforming to other standards.

[0065] In describing embodiments of this disclosure, the main focus is on UE information (UE context) processed / managed by the NF. UE information (UE context) may include, but is not limited to, a mobility management (MM) context related to UE mobility, an access management (AM) context related to radio connectivity, and a session management (SM) context related to sessions. It may also include all necessary types stored / processed / generated for services in the communication network.

[0066] In this disclosure, the term "service" is used to refer to a particular communication device (or NF) performing a request from another communication device (or NF), i.e., an NF service, and when specifically referring to a service delivered to an actual user (end user), the term "service" can be distinguished as customer service.

[0067] According to embodiments of this disclosure, to improve communication efficiency and customer service quality in a system, a structure and communication method for exchanging or storing user data (context) processed by NFs are provided. Furthermore, according to embodiments of this disclosure, a method is proposed to prevent service processing conflicts (transaction conflicts or race conditions) that may occur between NFs when introducing a structure for exchanging and storing user data processed by NFs. Additionally, according to embodiments of this disclosure, a method is proposed to increase the speed of data exchange and processing between NFs to improve service quality and network operating efficiency.

[0068] Other aspects will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of the embodiments described herein.

[0069] Although the embodiments described below relate to LTE, LTE-advanced (LTE-a), LTE Pro, or 5G (or NR as next-generation mobile communications) systems, the embodiments of this disclosure are applicable to other communication systems with similar technical backgrounds and channel configurations. Furthermore, those skilled in the art will understand that the embodiments of this disclosure are applicable to other communication systems, albeit with modifications, without departing from the scope of this disclosure.

[0070] This disclosure will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments are illustrated.

[0071] Figure 1 This illustrates a fifth-generation (5G) system architecture based on a service-based architecture (SBA) according to an embodiment of the present disclosure.

[0072] To support various 5G services, new system architectures and protocols are needed, and 3GPP decided to introduce a new technology called SBA. The main feature of SBA is that it divides the functionalities of NFs defined in the 3GPP standard into service units, taking into account virtualization technology, the introduction of cloud environments, and the expansion of web-based services, and uses the HTTP / 2 protocol to implement these services. The main features of SBA are not limited to these examples.

[0073] Reference Figure 1 Access and Mobility Management Function (AMF) is the NF that manages radio network access and mobility related to User Equipment (UE). Session Management Function (SMF) is the NF that manages sessions for the UE; session information includes Quality of Service (QoS) information, charging information, and packet processing information. User Plane Function (UPF) is the NF that processes user plane traffic and is controlled by the SMF. Although not mentioned in... Figure 1 As shown, however, 5G systems can include Unstructured Data Storage Network Function (UDSF), which is an NF that stores unstructured data. Any type of data can be stored or retrieved according to the NF's request.

[0074] Reference Figure 1 Radio Access Network (RAN) can refer to the radio access network itself, or it can refer to the radio network between the UE and the base station, or the radio network within the base station itself. Data Network (DN) can refer to the data network. The DN can transmit Packet Data Units (PDUs) destined for the UE to the UPF, and it can also receive PDUs transmitted by the UE through the UPF.

[0075] Policy Control Function (PCF) can be an NF that determines policies related to charging; Application Function (AF) can be an NF that provides information about packet flows that guarantee QoS; Authentication Server Function (AUSF) can be an NF that stores information used for UE authentication; and Unified Data Management (UDM) can be an NF that stores information about users.

[0076] Reference Figure 1 The Network Slice Selection Function (NSSF) can be an NF that selects the network slice corresponding to the UE, and the Network Open Function (NEF) can be an NF that provides, for example, third-party, internal open / reopen, application functions, and means for securely opening services and capabilities for edge computing provided by 3GPP network functions.

[0077] The Network Repository Function (NRF) can support service discovery. It can be an NF that maintains available NF instances and services supported by those NF instances, and the Service Communication Agent (SCP) can be an NF that controls network services.

[0078] According to embodiments of this disclosure, NFs can communicate with each other using predetermined interfaces. For example, the AMF and UE can communicate using interface N1, and the UPF and SMF can communicate using interface N4. Other NFs can also communicate with each other using predetermined interfaces, such as... Figure 1 As shown. This is obvious to those skilled in the art, therefore a detailed description is omitted.

[0079] Figure 1 The 5G system can be configured by excluding at least one of the illustrated NFs, and is not limited to the examples above.

[0080] Figure 2 This illustrates a network function (NF) configuration and context management structure according to an embodiment of the present disclosure.

[0081] Reference Figure 2 UE information (UE context) (which is data within an NF) can be exchanged / shared between NFs. A group of NFs that share and use data within an NF is called an NF set 200. Depending on the implementation environment, a particular NF can be operated / managed as an NF instance, and the embodiments of this disclosure are applicable to the management and operation environment of any type of NF or NF instance.

[0082] According to embodiments of this disclosure, an NF can be replaced by an NF service during the operation of an NF service unit, rather than during the implementation / establishment of an NF unit. Therefore, the term "NF" in this disclosure can include an NF instance, an NF service, and an NF service instance.

[0083] According to embodiments of this disclosure, if multiple NF sets coexist, they can be assigned mutually identifiable identifiers (IDs) or names to distinguish them. Even when NFs within an NF set operate by sharing different contexts, these NFs can be assigned different IDs / names depending on management / operation.

[0084] Figure 3 This is an example illustrating the operation of a 5G system including a user equipment (UE), a base station, and a core according to embodiments of the present disclosure.

[0085] refer to Figure 3 SMF#1 301 and SMF#2 302 can be SMF instances contained in the same SMF set. Two SMFs (e.g., SMF#1 301 and SMF#2 302) can connect to UPF 303 and provide services.

[0086] When SMF#1 301 is providing service to UE 304, and SMF#1 301 is no longer able to provide service to UE 304, SMF#1 301 can provide the UE context (more specifically, the Session Management (SM) context) contained therein to SMF#2 302, and then provide service to UE 304 by interacting with UPF 303. In this case, SMF#1 301 and SMF#2 302 must transmit the UE context in such a way that no conflicts, race conditions, or UE context changes occur between them during the transmission of the UE context.

