Method and apparatus for supporting inter-system mobility in wireless communication system

Abstract

A method for supporting inter-system mobility of a first entity includes: receiving a create session request message, which includes information about an access point name (APN) for which a user equipment requests a packet data network (PDN) connection, user identification information of the user equipment, and a field indicating capability information of the user equipment regarding slice identification information; based on the create session request message, determining whether the PDN connection needs to be moved to a 5G system (5GS); based on the determination result, sending a user information request including user identification information and APN information to a second entity; receiving a response to the user information request from the second entity, which includes identification information of one or more subscribed network slices corresponding to the user identification information; and providing at least one identification information of the one or more subscribed network slices to the user equipment.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for providing services in a wireless communication system, and more particularly, to a method and apparatus for providing inter-system mobility support in a wireless communication system. Background Art

[0002] Since the commercialization of the 4th generation (4G) communication system, efforts have been underway to develop advanced 5th generation (5G) or pre-5G communication systems to meet the growing demand for wireless data services. For this reason, 5G or pre-5G communication systems are also referred to as network communication systems beyond 4G or post-Long Term Evolution (LTE) systems.

[0003] Consideration is currently being given to implementing 5G communication systems using ultra-high frequency (millimeter wave (mmWave)) frequency bands (e.g., the 60 gigahertz (GHz) band) to achieve even higher data transmission rates. To reduce radio wave propagation losses and increase the transmission range of radio waves in these ultra-high frequency bands, beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technologies are being discussed.

[0004] In addition, in order to improve the system network, in the 5G communication system, various technologies are being developed, 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 receiver-side interference cancellation.

[0005] In addition, for 5G systems, evolved coding and modulation (ACM) technologies (such as hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) (FQAM) and sliding window superposition coding (SWSC)) and advanced access technologies (such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse coded multiple access (SCMA)) have been developed.

[0006] With the development of various information technologies (IT), network devices have evolved into virtualized network functions (NFs) thanks to the application of virtualization technology. Virtualized NFs are freed from physical constraints and implemented in software. They can be installed and run in various types of clouds or data centers (DCs). Specifically, NFs can be freely scaled up or down, installed (started), or terminated based on service requirements, system capacity, and network load.

[0007] To support various services across these diverse network structures, network slicing has been introduced. Network slicing is a technology that logically configures a network using a set of network elements (NFs) to support specific services and separates them from other slices. A user device can access two or more slices when receiving various services. Summary of the Invention

[0008] Technical issues

[0009] The present disclosure provides an apparatus and method for efficiently providing services in a wireless communication system.

[0010] Solution to the problem

[0011] An object of the present disclosure is to provide an efficient wireless communication system.

[0012] Beneficial effects

[0013] The present disclosure provides an apparatus and method for efficiently providing services in a wireless communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A wireless communication system according to an embodiment of the present disclosure is shown.

[0015] Figure 2 The interworking structure between 5GS and EPS in a non-roaming situation according to an embodiment of the present disclosure is shown.

[0016] Figure 3 A method for sending NW slice information in a 5G-4G intercommunication environment according to an embodiment of the present disclosure is shown.

[0017] Figure 4 A method for sending NW slice information in a 5G-4G intercommunication environment according to an embodiment of the present disclosure is shown.

[0018] Figure 5 The present invention illustrates a method for sending NW slice information in a 5G-4G intercommunication environment according to an embodiment of the present disclosure.

[0019] Figure 6 is a flowchart of a communication method performed by a user equipment according to an embodiment.

[0020] Figure 7 4 is a flow chart of a communication method of a packet data network (PDN) gateway (PGW) according to an embodiment of the present disclosure.

[0021] Figure 8 is a block diagram illustrating a structure of a user equipment according to an embodiment of the present disclosure.

