Method and apparatus for performing communication using network slicing in a wireless communication system

Abstract

The present disclosure relates to a communication technology and system thereof for supporting the integration of a fifth generation (5G) communication system with a higher data rate after a fourth generation (4G) system and the Internet of Things (IoT). The present disclosure provides a method performed by a first network entity that manages a packet data network (PDN) session in a wireless communication system that supports intercommunication between a first network and a second network. The method includes: receiving subscription update information of a user equipment (UE), establishing a PDN connection associated with a network slice for the UE in the second network, and the network slice is subscribed in the first network; if the subscription update information includes information notifying the UE that the network slice-related information is changed, determining whether to release the PDN connection; and if it is determined to release the PDN connection, executing the release of the PDN connection associated with the network slice.

Description

Technical Field

[0001] The present disclosure relates to a communication device and method for providing network slicing in a wireless communication system. Background Art

[0002] In order to meet the increasing demand for wireless data services since the commercialization of the fourth generation (4G) communication system, efforts are being made to develop an advanced fifth generation (5G) communication system or a quasi-5G communication system. For this reason, the 5G communication system or the quasi-5G communication system is called a super 4G network communication system or a post-long term evolution (LTE) system. The 5G communication system specified by the Third Generation Partnership Project (3GPP) is called a new radio (NR) system.

[0003] In order to achieve high data rates, 5G communication systems are being considered for implementation in the millimeter wave (mmWave) frequency band (e.g., 60 GHz). For 5G communication systems, in order to reduce wave propagation losses and increase wave transmission distances, technologies such as beamforming, large-capacity multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antennas have been discussed. These technologies are being applied to NR systems.

[0004] In order to improve the system network, in the 5G communication system, technologies such as evolved small cells, advanced small cells, cloud radio access network (cloud RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, collaborative communication, coordinated multi-point (CoMP) and reception interference cancellation are being developed.

[0005] In addition, for 5G systems, advanced coding modulation (ACM) schemes including hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) have been developed, as well as advanced access schemes including filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA).

[0006] In addition, for 5G systems, advanced coding modulation (ACM) schemes including hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) have been developed, as well as advanced access schemes including filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA).

[0007] The Internet has evolved from a human-centered connected network where humans create and consume information to the Internet of Things (IoT), in which information is exchanged and processed between distributed components such as objects. The Internet of Everything (IoE) has also emerged, in which the Internet of Everything (IoE) is combined with big data processing technology based on connection with cloud servers. Since the implementation of IoE requires technical elements such as sensing, wired and wireless communications, network infrastructure, service interfaces, and security, technologies such as sensor networks, machine-to-machine (M2M), and machine-type communications (MTC) are being studied to interconnect everything. In the IoT environment, intelligent Internet technology (IT) services can be provided that create new value in human life by collecting and analyzing data generated from connected things. Through the integration and combination between existing information technology (IT) and various industrial applications, IoT can be applied to various fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart homes, advanced medical services, etc.

[0008] In line with this, various attempts are being made to apply 5G communication systems to IoT networks. For example, 5G communications such as sensor networks, M2M, and MTC are being implemented through technologies such as beamforming, MIMO, and array antennas. The application of cloud radio access networks (cloud RAN), which is the above-mentioned big data processing technology, can also be considered an example of the integration of 5G and IoT.

[0009] With the recent development of communication systems, various studies have been conducted to provide different network layers (network slicing) in 5G-based wireless communication systems. Summary of the invention

[0010] [Technical issues]

[0011] Provided are an efficient communication method and apparatus for using network slicing in a wireless communication system.

[0012] Provided are an effective communication method and apparatus for using network slicing in a wireless communication system that supports intercommunication between different networks.

[0013] Provided are a method and apparatus for intercommunication between a fifth generation (5G) network system structure (e.g., 5G core (5GC)) for supporting a network slicing function and a network system (e.g., evolved packet core (EPC)) of an evolved packet system (EPS) in a wireless communication system.

[0014] [Technical solution]

[0015] Additional 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 presented in the disclosure.

[0016] According to an embodiment of the present disclosure, there is provided a method performed by a first network entity that manages a packet data network (PDN) session in a wireless communication system that supports intercommunication between a first network and a second network, the method comprising: receiving subscription update information of a user equipment (UE) from a second network entity that manages subscription information, establishing a PDN connection associated with a network slice for the UE in the second network, the network slice being subscribed in the first network; determining whether to release the PDN connection when the subscription update information includes information notifying the UE that information related to the network slice has been changed; and performing an operation for releasing the PDN connection associated with the network slice when it is determined to release the PDN connection.

[0017] In addition, according to an embodiment of the present disclosure, a first network entity for managing a packet data network (PDN) session in a wireless communication system supporting intercommunication between a first network and a second network is provided, the first network entity including a transceiver and a processor. The processor is configured to: receive subscription update information of a user equipment (UE) from a second network entity that manages subscription information via the transceiver, establish a PDN connection associated with a network slice for the UE in the second network, and the network slice is subscribed in the first network; determine whether to release the PDN connection when the subscription update information includes information notifying the UE that the network slice related information is changed; and perform an operation for releasing the PDN connection associated with the network slice when it is determined to release the PDN connection.

[0018] In addition, according to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system supporting intercommunication between a first network and a second network is provided, the method comprising: establishing a packet data network (PDN) connection associated with a network slice in the second network, the network slice being subscribed in the first network; and identifying the release of the PDN connection when the UE receives information indicating a reason associated with releasing the PDN connection from a first network entity that manages the PDN session via the second network, the first network entity having received subscription update information, the subscription update information including information notifying the UE that network slice related information has been changed.

[0019] In addition, according to an embodiment of the present disclosure, a user equipment (UE) in a wireless communication system supporting intercommunication between a first network and a second network includes a transceiver and a processor. The processor is configured to: establish a packet data network PDN connection associated with a network slice in the second network, the network slice being subscribed in the first network; and identify the release of the PDN connection when the UE receives information indicating a reason associated with releasing the PDN connection from a first network entity managing a PDN session via the second network, the first network entity having received subscription update information, the subscription update information including information notifying the UE that the network slice related information is changed.

[0020] Before proceeding to the following detailed description, it may be helpful to set forth definitions of certain words and phrases used in this patent document: the terms "include" and "comprising" and their derivatives mean inclusion without limitation; the term "or" is inclusive, meaning and / or; the phrases "associated with" and "associated with" and their derivatives may mean include, be included, interconnected with, contain, be contained within, connect to or be connected with, be connected to or be connected with, be communicative with, cooperate with, interleave, juxtapose, be adjacent to, be bound to or be bound with, have, have the property of, etc.; and the term "controller" means any device, system, or portion thereof that controls at least one operation, such device may be implemented in hardware, firmware, or software, or a combination of at least two thereof. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether local or remote.

[0021] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and is contained in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data, or parts thereof suitable for implementation in appropriate computer-readable program codes. The phrase "computer-readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. "Non-transitory" computer-readable medium excludes wired, wireless, optical, or other communication links that transmit temporary electrical signals or other signals. A non-transitory computer-readable medium includes a medium that can permanently store data, and a medium that can store data and then rewrite data, such as a rewritable optical disc or an erasable storage device.

[0022] Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0024] Figure 1 is a diagram showing an exemplary configuration of a network slice related information element (IE) according to an embodiment of the present disclosure;

[0025] Figure 2 is a diagram showing a structure of a wireless communication system supporting intercommunication between networks to use network slicing related to an embodiment of the present disclosure;

[0026] Figure 3 is a diagram showing a signal flow of a session release method based on subscription data update according to an embodiment of the present disclosure;

[0027] Figure 4 is a diagram showing a signal flow of a session modification method based on subscription data update according to an embodiment of the present disclosure;

[0028] Figure 5 is a diagram showing a signal flow of a session modification method based on subscription data update (when using the N26 interface) according to an embodiment of the present disclosure;

[0029] Figure 6 is a diagram showing a signal flow of a session modification method based on subscription data update (when the N26 interface is not used) according to an embodiment of the present disclosure;

[0030] Figure 7 is a diagram showing a signal flow of a session release method based on policy update according to an embodiment of the present disclosure;

[0031] Figure 8 is a diagram showing a signal flow of a session modification method based on policy update according to an embodiment of the present disclosure;

[0032] Fig. 9 is a diagram showing a signal flow of a session modification method based on policy update (when using the N26 interface) according to an embodiment of the present disclosure;

[0033] Fig.10 is a diagram showing a signal flow of a session modification method based on policy update according to an embodiment of the present disclosure (when the N26 interface is not used);

[0034] Fig.11is a diagram showing a signal flow of a session release method based on access point name (APN) information update and a temporary session deletion indicator according to an embodiment of the present disclosure;

[0035] Fig.12 is a diagram showing a signal flow of a session modification method based on APN information update and a temporary session deletion indicator according to an embodiment of the present disclosure;

[0036] Fig.13A and 13B is a diagram showing a signal flow of a method for establishing a fifth generation system (5GS) protocol data unit (PDU) session based on an APN information update and a temporary session deletion indicator (when using an N26 interface) according to an embodiment of the present disclosure;

[0037] Fig.14A and Fig. 14B is a diagram showing a signal flow of a method for establishing a 5GS PDU session based on an APN information update and a temporary session deletion indicator according to an embodiment of the present disclosure (when the N26 interface is not used);

[0038] Fig.15 is a diagram showing a signal flow of a session release method based on APN information and single network slice selection assistance information (S-NSSAI) update information according to an embodiment of the present disclosure;

[0039] Fig.16 is a diagram showing a signal flow of a session modification method based on APN information and S-NSSAI update information according to an embodiment of the present disclosure;

[0040] Fig.17A and Fig. 17B is a diagram showing a signal flow of a method for establishing a 5GS PDU session based on APN information and S-NSSAI update information according to an embodiment of the present disclosure (when an N26 interface exists);

[0041] Fig.18A and Fig.18B is a diagram showing a signal flow of a method for establishing a 5GS PDU session based on APN information and S-NSSAI update information (when the N26 interface does not exist) according to an embodiment of the present disclosure;

[0042] Fig.19 is a diagram showing an example of association between an APN and an S-NSSAI according to an embodiment of the present disclosure;

[0043] Fig. 20 is a block diagram showing the structure of a user equipment (UE) related to an embodiment of the present disclosure;

[0044] Fig.21is a block diagram showing the structure of a network function (NF) related to an embodiment of the present disclosure;

[0045] Fig. 22 is a block diagram showing the structure of a base station (BS) related to an embodiment of the present disclosure;

[0046] Fig.23A and Fig. 23B is a diagram showing a signal flow of another exemplary session release method based on policy update according to an embodiment of the present disclosure;

[0047] Fig.24A and Fig. 24B is a diagram showing a signal flow of another exemplary session modification method based on policy update according to an embodiment of the present disclosure;

[0048] Fig.25A and Fig.25B is a diagram showing a signal flow of another exemplary session modification method based on policy update (when using the N26 interface) according to an embodiment of the present disclosure; and

[0049] Fig.26A and Fig.26B is a diagram showing a signal flow of another exemplary session modification method based on policy update (when the N26 interface is not used) according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0050] Discussed below Figures 1 to 26B , and the various embodiments used to describe the principles of the present disclosure in this patent document are merely exemplary and should not be interpreted in any way to limit the scope of the present disclosure. Those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any suitably arranged system or device.

[0051] The preferred embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be noted that, if possible, the same reference numerals represent the same components. In order to avoid confusing the subject matter of the present disclosure, detailed descriptions of functions and structures known in the art will be avoided.

[0052] In describing the embodiments of this document, technologies that are well known in the technical field of the present disclosure and are not directly related to the present disclosure will not be described. This is intended to clearly convey the subject matter of the present disclosure by avoiding unnecessary descriptions without confusing it.

[0053] For the same reason, some components shown in the drawings are exaggerated, omitted or schematically shown, and the drawing size of each component does not accurately reflect its actual size. In each of the drawings, the same reference numerals are assigned to the same or corresponding components.

[0054] By referring to the embodiments described in detail below in conjunction with the accompanying drawings, the advantages and features of the present disclosure and the methods for implementing them will become apparent. However, the present disclosure can be implemented in various ways and is not limited to the embodiments described herein. Of course, these embodiments are provided so that the present disclosure is complete and thorough, and its scope is fully conveyed to those skilled in the art, and the present disclosure is limited only by the attached claims. Throughout the specification, the same reference numerals represent the same components.

[0055] It should be understood that each frame of the flow chart and / or block diagram and the combination of frames in the flow chart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be loaded onto a processor of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the instructions executed by the processor of the computer or other programmable data processing device create a device for implementing the function / action specified in the flow chart and / or block diagram block. These computer program instructions can also be stored in a computer-available or computer-readable memory, which can guide the computer or other programmable data processing device to run in a specific manner, so that the instructions stored in the computer-available or computer-readable memory produce a product including an instruction device for implementing the function / action specified in the flow chart and / or block diagram frame. The computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operations are performed on the computer or other programmable data processing device, thereby generating a computer-implemented process, so that the instructions executed on the computer or other programmable device provide operations for implementing the function / action specified in the flow chart and / or block diagram frame.

[0056] In addition, each block diagram may show a module, segment or part of a code that includes one or more executable instructions for performing a specific logical function. In addition, it should be noted that the functions of the blocks may be performed in different orders in several modifications. For example, two consecutive blocks may be performed substantially simultaneously, or may be performed in reverse order according to their functions.