[0087] In this disclosure, the following embodiments are considered, wherein the UE continuously provides service in an idle or inactive state to prevent errors such as collisions during transmission, race conditions, and UE context changes. Of course, this disclosure is not limited to the examples above, and embodiments of this disclosure may be applied in only one of the two selected states, depending on network settings and operator preferences.

[0088] Figure 4 This is a flowchart illustrating a method for processing a service according to an embodiment of the present disclosure, which is able to maintain the service without conflict when changes to the SMF are required during service provision.

[0089] In operation 401, SMF#1 430 represents the old SMF that provided service to UE 410. In operation 401, conditions can be met in SMF#1 430 to forward service processing to another SMF. The operation to change the SMF can be initiated based on an operator's instruction or a request from the Operation and Management (OAM) system. In this case, the instruction or request to change the SMF may include the designation of a specific UE (or subscriber), a specific session, and a specific DNN / APN / Slice, or may include the designation of a target (target SMF; in this embodiment, SMF#2 440) from which services will subsequently be received.

[0090] SMF#1 430 can wait for a state where no UE traffic transmission or transaction occurs, so that the aforementioned errors (such as collisions or race conditions) will not occur when transferring the service of a specific UE (or subscriber) to another SMF. When SMF#1 430 knows that the Protocol Data Unit (PDU) session of UE 410 is in an idle or inactive state, the method can directly proceed to operation 406.

[0091] In operation 402, to determine whether a UE 410's PDU session has entered an idle or inactive state, SMF#1 430 can send a subscription message to AMF 420 to receive an alert when the UE 410's state becomes idle or inactive. The subscription message may include, but is not limited to, the target UE (subscriber) ID and the target PDU session ID.

[0092] In operation 403, AMF 420 can monitor changes in the state of UE 410.

[0093] When the PDU session state of UE 410 requested in SMF#1 430 in operation 402 is satisfied in operation 404 (e.g., idle or inactive state), AMF 420 may execute operation 405.

[0094] In operation 405, AMF 420 can notify SMF#1 430 that the state of UE 410's PDU session has changed.

[0095] In operation 406, SMF#1 430 can know that the state of UE 410 is suitable for performing the operation of transferring the SMF, and can perform the operation of transferring the context of a specific PDU session to the target SMF.

[0096] According to embodiments of this disclosure, SMF#1 430 may request the Nsmf_PDUSession_ContextPush service from SMF#2 440. The request for the Nsmf_PDUSession_ContextPush service may include the UE context of the PDU session. The request for the Nsmf_PDUSession_ContextPush service may also include an explicit requester (SMF reallocation / change indication) indicating that not only the transport context is needed, but also a change to the SMF used for the corresponding PDU session, and that the service for the PDU session needs to be subsequently provided to UE 410.

[0097] In operation 407, SMF#2 440 determines whether the request can be processed based on the received context. When it is determined that the SMF can be modified, SMF#2 440 can perform the process of searching for UPF(PGW-U) 450 by using the PGW-U tunnel information contained in the received context and changing the N4 path to the modified SMF. At this time, SMF#2 440 can use the N4 session modification procedure to update the SMF information. Although not in Figure 5 The data shows that SMF#2 440 can perform the release and then establish an N4 session.

[0098] In operation 408, SMF#2 440 can receive a response from UPF 450.

[0099] In Operation 409-1, SMF#2 440 can notify SMF#1 430 of the result of the request. When the request fails, and SMF#2 440 notifies SMF#1 430 of the result of the request, SMF#2 440 can add the reason for the failure to the notification and transmit the notification. Each reason for failure can be replaced with a pre-arranged number.

[0100] Reason #1: Insufficient resources, i.e., when there are insufficient resources in SMF #2;

[0101] Reason #2: N4 session failure, i.e., when the session change / generation between SMF#2 440 and UPF fails;

[0102] Reason #3: Authorization, i.e., when the SMF#1 request is unacceptable;

[0103] Reason #4: Semantic error, i.e., when an error is generated when processing the received context.

[0104] The entire process terminates when processing fails.

[0105] When the request is successful, in operation 409-2, SMF#2 440 can perform operations to change the SMF, send or receive Session Management (SM) messages, and process SM messages with AMF 420. To search for AMF 420, SMF#2 440 can use the AMF information (AMF ID) contained in the received UE context and can request an update for N2. This update request can include the target UE (subscriber), PDU session ID, and SMF ID / address.

[0106] In operation 410, AMF 420 sends a response to SMF#2 440, which is used to update the processing of SMF information.

[0107] In operation 411, SMF#2 440 may perform the remaining procedures required due to the SMF change. These remaining procedures may include, for example, performing registration processing in the UDM and setting up the PCC session with the PCF. Embodiments of this disclosure are not limited thereto.

[0108] Figure 5 This is a flowchart illustrating a method for processing a service according to an embodiment of the present disclosure, which is able to maintain the service without conflict when changes are needed in the NF during the service.

[0109] In operation 501, SMF#1 430 represents the old SMF that provides services to UE 410. In operation 501, the conditions for forwarding UE 410's services to another SMF can be met in SMF#1 430. The operation to change the SMF can be initiated based on an operator's instruction or a request from the OAM system. In this case, the instruction or request to change the SMF may include the designation of a specific UE (or subscriber), a specific session, and a specific DNN / APN / Slice, or it may include the designation of a target (target SMF; in this embodiment, SMF#2 440) from which services will subsequently be received.

[0110] SMF#1 430 can wait for a state where no UE traffic transmission or transaction occurs, so that when the service of a specific UE (or subscriber) is transferred to another SMF, errors such as conflicts or race conditions mentioned above will not occur.

[0111] In operation 502, when the PDU session of UE 410 is in an idle or inactive state, SMF#1 430 can send a notification to the AMF 420 to request an SMF change when the state of the UE's PDU session changes. Before performing operation 502, a subscription procedure can be performed to receive notifications from AMF 420 to SMF#1 430 when the state of a specific PDU session changes.

[0112] When a change in PDU session state is notified, and the SMF#1 430 is able to identify the target context as a separate ID, the SMF#1 430 can include the context ID, context type, and the ID of the SMF to be changed in the notification of the PDU session state change, and can transmit the notification. If the context ID cannot be specified, the SMF#1 430 can include the target UE (subscriber) ID, PDU session ID, context type, and the ID of the SMF to be changed in the notification, and can transmit the notification.