[0022] Figure 9is a block diagram illustrating the structure of a NF according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] Best Practice

[0024] According to an embodiment of the present disclosure, a method for supporting inter-system mobility of a first entity includes: receiving a create session request message, which includes information about an access point name (APN) for which a user equipment requests a packet data network (PDN) connection, user identification information of the user equipment, and a field indicating capability information of the user equipment regarding slice identification information; based on the create session request message, determining whether the PDN connection needs to be moved to a 5G system (5GS); based on the determination result, sending a user information request including user identification information and APN information to a second entity; receiving a response to the user information request from the second entity, which includes identification information of one or more subscribed network slices corresponding to the user identification information; and providing at least one identification information of the one or more subscribed network slices to the user equipment.

[0025] The capability information of the user equipment regarding the slice identification information may include information indicating whether the user equipment is capable of receiving two or more network slice identification information, and providing at least one identification information of one or more subscribed network slices to the user equipment may include: based on the field indicating the capability information of the user equipment regarding the slice identification information, providing the user equipment with one identification information or multiple network slice identification information of one or more subscribed network slices.

[0026] At least one identification information of one or more subscribed network slices provided to the user equipment may be included in a specific field of the create session response message.

[0027] The method may also include: sending a message to a third entity requesting selection of a network slice based on identification information of one or more subscribed network slices, and receiving a response message including one or more slice identification information selected by the third entity from among the identification information of one or more subscribed network slices.

[0028] Providing at least one identification information of one or more subscribed network slices to a user device may include: sending at least one of the selected slice identification information to the user device.

[0029] When the response to the user information request includes two or more network slice identification information, the response to the user information request may include information for determining a default network slice, or information about a priority between the two or more network slice identification information.

[0030] When the user equipment moves to 5GS, at least one identification information of one or more subscribed network slices provided to the user equipment may be used.

[0031] The first entity may include a combined node of a PDN Gateway Control (PGW-C) of an Evolved Packet System (EPS) and a Session Management Function (SMF) of 5GS, the second entity may include one of a Unified Data Management (UDM), a Home Subscriber Server (HSS), a Unified Data Repository (UDR), and the third entity may include a Network Slice Selection Function (NSSF).

[0032] According to an embodiment of the present disclosure, a communication method performed by a user equipment receiving network slice identification information includes: sending a packet data network (PDN) connection request message including information about a specific access point name (APN) to a mobility management entity (MME); receiving a response message including at least one network slice information corresponding to the APN as a response to the connection request message; and storing at least one network slice information of the response message, wherein the at least one network slice information is used when the user equipment moves to a 5G system (5GS).

[0033] According to an embodiment of the present disclosure, a first entity supporting inter-system mobility includes: a transceiver; and a processor, which is coupled to the transceiver and is configured to: receive a create session request message, which includes information about an access point name (APN) for which a user equipment requests a packet data network (PDN) connection, user identification information of the user equipment, and a field indicating capability information of the user equipment regarding slice identification information; based on the create session request message, determine whether the PDN connection needs to be moved to a 5G system (5GS); based on the determination result, send a user information request including user identification information and APN information to a second entity; receive a response to the user information request from the second entity, which includes identification information of one or more subscribed network slices corresponding to the user identification information; and provide at least one identification information of the one or more subscribed network slices to the user equipment.

[0034] The capability information of the user equipment regarding the slice identification information may include information indicating whether the user equipment is capable of receiving two or more network slice identification information.

[0035] The processor can also be configured to: provide one or more network slice identification information of one or more subscribed network slices to the user equipment based on the field indicating the capability information of the user equipment regarding the slice identification information.

[0036] At least one identification information of one or more subscribed network slices provided to the user equipment may be included in a specific field of the create session response message.

[0037] The processor can also be configured to: send a message to a third entity requesting selection of a network slice based on identification information of one or more subscribed network slices.

[0038] The processor can also be configured to: receive a response message including one or more slice identification information selected by a third entity from identification information of one or more subscribed network slices, and send at least one of the selected slice identification information to the user equipment.

[0039] When the response to the user information request includes two or more network slice identification information, the response to the user information request may include information for determining a default network slice, or information about a priority between the two or more network slice identification information.

[0040] The first entity may include a combined node of a PDN Gateway Control (PGW-C) of an Evolved Packet System (EPS) and a Session Management Function (SMF) of 5GS, the second entity may include one of a Unified Data Management (UDM), a Home Subscriber Server (HSS), a Unified Data Repository (UDR), and the third entity may include a Network Slice Selection Function (NSSF).