[0057] The term "unit" used herein refers to but is not limited to the software or hardware components that perform certain tasks, such as field programmable gate arrays (FPGAs) or application specific integrated circuits (ASICs). Units can advantageously be configured to reside on addressable storage media and be configured to execute on one or more processors. Therefore, as an example, units can include components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays and variables. The functions provided in components and "units" can be combined into fewer components and "units", or further separated into additional components and "units". In addition, components and "units" can be implemented so that they are executed on one or more central processing units (CPUs) in a device or a secure multimedia card.

[0058] In an embodiment of the present disclosure, a base station (BS) as an entity that allocates resources to a user equipment (UE) may be at least one of a next generation node B (gNode B or gNB), an evolved node B (eNode B or eNB), a node B, a radio access unit, a base station controller (BSC), or a network node. In addition, the BS may be a network entity including at least one of: an integrated access and backhaul (IAB) donor of a gNB that provides network access to a UE through a network of backhaul and access links, an IAB node that is a radio access network (RAN) node that supports an NR access link to the UE and supports an NR backhaul link to the IAB donor, or another IAB node in a new radio (NR) system. The UE may be wirelessly connected through the IAB node, and transmit and receive data to and from the IAB donor connected to at least one IAB node via a backhaul link.

[0059] In addition, UE may include a terminal, a mobile station (MS), a cellular phone, a smart phone, a computer, or various devices capable of performing communication functions. In the present disclosure, a downlink (DL) is a wireless transmission path for sending a signal from a BS to a UE, and an uplink (UL) is a wireless transmission path for sending a signal from a UE to a BS. Although a long-term evolution (LTE) or LTE-Advanced (LTE-A) system may be described as an example below, the embodiments of the present disclosure may be applied to other communication systems with similar technical backgrounds or channel structures. For example, a communication system may include a fifth generation (5G) mobile communication technology (5G NR) developed after LTE-A, and 5G may be a concept including conventional LTE, conventional LTE-A, and other similar services described below. In addition, the present disclosure may also be applied to other communication systems through some modifications without greatly deviating from the scope of the present disclosure as judged by those skilled in the art.

[0060] The present disclosure proposes an apparatus and method for providing intercommunication for network slicing (or network layering) in a wireless communication system. Specifically, a description of the intercommunication technology between a 5G network system and an evolved packet system (EPS) network system that provide a network slicing function in a wireless communication system according to the present disclosure will be given. In the present disclosure, the 5G network system may also be referred to as a first wireless communication system, the EPS network system may also be referred to as a second wireless communication system, and the two systems may be collectively referred to as a wireless communication system.

[0061] For the convenience of description, terms indicating signals, terms indicating channels, terms indicating control information, terms indicating network entities, and terms indicating device components used in the following description are given. In addition, for the convenience of description, terms indicating nodes used in the following description, terms indicating messages, terms indicating interfaces between network entities, terms indicating various information, etc. are given. Therefore, the present disclosure is not limited to the terms described below, and the terms may be replaced by other equivalent terms in the technical meaning.

[0062] In addition, although various embodiments are described by using terms defined in some communication standards (eg, 3GPP) in the present disclosure, they are merely exemplary for illustrative purposes. Various embodiments of the present disclosure can be easily modified and applied to other communication systems.

[0063] 3GPP has standardized the 5G network system architecture and processes. Mobile communication operators can provide various services in 5G networks. In order to provide services, mobile communication operators need to meet different service requirements (e.g., waiting time, communication range, data rate, bandwidth, reliability, etc.) of different services. In this disclosure, a technology for supporting various services by using network slicing in a wireless communication system will be described.

[0064] In a wireless communication system supporting network slicing, services for different network slices may be handled by different protocol data unit (PDU) sessions. A PDU session may refer to an association between a data network and a UE that provides a PDU connection service. Network slicing may be understood as a technology that logically configures a network with a set of network functions (NFs) and separates different network slices to support various services with different characteristics, such as mission-critical services including broadband communication services, massive Internet of Things (IoT), and vehicle-to-everything (V2X). Therefore, even if a communication failure occurs in one network slice, communications in other network slices will not be affected, thereby enabling stable communication services to be provided. In the present disclosure, "slice" and "network slice" may be used interchangeably with the same meaning. In such a network environment, the UE may access multiple network slices when receiving various services. As a software instance driven in hardware, an NF may be implemented as an instantiated virtual function in a network element or an appropriate platform.

[0065] Mobile communication operators can configure network slices based on network slices or based on network slice sets and allocate network resources suitable for specific services. Network resources can refer to NFs, logical resources provided by NFs, or radio resource allocations of BSs.

[0066] For example, a mobile communications operator can configure network slice A to provide mobile broadband services, configure network slice B to provide vehicle communication services, and configure network slice C to provide IoT services. That is, 5G networks can use this method to efficiently provide each service through network slices specific to service characteristics.

[0067] Figure 1 is a diagram showing an exemplary configuration of network slice related information elements (IEs) according to an embodiment of the present disclosure.

[0068] Single Network Slice Selection Assistance Information (S-NSSAI) defined by 3GPP may be used as an identifier (or identification information) for identifying a network slice. Figure 1 An example of an S-NSSAI IE configuration is shown. An S-NSSAI may include at least one of a slice / service type (SST) 116 used in a home public land mobile network (HPLMN), a slice differentiator (SD) 118 used in the HPLMN, an SST 112 used in a serving PLMN, and an SD 114 used in a serving PLMN. The S-NSSAI IE may also include a field 110 indicating the length of the S-NSSAI IE content.

[0069] In a non-roaming case, the SST 112 used in the serving PLMN may be the same as the SST 116 used in the HPLMN, and the SD 114 used in the serving PLMN may be the same as the SD 118 used in the HPLMN.

[0070] In a roaming case, the SST 112 used in the serving PLMN may be the SST used in the visited PLMN (VPLMN), and the SD 114 used in the serving PLMN may be the SD used in the VPLMN.

[0071] Depending on the situation, values ​​for each SST and each SD may or may not exist in one S-NSSAI.

[0072] The network slice selection assistance information (NSSAI) may include one or more S-NSSAI. Examples of NSSAI may include a configuration-type NSSAI stored in the UE, a request-type NSSAI requested by the UE, a permission-type NSSAI determined by the NF in the 5G core network (e.g., access and mobility function (AMF), user plane function (UPF), policy control function (PCF), user data management (UDM), user data repository (UDR), network slice selection function (NSSF), etc.) and allowed to be used by the UE, and a subscription-type NSSAI subscribed by the UE. These NSSAIs are merely exemplary and do not limit examples of NSSAI.

[0073] Mobile communication operators can operate 5G networks and EPS networks (referred to as LTE-based networks or 4G networks). UE can access the 5G network, use services in the 5G network, and then move to the EPS network. Alternatively, the UE can access the EPS network, use services in the EPS network, and then move to the 5G network. The intercommunication between networks (systems) related to the mobility of the UE can be referred to as 5G Core (5GC)-EPC intercommunication or 5G System (5GS)-EPS intercommunication.

[0074] The present disclosure proposes an example of a method for intercommunication between a 5G network system that provides network slicing and an EPS network system (i.e., 5G-EPS intercommunication or 5GC-EPC intercommunication).

[0075] In addition, a description will be given of examples of network operations and UE operations that allow the UE to seamlessly use services: when the UE establishes a session connection in 5GS, uses communication services in 5GS, and then moves to EPS; or when the UE establishes a session connection in EPS, uses communication services in EPS, and then moves to 5GS.

[0076] Figure 2It is a diagram showing the structure of a wireless communication system that supports inter-network communication to use network slicing according to an embodiment of the present disclosure.

[0077] In the present disclosure, standard specifications (e.g., TS 23.501, TS 23.502, TS 23.503, etc.) defined by the International Telecommunication Union (ITU) or 3GPP may be referred to as network technologies and are included in Figure 2 Each component in the network structure can be a physical entity that performs a separate function, or software, or a combination of hardware and software. Figure 2 In the figure, reference numerals Nx such as N1, N2, N3, ... indicate known interfaces between NFs in the 5G core network (CN), and the relevant description can be referred to the standard specification (TS23.501). Therefore, a detailed description of the interface will not be provided here. NFs that are not directly related to the present disclosure will not be illustrated / described.

[0078] Figure 2 An example of a 5GS-EPS interworking structure in a non-roaming situation is shown. The 5GS may include a new radio (NR) BS (next generation radio access network (NG-RAN) or gNB) 203, an access and mobility management function (AMF) 205, a session management function (SMF), a user plane function (UPF), a policy control function (PCF), a network slice selection function (NSSF), a unified data management (UDM), a unified data repository (UDR), etc., for wireless access by UE 201. EPS may include an evolved universal mobile telecommunications system (UMTS) terrestrial radio access (E-UTRA) BS (E-UMTS radio access network (E-UTRAN) or eNB) 219, a mobility management entity (MME) 217, a serving gateway (SGW) 215, a packet data network gateway (PGW, including PGW-U and PGW-C), a policy and charging rules function (PCRF), a home subscriber server (HSS), etc.

[0079] According to an embodiment, AMF 205 and MME 217 are NFs that manage wireless network access and mobility of UE. SMF, SGW and PGW are NFs that manage sessions of UE, and session information includes quality of service (QoS) information, charging information and packet processing information. UPF and PGW are NFs that process user plane services and are under the control of SMF and SGW. PCF and PCRF are NFs that manage operator policies and / or PLMN policies for providing services in a wireless communication system. In addition, PCF can be divided into a PCF responsible for access and mobility (AM) policies and UE policies, and a PCF responsible for session management (SM) policies. The PCF responsible for AM / UE policies and the PCF responsible for SM policies can be multiple separate logical or physical NFs or one logical or physical NF. UDM and HSS are NFs that store and manage UE subscription data. UDR is an NF or database (DB) that stores and manages data. UDR can store UE subscription data and provide UE subscription data to UDM. In addition, UDR can store operator policy information and provide operator policy information to PCF. The NSSF may be the NF that selects the network slice instance that serves the UE or determines the NSSAI.

[0080] An instance may refer to a state in which a NF exists in the form of software code, and in order to execute the function of the NF in a physical computing system (e.g., a specific computing system present in the CN), physical and / or logical resources are allocated by the computing system, so that the function of the NF is executable. For example, an AMF instance, an SMF instance, an NSSF instance, etc. refer to a state in which physical and / or logical resources can be allocated by a specific computing system in the CN for the operation of AMF, SMF, NSSF, etc., thereby making the resource available. Therefore, physical AMF, SMF, and NSSF devices can perform the same operations as AMF instances, SMF instances, and NSSF instances, where the physical and / or logical resources used for the operations of AMF, SMF, and NSSF are allocated to the AMF instances, SMF instances, and NSSF instances by a specific computing system in the network.

[0081] The UDM in 5GS and the HSS in EPS may be configured as a combined (combo) node (referred to as UDM+HSS) 207. The UDM+HSS node 207 may store UE subscription data. The SMF in 5G and the PGW-C in EPS may be configured as a combined (combo) node (referred to as SMF+PGW-C) 211. The PCF in 5G and the PCRF in EPS may be configured as a combined node (referred to as PCF+PCRF) 209. The UPF in 5G and the PGW-U in EPS may be configured as a combined node (referred to as UPF+PGW-C) 213. The UE 201 may use EPS network services by accessing the MME 217 in EPS via the E-UTRAN or the eNB 219. In addition, the UE 201 may use 5GS network services by accessing the AMF 205 in the 5GS via the NR-RAN or the gNB 203.

[0082] In this way, one NF or network entity can support different network systems at the same time, and the NF, network node or network entity can be referred to as a combination (combo) node, a combination NF, a combined node, a combined NF, an intercommunication node, an intercommunication NF, etc. as described above. In addition, the function of the NF exemplified as a combination node can be performed by intercommunication between two or more network entities. In addition, for ease of illustration and description, the NF supporting different network systems at the same time can be indicated by using a "+" symbol or a " / " symbol. For example, when SMF and PGW-C are configured as a combination node, the combination node can be represented as PGW-C / SMF, PGW-C+SMF, SMF / PGW-C or SMF+PGW-C.

[0083] The UE establishes a session by accessing a data network (e.g., a network providing Internet services) through a 5GS or EPS system. The UE can identify each data network by an identifier called a data network name (DNN) or an access point name (APN). In order to distinguish data networks from each other, the 5GS can use the DNN, and the EPS can use the APN. When the UE is connected to a session with a network system, the DNN and APN can be used by the UE to determine the NF related to the user plane, the interface between the NFs, the operator's policy, etc. The DNN and APN can be understood as equivalent information and transmit the same information. The DNN can be used, for example, to select the SMF and UPF for a PDU session, and to select the interface between the data network and the UPF for the PDU session (e.g., the N6 interface). In addition, the DNN can be used to determine the policy applied by the mobile communication operator for the PDU session.

[0084] In 5GS, the UE can be connected to one data network through at least one network slice. When the UE moves to EPS after establishing a PDU session connection with some data networks through multiple network slices in 5GS, the UE can select a network slice according to the determination of the SMF+PGW-C node 211 and establish a packet data network PDN session with the data network.