[0113] In operation 503, AMF 420 can monitor changes in the state of UE 410.

[0114] When the PDU session state of UE 410 requested from SMF#1 430 in operation 502 is satisfied in operation 504 (e.g., idle or inactive state), AMF 420 may execute operation 505.

[0115] In operation 505, AMF 420 can perform an operation to change the SMF because the state of UE 410's PDU session has been appropriately changed to perform the operation of transferring the SMF to SMF#1430. AMF 420 can use the ID of SMF#2 404 received in operation 502 to send a request to SMF#2 404 for the context of receiving the PDU session and to provide services. The message from AMF 420 to SMF#2 440 may include the ID of the SMF (SMF#1 430) that has been providing services to UE 410, the ID and type of the target context, or the ID of the target UE, the ID of the PDU session, and the context type.

[0116] In operation 506, SMF#2 440 can send a context request to receive context from SMF#1 430 and provide services.

[0117] According to embodiments of this disclosure, SMF#2 440 can request context transfer by using the Nsmf_PDUSession_ContextRequest service as a consumer operation. For example, when SMF#2 440 receives a context ID, SMF#2 440 can request SMF#1 430 to transfer the context using the context ID and context type. Otherwise, SMF#2 440 can request SMF#1 430 to transfer the context using the target UE (subscriber) ID, the PDU session ID, and the context type.

[0118] If SMF#2 440 is unable to receive or provide service after a certain point, it can reject the request. When SMF#2 440 rejects a request, it can include the reason for failure in the rejection message and transmit the rejection message. Each reason for failure can be replaced with a pre-arranged number.

[0119] Reason #1: Insufficient resources, i.e., when there are insufficient resources in SMF #2;

[0120] Reason #2: N4 session failed, i.e., when a session with UPF cannot be modified / generated;

[0121] Reason #3: Authorization, i.e., when the SMF#1 request is unacceptable;

[0122] Reason #4: Semantic error, i.e., an error is generated when processing the context.

[0123] The entire process terminates when processing fails.

[0124] In Operation 507, the SMF#1 430 can determine whether it is possible to process the context transfer request, and when it is determined that it is possible to process the context transfer request, the SMF#1 430 can perform the process of releasing the N4 session. Although not in Figure 5 The document indicates that this process can be replaced by a process that changes the N4 session with UPF 450 from SMF#1 430 to SMF#2 440.

[0125] In Operation 508, SMF#1 430 can respond to a context transfer request by inserting the context requested by SMF#2 440 in Operation 506 into the container. When the request fails, SMF#1 430 can add a failure reason to the response and transfer the response. Each failure reason can be replaced with a pre-arranged number.

[0126] Reason #2: N4 session failed, i.e., when SMF#2 440 failed to modify / generate a session with UPF;

[0127] Reason #3: Authorization, i.e., when the SMF #2 request is unacceptable;

[0128] Reason #4: Semantic error, i.e., an error is generated when processing the received context.

[0129] The entire process terminates when processing fails.

[0130] When the process for releasing the N4 session is applied in operation 507 and operation 508 is successful, SMF#2 440 can, in operation 509, perform the process of establishing the N4 session (between the SMF and the UPF) together with UPF 450. At this time, SMF#2 440 can know which UPF to establish the N4 session with by using the PGW-U tunnel information contained in the context, and SMF#2 440 can perform UPF selection processing when the UPF needs to be changed during N4 setup.

[0131] In Operation 510, SMF#2 440 can send a response indicating that the SMF has been changed, based on a request from AMF 420.

[0132] In operation 511, SMF#2 440 can perform the remaining procedures required due to the SMF change. These remaining procedures may include, for example, performing registration processing in the UDM and setting up the PCC session with the PCF. Embodiments of this disclosure are not limited thereto.

[0133] When an NF set contains multiple NFs (or NF instances) and the state of each NF changes dynamically, for older NFs (SMF#1 430), selecting the target NF based on the context in which it actually moves may be more efficient than specifying a target NF.

[0134] Figure 6 This is a flowchart illustrating a method for selecting an NF (Network Function) taking into account network conditions according to an embodiment of the present disclosure.

[0135] According to another embodiment of this disclosure, a method for selecting an NF when a change is required is proposed, which selects the NF by taking into account the network conditions that may actually occur during context transfer, rather than selecting and specifying the target NF based on a request.

[0136] In Operation 601, SMF#1 430 represents the old SMF providing services to UE 410. In Operation 601, SMF#1 430 may meet the conditions for forwarding UE 410's services to another SMF. The operation to change the SMF can be initiated based on an operator's instruction or a request from the OAM system. In this case, the instruction or request for changing the SMF may include the specification of a specific UE (or subscriber), a specific session, a specific DNN / APN / Slice, or the target SMF to be changed (target SMF) can be dynamically selected from the same set of SMFs as the current SMF without specification.

[0137] In operation 602, SMF#1 430 can wait for a state where no UE traffic transmission or transaction occurs, so that the aforementioned errors (such as conflicts or race conditions) will not occur when transferring the service of UE 410 (or the subscriber) to another SMF. When the PDU session of UE 410 is in an idle or inactive state, SMF#1 430 can send a notification of a state change of the UE's PDU session to request AMF 420 to perform an SMF change operation. Before performing operation 602, a subscription procedure can be performed to receive notifications from AMF 420 to SMF#1 430 when the state of a specific PDU session changes.

[0138] When a PDU session state change is notified, and the SMF#1 430 is able to identify the target context as a separate ID, the SMF#1 430 may include the context ID, context type, and the ID of the set of SMFs to be changed in the notification of the PDU session state change, and may transmit the notification. If the context ID cannot be specified, the SMF#1 430 may include the target UE (subscriber) ID, the PDU session ID, the context type, and the ID of the set of SMFs to be changed in the notification, and may transmit the notification.

[0139] In operation 603, AMF 420 can monitor changes in the state of UE 410.

[0140] When the PDU session state of UE 410 requested in SMF#1 430 in operation 602 is satisfied in operation 604 (e.g., idle or inactive state), AMF 420 may execute operation 605-1 or operation 605-2.

[0141] In operation 605-1, AMF 420 performs an SMF change operation because UE 410's PDU session state has entered SMF#1 430. AMF 420 can select SMF#2 440, the target SMF, by using the ID of the set received in operation 602. When the set contains information for selecting the SMF (capacity, current load status, and operator preferences for each SMF), AMF 420 can select the target SMF by using that information.