[0041] According to an embodiment of the present disclosure, a user device configured to receive network slice identification information includes: a transceiver; and a processor, which is coupled to the transceiver and configured to: send a packet data network (PDN) connection request message including information about a specific access point name (APN) to a mobility management entity (MME); receive a response message including at least one network slice information corresponding to the APN as a response to the connection request message; and store the at least one network slice information of the response message.

[0042] At least one network slice information is used when the user equipment moves to a 5G system (5GS).

[0043] Implementation of the present disclosure

[0044] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. While describing the present disclosure, detailed descriptions of related well-known functions or configurations that may confuse the main points of the present disclosure are omitted. The terms used herein are defined in consideration of the functions of the present disclosure, but these terms may vary according to the intentions of the user or operator, precedents, etc. Therefore, the terms used in this specification should be understood based on the overall description of the present disclosure.

[0045] The advantages and features of the present disclosure and the methods for achieving these advantages and features will become apparent by reference to the embodiments of the present disclosure described in detail below and the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments of the present disclosure set forth herein; rather, these embodiments of the present disclosure are provided to make the disclosure thorough and complete and to fully convey the scope of the disclosure to those skilled in the art, and the scope of the disclosure is defined solely by the appended claims. In this specification, like reference numerals represent like elements.

[0046] It is understood that the combination of the blocks in the flowchart or the flowchart can be performed by computer program instructions. Because these computer program instructions can be loaded into a processor of a general-purpose computer, a special-purpose computer or other programmable data processing device, the instructions executed by the processor of the computer or other programmable data processing device generate a device (means) that realizes the function specified in the flowchart frame. These computer program instructions can also be stored in a computer-executable or computer-readable memory, which can guide the computer or other programmable data processing device to operate in a particular manner so that the instructions stored in the computer-executable or computer-readable memory generate an article of manufacture of an instruction device comprising the function specified in the flowchart frame. The computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable data processing device to generate a computer-executable process so that the instructions executed on the computer or other programmable data processing device provide the steps for realizing the function specified in the flowchart frame.

[0047] In addition, each block of the flowchart illustration may identify a module, segment, or portion of code that includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may not appear in the order shown. For example, two consecutive blocks may be executed simultaneously, or in reverse order, depending on the functions they correspond to.

[0048] As used herein, the term "unit" refers to a software element or a hardware element, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), that performs a specific function. However, "unit" is not limited to software or hardware. The term "unit" can be configured in an addressable storage medium or configured to operate one or more processors. Therefore, the term "unit" or "machine" can include, for example, object-oriented software components, class components, and task components, as well as processes, functions, properties, procedures, subroutines, fragments of program code, drivers, firmware, microcode, 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 to operate one or more central processing units (CPUs) in a device or secure multimedia card. In addition, "units" can include at least one processor.

[0049] The terms used in this disclosure are only used to describe specific embodiments and may not be intended to limit the scope of other embodiments. The expression used in the singular may include the expression in the plural form, unless it has a significantly different meaning in the context. The terms used herein (including technical or scientific terms) may have the same meaning as those generally understood by those of ordinary skill in the art described by the disclosure. Among the terms used in the disclosure, the terms defined in the commonly used dictionaries may be interpreted as being identical or similar to the meaning in the context of the relevant technology, and unless clearly defined in the disclosure, the terms are not ideally or excessively interpreted as having a formal meaning. Depending on the circumstances, the unchanged terms defined in the disclosure should not be interpreted as excluding embodiments of the disclosure.

[0050] In various embodiments of the present disclosure described below, a hardware-based method is described as an example. However, since various embodiments of the present disclosure include techniques using both hardware and software, various embodiments of the present disclosure do not exclude a software-based method.

[0051] The present disclosure relates to a method and apparatus for supporting various services in a wireless communication system. Specifically, the present disclosure describes a technology for supporting various services by supporting user equipment mobility in a wireless communication system.