[0085] The present disclosure proposes that when network slice-related subscription information of a UE for which a session connection is established with respect to EPS and which is receiving communication services in EPS changes, network operations and UE operations can apply changes to the connected session. The UE may have been registered as a subscriber of 5GS.

[0086] In order to apply the change of network slice related subscription information that has occurred during the session connection established by EPS to the ongoing session, the following two steps are mainly performed. One step is to send a notification of the change of network slice related subscription information to the NF responsible for session management; the other step is to apply the change to the session in EPS where the current session is already connected and ongoing according to the determination of the NF responsible for session management when the UE moves to 5GS and establishes a session again in 5GS, or wait in EPS without performing any action and then apply the change.

[0087] For network slicing, the operation of the network system is performed in 5GS, and EPS performs operations to prevent the loss of network slice-related subscription information about the UE. As described above, the network slice-related subscription information can be stored as a type of subscription data, such as a subscription S-NSSAI in the UDR. In addition, the NF responsible for session management can be, for example, an SMF+PGW-C node in the 5GS-EPS system.

[0088] Even when the UE has established a session with either 5GS and EPS, network slice related subscription information can be changed at any time.

[0089] In the embodiments of the present disclosure, the following methods (1), (2) and (3) are proposed as examples of methods for notifying the NF responsible for session management of changes in network slice-related subscription information. In the embodiments of the present disclosure, the terms "subscription information" and "subscription data" are used interchangeably with the same meaning:

[0090] (1) Use the subscription data update method;

[0091] (2) using a strategy update method; and

[0092] (3) Method of using APN information update.

[0093] A detailed description of methods (1), (2) and (3) will be given later.

[0094] In a traditional EPS system, when a UE establishes a new session, the UE receives network slice-related subscription information from an entity responsible for session management (e.g., PGW) through a protocol configuration option (PCO). PCO may be included in various messages for PDN connection requests, bearer requests, etc. For a basic description of PCO, refer to 3GPP TS 24.008. The UE may store network slice-related subscription information as part of the PCO. When the UE then moves to 5GS, the UE may request the use of network slices based on this information. Therefore, a process is needed to modify or release an ongoing session based on changes in network slice-related subscription information that occur after the session is fully established. The present disclosure proposes the following methods (a) and (b) as examples of methods for applying changes in network slice-related subscription information to an ongoing session:

[0095] (a) A method for releasing an ongoing session in EPS;

[0096] (b) methods for modifying an ongoing session in the EPS; and

[0097] (c) No action is taken in EPS, and when the UE then moves to 5GS, the UE establishes a session based on the change in subscription information.

[0098] A detailed description of the methods (a) and (b) will be given later.

[0099] Among the NF services provided by the SMF that manages the session, the service operations related to the PDU session are defined in the 5G standard (TS23.502), as shown in Table 1 below.

[0100] NF services provided by SMF

[0101]

[0102] Figure 2The 5G system structure shown supports a service-based interface, and the service-based interface related to the SMF is defined by "Nsmf" shown in Table 1 above. In Table 1, "Nsmf_PDUSession" represents a service operating in a PDU session, and the service includes the creation / deletion / modification of a PDU session, and these operations can be performed by sending and receiving a PDU session request message and a PDU session response message between the AMF and the SMF. As shown in the example of Table 1, in the operation of creating an association between the AMF and the SMF to support the PDU session, the SMF may receive a "Nsmf_PDUSession_CreateSMContext" request message as a PDU session request message from the AMF, and send a "Nsmf_PDUSession_CreateSMContext" response message to the AMF in response to the "Nsmf_PDUSession_CreateSMContext" request message. For other service operations in Table 1, refer to the relevant standards, and this article will avoid describing them in detail.

[0103] The proposed embodiments will be described under the premise of supporting some or all of the above-mentioned various methods and their combinations. Figure 3 to Figure 2 In the embodiment of 6, each NF is substantially the same as the above reference Figure 2 The NF operates in the same manner as described above and a detailed description of NF will be avoided here. Figure 3 to Figure 2 The embodiments of 6 are based on the following assumptions: the UE has subscribed to the 5GS as the first wireless communication system (or the first network), has moved from the 5GS to the EPS as the second wireless communication system (or the second network), and has been connected to the E-UTRAN in the EPS. For the convenience of description, the following embodiments will be described based on the understanding that combined nodes such as UDM+HSS node, PCF+PCRF node, SMF+PGW-C node, and UPF+PGW-C node are referred to as names without "node" when they appear. In addition, in the following embodiments, the definition of a message in one embodiment may be applied to other embodiments using the same message with the same meaning. In addition, for the convenience of description, although they have been described separately Figure 3 to Figure 2 6, these embodiments may be implemented individually or in combination of two or more.

[0104] Figure 3 is a diagram showing a signal flow of a session release method based on subscription data update according to an embodiment of the present disclosure.

[0105] refer to Figure 3, the UDM+HSS may receive updated subscription S-NSSAI information from the UDR, and then send the updated subscription S-NSSAI information and information about the APN associated with the corresponding S-NSSAI to the SMF+PGW-C. The SMF+PGW-C may determine whether there are any other alternative S-NSSAIs that can enable the UE to access the APN. When there are no other alternative S-NSSAIs, the SMF+PGW-C may release the session to indicate the reason for the session release to the UE.

[0106] Specifically, in step 301, the SMF+PGW-C sends a Nudm_SDM_subscribe message to the UDM+HSS. The Nudm_SDM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudm_SDM_subscribe message may include information indicating the following operations: when an event occurs that changes or deletes the subscription S-NSSAI for the UE, information about the changed or deleted subscription S-NSSAI is transmitted to the SMF+PGW-C that has sent the Nudm_SDM_subscribe message.

[0107] As known from the name of the Nudm_SDM_subscribe message, the service-based interface related to UDM is defined by "Nudm", and Nudm_subscriber Data Management (SDM) is one of the services provided by UDM+HSS. UDM+HSS can allow SMF+PGW-C to detect the subscription data of the UE and provide updated subscription data to SMF+PGW-C through Nudm_SDM when necessary.

[0108] In step 302, when the subscription data of the UE changes, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR, requesting notification of the subscription data change of the UE. As known from the name of the Nudr_DM_subscribe message, the service-based interface related to the UDR is defined by "Nudr", and Nudr_data management (DM) is one of the services provided by the UDR. With respect to the data stored in the UDR, the UDR can perform detection, generation, update, subscription change notification, unsubscription to change notification, and / or deletion through Nudr_DM.

[0109] In various embodiments of the present disclosure, the Nudr_DataRepository_subscribe message disclosed in TS 29.513 may also be used instead of the Nudm_SDM_subscribe message and / or the Nudr_DM_subscribe message. For example, the Nudm_SDM_subscribe message and / or the Nudr_DM_subscribe message may be used in the network registration process of the UE, and the Nudr_DataRepository_subscribe message may be used in the session establishment process or the session modification process of the SMF+PGW-C.

[0110] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 303, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message to the UDM+HSS in step 304. The result of the change may include an updated subscription S-NSSAI for the UE (hereinafter, referred to as updated S-NSSAI).

[0111] In various embodiments of the present disclosure, the Nudr_DataRepository_Notify message disclosed in TS 29.513 may also be used instead of the Nudr_DM_notify message. For example, the Nudr_DM_notify message may be used during the network registration process of the UE, and the Nudr_DataRepository_Notify message may be used during the session establishment process or session modification process of the SMF+PGW-C.

[0112] In step 305, the UDM+HSS having received the Nudr_DM_notify message sends a Nudm_SDM_Notification message to the SMF+PGW-C, the Nudm_SDM_Notification message including at least one of the following: the updated S-NSSAI received as a result of the change, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., reason value). For example, assuming that S-NSSAI A, S-NSSAI B, and S-NSSAI C are subscription S-NSSAIs for the UE, when S-NSSAI A and S-NSSAI B are connected to APN 1 and S-NSSAI C is connected to APN 2, S-NSSAI C may be deleted from the subscription S-NSSAI list as a result of the subscription data change in the UDR. In this case, the UDM+HSS may send a Nudm_SDM_Notification message to the SMF+PGW-C, sending the subscribed S-NSSAI list from which S-NSSAI C has been deleted, information about APN 1 associated with S-NSSAI A and S-NSSAI B, and cause information (e.g., cause value) indicating that the change is due to a subscription S-NSSAI change rather than an APN change.

[0113] In step 306, upon receiving the Nudm_SDM_Notification message from the UDM+HSS, the SMF+PGW-C may identify the cause information (e.g., cause value) in the received message, and determine a method for adjusting the ongoing PDN session based on the information included in the received message. The determination method is performed in the following processes 1-1) to 1-4).

[0114] 1-1) Identify whether any S-NSSAI has been deleted from the subscribed S-NSSAI list.

[0115] 1-2) There is a deleted S-NSSAI, and it is determined whether there are any ongoing PDN sessions for the APN connection associated with the deleted S-NSSAI.

[0116] 1-3) When there is an ongoing PDN session connected to the APN, identify whether there is any other alternative S-NSSAI in the subscribed S-NSSAI list that can be used to access the APN.

[0117] 1-4) When one S-NSSAI is available for accessing the APN and corresponds to the deleted S-NSSAI, or when there are multiple S-NSSAIs available for accessing the APN but no available S-NSSAI is included in the subscription S-NSSAI list received from the UDM+HSS in step 305, the SMF+PGW-C determines to release all PDN sessions connected to the APN. According to the example described with respect to step 305, the S-NSSAI C has been deleted from the subscription data, and no other S-NSSAI is available for accessing APN 2. Therefore, the SMF+PGW-C may determine to release all PDN sessions connected to APN 2.

[0118] In step 307, the SMF+PGW-C requests the PCF+PCRF to release / terminate the PDN session (e.g., IP Connectivity Access Network (IP-CAN) session) connected to the APN according to the determination result made in step 306, thereby releasing / terminating the PDN session. The IP-CAN session refers to the association between the UE and the IP network (i.e., the APN).

[0119] Subsequently, in steps 308 to 311, the SMF+PGW-C allows the UE to release the PDN session and disable the EPS bearer through the SGW, MME and E-UTRAN. In this case, as in step 305, the SMF+PGW-C can inform the UE that the reason for releasing / terminating the PDN session is not that the APN is unavailable to the UE, but that the network slice related information has changed.

[0120] In step 312, the UE may then reestablish or change the PDN session for the APN based on the cause information (cause value) received from the SMF+PGW-C via the EPS. Within a predetermined time set by the UE and / or the network, the UE and / or the network may start or may start and end the operation of reestablishing or changing the PDN session for the APN. The predetermined time may be set individually for each of the UE and the network, or may be signaled to the UE via signaling from the network (e.g., RRC signaling, system information, etc.). In addition, when the UE reestablishes or changes the PDN session, the UE may allocate an ID that has not been previously used as a PDN session ID and a PDU session ID corresponding to the PDN session ID. The operation of the UE and / or the operation of the network may be equally applied to other embodiments to be described below.

[0121] Figure 4 is a diagram showing a signal flow of a session modification method based on subscription data update according to an embodiment of the present disclosure.

[0122] refer to Figure 4, the UDM+HSS may receive updated subscription S-NSSAI information from the UDR, and then send the updated subscription S-NSSAI information and information about the APN associated with the corresponding S-NSSAI to the SMF+PGW-C. The SMF+PGW-C may determine whether there are any other alternative S-NSSAIs that may enable the UE to access the APN. When any alternative S-NSSAI exists, the SMF+PGW-C may modify the session to indicate the reason for the session modification and the changed S-NSSAI to the UE.

[0123] Specifically, in step 401, the SMF+PGW-C sends a Nudm_SDM_subscribe message to the UDM+HSS. The Nudm_SDM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudm_SDM_subscribe message may include information indicating the following operations: when an event occurs that changes or deletes the subscription S-NSSAI for the UE, information about the changed or deleted subscription S-NSSAI is transmitted to the SMF+PGW-C that has sent the Nudm_SDM_subscribe message.

[0124] In step 402, when the subscription data of the UE changes, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR to request notification of the subscription data change of the UE.

[0125] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 403, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message to the UDM+HSS in step 404. The result of the change may include an updated S-NSSAI for the UE.

[0126] In step 405, the UDM+HSS having received the Nudr_DM_notify message sends a Nudm_SDM_Notification message to the SMF+PGW-C, the Nudm_SDM_Notification message including at least one of the following: the updated S-NSSAI received as a result of the change, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., reason value). For example, it can be assumed that S-NSSAI A, S-NSSAI B, and S-NSSAI C are subscription S-NSSAIs for the UE, S-NSSAI A and S-NSSAI B are connected to APN 1, and S-NSSAI C is connected to APN 2, and as a result of the subscription data change in the UDR, S-NSSAI A is deleted from the subscription S-NSSAI list. In this case, the UDM+HSS may send a Nudm_SDM_Notification message to the SMF+PGW-C, sending the subscribed S-NSSAI list from which S-NSSAI A has been deleted, information about APN 1 associated with S-NSSAI A and S-NSSAI B, and cause information (e.g., cause value) indicating that the change is due to a subscription S-NSSAI change rather than an APN change.

[0127] In step 406, upon receiving the Nudm_SDM_Notification message from the UDM+HSS, the SMF+PGW-C may identify the cause information (e.g., cause value) in the received message, and determine a method for adjusting the ongoing PDN session based on the information included in the received message. The determination method is performed in the following processes 2-1) to 2-4).