[0142] Alternatively, in operation 605-2, AMF 420 can perform a discovery and selection process in conjunction with NRF or SCP 660 to select an SMF. In this case, AMF 420 can use the set ID of the SMF received in operation 602 and can transmit a message including information indicating the selection process for changing the SMF. When a single SMF has previously been set for an SMF change operation, that single SMF can be explicitly selected. The subsequently selected SMF is referred to as SMF#2 440.

[0143] In operation 606, AMF 420 can send a request to SMF#2 440 for a context to receive a PDU session and provide services, using the ID of the SMF selected in operation 602. The request message from AMF 420 to SMF#2 440 may include the ID of the SMF (SMF#1 430) that provided services to UE 410, the ID and type of the target context, or the ID of the target UE 410, the ID of the PDU session, and the context type.

[0144] In Operation 607, SMF#2 440 can send a context request to receive context from SMF#1430 and provide services.

[0145] According to embodiments of this disclosure, SMF#2 440 can request context transfer by acting as a consumer through the Nsmf_PDUSession_ContextRequest service. For example, when SMF#2 440 receives a context ID, SMF#2 440 can use the context ID and context type to request SMF#1 430 to transfer the context. Otherwise, SMF#2 440 can request SMF#1 430 to transfer the context using the target UE (subscriber) ID, the PDU session ID, and the context type.

[0146] If SMF#2 440 is unable to receive or provide service after a certain point, it can reject the request. When SMF#2 440 rejects a request, it can include the reason for failure in the rejection message and transmit the rejection message. Each reason for failure can be replaced with a pre-arranged number.

[0147] Reason #1: Insufficient resources, i.e., when there are insufficient resources in SMF #2;

[0148] Reason #2: N4 session failed, i.e., when a session with UPF cannot be modified / generated;

[0149] Reason #3: Authorization, i.e., when the SMF#1 request is unacceptable;

[0150] Reason #4: Semantic error, i.e., an error is generated when processing the context.

[0151] The entire process terminates when processing fails.

[0152] In operation 608, SMF#1 430 can determine whether it is possible to process the context transfer request, and when it is determined that it is possible to process the context transfer request, SMF#1 430 can perform the process of releasing the N4 session. Although not in Figure 5 The document indicates that this process can be replaced by the process of changing the N4 session with UPF 450 from SMF#1 430 to SMF#2 440.

[0153] In Operation 609, SMF#1 430 can respond to a context transfer request by inserting the context requested by SMF#2 440 in Operation 606 into the container. When the request fails, SMF#1 430 can add a failure reason to the response and transfer the response. Each failure reason can be replaced with a pre-arranged number.

[0154] Reason #2: N4 session failure, i.e., when the session change / generation between SMF#2 440 and UPF fails;

[0155] Reason #3: Authorization, i.e., when the SMF #2 request is unacceptable;

[0156] Reason #4: Semantic error, i.e., an error is generated when processing the received context.

[0157] The entire process terminates when processing fails.

[0158] When the N4 session release process is applied in operation 608 and operation 609 is successful, SMF#2 440 can perform the N4 session establishment process (between SMF and UPF) in operation 610, together with UPF 450. At this time, SMF#2 440 can know which UPF to establish the N4 session with by using the PGW-U tunnel information contained in the context, and SMF#2 440 can perform UPF selection processing when the UPF needs to be changed during N4 setup.

[0159] In Operation 611, SMF#2 440 can send a response indicating that the SMF has been changed, based on a request from AMF 420.

[0160] In operation 612, SMF#2 440 can perform the remaining procedures required due to the SMF change. These remaining procedures may include, for example, performing registration processing in the UDM and setting up the PCC session with the PCF. Embodiments of this disclosure are not limited thereto.

[0161] In the above embodiments, it has been based on Figure 5 This describes the scenario where AMF 420 directly requests SMF#2 440 to generate a context. However, performing NF selection when the UE (subscriber) state changes also applies. Figure 4 This is an example of an implementation. In this case, the SMF (SMF#1) can select the target SMF (SMF#2). When the SMF (SMF#1) can select the target SMF (SMF#2), the above operation 607 is modified as follows, and other operations can be the same as described above.

[0162] In operation 607, SMF#1 430 can determine that the state of UE 410 is suitable for performing the SMF transfer operation and can perform the operation of selecting a target SMF. When the set contains information for selecting an SMF (capacity, current load status, and operator preference for each SMF), AMF 420 can select a target SMF by using the information for selecting the SMF.

[0163] Alternatively, SMF#1 430 can perform a discovery and selection process in conjunction with NRF or SCP 660 to select an SMF. In this case, SMF#1 430 can use the set ID of the SMF received in operation 602 and can transmit a message including information indicating the selection process for changing the SMF. When a single SMF has been previously set for an SMF change operation, that single SMF can be explicitly selected. The subsequently selected SMF is referred to as SMF#2 440.

[0164] According to the above embodiments regarding NF operation changes, to prevent conflicts or race conditions related to transactions / procedures, context switching between NFs is performed only after the UE's session enters an idle or inactive state. However, when the above embodiments are applied to multiple UEs (subscribers), and the connection state is maintained for a long time depending on the traffic transmission pattern, transferring a UE (subscriber) providing services from one NF to another may take a long time. Therefore, Figure 7 The following method is described to change the NF by reducing the duration when the UE becomes idle or inactive.

[0165] Figure 7 This is a flowchart of a method for rapidly moving NF context according to an embodiment of the present disclosure, which takes into account service type or operator settings and achieves this by reducing the duration during which the UE state changes to an idle or inactive state.

[0166] In Operation 701, SMF#1 430 represents the old SMF that provides services to UE 410. In Operation 701, conditions can be met at SMF#1 430 to forward the service of UE 410 to another SMF. The SMF change operation can be initiated based on operator instructions or a request from the OAM system. Instructions or requests to change the SMF can include specifying a particular UE (or subscriber), a particular session, or a particular DNN / APN / Slice. Depending on the service type or operator settings, a standby time period until the UE's (subscriber's) session changes to an idle or inactive state can be explicitly specified.