[0052] In the following, for the convenience of description, the terms indicating connection nodes, network entities or network functions (NFs), messages, interfaces between network entities, and various identification information used herein are exemplified. Therefore, the present disclosure is not limited to the terms to be described below, but other terms indicating objects with equivalent technical meanings may be used. For example, the function of the network slice selection function (NSSF) as the NF in the embodiment of the present disclosure may be performed by the network repository function (NRF) as another NF.

[0053] In the following, for the convenience of description, some terms and names defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard or the 5G standard may be used in the present disclosure. However, the present disclosure is not limited to these terms and names and may be equally applicable to wireless communication systems that comply with other standards. Specifically, the present disclosure may be applicable to 3GPP New Radio (NR, the 5th generation mobile communication standard). In the present disclosure, for the convenience of description, eNB may be used interchangeably with gNB. That is, a base station described as an eNB may refer to a gNB. Alternatively, a base station described as a gNB may refer to an eNB. Alternatively, a node described as a base station may refer to an eNB or a gNB. In addition, the term "user equipment" may refer to other wireless communication devices, as well as mobile phones, NB-IoT devices, and sensors.

[0054] Hereinafter, a base station is an entity that allocates resources to a user equipment and may be at least one of a gNode B, an eNode B, a base station (BS), a wireless access unit, a base station controller, or a node on a network. Examples of user equipment may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. However, the present disclosure is not limited to the above examples.

[0055] Figure 1 A wireless communication system according to an embodiment of the present disclosure is shown.

[0056] refer to Figure 1 In a wireless communication system, as some nodes using a wireless channel, a base station (radio access node (RAN)) 110 and a user equipment (UE) 120 are shown as examples. Figure 1 In FIG, a base station 110 and a user equipment 120 are shown. However, other base stations that are the same as or similar to the base station 110 may also be included. Figure 1 Only a case where only one user equipment 120 communicates within one base station 110 is shown. However, it can be seen that in reality, multiple user equipments may communicate within one base station 110.

[0057] According to an embodiment of the present disclosure, base station 110 may be a network infrastructure that provides radio access for user equipment 120. The coverage of base station 110 is defined as a specific geographical area based on the range of transmitted signals. In addition to being called a base station, base station 110 may also be called an access point (AP), an evolved Node B (eNB), a 5G node, a wireless point, a transmission / reception point (TRP), or another term with equivalent technical meaning. However, the present disclosure is not limited to the above examples.

[0058] According to an embodiment of the present disclosure, user equipment 120 is a device used by a user and can communicate with base station 110 via a wireless channel. In some cases, user equipment 120 can operate without user participation. For example, user equipment 120 is a device that performs machine type communication (MTC) and may not be carried by the user. Figure 1 The illustrated user equipment 120 may include at least one portable user equipment and may include at least one MTC device. Figure 1 The user equipment 120 may be referred to as terms such as “terminal”, “mobile station”, “subscriber station”, “remote terminal”, “wireless terminal” or “user device” or other terms having equivalent technical meanings.

[0059] According to an embodiment of the present disclosure, the AMF 131 may be a network entity that manages wireless network access and mobility of the user equipment 120. The SMF 132 may be a network entity that manages a connection to a packet data network for providing packet data to the user equipment 120. The connection between the user equipment 120 and the SMF 132 may be a packet data unit (PDU) session.

[0060] According to an embodiment of the present disclosure, the user plane function (hereinafter referred to as UPF) 133 may be a gateway that transmits packets transmitted and received by the user equipment 120 or a network entity that serves as a gateway. The UPF 133 may be connected to a data network (DN) 140 connected via the Internet to provide a path for data transmission / reception between the user equipment 120 and the DN 140. Therefore, the UPF 133 may route data to be transmitted via the Internet among packets transmitted by the user equipment 120 to the Internet data network.

[0061] According to an embodiment of the present disclosure, the network slice selection function (NSSF) 134 may be a network entity that performs the network selection operation described in the present disclosure (e.g., an operation for selecting a network slice). The operation of the NSSF entity 134 will be described in detail with reference to the drawings to be described later.