[0128] 2-1) Identify whether any S-NSSAI has been deleted from the subscribed S-NSSAI list.

[0129] 2-2) There is a deleted S-NSSAI, and it is determined whether there is any ongoing PDN session for the APN connection associated with the deleted S-NSSAI.

[0130] 2-3) When there is an ongoing PDN session connected to the APN, identify whether there are any other S-NSSAIs available to access the APN in the subscribed S-NSSAI list.

[0131] 2-4) When at least one S-NSSAI other than the deleted S-NSSAI is available for accessing the APN and vein is included in the subscribed S-NSSAI list received from the UDM+HSS in step 405, the SMF+PGW-C determines to modify all PDN sessions connected to the APN so that the APN is accessed by another S-NSSAI that is available for accessing the APN and is included in the subscribed S-NSSAI list. For example, when APN 1 is accessible to S-NSSAI A and S-NSSAI B, and S-NSSAI A is deleted from the subscribed S-NSSAI list as described above, all PDN sessions connected to APN 1 may be modified so that S-NSSAI B is associated with APN 1 instead of S-NSSAI A.

[0132] In step 407, the SMF+PGW-C requests the PCF+PCRF to modify the PDN session (eg, IP-CAN session) connected to the APN according to the determination result made in step 406, thereby modifying the PDN session.

[0133] Subsequently, in steps 408 to 411, the SMF+PGW-C may allow the UE to modify the PDN session and modify the EPS bearer through the SGW, MME, and E-UTRAN. In this case, as in step 405, the SMF+PGW-C may inform the UE that the reason for modifying the PDN session is not that the APN is unavailable to the UE, but that the network slice related information has changed. In addition, the SMF+PGW-C may send to the UE information about the S-NSSAI associated with the PDN session in the PCO that is updated due to the modification. In addition, the SMF+PGW-C may send to the UE the updated subscription S-NSSAI information received from the UDM+HSS in the updated PCO. When it has been determined that S-NSSAI B was associated with APN1 when the PDN session was initially established for APN 1, steps 407 to 411 may be skipped.

[0134] In step 412, the UE may then reestablish or change the PDN session for the APN based on the cause information (cause value) received from the SMF+PGW-C via the EPS. Within a predetermined time set by the UE and / or the network, the UE and / or the network may start or may start and end the operation of reestablishing or changing the PDN session for the APN. The predetermined time may be set individually for each of the UE and the network, or may be signaled to the UE via signaling from the network (e.g., RRC signaling, system information, etc.). In addition, when the UE reestablishes or changes the PDN session, the UE may allocate an ID that has not been previously used as a PDN session ID.

[0135] Figure 5is a diagram showing a signal flow of a session modification method based on subscription data update (when using the N26 interface) according to an embodiment of the present disclosure.

[0136] refer to Figure 5 , UDM+HSS can receive updated subscription S-NSSAI information from UDR, and then send the updated subscription S-NSSAI information and information about the APN associated with the corresponding S-NSSAI to SMF+PGW-C. SMF+PGW-C can determine whether there are any other alternative S-NSSAI that can enable the UE to access the APN, and then modify or release the relevant session when the UE moves to 5GS later.

[0137] Specifically, in step 501, the SMF+PGW-C sends a Nudm_SDM_subscribe message to the UDM+HSS. The Nudm_SDM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudm_SDM_subscribe message may include information indicating the following operations: when an event of changing or deleting the subscription S-NSSAI for the UE occurs, information about the changed or deleted subscription S-NSSAI is transmitted to the SMF+PGW-C that has sent the Nudm_SDM_subscribe message.

[0138] In step 502, when the subscription data of the UE changes, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR to request notification of the subscription data change of the UE.

[0139] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 503, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message to the UDM+HSS in step 504. The result of the change may include an updated S-NSSAI for the UE.

[0140] In step 505, the UDM+HSS having received the Nudr_DM_notify message sends a Nudm_SDM_Notification message to the SMF+PGW-C, the Nudm_SDM_Notification message including at least one of the following: the updated S-NSSAI received as a result of the change, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., reason value). For example, assuming that S-NSSAI A, S-NSSAI B, and S-NSSAI C are the subscription S-NSSAIs of the UE, when S-NSSAI A and S-NSSAI B are connected to APN 1, and S-NSSAI C is connected to APN 2, S-NSSAI C may be deleted from the subscription S-NSSAI list as a result of the subscription data change in the UDR. In this case, the UDM+HSS can send the subscribed S-NSSAI list from which S-NSSAI C has been deleted, information about APN 1 associated with S-NSSAI A and S-NSSAI B, and reason information (e.g., reason value) indicating that the change is due to a subscription S-NSSAI change rather than an APN change to the SMF+PGW-C by sending a Nudm_SDM_Notification message.

[0141] In step 506, upon receiving the Nudm_SDM_Notification message from the UDM+HSS, the SMF+PGW-C may Figure 3 The method of step 306 in the embodiment of the present invention or Figure 4 The method of step 406 in the implementation manner determines whether to release or modify the PDN session.

[0142] Subsequently, in step 507, as the UE moves, the UE or NG-RAN may recognize that the UE has moved from EPS to 5GS and trigger a mobility registration procedure from EPS to 5GS.

[0143] In step 508, when the mobility registration procedure is triggered, the UE may send a registration request message to the NG-RAN including the PCO stored when the UE initially established the PDN session in the EPS. The PCO may not include information about changes in the S-NSSAI associated with the used APN or subscribed S-NSSAI updates as described in steps 501 to 506.

[0144] Subsequently, in step 509, the UE that has moved from EPS to 5GS performs a registration procedure by using the N26 interface. A 5GS that supports interworking with EPS may support an interworking procedure using the N26 interface. Section 4.11.1.3.3 of TS 23.502 (v16.6.0) and its related annexes Figure 4 .11.1.3.3-1 discloses a mobility registration procedure from EPS to 5G using the N26 interface. As in step 509, a portion of the mobility registration procedure may be performed.

[0145] In step 510, the AMF requests the SMF+PGW-C to create an SM context for the PDU session during the mobility registration process. In order to request the SM context creation, the "Nsmf_PDUSession_CreateSMContext" request message described in Table 1 as the PDU session request message may be used. In step 511, the SMF+PGW-C may determine to release or modify the PDN session connected to the corresponding DNN (APN) based on the determination in step 506.

[0146] Subsequently, in step 512, step 513 and step 514, SMF+PGW-C releases or modifies the N4 session (session between SMF and UPF) and the SM policy association according to the determination in step 511, and sends a "Nsmf_PDUSession_CreateSMContext" response message to AMF in response to the "Nsmf_PDUSession_CreateSMContext" request message received in step 510.

[0147] In step 515, by referring to Section 4.11.1.3.3 and its related appendices in TS 23.502 (v16.6.0), Figure 4 .11.1.3.3-1, continue to perform the remaining operations of the mobility registration process, such as Figure 5 shown.

[0148] Figure 6 is a diagram showing a signal flow of a session modification method based on subscription data update according to an embodiment of the present disclosure (when the N26 interface is not used).

[0149] refer to Figure 6, UDM+HSS can receive updated subscription S-NSSAI information from UDR, and then send the updated subscription S-NSSAI information and information about the APN associated with the corresponding S-NSSAI to SMF+PGW-C. SMF+PGW-C can determine whether there are any other alternative S-NSSAI that can enable the UE to access the APN, and then modify or release the relevant session when the UE moves to 5GS later.

[0150] Specifically, in step 601, the SMF+PGW-C sends a Nudm_SDM_subscribe message to the UDM+HSS. The Nudm_SDM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudm_SDM_subscribe message may include information indicating the following operations: when an event occurs that changes or deletes the subscription S-NSSAI for the UE, information about the changed or deleted subscription S-NSSAI is sent to the SMF+PGW-C that has sent the Nudm_SDM_subscribe message.

[0151] In step 602, when the subscription data of the UE changes, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR to request notification of the subscription data change of the UE.

[0152] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 603, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message to the UDM+HSS in step 604. The result of the change may include an updated S-NSSAI for the UE.

[0153] In step 605, the UDM+HSS having received the Nudr_DM_notify message sends a Nudm_SDM_Notification message to the SMF+PGW-C, the Nudm_SDM_Notification message including at least one of the following: the updated S-NSSAI received as a result of the change, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., reason value). For example, assuming that S-NSSAI A, S-NSSAI B, and S-NSSAI C are the subscription S-NSSAIs of the UE, when S-NSSAI A and S-NSSAI B are connected to APN 1, and S-NSSAI C is connected to APN 2, S-NSSAI C may be deleted from the subscription S-NSSAI list as a result of the subscription data change in the UDR. In this case, the UDM+HSS can send the subscribed S-NSSAI list from which S-NSSAI C has been deleted, information about APN 1 associated with S-NSSAI A and S-NSSAI B, and reason information (e.g., reason value) indicating that the change is due to a subscription S-NSSAI change rather than an APN change to the SMF+PGW-C by sending a Nudm_SDM_Notification message.

[0154] In step 606, upon receiving the Nudm_SDM_Notification message from the UDM+HSS, the SMF+PGW-C may Figure 3 The method of step 306 in the embodiment of the present invention or Figure 4 The method of step 406 in the implementation manner determines whether to release or modify the PDN session.

[0155] As the UE moves, the UE or the NG-RAN may recognize that the UE has moved from EPS to 5G. In step 608, the UE may send a registration request message to the NG-RAN including the PCO stored when the UE initially established the PDN session in the EPS. The PCO may not include information about changes in the S-NSSAI associated with the APN used or updates of the subscribed S-NSSAI as described in steps 601 to 606. Although according to an optional embodiment, Figure 6 The example omitted Figure 5 However, step 507 may also be performed before step 608.

[0156] Subsequently, in step 609, the UE that has moved from EPS to 5GS may start a registration procedure that does not use the N26 interface. A 5GS that supports interworking with EPS may support interworking procedures that do not use the N26 interface. Section 4.11.2.3 of TS 23.502 (v16.6.0) and its related annexes Figure 4 .11.2.3-1 discloses a mobility registration procedure from EPS to 5GS without using the N26 interface. As in step 609, a portion of the mobility registration procedure may be performed.

[0157] In step 610, the AMF requests the SMF+PGW-C to create an SM context for the PDU session during the mobility registration procedure. In order to request SM context creation, the "Nsmf_PDUSession_CreateSMContext" request message described in Table 1 as a PDU session request message may be used.

[0158] In step 611, the SMF+PGW-C may determine to establish a PDU session connected to the corresponding DNN (APN) based on the determination in step 606.

[0159] In step 612, SMF+PGW-C creates an SM context for the PDU session determined to be established, and sends a "Nsmf_PDUSession_CreateSMContext" response message to AMF in response to the "Nsmf_PDUSession_CreateSMContext" request message received in step 610.

[0160] Subsequently, in steps 613 and 614, according to the determination in step 611, the method described in sections 4.3.2.2 and 4.11.2.3 of TS 23.502 (v16.6.0) and its related appendixes are used. Figure 4 .3.2.2.1-1 and 4.11.2.3-1, continue to perform the remaining operations of the session establishment process and mobility registration process initiated by the UE, such as Figure 6 shown.

[0161] Figure 7 is a diagram showing a signal flow of a session release method based on policy update according to an embodiment of the present disclosure.

[0162] refer to Figure 7, PCF+PCRF may receive updated subscription S-NSSAI information from UDR, update policy based on updated subscription S-NSSAI information and information about APN associated with corresponding S-NSSAI, and then send the policy update to SMF+PGW-C. SMF+PGW-C may determine whether there are any other alternative S-NSSAI that can enable UE to access APN. When there are no other alternative S-NSSAI, SMF+PGW-C may release the session to indicate the reason for the session release to the UE.

[0163] Specifically, in step 701, the PCF+PCRF sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event occurs that changes or deletes the subscription S-NSSAI for the UE, information about the changed or deleted subscription S-NSSAI is sent to the PCF+PCRF that has sent the Nudr_DM_subscribe message. As known from the name of the Nudr_DM_subscribe message, the service-based interface related to the UDR is defined by "Nudr", and Nudr_DM is one of the services provided by the UDR. Regarding the data stored in the UDR, the UDR can perform detection, generation, update, subscription change notification, cancellation of subscription to change notification, and / or deletion through Nudr_DM. In the present disclosure, the PCF+PCRF and the UDM+HSS can use the Nudr_DM service.

[0164] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 702, the UDR notifies the PCF+PCRF of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message to the PCF+PCRF in step 703. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0165] In step 704, upon receiving the Nudr_DM_notify message, the PCF+PCRF may update the policy based on the change result. For example, when the S-NSSAI has been deleted as a result of the update, the policy applied to the deleted S-NSSAI and the APN associated with the deleted S-NSSAI may be deleted.

[0166] In step 705, the PCF+PCRF sends information about the updated policy to the SMF+PGW-C.

[0167] The subsequent steps 706 to 712 are Figure 3 Steps 306 to 312 in the embodiment of the present invention are performed in the same manner, so a detailed description thereof is avoided herein.

[0168] Fig.23A and Fig. 23B is a diagram illustrating another exemplary session release method based on policy update according to an embodiment of the present disclosure.