[0167] In operation 702, SMF#1 430 can wait for a state where no UE traffic transmission or transaction occurs, so that the aforementioned errors (e.g., conflicts or race conditions) will not occur when transferring the UE's (or subscriber's) service to another SMF. When the UE 410's PDU session is in an idle or inactive state, in order to request AMF 420 to perform an operation to change the SMF, SMF#1 430 can send a notification notifying the UE of the PDU session state change. Before performing operation 702, a subscription procedure can be performed to receive notifications from AMF 420 to SMF#1 430 when the state of a specific PDU session changes.

[0168] When a change in PDU session state is notified, and the SMF#1 430 is able to identify the target context as a separate ID, the SMF#1 430 may include the context ID, context type, and the ID of the SMF to be changed, or the SMF set ID including that SMF, in the notification of the PDU session state change, and may transmit the notification. If the context ID cannot be specified, the SMF#1 430 may include the target UE (subscriber) ID, the PDU session ID, the context type, and the ID of the SMF to be changed in the notification, and may transmit the notification. The notification of the change in PDU session state may include the expected activity period until the UE (subscriber) session changes to an idle or inactive state.

[0169] In other words, the expected activity period can be a parameter that allows a UE to transition to an idle or inactive state when it has not sent / received any traffic (user data) or signals to the UE within a certain time period. By setting the expected activity period (e.g., 1 second) for the UE (subscriber) to which the SMF change is to be applied to to a shorter time period than the normal time period for transitioning the UE to an idle state, SMF#1430 can transition the UE (or subscriber) to an idle or inactive state more quickly.

[0170] In operation 703, AMF 420 can update the UE's expected activity period using the received information. In operation 704, AMF 420 can send the UE's expected activity period to base station (RAN) 760 via NG-AP message. Specifically, AMF 420 can insert the expected activity period into the expected UE activity behavior in the core network auxiliary information within the UE context modification request message, and can transmit the core network auxiliary information to RAN 760.

[0171] In operation 705, RAN 760 can store the received core network assistance information, send a response to the received core network assistance information to AMF 420, and control the connection status of UE 410 using the expected activity cycle.

[0172] When the PDU session state of UE 410 requested in SMF#1 430 in operation 702 is satisfied in operation 706 (e.g., idle or inactive state), AMF 420 may execute operation 707.

[0173] In operation 707, AMF 420 can perform an SMF change operation because the PDU session state of UE 410 has been appropriately changed to perform the operation of transferring the SMF to SMF#1 430. AMF 420 can select a target SMF using the set ID received in operation 702. When the set contains information for selecting an SMF (capacity, current load status, and operator preference for each SMF), AMF 420 can select a target SMF using the information for SMF selection. Otherwise, AMF 420 can perform a discovery and selection process to select an SMF together with NRF or SCP. In this case, AMF 420 can use the set ID of the SMF received in operation 702 and can transmit a message including information indicating the selection process for changing the SMF. When a single SMF has been previously set for the SMF change operation, that single SMF can be explicitly selected. The SMF selected subsequently is referred to as SMF#2 440.

[0174] AMF 420 can send a request to SMF#2 440 for a context to receive a PDU session and provide services by using the ID of the SMF selected in Operation 702. The request message from AMF 420 to SMF#2 440 may include the ID of the SMF (SMF#1 430) that has provided services to UE 410, the ID and type of the target context, or the ID of the target UE, the ID of the PDU session, and the context type.

[0175] In operation 708, SMF#2 440 can send a context request to receive context from SMF#1430 and provide services.

[0176] According to embodiments of this disclosure, SMF#2 440 can request context transfer by using the Nsmf_PDUSession_ContextRequest service as a consumer operation. For example, when SMF#2 440 receives a context ID, SMF#2 440 can use the context ID and context type to request SMF#1 430 to transfer the context. Otherwise, SMF#2 440 can request SMF#1 430 to transfer the context using the target UE (subscriber) ID, the PDU session ID, and the context type.

[0177] If SMF#2 440 is unable to receive or provide service after a certain point, it can reject the request. When SMF#2 440 rejects a request, it can include the reason for failure in the rejection message and transmit the rejection message. Each reason for failure can be replaced with a pre-arranged number.

[0178] Reason #1: Insufficient resources, i.e., when there are insufficient resources in SMF #2;

[0179] Reason #2: N4 session failed, i.e., when it is not possible to change / generate a session with UPF;

[0180] Reason #3: Authorization, i.e., when the SMF#1 request is unacceptable;

[0181] Reason #4: Semantic error, i.e., an error is generated when processing the context.

[0182] The entire process terminates when processing fails.

[0183] In Operation 709-1, the SMF#1 430 can determine whether it is possible to process the context transfer request, and when it is determined that it is possible to process the context transfer request, the SMF#1 430 can perform the process of releasing the N4 session. Although not in Figure 5 The document indicates that this process can be replaced by the process of changing the N4 session with UPF 450 from SMF#1 430 to SMF#2 440.

[0184] In operation 710, SMF#1 430 can respond to a context transfer request by inserting the context requested by SMF#2 440 in operation 706 into the container. When the request fails, SMF#1 430 can add a failure reason to the response and transfer the response. Each failure reason can be replaced with a pre-arranged number.

[0185] Reason #2: N4 session failure, i.e., when the session change / generation between SMF#2 440 and UPF fails;

[0186] Reason #3: Authorization, i.e., when the SMF #2 request is unacceptable;

[0187] Reason #4: Semantic error, i.e., an error is generated when processing the received context.

[0188] The entire process terminates when processing fails.

[0189] When the N4 session release process is applied in operation 709-1 and operation 708 is successful, in operation 709-2, SMF#2 440 can perform the N4 session establishment process together with UPF 450 (between the SMF and the UPF). At this time, SMF#2 440 can know which UPF to establish the N4 session with by using the PGW-U tunnel information contained in the context, and SMF#2 440 can perform UPF selection processing when the UPF needs to be changed during N4 setup.

[0190] In Operation 711, SMF#2 440 can send a response indicating that the SMF has been changed, based on a request from AMF 420.

[0191] In operation 712, SMF#2 440 can perform the remaining procedures required due to the SMF change. These remaining procedures may include, for example, performing registration processing in the UDM and setting up the PCC session with the PCF. Embodiments of this disclosure are not limited thereto.