[0062] According to an embodiment of the present disclosure, the authentication server function (AUSF) entity 151 may be a network entity that provides a service for user authentication processing.

[0063] According to an embodiment of the present disclosure, the network exposure function (NEF) 152 may be a network entity capable of accessing information for managing the user equipment 120 in the 5G network, and may subscribe to mobility management events of the corresponding user equipment, subscribe to session management events of the corresponding user equipment, make requests for session-related information, set billing information of the corresponding user equipment, make requests to change the PDU session policy of the corresponding user equipment, and send small data about the corresponding user equipment.

[0064] According to an embodiment of the present disclosure, the Network Repository Function (NRF) 153 may be an NF that stores state information of an NF (network entity) and has a function of processing a request for finding an NF accessible to other NFs.

[0065] According to an embodiment of the present disclosure, the policy and charging function (PCF) 154 may be a network entity that applies a mobile communication operator's service policy, charging policy, and PDU session policy to the user equipment 120 .

[0066] According to an embodiment of the present disclosure, the unified data management (UDM) 155 may be a network entity that stores information about users and / or user devices 120 .

[0067] According to an embodiment of the present disclosure, the application function (AF) 156 may be an NF (network entity) having a function of providing services to users by interworking with a mobile communication network.

[0068] According to an embodiment of the present disclosure, the service communication proxy (SCP) 157 may be a network entity (NF) that provides functions such as NF discovery for communication between NFs and message transmission between NFs. The SCP 157 may be operated in an integrated form with the NRF 153 according to the operator's choice; in this case, the SCP 157 may include the functions of the network repository function (NRF) 153, or conversely, the NRF 153 may include the functions of the SCP 157.

[0069] In the following, for the convenience of description, objects used to exchange information for access control and state management will be collectively referred to as NFs. NFs may be, for example, at least one of an access and mobility management function (hereinafter referred to as AMF) entity, a session management function (hereinafter referred to as SMF) entity, or a network slice selection function (NSSF) entity. However, even when NFs are actually implemented as one instance (each as an AMF instance, an SMF instance, an NSSF instance, etc.), the embodiments of the present disclosure may be equally applicable. In addition, according to the embodiments of the present disclosure, NFs may be referred to as entities.

[0070] In the present disclosure, NFs can be merged with each other, or one NF can include the functionality of another NF. For example, an NRF can include the functionality of an NSSF. In addition, when describing the embodiments of the present disclosure, specific operations are described with reference to one NF, but the key points of the present disclosure can also be applied to enable another NF to include the functionality and operate.

[0071] In the present disclosure, an instance may refer to a specific NF implemented in the form of software code. An instance may perform the functions of a given NF by being allocated physical and / or logical resources from a computing system to perform the functions of the NF in a physical computing system (e.g., a specific computing system present on a core network). Therefore, an AMF instance, an SMF instance, or an NSSF instance may each be allocated physical and / or logical resources for AMF, SMF, and NSSF operations from a specific computing system present on a core network, and use these resources. As a result, a physical AMF, SMF, or NSSF entity and an AMF instance, SMF instance, or NSSF instance, each allocated physical and / or logical resources for AMF, SMF, and NSSF operations from a specific computing system present on a core network, may perform the same operations.

[0072] As a result, physical AMF, SMF or NSSF entities and AMF instances, SMF instances or NSSF instances that are respectively allocated physical and / or logical resources for AMF, SMF and NSSF operations from a specific computing system present on the core network can perform the same operations. Therefore, in the embodiments of the present disclosure, the details described for NF (AMF, SMF, UPF, NSSF, NRF, SCP, etc.) can be replaced with details for NF instance, or conversely, the details described for NF instance can be replaced with details for NF and applied. Similarly, in the embodiments of the present disclosure, the details described for network slice (NW slice) can be replaced with details for NW slice instance, or conversely, the details described for NW slice instance can be replaced with details for NW slice and applied. In addition, in the embodiments of the present disclosure, subscriber and user equipment can be used interchangeably because they have the same meaning.