[0169] exist FIG. 23A to FIG. 26B In the embodiment of the present invention, at least one of the messages sent and received between SMF+PGW-C, PCF+PCRF and UDR can basically be a message used in the SM policy association management process in NR standard TS 29.513. Various information according to the following embodiments can be transmitted using this message. However, it should be noted that the messages exemplified in the following embodiments are merely examples and are not limited to the format of specific messages.

[0170] refer to Fig.23A and Fig. 23B , SMF+PGW-C may request PCF+PCRF for information related to a specific session, and PCF+PCRF may request UDR for information related to the service to be used through a specific session and receive the requested information from UDR. When there is a change in the information (e.g., subscription data, UE policy data, or session management policy data) that can be received from UDR, PCF+PCRF may request UDR to subscribe to notifications of changes or no changes and the content of the changes. When any one of the subscription data, UE policy data, and session management policy data changes, UDR may notify the PCF+PCRF that manages the changed data of the change. PCF+PCRF may determine a policy based on the information received from UDR and notify SMF+PGW-C of the policy. SMF+PGW-C may determine that the subscription S-NSSAI information has been changed, and determine whether there are any other alternative S-NSSAIs that enable the UE to access the APN associated with the corresponding S-NSSAI based on the policy received from PCF+PCRF. When there is no other alternative S-NSSAI, SMF+PGW-C may release the session to indicate the reason for the session release to the UE.

[0171] Specifically, in step 2301, SMF+PGW-C may send an Npcf_SMPolicyControl_Create request to PCF+PCRF to request policy information for managing the session to be established by SMF+PGW-C. PCF+PCRF may generate session management policy related information (e.g., session management policy association or SM policy association) and provide session management policy related information to SMF+PGW-C. The session management policy related information may include at least one item of information described in Table 2a and Table 2b. For ease of description, Table 2a and Table 2b below show a table separately. Session management policy related information may be referred to as session policy related information or session policy management / control subscription information.

[0172] Table 2a PDU session policy control subscription information

[0173]

[0174]

[0175]

[0176] Table 2b

[0177]

[0178]

[0179] exist Fig.23A In step 2302, the PCF+PCRF sends a Nudr_DataRepository_Query request message to the UDR to request information about the session for which SMF+PGW-C information is requested, information about services to be used through the session, and user-related information about the UDR. When the PCF+PCRF requests information from the UDR, the PCF+PCRF may determine the required information based on a subscription permanent identifier (SUPI), a DNN, and an S-NSSAI, and request the required information based on the determination.

[0180] In step 2303, the UDR may send the session management policy data (eg, session management policy data) for the session requested by the PCF+PCRF to the PCF+PCRF by sending a Nudr_DataRepository_Query response message in response to the Nudr_DataRepository_Query request message.

[0181] In step 2304, the PCF+PCRF may send a Nudr_DataRepository_Subscribe request message to the UDR to request the UDR to send a notification of whether the policy data for the session managed by the PCF+PCRF has changed and / or information of the change when a change occurs.

[0182] In step 2305, when the UDR determines whether to accept the request of step 2304 and accepts the request, in response thereto, the UDR may send a Nudr_DataRepository_Subscribe response message to notify the PCF+PCRF of the request acceptance.

[0183] In step 2306, the PCF+PCRF may determine a session management policy based on the information received from the UDR.

[0184] In step 2307 , the PCF+PCRF may generate session management policy related information and send a Nudr_DataRepository_Create response message including the generated information to the SMF+PGW-C. The session management policy related information may include information about the policy determined in step 2306 .

[0185] In step 2308, the UDR may recognize / identify whether at least one of subscription data, UE policy data, or session management policy data in the subscription S-NSSAI or subscription S-NSSAI related information has changed.

[0186] In step 2309, the UDR may determine whether there is session management policy data to be changed due to the subscription S-NSSAI change. In an exemplary method for determining whether there is session management policy data to be changed, it may be identified whether there is information to be affected by the subscription S-NSSAI change in the session management policy related information illustrated in Table 2a and Table 2b. Whether the information is affected by the change of the subscription S-NSSAI can be identified by determining the following: whether there is an S-NSSAI deleted from the subscription S-NSSAI list, whether there is a deleted subscription DNN, and whether the S-NSSAI associated with the DNN is included in the subscription S-NSSAI list, whether there is a deleted subscription S-NSSAI or DNN, and whether there is a subscription GBR associated with the S-NSSAI or DNN, whether there is a deleted subscription S-NSSAI or DNN, and whether there is a subscription S-NSSAI subscription information associated with the S-NSSAI or DNN. This determination may be made based on the subscription GBR information, S-NSSAI subscription information, etc. in Table 2a and Table 2b.

[0187] In step 2310, the UDR may send a Nudr_DataRepository_Notify request message to the PCF+PCRF that has requested to subscribe to the session management policy related information described in step 2304 based on the session management policy related information changes determined in step 2309, so as to notify the PCF+PCRF of the session management policy related information changes.

[0188] In step 2311 , the PCF+PCRF may send a Nudr_DataRepository_Notify response message to the UDR in response to the Nudr_DataRepository_Notify request message received in step 2310 .

[0189] In step 2312, the PCF+PCRF identifies the information about the change of the session management policy related information (e.g., the removal of the session policy control data) received from the UDR in step 2310, and determines whether there is a session to be affected based on the information about the change of the session management policy related information. For example, the PCF+PCRF can determine whether specific session management policy related information has been deleted and whether there is an SMF-PCW-C that manages the session to which the corresponding policy has been applied by analyzing the information about the change of the session management policy related information. In addition, in step 2312, the PCF+PCRF can determine whether it is necessary to release / terminate the session.

[0190] In step 2313, the PCF+PCRF may send an Npcf_SMPolicyControl_UpdateNotify request message to the SMF+PGW-C that manages the session to be changed based on the determination in step 2312, to notify that the session management policy should be changed.

[0191] In step 2314 , the SMF+PGW-C may send an Npcf_SMPolicyControl_UpdateNotify response message in response to the Npcf_SMPolicyControl_UpdateNotify request message received in step 2313 .

[0192] In step 2315, SMF+PGW-C may determine a method for adjusting the ongoing PDN session. The determination method is performed in the following processes 3-1) to 3-4).

[0193] 3-1) Identify whether there is any S-NSSAI deleted from the subscribed S-NSSAI list.

[0194] 3-2) There is a deleted S-NSSAI, and it is determined whether a PDN session of an APN connection associated with the deleted S-NSSAI is in progress.

[0195] 3-3) When there is a PDN session connected to the APN, identify whether any other S-NSSAI that can be used to access the APN exists in the subscribed S-NSSAI list.

[0196] 3-4) When one S-NSSAI is available for accessing the APN and corresponds to the deleted S-NSSAI, or when multiple S-NSSAIs are available for accessing the APN but no S-NSSAI is included in the subscribed S-NSSAI list, the SMF+PGW-C determines to release all PDN sessions connected to the APN. For example, assuming that S-NSSAI A, S-NSSAI B, and S-NSSAI C are subscribed S-NSSAIs for the UE, when S-NSSAI C changes due to a subscription data change in the UDR, S-NSSAI A and S-NSSAI B can be connected to APN 1, and S-NSSAI C can be connected to APN 2. This corresponds to the case of "one S-NSSAI is available for accessing the APN and corresponds to the deleted S-NSSAI" in process 3-4). Since S-NSSAI C has been deleted from the subscription data and there is no other S-NSSAI available for accessing APN 2, the SMF+PGW-C can determine to release all PDN sessions connected to APN 2.

[0197] Before step 2313, SMF+PGW-C may have subscribed to the S-NSSAI list. This corresponds to the case where UDR or UDM+HSS sends user data information directly or through another NF (or network entity) during the network registration process of the UE or the session establishment process or session modification process of SMF+PGW-C. The message for transmitting subscription data may be Nudr_DataRepository_Query, Nudr_DM_Notify, or Nudm_SDM_Notification.

[0198] In step 2315, it may be determined whether there is a deleted or affected APN by determining whether there is a deleted or affected DNN and whether there is an APN indicating the same data network as the data network indicated by the DNN. This determination may be made by the UDR in step 2309 or by the PCF+PCRF in step 2312.

[0199] In step 2316, SMF+PGW-C requests PCF+PCRF to release / terminate the PDN session (e.g., IP-CAN session) connected to the APN to release / terminate the PDN session according to the determination result of step 2315. The IP-CAN session refers to the association between the UE and the IP network (i.e., APN).

[0200] Subsequently, in steps 2317 to 2320, SMF+PGW-C allows the UE to release the PDN session and disable the EPS bearer through the SGW, MME and E-UTRAN. In this case, SMF+PGW-C can notify the UE that the reason for releasing / terminating the PDN session is not the unavailability of the APN to the UE, but the change of network slice related information.

[0201] In step 2321, the UE may then reestablish or change the PDN session for the APN based on the cause information (cause value) received from the SMF+PGW-C via the EPS. Within a predetermined time set by the UE and / or the network, the UE and / or the network may start or may start and end the operation of reestablishing or changing the PDN session for the APN. The predetermined time may be set individually for each of the UE and the network, or may be signaled to the UE via signaling from the network (e.g., RRC signaling, system information, etc.). In addition, when the UE reestablishes or changes the PDN session, the UE may allocate an ID that has not been previously used as a PDN session ID and a PDU session ID corresponding to the PDN session ID. The operation of the UE and / or the operation of the network may be applicable to other embodiments to be described below.

[0202] Figure 8 is a diagram showing a signal flow of a session modification method based on policy update according to an embodiment of the present disclosure.

[0203] refer to Figure 8 , PCF+PCRF may receive updated subscription S-NSSAI information from UDR, update policy based on updated subscription S-NSSAI information and information about APN associated with corresponding S-NSSAI, and then send the policy update to SMF+PGW-C. SMF+PGW-C may determine whether there are any other alternative S-NSSAI that can enable UE to access APN. When there are any alternative S-NSSAI, SMF+PGW-C may modify the session to indicate the reason for the session modification and the changed S-NSSAI to the UE.

[0204] Specifically, in step 801, the PCF+PCRF sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting the subscription S-NSSAI for the UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the PCF+PCRF that has sent the Nudr_DM_subscribe message.

[0205] When the subscription data change of the S-NSSAI is detected in step 802, the UDR that has received the Nudr_DM_subscribe message notifies the PCF+PCRF of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0206] When the Nudr_DM_notify message is received, the PCF+PCFR updates the policy based on the change result in step 804. For example, when there is a deleted S-NSSAI as a change result and another S-NSSAI is available for accessing the APN associated with the deleted S-NSSAI, the S-NSSAI of the policy applied to the associated APN may be changed.

[0207] In step 805, PCF+PCFR sends information about the updated policy to SFM+PGW-C.

[0208] The subsequent steps 806 to 812 are Figure 4 Steps 406 to 412 in the embodiment of the present invention are performed in the same manner, so they will not be described in detail herein.

[0209] Fig.24A and Fig. 24B is a diagram illustrating another exemplary session modification method based on policy update according to an embodiment of the present disclosure.

[0210] refer to Fig.24A and Fig. 24B, SMF+PGW-C may request information related to a specific session from PCF+PCRF, and PCF+PCRF may request information related to the subscriber's UE and the service that SMF+PGW-C intends to use from UDR through the session and receive the information from UDR. In addition, when there is a change in the information (e.g., subscription data, UE policy data, or session management policy data) that can be received from UDR, PCF+PCRF may request UDR to subscribe to notifications of changes or no changes and the content of the changes. When any one of the subscription data, UE policy data, and session management policy data changes, UDR may indicate the change to PCF+PCRF, which manages the changed data. PCF+PCRF may determine a policy based on the information received from UDR and notify SMF+PGW-C of the policy. SMF+PGW-C may determine that the subscription S-NSSAI information has been changed, and determine whether there are any other alternative S-NSSAIs that enable the UE to access the APN associated with the corresponding S-NSSAI based on the policy notified by PCF+PCRF. When there is any alternative S-NSSAI, the SMF+PGW-C may modify the session to indicate the reason for the session modification and the changed S-NSSAI to the UE.

[0211] exist Fig.24A and Fig. 24B In the implementation mode, steps 2401 to 2414 are performed with Fig.23A and Fig. 23B Steps 2301 to 2314 in the implementation mode of the present invention are performed in the same manner, so they will not be described in detail herein.

[0212] exist Fig.24AIn step 2415, method 3-1) to 3-4 of step 2315 are executed. In process 3-4), when multiple S-NSSAIs are available for accessing the corresponding APN and any other S-NSSAIs that can be used to access the APN are included in the subscribed S-NSSAI list, the SMF+PGW-C determines to modify the S-NSSAI associated with the APN without releasing all PDN sessions connected to the APN. For example, assuming that there are S-NSSAI A, S-NSSAI B, and S-NSSAI C that are subscribed S-NSSAIs of the UE, when S-NSSAI A changes due to a change in subscription data in the UDR, S-NSSAI A and S-NSSAI B can be connected to APN1, and S-NSSAI C can be connected to APN 2, which corresponds to the case where "multiple S-NSSAIs are available for accessing the APN and any other S-NSSAIs that can be used to access the APN are included in the subscribed S-NSSAI list". Since S-NSSAI A has been deleted from the subscription data and there is another S-NSSAI available to access APN 1, the SMF+PGW-C can determine to modify all PDN sessions connected to APN 1.