[0192] Figure 7 The implementation can be modified as follows, wherein when the UE does not enter an idle or inactive state within a preset time period, a state change of the UE will be explicitly triggered to perform an SMF change. The method of changing the NF by explicitly triggering a state change of the UE will now be referred to... Figure 8 To provide a more detailed description.

[0193] Figure 8 This is a flowchart illustrating a method for changing the NF by triggering a state change of the UE according to an embodiment of the present disclosure.

[0194] In Operation 801, SMF#1 430 represents the old SMF that provides service to UE 410. In Operation 801, the conditions for transferring UE 410's service to another SMF can be met in SMF#1 430. The SMF change operation can be initiated based on operator instructions or a request from the OAM system. Instructions or requests to change the SMF can include specifying a particular UE (or subscriber), a particular session, and a particular DNN / APN / Slice. Depending on the service type or operator settings, a standby time period until the UE's (subscriber's) session is changed to an idle or inactive state can be explicitly specified.

[0195] In operation 802, SMF#1 430 can wait for a state where no UE traffic transmission or transaction occurs, so that the aforementioned errors (such as conflicts or race conditions) will not occur when transferring the service of UE410 (or the subscriber) to another SMF. When the PDU session of UE410 is in an idle or inactive state, in order to request AMF 420 to perform an operation to change the SMF, SMF#1 430 can send a notification notifying the UE of the PDU session state change. Before performing operation 802, a subscription procedure can be performed to receive notifications from AMF 420 to SMF#1 430 when the state of a specific PDU session changes.

[0196] When a change in PDU session state is notified, and SMF#1 430 is able to identify the target context as a separate ID, SMF#1 430 may include the context ID, context type, and the ID of the SMF to be changed, or the ID of the SMF set including that SMF, in the notification of the PDU session state change, and may transmit the notification. If the context ID cannot be specified, SMF#1 430 may include the target UE (subscriber) ID, PDU session ID, context type, and the ID of the SMF to be changed, or the ID of the set including that SMF, in the notification, and may transmit the notification. The notification of the PDU session state change may include a maximum waiting time until the UE (subscriber) session changes to an idle or inactive state.

[0197] In operation 803, AMF 420 executes a timer based on the received information, and when the UE does not enter an idle or idle state within a specific time period, in order to change the UE's state to an idle state, AMF 420 sends a UE context release request to RAN 760.

[0198] In operations 804 to 806, RAN 760 may, upon request from AMF 420, perform an operation to change the UE to an idle state.

[0199] Operations 807 to 813 correspond to the operations described above, therefore their detailed descriptions will be omitted.

[0200] According to embodiments of this disclosure, when UE 410 is in an inactive state (more specifically, RRC (Radio Resource Control) is inactive), traffic is transmitted between UE 410 and RAN 760, and the core network (AMF 420 or SMF (430 or 440)) may be unaware of this state. In this case, when an SMF change is triggered, it may affect the quality of service. Therefore, the RRC inactive state can be set not to apply to UEs (subscribers) that require SMF changes.

[0201] In other words, when the RRC inactivity state can be applied to UE 410, and the RRC inactivity auxiliary information has been transmitted to the base station (e.g., RAN or NG-RAN) 760, AMF 420 can delete the RRC inactivity auxiliary information through the UE context modification procedure. When the RRC inactivity auxiliary information of UE 410 has not been transmitted to NG-RAN 760, AMF 420 needs not to include the RRC inactivity auxiliary information in the UE context later transmitted to RAN 760 for UE 410.

[0202] According to embodiments of this disclosure, as described above, NFs (including SMFs) are capable of sending or receiving context to each other and providing services. This structure can be used to subsequently provide services to UEs that have already received services in the relevant technology when an error occurs in a specific NF or when a specific NF is removed due to reasons such as capacity reduction, or when operations such as changing or updating the settings of a specific NF occur. As in the embodiments described above, the NF that will subsequently receive services provided by a specific NF can be selected, taking into account the designation of OAM or the state of the dynamic network. However, according to a network redundancy scheme, specific NFs can be pre-designated as backups. According to this scheme, the time required to generate a new NF that will subsequently receive services or to search for an NF in case of an emergency such as an error can be reduced.

[0203] According to embodiments of this disclosure, the backup NF can be configured using free methods, such as designating one or more NFs as backup NFs in a specific set of NFs, or designating a backup NF for each NF.

[0204] Figure 9 This is a flowchart illustrating a method for exchanging information about an NF as a backup NF according to an embodiment of the present disclosure.

[0205] In operation 901, NF#1 920 receives or sets information related to the NF that will be used as a backup NF operation. The list of NFs used as backup NF operations can include the IDs of the NFs that will be used as backup NFs, and can be divided according to their purpose, i.e., into failed backups, planned removal backups, and operational backup items.

[0206] In operation 902, NF#2 940 can register or update its own information in NRF / SCP 930. At this time, NF#2 940 can transfer its own NF configuration file. The NF configuration file can include a list of NFs that will be used as backup NFs, and this list can include the IDs of the NFs used as backup NFs. This list can be categorized by purpose as fault backup, scheduled removal backup, and operational backup items.

[0207] In operation 903, the NRF / SCP 930 stores the received NF configuration file. The NF configuration file may include a list of NFs that will be used as backup NFs. This list may include the IDs of the NFs that will be used as backup NFs and may be categorized according to their purpose, namely, fault backup, scheduled removal backup, and operational backup items.

[0208] In Operation 904, another NF (referred to as NF#2 940) can use the services provided by NF#1 920, or can send an NF discovery request to NRF / SCP 930 to receive information from NF#1 920.

[0209] In Operation 905, NRF / SCP 930 can transmit the NF profile while responding to the NF discovery in Operation 904. The NF profile may include a list of NFs that will be used as backup NFs. This list may include the IDs of the NFs to be used as backup NFs and may be categorized according to their purpose, namely, fault backup, scheduled removal backup, and operational backup items.

[0210] In operation 906, NF#2 940 can store the received NF configuration file. When there is a service associated with NF#1 920, and an NF (referred to as NF#3) needs to be selected to replace NF#1 920 due to failure or similar reasons, NF#2 940 can provide the service by using the NF included in the backup list of NF#1 920.