[0073] Figure 2 The interworking structure between the 5G system (5GS) and the evolved packet system (EPS) in a non-roaming situation according to an embodiment of the present disclosure is shown.

[0074] 5GS may consist of New Radio (NR) base stations 150, AMF 145, SMF 120, UPF 125, PCF 115, and UDM 110. EPS may consist of E-UTRA base stations 140, MME 135, SGW 130, PGW-U 125, PGW-C 120, PCRF 115, and HSS 110. EPS may also consist of Figure 2 The entities shown may be composed of fewer or more entities.

[0075] According to an embodiment of the present disclosure, the UDM 110 of the 5GS and the HSS 110 of the EPS can be configured as a single combined node. The SMF 120 of the 5GS and the PGW-C 120 of the EPS can also be configured as a single combined node. Furthermore, according to an embodiment of the present disclosure, the UDM+HSS 110 node can store user information of user devices. The UPF 125 of the 5GS and the PGW-U 125 of the EPS can also be configured as a single combined node. User devices 155 can access the MME 135 of the EPS via the E-UTRA base station 140 and use EPS network services. However, the present disclosure is not limited to the above example.

[0076] In addition, the user equipment 155 can use the 5GS network services by accessing the 5GS AMF 145 through the NR base station 150. Figure 2 An interworking structure for a non-roaming case is shown, but other embodiments of the present disclosure are applicable not only to the non-roaming case but also to the roaming case (local disconnect or home routing).

[0077] When a 5G-capable user device can selectively access 5GS and EPS, depending on the network situation, the user device may first access 5GS and then move to EPS (5GS to EPS interworking), or conversely, may first access EPS and then move to 5GS (EPS to 5GS interworking). When the user device first accesses EPS and then moves to 5GS, the PDN connection established in EPS may be converted to a PDU session of 5GS, and the user device needs to input information about the network (NW) slice (NW slice identifier) ​​when requesting to create a PDU session of 5GS. Since the network cannot be configured or selected with the NW slice in EPS, a method of sending an NW slice identifier that can be used in 5GS in advance during access to EPS may be required to support this mobility of the user device to 5GS.

[0078] Depending on the configuration of the 5GS network, two or more Data Network Names (DNNs) (equivalent to or similar to the concept of Access Point Names (APNs)) may be mapped to one NW slice, or conversely, one DNN may be supported in two or more NW slices. In this case, when the NW slice identifier sent from the EPS to the user equipment does not match the NW slice identifier to be used in the 5GS network, or is configured to be mapped differently to the DNN, when the user equipment moves from the EPS to the 5GS, the transition to the PDU session may fail or service continuity may not be guaranteed. Therefore, a method for solving the above problem may be needed.

[0079] Figure 3 A method for sending NW slice information in a 5G-4G intercommunication environment according to an embodiment of the present disclosure is shown.

[0080] In operation 301, a process for establishing a PDN connection in an EPS (e.g., a 4G network) may be performed based on a user equipment request. Operation 301 may be combined with an Attach request from the user equipment. In operation 301, the user equipment may include the APN in the request message, which the PDN connection will be established with.

[0081] According to an embodiment of the present disclosure, the request sent by the user equipment may include information indicating whether two or more S-NSSAIs can be received through a protocol configuration option (PCO) or an extended PCO (ePCO). This information may be indicated as a capability or a separate indicator of a NAS message sent by the user equipment, or may be included in part of a PCO (protocol option, etc.). The present disclosure is not limited to the above example, and the method of sending information indicating whether two or more S-NSSAIs can be received is not limited.

[0082] According to an embodiment of the present disclosure, a NAS-level PDN connection establishment request message sent by a user equipment is sent to a mobility management entity (MME) through a base station, and the MME can select a serving GW (SGW) or a PDN GW (PGW) for which a PDN connection will be established based on a request from the user equipment or subscription information of the user equipment. The MME can send a request message (Create Session Request) to create a session to the SGW, and the message to create the session can include an identifier (International Mobile Subscriber Identity (IMSI)) of the UE / user that is the target of the PDN connection, an APN, and a PCO. The SGW can send a request message (Create Session Request) to create a session to the PGW-C, and the message to create the session can include an identifier (IMSI) of the UE / user that is the target of the PDN connection, an APN, and a PCO.