[0213] In step 2415, it can be determined whether there is an affected APN by determining whether there is an affected DNN and whether there is an APN indicating the same data network as the data network indicated by the DNN. This determination can be made by the UDR in step 2409 or by the PCF+PCRF in step 2412.

[0214] In step 2416, SMF+PGW-C requests PCF+PCRF to modify the PDN session (e.g., IP-CAN session) connected to the APN to modify the PDN session according to the determination result of step 2415. The IP-CAN session refers to the association between the UE and the IP network (i.e., APN).

[0215] Subsequently, in steps 2417 to 2420, the SMF+PGW-C allows the UE to modify the PDN session and update the EPS bearer through the SGW, MME and E-UTRAN. In this case, the SMF+PGW-C may notify the UE of the cause information (cause value) and the change of the network slice related information, indicating that the modification of the PDN session is due to the change of the network slice related information rather than the unavailability of the APN to the UE.

[0216] In step 2421, the UE may then reestablish or change the PDN session for the APN based on the cause information (cause value) received from the SMF+PGW-C via the EPS. Within a predetermined time set by the UE and / or the network, the UE and / or the network may start or may start and end the operation of reestablishing or changing the PDN session for the APN. The predetermined time may be set individually for each of the UE and the network, or may be signaled to the UE via signaling from the network (e.g., RRC signaling, system information, etc.). In addition, when the UE reestablishes or changes the PDN session, the UE may allocate an ID that has not been previously used as a PDN session ID and a PDU session ID corresponding to the PDN session ID. The operation of the UE and / or the operation of the network may also be applied to other embodiments described below.

[0217] Fig. 9 is a diagram showing a signal flow of a session modification method based on policy update (when using the N26 interface) according to an embodiment of the present disclosure.

[0218] refer to Fig. 9 , PCF+PCRF can receive updated subscription S-NSSAI information from UDR, update policy based on updated subscription S-NSSAI information and information about APN associated with corresponding S-NSSAI, and then send the policy update to SMF+PGW-C. SMF+PGW-C can determine whether there are any other alternative S-NSSAI that can enable UE to access APN. Then, when UE moves to 5GS later, the associated session is modified or released.

[0219] Specifically, in step 901, the PCF+PCRF sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting the subscription S-NSSAI for the UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the PCF+PCRF that has sent the Nudr_DM_subscribe message.

[0220] When the subscription data change of the S-NSSAI is detected in step 902, the UDR that has received the Nudr_DM_subscribe message indicates the result of the subscription S-NSSAI change to the PCF+PCFR by sending a Nudr_DM_notify message to the PCF+PCFR. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0221] In step 904, when the Nudr_DM_notify message is received, the PCF+PCFR updates the policy based on the change result. For example, when there is a deleted S-NSSAI as an update result and another S-NSSAI can be used to access the APN associated with the deleted S-NSSAI, the S-NSSAI of the policy applied to the associated APN may be changed.

[0222] In step 905, PCF+PCFR sends updated policy information to SFM+PGW-C. Upon receiving the updated policy information, SMF+PGW-C can use Figure 3 The method of step 306 in the embodiment of the present invention or Figure 4 The method of step 406 in the implementation manner determines whether to release or modify the PDN session.

[0223] In step 907, as the UE moves, the UE or NG-RAN may recognize that the UE has moved from EPS to 5GS and trigger a mobility registration procedure from EPS to 5GS.

[0224] In step 908, when the mobility registration procedure is triggered, the UE may send a registration request message to the NG-RAN including the PCO stored when the UE initially established the PDN session in the EPS. The PCO may not include information about changes in the S-NSSAI associated with the used APN or subscribed S-NSSAI updates as described in steps 901 to 906.

[0225] Subsequently, in step 909, the UE that has moved from EPS to 5GS performs a registration procedure by using the N26 interface. The 5GS that supports interworking with EPS may support interworking procedures using the N26 interface. Section 4.11.1.3.3 of TS 23.502 (v16.6.0) and its related annexes Figure 4 .11.1.3.3-1 discloses the mobility registration procedure from EPS to 5G using the N26 interface.

[0226] In step 910, the AMF requests the SMF+PGW-C to create an SM context for the PDU session during the mobility registration process. In order to request the SM context creation, the "Nsmf_PDUSession_CreateSMContext" request message described in Table 1 as the PDU session request message may be used. In step 911, the SMF+PGW-C may determine to release or modify the PDN session connected to the corresponding DNN (APN) based on the determination in step 906.

[0227] Subsequently, in step 912, step 913 and step 914, SMF+PGW-C releases or modifies the N4 session (session between SMF and UPF) and the SM policy association according to the determination in step 911, and sends a "Nsmf_PDUSession_CreateSMContext" response message to AMF in response to the "Nsmf_PDUSession_CreateSMContext" request message received in step 910.

[0228] In step 915, by TS 23.502 (v16.6.0) section 4.11.1.3.3 and its related appendix Figure 4 .11.1.3.3-1, continue to perform the remaining operations of the mobility registration process, such as Fig. 9 shown.

[0229] Fig.25A and Fig.25B is a diagram illustrating another exemplary session modification method based on policy update (when using the N26 interface) according to an embodiment of the present disclosure.

[0230] refer to Fig.25A and Fig.25B, SMF+PGW-C may request information related to a specific session from PCF+PCRF, and PCF+PCRF may request information related to the subscriber's UE and the service that SMF+PGW-C intends to use from UDR through the session and receive the information from UDR. In addition, when there is a change in the information (e.g., subscription data, UE policy data, or session management policy data) that can be received from UDR, PCF+PCRF may request UDR to subscribe to notifications of changes or no changes and the content of the changes. When any one of the subscription data, UE policy data, and session management policy data changes, UDR may indicate the change to PCF+PCRF, which manages the changed data. PCF+PCRF may determine a policy based on the information received from UDR and notify SMF+PGW-C of the policy. SMF+PGW-C may determine that the subscription S-NSSAI information has been changed, and determine whether there are any other alternative S-NSSAIs that enable the UE to access the APN associated with the corresponding S-NSSAI based on the policy indicated by PCF+PCRF. Therefore, when the UE moves to 5GS, SMF+PGW-C can modify or release the related sessions.

[0231] exist Fig.25A and Fig.25B In the implementation mode, steps 2501 to 2514 are performed with Fig.23A and Fig. 23B The steps 2301 to 2314 of the embodiment of the present invention are performed in the same manner. Therefore, they will not be described in detail herein.

[0232] In step 2515 of FIG. 25 , when receiving policy related information from PCF+PCRF, SMF+PGW-C may Fig.23A and Fig. 23B The method of step 2315 in the embodiment of the present invention or Fig.24A and Fig. 24B The method of step 2415 in the implementation mode determines whether to release or modify the PDN session.

[0233] Subsequently, in step 2516, the UE or NG-RAN may recognize that the UE has moved from EPS to 5GS and trigger a mobility registration procedure from EPS to 5GS.

[0234] In step 2517, when the mobility registration procedure is triggered, the UE may send a registration request message to the NG-RAN including the PCO stored when the UE initially established the PDN session in the EPS. The PCO may not include information about S-NSSAI changes associated with the used APN or subscribed S-NSSAI updates.

[0235] Subsequently, in step 2518, the UE that has moved from EPS to 5GS performs a registration procedure by using the N26 interface. A 5GS that supports interworking with EPS may support an interworking procedure using the N26 interface. Section 4.11.1.3.3 of TS 23.502 (v16.6.0) and its related annexes Figure 4 .11.1.3.3-1 discloses a mobility registration process from EPS to 5G using the N26 interface. As in step 2518, a portion of the mobility registration process may be performed.

[0236] In step 2519, the AMF requests the SMF+PGW-C to create an SM context for the PDU session during the mobility registration process. In order to request the SM context creation, the "Nsmf_PDUSession_CreateSMContext" request message described in Table 1 as the PDU session request message may be used. In step 2520, the SMF+PGW-C may determine to release or modify the PDN session connected to the corresponding DNN (APN) based on the determination in step 2515.

[0237] Subsequently, in steps 2521, 2522 and 2523, SMF+PGW-C releases or modifies the N4 session (session between SMF and UPF) and the SM policy association according to the determination in step 2520, and sends a "Nsmf_PDUSession_CreateSMContext" response message to AMF in response to the "Nsmf_PDUSession_CreateSMContext" request message received in step 2519.

[0238] In step 2524, by TS 23.502 (v16.6.0) section 4.11.1.3.3 and its related appendix Figure 4 .The method described in 11.1.3.3-1 continues to perform the remaining operations of the mobility registration process, as shown in Figure 25.

[0239] Fig.10 is a diagram showing a signal flow of a session modification method based on policy update according to an embodiment of the present disclosure (when the N26 interface is not used).

[0240] refer to Fig.10, PCF+PCRF can receive updated subscription S-NSSAI information from UDR, update the policy based on the updated subscription S-NSSAI information and the information about the APN associated with the corresponding S-NSSAI, and send the policy update to SMF+PGW-C. SMF+PGW-C can determine whether there are any other alternative S-NSSAIs that can enable the UE to access the APN, and then modify or release the associated session when the UE moves to 5GS later.

[0241] Specifically, in step 1001, the PCF+PCRF sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event occurs that changes or deletes the subscription S-NSSAI for the UE, information about the changed or deleted subscription S-NSSAI is sent to the PCF+PCRF that has sent the Nudr_DM_subscribe message.

[0242] When the subscription data change of the S-NSSAI is detected in step 1002, the UDR that has received the Nudr_DM_subscribe message indicates the result of the subscription S-NSSAI change to the PCF+PCFR by sending a Nudr_DM_notify message to the PCF+PCFR in step 1003. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0243] Upon receiving the Nudr_DM_notify message, the PCF+PCFR updates the policy based on the result of the change in step 1004. For example, when there is a deleted S-NSSAI as a result of the update and another S-NSSAI is available for accessing the APN associated with the deleted S-NSSAI, the S-NSSAI of the policy applied to the associated APN may be changed.

[0244] In step 1005, PCF+PCFR sends updated policy information to SFM+PGW-C.

[0245] In step 1006, upon receiving the Nudm_SDM_Notification message (not shown), the SMF+PGW-C may use Figure 3 The method of step 306 in the embodiment of the present invention or Figure 4 The method of step 406 in the implementation manner determines whether to release or modify the PDN session.

[0246] In step 1007, as the UE moves, the UE or NG-RAN can recognize that the UE has moved from EPS to 5GS.

[0247] In step 1008, the UE may send a registration request message to the NG-RAN including the PCO stored when the UE initially established the PDN session in the EPS. The PCO may not include information about changes in the S-NSSAI associated with the used APN or subscribed S-NSSAI updates as described in steps 1001 to 1006.

[0248] Subsequently, in step 1009, the UE that has moved from EPS to 5GS may start a registration procedure that does not use the N26 interface. A 5GS that supports interworking with EPS may support interworking procedures that do not use the N26 interface. Section 4.11.2.3 of TS 23.502 (v16.6.0) and its related annexes Figure 4 .11.2.3-1 discloses a mobility registration procedure from EPS to 5GS without using the N26 interface. As in step 1009, a portion of the mobility registration procedure may be performed.

[0249] In step 1010, the AMF requests the SMF+PGW-C to create an SM context for the PDU session during the mobility registration procedure. In order to request SM context creation, the "Nsmf_PDUSession_CreateSMContext" request message described in Table 1 as a PDU session request message may be used.

[0250] In step 1011, the SMF+PGW-C may determine to establish a PDU session connected to the corresponding DNN (APN) based on the determination in step 1006.

[0251] In step 1012, SMF+PGW-C creates an SM context for the PDU session determined to be established, and sends a "Nsmf_PDUSession_CreateSMContext" response message to AMF in response to the "Nsmf_PDUSession_CreateSMContext" request message received in step 1010.

[0252] Subsequently, in steps 1013 and 1014, according to the determination in step 1011, the method described in sections 4.3.2.2 and 4.11.2.3 of TS 23.502 (v16.6.0) and its related appendixes are used. Figure 4.3.2.2.1-1 and 4.11.2.3-1, continue to perform the remaining operations of the session establishment process and mobility registration process initiated by the UE, such as Fig.10 shown.

[0253] Fig.26A and Fig.26B is a diagram showing a signal flow of another exemplary session modification method based on policy update (when the N26 interface is not used) according to an embodiment of the present disclosure.

[0254] refer to Fig.26A and 26B , SMF+PGW-C can request information related to a specific session from PCF+PCRF, and PCF+PCRF can request information related to the subscriber's UE and the service that SMF+PGW-C intends to use from UDR through the session and receive the information from UDR. In addition, when there is a change in the information (e.g., subscription data, UE policy data, or session management policy data) that can be received from UDR, PCF+PCRF can request UDR to subscribe to notifications of changes or no changes and the content of the changes. When any one of the subscription data, UE policy data, and session management policy data changes, UDR can indicate the change to PCF+PCRF, which manages the changed data. PCF+PCRF can determine a policy based on the information received from UDR and notify SMF+PGW-C of the policy. SMF+PGW-C can determine that the subscription S-NSSAI information has been changed, and based on the policy indicated by PCF+PCRF, determine whether there are any other alternative S-NSSAIs that enable the UE to access the APN associated with the corresponding S-NSSAI, so as to modify or release the relevant session when the UE moves to 5GS later.