[0211] NF#2 940 can know that it needs to switch to another NF by being directly notified that NF#1 920 is no longer providing services (notification of NF status change); or NF#2 940 can know that NF#1 920 is no longer providing services and needs to switch to another NF by being notified of the status of NF#1 920 by NRF / SCP 930 when NF#1 920 notifies NRF / SCP 930 of the status change.

[0212] When NF#2 940 requests a specific service from NF#1 920 or when there is no response to a sent message, NF#2 940 can also know that NF 920#1 no longer provides the service and needs to be moved to another NF.

[0213] In the above embodiment, NF#1 920 transmits its own backup NF information via NRF / SCP930 by notifying other NFs of its backup NF information. However, NF#1 920 can also directly transmit its own backup NF information during message exchange between NFs. In other words, when NF#1 920 interoperates with another NF to provide a specific service (when establishing registration or association or transferring NF status), NF#1 920 can transmit its own backup NF information (as described above). Figure 9 The information (the same information as described in the embodiments above) is directly transmitted to other NFs. NFs that have received backup NF information use the backup NF information in the same way as in the embodiments described above.

[0214] Figure 10 This is a block diagram illustrating a network entity according to an embodiment of the present disclosure. A network entity is a concept that includes network functions implemented according to the system.

[0215] Reference Figure 10 The network entity may include a transceiver 1000, a memory 1010, and a processor 1020. The processor 1020, transceiver 1000, and memory 1010 of the network entity can operate according to the communication method of the network entity described above. However, the components of the network entity are not limited thereto. For example, the network entity may include more than […]. Figure 10 The diagram shows a greater or lesser number of components. Furthermore, the processor 1020, transceiver 1000, and memory 1010 can be implemented as a single chip. The processor 1020 may include one or more processors.

[0216] Transceiver 1010, a collective term for both the receiver and transmitter of a network entity, is capable of transmitting or receiving signals with a base station. Signals transmitted or received from the base station may include control information and data. For this purpose, transceiver 1000 may include a radio frequency (RF) transmitter that up-converts and amplifies the frequency of the signal to be transmitted, and an RF receiver that amplifies the received signal with low noise and down-converts the frequency of the received signal. However, this is only one embodiment of transceiver 1000, and the components of transceiver 1000 are not limited thereto. Transceiver 1000 may transmit signals to or receive signals from other network entities.

[0217] The transceiver 1000 can receive signals through a wireless channel and output the signals to the processor 1020, and can also transmit signals output by the processor 1020 through a wireless channel.

[0218] The memory 1010 can store data and programs required for the operation of the network entity. Furthermore, the memory 1010 can store control information or data contained in signals obtained by the network entity. The memory 1010 may include storage media such as read-only memory (ROM), random access memory (RAM), hard disk, optical disc (CD)-ROM, and digital versatile optical disc (DVD), or combinations thereof.

[0219] The processor 1020 can control a series of processes so that network entities can operate according to embodiments of the present disclosure. For example, the processor 1020 can receive control signals and data signals through the transceiver 1000 and process the received control signals and data signals. Furthermore, the processor 1020 can transmit the processed control signals and processed data signals to the transceiver 1000.

[0220] The transceiver 1000, memory 1010, and processor 1020 can be electrically connected to each other. For example, the controller 910 can be a circuit, a dedicated circuit, or at least one processor. Furthermore, the operation of the network entity can be achieved by including a storage device storing the corresponding program code in any component of the network entity.

[0221] Network entities can be base stations (RAN), AMF, SMF, UPF, NF, NEF, NRF, CF, NSSF, UDM, AF, AUSF, SCP, UDSF, context store, OAM, EMS, configuration servers, or ID management servers. Embodiments disclosed herein are not limited thereto.

[0222] Figure 11 This is a block diagram illustrating a UE according to an embodiment of the present disclosure.

[0223] Reference Figure 11The UE may include a transceiver 1100, a memory 1110, and a processor 1120. The processor 1120, transceiver 1100, and memory 1110 of the UE can operate according to the communication method of the UE described above. However, the components of the UE are not limited to this. For example, the UE may include more than... Figure 11 The diagram shows a greater or lesser number of components. Furthermore, the processor 1120, transceiver 1100, and memory 1110 can be implemented as a single chip. The processor 1120 may include one or more processors.

[0224] Transceiver 1100, a collective term for the receiver and transmitter of a network entity, is capable of transmitting or receiving signals with a base station. Signals transmitted or received from the base station may include control information and data. Therefore, transceiver 1100 may include a radio frequency transmitter that up-converts and amplifies the frequency of the signal to be transmitted, and a radio frequency receiver that amplifies the received signal with low noise and down-converts the frequency of the received signal. However, this is only one embodiment of transceiver 1100, and the components of transceiver 1100 are not limited thereto.

[0225] The transceiver 1100 can receive signals through a wireless channel and output the signals to the processor 1120, and can also transmit signals output by the processor 1120 through a wireless channel.

[0226] The memory 1110 can store data and programs required for the operation of the network entity. Furthermore, the memory 1110 can store control information or data contained in signals obtained by the network entity. The memory 1110 may include storage media such as read-only memory (ROM), random access memory (RAM), hard disk, optical disc (CD)-ROM, and digital versatile optical disc (DVD), or combinations thereof.

[0227] The processor 1120 can control a series of processes so that the UE can operate according to embodiments of the present disclosure. For example, the processor 1120 can receive control signals and data signals through the transceiver 1100 and process the received control signals and data signals. In addition, the processor 1120 can transmit the processed control signals and processed data signals to the transceiver 1100.

[0228] Figures 1 to 11 The diagrams, flowcharts, and descriptions of the control / data signal transmission methods shown are not intended to limit the scope of this disclosure. In other words, the above references... Figures 1 to 11 All components, entities, or operations described should not be construed as essential components of implementing this disclosure, which may also include only some components without departing from the spirit of this disclosure.

[0229] The methods of embodiments of this disclosure as described in this specification or the appended claims can be implemented as hardware, software, or a combination of hardware and software.

[0230] When implemented as software, a computer-readable storage medium or computer program product may be provided storing one or more programs (e.g., software modules). The one or more programs stored in the computer-readable storage medium or computer program product are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions directing the electronic device to perform a method according to embodiments of this disclosure as described in or appended to this specification.