[0083] In operation 302, the PDN gateway control plane (PGW-C) can support interworking with 5GS and can include the functions of SMF. PGW (or a combined node of PGW-C and PGW-U) instead of PGW-C can perform the above functions. When the create session request received in operation 301 is targeted at 5GS interworking (this can be determined based on the local settings of PGW-C or information received through MME or SGW), PGW-C can send a request to receive NW slice information of 5GS for the corresponding user (requested APN) to the NF that stores user information. The NF can be one of UDM, HSS or UDR, and the service requested by PGW-C can be a slice selection subscription data retrieval request. The slice selection subscription data retrieval request includes an identifier of the target user (SUPI, the user ID received in operation 301 can be used), and the APN for the current session can be sent here in addition.

[0084] In operation 303, the NF storing the user information may send slice information about the user in response to the request from the PGW-C. The NF may be one of the UDM, HSS, or UDR, and the response service may be a slice selection subscription data retrieval response. The response message may include the user's subscribed NSSAI (one or more subscribed S-NSSAIs).

[0085] In operation 304, the PGW-C may select an identifier of the NW slice (i.e., S-NSSAI) to be notified to the user equipment by using the NSSAI received in the response message. When the NSSAI in the response message includes only one S-NSSAI, the S-NSSAI may be notified to the user equipment. When the NSSAI in the response message includes two or more S-NSSAIs, all of the S-NSSAIs may be notified to the user equipment.

[0086] When the PGW-C supports only some of the S-NSSAIs included in the NSSAI of the response message, only those S-NSSAIs supported by the PGW-C can be notified to the user equipment. When only some of the S-NSSAIs included in the NSSAI of the response message can be interoperable with the current target APN, only those S-NSSAIs mapped to the APN can be notified to the user equipment. The S-NSSAI notified to the user equipment can use a protocol configuration option (PCO) or an ePCO. That is, the PGW-C can create a PCO including at least one S-NSSAI to be notified to the user equipment. When two or more S-NSSAIs can be notified to the user equipment, but two or more S-NSSAIs cannot be received, considering the information received in operation 301 about whether the corresponding function is supported by the user equipment, only one S-NSSAI can be selected and sent.

[0087] In operation 305 , the PCO may be included in a create session response message in response to the SGW or the MME and transmitted.

[0088] In operation 306, the MME may include the PCO including the slice information (one or more S-NSSAIs) received from the PGW-C or SGW in the NAS response message sent to the user equipment.

[0089] In operation 307, the user equipment stores the NSSAI received from the MME as information (context) of the corresponding PDN connection. When moving to 5GS or when it is necessary to move the corresponding PDN connection to 5GS, the user equipment may use the stored NSSAI when determining the requested NSSAI during the registration process.

[0090] According to an embodiment of the present disclosure, the NSSAI included in the registration request message sent after the user equipment moves to 5GS can be a union of the NSSAIs received for all created PDN connections. When two or more S-NSSAIs are stored for the corresponding PDN connection, the user equipment can apply a method for selecting the S-NSSAI when creating a PDU session in 5GS, and include the stored S-NSSAI in the PDU session request message to be sent to 5GS, and send the PDU session request message. In addition, according to an embodiment of the present disclosure, among the allowed NSSAIs included in the registration accept message received from the AMF when moving to 5GS, only those S-NSSAIs that overlap with the S-NSSAI stored for the corresponding PDN connection can be included in the PDU session request message and sent.

[0091] Figure 4 A method for sending NW slice information in a 5G-4G intercommunication environment according to an embodiment of the present disclosure is shown.

[0092] In operation 401, a process for establishing a PDN connection in an EPS (e.g., a 4G network) may be performed based on a request from a user equipment. Operation 401 may be combined with an Attach request from the user equipment. In operation 401, the user equipment may include the APN in the request message, which the PDN connection will be established with.