[0255] exist Fig.26A and Fig.26B In the implementation mode, steps 2601 to 2614 are performed with Fig.23A and Fig. 23B The steps 2301 to 2314 of the embodiment of the present invention are performed in the same manner. Therefore, they will not be described in detail herein.

[0256] exist Fig.26A In step 2615, when receiving policy related information from PCF+PCRF, SMF+PGW-C can Fig.23A and Fig. 23B The method of step 2315 in the embodiment of the present invention or Fig.24A and Fig. 24B The method of step 2415 in the implementation mode determines whether to release or modify the PDN session.

[0257] Subsequently, as the UE moves, the UE or NG-RAN can recognize that the UE has moved from EPS to 5GS.

[0258] In step 2616, when the mobility registration procedure is triggered, the UE may send a registration request message to the NG-RAN including the PCO stored when the UE initially established the PDN session in the EPS. The PCO may not include information about S-NSSAI changes associated with the used APN or subscribed S-NSSAI updates.

[0259] Subsequently, in step 2617, the UE that has moved from EPS to 5GS may start a registration procedure that does not use the N26 interface. A 5GS that supports interworking with EPS may support interworking procedures that do not use the N26 interface. Section 4.11.1.3.3 of TS 23.502 (v16.6.0) and its related annexes Figure 4 .11.1.3.3-1 discloses a mobility registration procedure from EPS to 5G without using the N26 interface. As in step 2617, a portion of the mobility registration procedure may be performed.

[0260] In step 2618, the AMF requests the SMF+PGW-C to create an SM context for the PDU session during the mobility registration procedure. In order to request SM context creation, the "Nsmf_PDUSession_CreateSMContext" request message described in Table 1 as a PDU session request message may be used.

[0261] In step 2619, the SMF+PGW-C may determine to establish a PDU session connected to the corresponding DNN (APN) based on the determination in step 2615.

[0262] In step 2620, SMF+PGW-C creates an SM context for the PDU session to be established, and sends a "Nsmf_PDUSession_CreateSMContext" response message to AMF in response to the "Nsmf_PDUSession_CreateSMContext" request message received in step 2618.

[0263] Subsequently, in steps 2621 and 2622, according to the determination in step 2619, by referring to Sections 4.3.2.2, 4.11.2.3 and their related appendices in TS 23.502 (v16.6.0), Figure 4 .3.2.2.1-1 and 4.11.2.3-1, continue to perform the remaining operations of the session establishment process and mobility registration process initiated by the UE, such as Fig.10 shown.

[0264] Fig.11 2 is a diagram showing a signal flow of a session release method based on APN information update and a temporary session deletion indicator according to an embodiment of the present disclosure.

[0265] refer to Fig.11 , UDM+HSS may receive updated subscription S-NSSAI information from UDR, and send APN information and temporary session deletion indicator associated with the updated subscription S-NSSAI to MME. MME may notify that all PDN sessions connected to the corresponding APN will be temporarily released, and SMF+PGW-C may determine whether there are any other alternative S-NSSAI that can enable the UE to access the APN. When there is no alternative S-NSSAI, SMF+PGW-C may release the session to indicate the reason for the session release to the UE.

[0266] Specifically, in step 1101, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting a subscription S-NSSAI for a UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the UDM+HSS that has sent the Nudr_DM_subscribe message.

[0267] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 1102, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message in step 1103. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0268] In step 1104, upon receiving the Nudr_DM_notify message, the UDM+HSS may identify the associated APN and SMF+PGW-C based on the result of the change. In step 1105, the UDM+HSS sends a message including subscription data to the MME, the subscription data including the APN information determined in step 1104 and a temporary session deletion indicator. In step 1106, the MME sends a response message to the UDM+HSS to confirm that the subscription data has been received / reflected.

[0269] Subsequently, in step 1107, the MME identifies the temporary session deletion indicator included in the received message, recognizes that all PDN sessions for the APN should be temporarily released, and thus triggers the PDN session release. In step 1108, the MME may send a message including at least one of the APN information or the cause information (cause value) to the SMF+PGW-C, the cause information indicating that the session release is due to a change in the subscription S-NSSAI rather than a change in the APN.

[0270] The subsequent steps 1109 to 1115 are Figure 3 Steps 306 to 312 in the embodiment are performed in the same manner, so a detailed description thereof is avoided herein.

[0271] Fig.12 is a diagram showing a signal flow of a session modification method based on APN information update and a temporary session deletion indicator according to an embodiment of the present disclosure.

[0272] refer to Fig.12 , UDM+HSS can receive the updated subscription S-NSSAI information from the UDR, and send the APN information associated with the updated subscription S-NSSAI and the temporary session deletion indicator to the MME. The MME notifies that all PDN sessions connected to the corresponding APN should be temporarily released, and the SMF+PGW-C can determine whether there are any other alternative S-NSSAI that can enable the UE to access the APN. When any alternative S-NSSAI exists, the SMF+PGW-C can modify the session to indicate the reason for the session modification and the changed S-NSSAI to the UE.

[0273] Specifically, in step 1201, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting a subscription S-NSSAI for a UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the UDM+HSS that has sent the Nudr_DM_subscribe message.

[0274] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 1202, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message in step 1203. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0275] In step 1204, upon receiving the Nudr_DM_notify message, the UDM+HSS may identify the associated APN and SMF+PGW-C based on the result of the change. In step 1205, the UDM+HSS sends a message including subscription data to the MME, the subscription data including the APN information determined in step 1204 and a temporary session deletion indicator. In step 1206, the MME sends a response message to the UDM+HSS to confirm that the subscription data has been received / reflected.

[0276] Subsequently, in step 1207, the MME identifies the temporary session release indicator included in the received message, recognizes that all PDN sessions for the APN should be temporarily released, and thus triggers the PDN session release. In step 1208, the MME may send a message including at least one of the APN information or the cause information (cause value) to the SMF+PGW-C, the cause information indicating that the session release is due to a change in the subscription S-NSSAI rather than a change in the APN.

[0277] The subsequent steps 1209 to 1215 are Figure 4 Steps 406 to 412 in the embodiment are performed in the same manner, so a detailed description thereof is avoided herein.

[0278] Fig.13A and Fig. 13B is a diagram showing a signal flow of a method for establishing a 5GS PDU session by using an APN information update and a temporary session deletion indicator according to an embodiment of the present disclosure (when using the N26 interface).

[0279] refer to Fig.13A and Fig. 13B, UDM+HSS can receive the updated subscription S-NSSAI information from UDR, and send the APN information associated with the updated subscription S-NSSAI and the temporary session deletion indicator to MME. MME notifies that all PDN sessions connected to the corresponding APN should be temporarily released, and SMF+PGW-C can determine whether there is any other alternative S-NSSAI that can enable the UE to access the APN, and then modify or release the session when the UE moves to 5GS.

[0280] Specifically, in step 1301, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting a subscription S-NSSAI for a UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the UDM+HSS that has sent the Nudr_DM_subscribe message.

[0281] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 1302, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message in step 1303. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0282] In step 1304, upon receiving the Nudr_DM_notify message, the UDM+HSS may identify the associated APN and SMF+PGW-C based on the result of the change. In step 1305, the UDM+HSS sends a message including subscription data to the MME, the subscription data including the APN information determined in step 1304 and a temporary session deletion indicator. In step 1306, the MME sends a response message to the UDM+HSS to confirm that the subscription data has been received / reflected.

[0283] Subsequently, in step 1307, the MME identifies the temporary session deletion indicator included in the received message, recognizes that all PDN sessions for the APN should be temporarily released, and thus triggers the PDN session release. In step 1308, the MME may send a message including at least one of the APN information or the cause information (cause value) to the SMF+PGW-C, the cause information indicating that the session release is due to a change in the subscription S-NSSAI rather than a change in the APN.

[0284] When receiving the message from the MME in step 1308, the SMF+PGW-C may, in step 1309, Figure 3 The method of step 306 in the embodiment of the present invention or Figure 4 The method of step 406 in the implementation manner determines whether to release or modify the PDN session.

[0285] The following steps 1310 to 1318 are performed with Figure 5 Steps 507 to 515 in the embodiment are performed in the same manner, so a detailed description thereof is avoided herein.

[0286] Fig.14A and Fig. 14B is a diagram showing a signal flow of a method for establishing a 5GS PDU session by using an APN information update and a temporary session deletion indicator according to an embodiment of the present disclosure (when the N26 interface is not used).

[0287] refer to Fig.14A and Fig. 14B , UDM+HSS can receive the updated subscription S-NSSAI information from UDR, and send the APN information associated with the updated subscription S-NSSAI and the temporary session deletion indicator to MME. MME notifies that all PDN sessions connected to the corresponding APN should be temporarily released, and SMF+PGW-C can determine whether there is any other alternative S-NSSAI that can enable the UE to access the APN, and then modify or release the session when the UE moves to 5GS.

[0288] Specifically, in step 1401, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting a subscription S-NSSAI for a UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the UDM+HSS that has sent the Nudr_DM_subscribe message.

[0289] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 1402, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message to the UDM+HSS in step 1403. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0290] In step 1404, upon receiving the Nudr_DM_notify message, the UDM+HSS may identify the associated APN and SMF+PGW-C based on the result of the change. In step 1405, the UDM+HSS sends a message including subscription data to the MME, the subscription data including the APN information determined in step 1404 and a temporary session deletion indicator. In step 1406, the MME sends a response message to the UDM+HSS to confirm that the subscription data has been received / reflected.

[0291] Subsequently, in step 1407, the MME identifies the temporary session deletion indicator included in the received message, recognizes that all PDN sessions for the APN should be temporarily released, and thus triggers the PDN session release. In step 1408, the MME may send a message including at least one of the APN information or the cause information (cause value) to the SMF+PGW-C, the cause information indicating that the session release is due to a change in the subscription S-NSSAI rather than a change in the APN.

[0292] When the message is received from the MME in step 1408, in step 1409, the SMF+PGW-C can Figure 3 The method of step 306 in the embodiment of the present invention or Figure 4 The method of step 406 in the implementation manner determines whether to release or modify the PDN session.

[0293] The subsequent steps 1411 to 1417 are Figure 4 Steps 608 to 614 in the embodiment are performed in the same manner, so a detailed description thereof is avoided herein.

[0294] Fig.15 is a diagram showing a signal flow of a session release method based on APN information and S-NSSAI update information according to an embodiment of the present disclosure.

[0295] exist Fig.15In the implementation manner, the list of S-NSSAIs that can be used to access the corresponding APN and the cause information (cause value) can be in Fig.11 In the implementation scheme, the UDM+HSS in the message notifying the MME of the APN information update sends a cause value indicating that the S-NSSAI information has changed but the APN information has not changed. The MME can determine to release the PDN session based on the cause value and S-NSSAI information received from the UDM+HSS. The SMF+PGW-C can determine whether there are any other alternative S-NSSAI that can enable the UE to access the APN. When there is no alternative S-NSSAI, the SMF+PGW-C can release the session to indicate the reason for the session release to the UE.

[0296] Specifically, in step 1501, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting a subscription S-NSSAI for a UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the UDM+HSS that has sent the Nudr_DM_subscribe message.

[0297] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 1502, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message to the UDM+HSS in step 1503. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0298] In step 1504, upon receiving the Nudr_DM_notify message, the UDM+HSS may identify the associated APN and SMF+PGW-C based on the result of the change. In step 1505, the UDM+HSS sends a message including subscription data to the MME, the subscription data including at least one of the APN information determined in step 1504, the updated S-NSSAI, or the cause information. In step 1506, the MME sends a response message to the UDM+HSS to confirm that the subscription data has been received / reflected.

[0299] Subsequently, in step 1507, the MME identifies the subscription data including the cause information, recognizes that all PDN sessions for the APN should be temporarily released, and thus triggers the PDN session release. In step 1508, the MME may send a message including at least one of the APN information or the cause information (cause value) to the SMF+PGW-C, the cause information indicating that the session release is due to a change in the subscription S-NSSAI rather than a change in the APN.

[0300] The subsequent steps 1509 to 1515 are Figure 3 Steps 306 to 312 in the embodiment are performed in the same manner, so a detailed description thereof is avoided herein.

[0301] Fig.16 is a diagram showing a signal flow of a session modification method based on APN information and S-NSSAI update information according to an embodiment of the present disclosure.

[0302] exist Fig.16 In the implementation manner, the list of S-NSSAIs that can be used to access the corresponding APN and the cause information (cause value) can be in Fig.12 In the implementation scheme, the UDM+HSS in the message notifying the MME of the APN information update sends a cause value indicating that the S-NSSAI information has changed but the APN information has not changed. The MME can determine to release the PDN session based on the cause value and S-NSSAI information received from the UDM+HSS. The SMF+PGW-C can determine whether there are any other alternative S-NSSAI that can enable the UE to access the APN. When any alternative S-NSSAI exists, the SMF+PGW-C can modify the session to indicate the reason for the session modification and the changed S-NSSAI to the UE.

[0303] Specifically, in step 1601, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting a subscription S-NSSAI for a UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the UDM+HSS that has sent the Nudr_DM_subscribe message.

[0304] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 1602, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message in step 1603. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0305] In step 1604, upon receiving the Nudr_DM_notify message, the UDM+HSS may identify the associated APN and SMF+PGW-C based on the result of the change. In step 1605, the UDM+HSS sends a message including subscription data to the MME, the subscription data including at least one of the APN information determined in step 1604, the updated S-NSSAI, or the cause information. In step 1606, the MME sends a response message to the UDM+HSS to confirm that the subscription data has been received / reflected.