[0231] The program (e.g., a software module or software) can be stored in non-volatile memory (including RAM or flash memory), ROM, electrically erasable programmable read-only memory (EEPROM), disk storage devices, CD-ROM, DVD, other optical storage devices, or magnetic tape. Alternatively, the program can be stored in a memory that includes some or all of the above storage media. Multiple such memories may be included.

[0232] Furthermore, the program can be stored on a storage device accessible via any communication network, such as the Internet, intranet, local area network (LAN), wide area network (WLAN), and storage area network (SAN), or a combination thereof. Such a storage device can access an electronic device executing embodiments of this disclosure via an external port. Additionally, a separate storage device on a communication network can access the device executing embodiments of this disclosure.

[0233] In the above embodiments of this disclosure, the elements included in this disclosure are represented in a singular or plural form. However, these singular or plural representations are appropriately chosen for ease of description based on the circumstances, and this disclosure is not limited to a single or multiple elements. Those elements described in plural form may be configured as a single element, while those elements described in singular form may be configured as a plural element.

[0234] It provides methods and devices that can effectively support services in wireless communication systems.

[0235] The embodiments of this disclosure disclosed in the specification and accompanying drawings are merely specific examples given to facilitate the explanation of the technical content of this disclosure and to promote understanding of this disclosure, and are not intended to limit the scope of this disclosure. In other words, it will be apparent to those skilled in the art that other modifications based on the technical spirit of this disclosure are possible. Furthermore, each of the above embodiments can be combined with each other if operation is required. For example, a part of one embodiment of this disclosure can be combined with a part of another embodiment. In addition, other modifications based on the technical spirit of the above embodiments can be implemented in various systems such as LTE systems and 5G or NR systems.

[0236] Although this disclosure has been described with reference to various embodiments, various changes and modifications are possible that can be made by those skilled in the art as taught therefrom. This disclosure is intended to include changes and modifications that fall within the scope of the appended claims.

Claims

1. A method performed by a first session management function (SMF), the method comprising: The SMF change operation was identified as triggered. In response to events where the user equipment (UE) becomes idle or inactive, a subscription procedure is performed with the Access and Mobility Management Function (AMF) entity. When the UE's state becomes idle or inactive, a notification message for reporting the event is received from the AMF; The process of sending a message indicating a change in the state of a Protocol Data Unit (PDU) session to the AMF to request an SMF change, wherein the message indicating the change in the state of the PDU session includes a context identifier ID; Based on the triggering of the SMF change operation, a PUSH service context request is sent to the second SMF; as well as Receive a PUSH service context response from the second SMF as a response to the PUSH service context request, the PUSH service context response indicating the result of the SMF change operation.

2. The method as described in claim 1, wherein, The PUSH service context request indicates whether the SMF change operation was successful or unsuccessful.

3. The method as described in claim 1, wherein, The second SMF is registered in the Unified Data Management (UDM).

4. The method of claim 1, wherein, The SMF change operation is triggered in response to a request to operate, manage, and maintain OAM, and the OAM request includes the identification information of the second SMF.

5. A method performed by a second session management function (SMF), the method comprising: If an SMF change operation is triggered at the first SMF, a PUSH service context request is received from the first SMF. as well as In response to the PUSH service context request, a PUSH service context response indicating the result of the SMF change operation is sent to the first SMF. The PUSH service context request is a process in which the first SMF performs a subscription procedure with the Access and Mobility Management Function Entity (AMF) in response to an event where the state of the User Equipment (UE) becomes idle or inactive. When the UE becomes idle or inactive, the SMF receives a notification message from the AMF to report the event and sends a message indicating a change in the state of the Protocol Data Unit (PDU) session to the AMF to request an SMF change. The message received from the first SMF, indicating the change in the state of the PDU session, includes a context identifier ID.

6. The method of claim 5, wherein, The PUSH service context request indicates whether the SMF change operation was successful or unsuccessful.

7. The method of claim 5, wherein, The second SMF is registered in the Unified Data Management (UDM).

8. A first session management function (SMF), the first SMF comprising: transceiver; and At least one processor, coupled to the transceiver and configured to: The SMF change operation was identified as triggered. In response to events where the user equipment (UE) becomes idle or inactive, a subscription procedure is performed with the Access and Mobility Management Function (AMF) entity. When the UE's state becomes idle or inactive, a notification message for reporting the event is received from the AMF; The process of sending a message indicating a change in the state of a Protocol Data Unit (PDU) session to the AMF to request an SMF change, wherein the message indicating the change in the state of the PDU session includes a context identifier ID; Based on the triggering of the SMF change operation, a PUSH service context request is sent to the second SMF; as well as Receive a PUSH service context response from the second SMF as a response to the PUSH service context request, the PUSH service context response indicating the result of the SMF change operation.

9. The first SMF as claimed in claim 8, wherein, The PUSH service context request indicates whether the SMF change operation was successful or unsuccessful.

10. The first SMF as claimed in claim 8, wherein, The second SMF is registered in the Unified Data Management (UDM).

11. The first SMF as claimed in claim 8, wherein, The SMF change operation is triggered in response to a request to operate, manage, and maintain OAM, and the OAM request includes the identification information of the second SMF.

12. A second session management function (SMF), the second SMF including: transceiver; and At least one processor, coupled to the transceiver and configured to: If an SMF change operation is triggered at the first SMF, a PUSH service context request is received from the first SMF; and In response to the PUSH service context request, a PUSH service context response indicating the result of the SMF change operation is sent to the first SMF. The PUSH service context request is a process in which the first SMF performs a subscription procedure with the Access and Mobility Management Function Entity (AMF) in response to an event where the state of the User Equipment (UE) becomes idle or inactive. When the UE becomes idle or inactive, the SMF receives a notification message from the AMF to report the event and sends a message indicating a change in the state of the Protocol Data Unit (PDU) session to the AMF to request an SMF change. The message received from the first SMF, indicating the change in the state of the PDU session, includes a context identifier ID.

13. The second SMF as claimed in claim 12, wherein, The PUSH service context request indicates whether the SMF change operation was successful or unsuccessful.

14. The second SMF as claimed in claim 12, wherein, The second SMF is registered in the Unified Data Management (UDM).

15. The second SMF as claimed in claim 12, wherein, The SMF change operation is triggered in response to a request to operate, manage, and maintain OAM, and the OAM request includes the identification information of the second SMF.

Images