[0306] Subsequently, in step 1607, the MME identifies the subscription data including the cause information, recognizes that all PDN sessions for the APN should be temporarily released, and thus triggers the PDN session release. In step 1608, the MME may send a message including at least one of the APN information or the cause information (cause value) to the SMF+PGW-C, the cause information indicating that the session release is due to a change in the subscription S-NSSAI rather than a change in the APN.

[0307] The subsequent steps 1609 to 1615 are Figure 4 Steps 406 to 412 in the embodiment are performed in the same manner, so a detailed description thereof is avoided herein.

[0308] Fig.17A and Fig. 17B is a diagram showing a signal flow of a method for establishing a 5GS PDU session by using APN information and S-NSSAI update information according to an embodiment of the present disclosure (when an N26 interface exists).

[0309] exist Fig.17A and Fig. 17B In the implementation manner, the list of S-NSSAIs that can be used to access the corresponding APN and the cause information (cause value) can be in Fig.13A and Fig. 13BIn the implementation scheme, the UDM+HSS in the message notifying the MME of the APN information update sends a cause value indicating that the S-NSSAI information has changed but the APN information has not changed. The MME can determine to release the PDN session based on the cause value and S-NSSAI information received from the UDM+HSS. The SMF+PGW-C can determine whether there are any other alternative S-NSSAIs that can enable the UE to access the APN, and then modify or release the associated session when the UE moves to the 5GS.

[0310] Specifically, in step 1701, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting a subscription S-NSSAI for a UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the UDM+HSS that has sent the Nudr_DM_subscribe message.

[0311] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 1702, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message in step 1703. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0312] In step 1704, upon receiving the Nudr_DM_notify message, the UDM+HSS may identify the associated APN and SMF+PGW-C based on the result of the change. In step 1705, the UDM+HSS sends a message including subscription data to the MME, the subscription data including at least one of the APN information determined in step 1704, the updated S-NSSAI, or the cause information. In step 1706, the MME sends a response message to the UDM+HSS to confirm that the subscription data has been received / reflected.

[0313] Subsequently, in step 1707, the MME identifies the subscription data including the cause information, recognizes that all PDN sessions for the APN should be temporarily released, and thus triggers the PDN session release. In step 1708, the MME may send a message including at least one of the APN information or the cause information (cause value) to the SMF+PGW-C, the cause information indicating that the session release is due to a change in the subscription S-NSSAI rather than a change in the APN.

[0314] In step 1709, upon receiving the message from the MME in step 1708, the SMF+PGW-C may Figure 3 The method of step 306 in the embodiment of the present invention or Figure 4 The method of step 406 in the implementation manner determines whether to release or modify the PDN session.

[0315] The subsequent steps 1710 to 1718 are Figure 5 Steps 507 to 515 in the embodiment are performed in the same manner, so a detailed description thereof is avoided herein.

[0316] Fig.18A and Fig.18B is a diagram showing a signal flow of a method for establishing a 5GS PDU session by using APN information and S-NSSAI update information according to an embodiment of the present disclosure (when the N26 interface does not exist).

[0317] exist Fig.18A and Fig.18B In the implementation manner, the list of S-NSSAIs that can be used to access the corresponding APN and the cause information (cause value) can be in Fig.14A and Fig. 14B In the implementation scheme, the UDM+HSS in the message notifying the MME of the APN information update sends a cause value indicating that the S-NSSAI information has changed but the APN information has not changed. The MME can determine to release the PDN session based on the cause value and S-NSSAI information received from the UDM+HSS. The SMF+PGW-C can determine whether there are any other alternative S-NSSAIs that can enable the UE to access the APN, and then modify or release the associated session when the UE moves to the 5GS.

[0318] Specifically, in step 1801, the UDM+HSS sends a Nudr_DM_subscribe message to the UDR. The Nudr_DM_subscribe message is a message for subscribing to information about changes in subscription data. The Nudr_DM_subscribe message may include information indicating the following operations: when an event of changing or deleting a subscription S-NSSAI for a UE occurs, information about the changed or deleted subscription S-NSSAI is sent to the UDM+HSS that has sent the Nudr_DM_subscribe message.

[0319] When the UDR having received the Nudr_DM_subscribe message detects that the subscription data of the S-NSSAI has changed in step 1802, the UDR notifies the UDM+HSS of the result of the subscription S-NSSAI change by sending a Nudr_DM_notify message in step 1803. The result of the change may include at least one of the following: an updated S-NSSAI for the UE, information about the APN associated with the updated S-NSSAI (i.e., information about the APN connected to the updated subscription S-NSSAI), or reason information about the subscription data change (e.g., a reason value).

[0320] In step 1804, upon receiving the Nudr_DM_notify message, the UDM+HSS may identify the associated APN and SMF+PGW-C based on the result of the change. In step 1805, the UDM+HSS sends a message including subscription data to the MME, the subscription data including at least one of the APN information determined in step 1804, the updated S-NSSAI, or the cause information. In step 1806, the MME sends a response message to the UDM+HSS to confirm that the subscription data has been received / reflected.

[0321] Subsequently, in step 1807, the MME identifies the subscription data including the cause information, recognizes that all PDN sessions for the APN should be temporarily released, and thus triggers the PDN session release. In step 1808, the MME may send a message including at least one of the APN information or the cause information (cause value) to the SMF+PGW-C, the cause information indicating that the session release is due to a change in the subscription S-NSSAI rather than a change in the APN.

[0322] In step 1809, upon receiving the message from the MME in step 1808, the SMF+PGW-C may Figure 3 The method of step 306 in the embodiment of the present invention or Figure 4 The method of step 406 in the implementation manner determines whether to release or modify the PDN session.

[0323] The subsequent steps 1811 to 1817 are Figure 6 Steps 608 to 614 in the embodiment are performed in the same manner, so a detailed description thereof is avoided herein.

[0324] Fig.19 is a diagram showing the association between APN and S-NSSAI according to an embodiment of the present disclosure.

[0325] refer to Fig.19 , Fig.19 (a) shows an example in which S-NSSAI#A 1905, which is the S-NSSAI of UE 1901 and can be used to access APN#1 1903, has been deleted from the subscribed S-NSSAI list. In this case, SMF+PGW-C may determine whether another alternative S-NSSAI is available for accessing APN#1 1903. When there is no alternative S-NSSAI, SMF+PGW-C may release the PDN session to indicate the reason for the session release to the UE.

[0326] Fig.19 (b) shows an example in which S-NSSAI#A 1905 among S-NSSAI#A 1905 and S-NSSAI#B 1907 that can be used to access APN#1 1903 has been deleted from the subscribed S-NSSAI list. In this case, the SMF+PGW-C may identify S-NSSAI#B 1907 as another alternative S-NSSAI that can be used to access APN#1 1903. The SMF+PGW-C may then modify the PDN session to indicate the reason for the session modification to the UE.

[0327] The above-mentioned embodiments may be implemented in combination with each other. For example, the whole or part of a specific embodiment may be implemented in combination with the whole or part of another embodiment. Obviously, the combination also falls within the scope of the present disclosure.

[0328] Fig. 20 is a block diagram showing the structure of a UE related to an embodiment of the present disclosure.

[0329] refer to Fig. 20 , the UE may include a transceiver 2001 and a processor 2003. In the present disclosure, the processor 2003 may be configured as a circuit or an application specific integrated circuit, or at least one processor.

[0330] The transceiver 2001 may send signals to the BS, another UE, and a network entity, and may receive signals from the BS, another UE, and a network entity. For example, the transceiver 2001 may receive system information from the BS, or may send data to the BS or receive data from the BS based on a synchronization signal, a reference signal, and / or control information.

[0331] Processor 2003 can be based on Figure 1 to Figure 2 6 to control the overall operation of the UE. For example, the processor 2003 may control the signal flow between the blocks to perform operations according to the above figures and flowcharts. Specifically, the processor 2003 may exchange messages or signals with the BS, another UE, and / or a network entity, and operate according to a control signal received from the BS.

[0332] In addition, the UE may include a memory that may store at least one of information transmitted and received by the transceiver 2001 or information generated by the processor 2003 .

[0333] Fig.21 is a diagram showing the structure of a NF according to an embodiment of the present disclosure. Fig.21 An NF may include NF instances.

[0334] Fig.21 The NF shown may refer to an entity that supports the various network functions described above. The NF may be, for example, MME, AMF, SMF, interworking NF, UDM, UDR, PCF, or any of the above references. Figure 2 At least one of the combined nodes described above is not limited to any specific NF. In addition, the NF may be provided in the form of an instance. When the NF is provided as an instance, the NF exists in the form of software code. Since the NF instance refers to a state in which physical and / or logical resources are allocated from a physical computing system (e.g., a specific computing system existing on a core network) to perform the functions of the NF, the functions of the NF are executable, and thus Fig.21 The structure can be divided physically or logically.

[0335] refer to Fig.21 , the NF may include a transceiver 2101 and a processor 2103.

[0336] The transceiver 2101 may send / receive signals to / from another network entity (NF). The transceiver 2101 may, for example, exchange signaling for sending control information and data to / from another network (NF) or BS.

[0337] Processor 2103 may be configured to Figure 1 to Figure 26 to control the overall operation of the NF. For example, the processor 2103 may control the signal flow between the blocks to perform operations according to the above-mentioned figures and flowcharts. Specifically, the processor 2103 may exchange messages or signals with the UE, the BS, and / or another network entity, and operate according to the signaling received from the network entity or the BS.

[0338] The NF may further include a memory that may store at least one of information transmitted and received by the transceiver 2101 or information generated by the processor 2103 .

[0339] Fig. 22 is a diagram showing a structure of a BS according to an embodiment of the present disclosure.

[0340] refer to Fig. 22 , the BS may include a transceiver 2201, a processor 2205, and a backhaul communication unit 2203. In the present disclosure, the processor 2205 may be configured as a circuit or an application specific integrated circuit or at least one processor.

[0341] The transceiver 2201 may send a signal to or receive a signal from the UE. The transceiver 2201 may send, for example, system information, a synchronization signal or a reference signal, or control information and data to the UE. The backhaul communication unit 2203 provides a wired or wireless interface for communicating with other nodes (NFs) in the network.

[0342] The processor 2205 may be configured according to Figures 1 to 2 6 to control the overall operation of the BS. For example, the processor 2205 can control the signal flow between the blocks to perform operations according to the above figures and flowcharts. Specifically, the BS controller can exchange messages or signals with the UE and / or network entity.

[0343] The BS may further include a memory storing at least one of information transmitted and received through the transceiver 2201 and the backhaul communication unit 2203 or information generated by the processor 2205 .

[0344] It is obvious from the above description that according to the apparatus and method of each embodiment of the present disclosure, a method for intercommunication between a 5G network system structure providing a network slicing function and an EPS network system is provided. Therefore, services can be effectively provided in a mobile communication system.

[0345] The embodiments of the present disclosure described with reference to the accompanying drawings are provided to easily describe the present disclosure and help understand the specific examples of the present disclosure, but are not intended to limit the scope of the present disclosure. Therefore, all modifications or changes obtained from the present disclosure and the embodiments disclosed herein should be interpreted as falling within the scope of the present disclosure.

[0346] Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

Claims

1. A method performed by SMF+PGW-C in a wireless communication system supporting intercommunication between a fifth generation system 5GS and an evolved packet system EPS, wherein the SMF+PGW-C is a combined node of a session management function SMF in the 5GS and a packet data network gateway control PGW-C in the EPS, wherein the method include: receiving subscription update information of a user equipment UE from a user data manager UDM managing subscription information, a packet data network PDN connection associated with a network slice subscribed in the 5GS is established for the UE in the EPS; In response to the subscription update information including information notifying that subscription single network slice selection assistance information S-NSSAI associated with the PDN connection of the UE is changed, identifying a cause associated with the release of the PDN connection; as well as sending, to the UE, information indicating the cause associated with the release of the PDN connection associated with the network slice, The information indicating the reason includes information indicating removal of subscription to the S-NSSAI subscription of the UE.

2. An SMF+PGW-C in a wireless communication system supporting intercommunication between a fifth generation system 5GS and an evolved packet system EPS, wherein the SMF+PGW-C is a combined node of a session management function SMF in the 5GS and a packet data network gateway control PGW-C in the EPS, wherein the SMF+PGW-C include: Transceiver; as well as A processor configured to: Receiving, via the transceiver, subscription update information of a user equipment UE from a user data manager UDM managing subscription information, a packet data network PDN connection associated with a network slice subscribed in the 5GS is established for the UE in the EPS; In response to the subscription update information including information notifying that subscription single network slice selection assistance information S-NSSAI associated with the PDN connection of the UE is changed, identifying a cause associated with the release of the PDN connection; as well as sending, to the UE, information indicating the cause associated with the release of the PDN connection associated with the network slice, The information indicating the reason includes information indicating removal of subscription to the S-NSSAI subscription of the UE.

3. The SMF+PGW-C according to claim 2, in, The processor is further configured to: identifying whether there is an available alternative S-NSSAI associated with the PDN connection of the UE, and In the presence of the available alternative S-NSSAI, accessing an access point name APN for the PDN connection using the available alternative S-NSSAI, wherein the available alternative S-NSSAI enables the UE to access the APN.

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