[0093] According to an embodiment of the present disclosure, the request sent by the user equipment may include information indicating whether two or more S-NSSAIs can be received through a protocol configuration option (PCO) or an ePCO. This information may be indicated as a capability or a separate indicator in a NAS message sent by the user equipment, or may be included in part of a PCO (protocol option, etc.). The present disclosure is not limited to the above example, and the method of transmitting the information indicating whether two or more S-NSSAIs can be received is not limited.

[0094] According to an embodiment of the present disclosure, a NAS-level PDN connection establishment request message sent by a user equipment is sent to the MME via the base station, and the MME can select the SGW or PGW to establish the PDN connection based on the request from the user equipment and the subscription information of the user equipment. The MME can send a request message (Create Session Request) to create a session to the SGW, and the message to create the session can include the identifier (IMSI) of the UE / user as the target of the PDN connection, the APN, and the PCO. The SGW can send a request message (Create Session Request) to create a session to the PGW-C, and the message to create the session can include the identifier (IMSI) of the UE / user as the target of the PDN connection, the APN, and the PCO.

[0095] In operation 402, the PGW-C may support interworking with the 5GS and may include the functionality of the SMF. When the session creation request received in operation 401 is the target of 5GS interworking (this may be determined based on the local settings of the PGW-C or information received through the MME or SGW), the PGW-C may send a request to receive NW slice information of the 5GS for the corresponding user (requested APN) to the NF storing the user information. The NF may be one of the UDM, HSS, UDR, and the service requested by the PGW-C may be a slice selection subscription data retrieval request. The slice selection subscription data retrieval request includes an identifier of the target user (SUPI, the user ID received in operation 401 may be used), and the APN for the current session may be sent here in addition.

[0096] In operation 403, the NF storing the user information may send slice information about the user in response to the request from the PGW-C. The NF may be one of the UDM, HSS, and UDR, and the response service may be a slice selection subscription data retrieval response. The response message may include the user's subscribed NSSAI (one or more subscribed S-NSSAIs).

[0097] When the NSSAI of the user's subscription includes two or more S-NSSAIs, the NF may additionally include information for determining the default S-NSSAI of the corresponding user in the response message. When the APN is included in the request received in operation 402, the request may include information that can be used to determine the S-NSSAI to be applied to the corresponding APN by default. Alternatively, the NF may determine the priority between the S-NSSAIs for the user's subscription in the response message, and configure information that allows determination of the priority of each S-NSSAI to be responded to. The priority may explicitly inform the corresponding priority value of the S-NSSAI, or a list including a set order of priorities may be included in the response message. However, the present disclosure is not limited to the above examples.

[0098] In operation 404, the PGW-C may select an identifier (i.e., S-NSSAI) of the NW slice to be notified to the user equipment by using the NSSAI received in the response message. When the NSSAI of the response message includes only one S-NSSAI, it may be notified to the user equipment. When the NSSAI of the response message includes two or more S-NSSAIs and a default S-NSSAI is specified in the response, the PGW-C may give priority to it. When the NSSAI of the response message includes two or more S-NSSAIs and the priority between the S-NSSAIs can be determined based on the response, the PGW-C may give priority to the S-NSSAI with a higher priority. The PGW-C may notify the user equipment of the selected S-NSSAI, and the S-NSSAI notified to the user equipment may use a PCO or an ePCO. That is, the PGW-C may create a PCO including at least one S-NSSAI to be notified to the user equipment. When two or more S-NSSAIs may be notified to the user equipment but two or more S-NSSAIs may not be received, only one S-NSSAI may be selected and transmitted considering the information received in operation 401 regarding whether the corresponding function is supported by the user equipment.

[0099] In operation 405 , the PCO may be included in a create session response message in response to the SGW and the MME and transmitted.

[0100] In operation 406, the MME may include the PCO including the slice information (one or more S-NSSAIs) received from the PGW-C or SGW in the NAS response message sent to the user equipment.

[0101] In operation 407, the user equipment stores the NSSAI received from the MME as information (context) of the corresponding PDN connection. When the user equipment moves to 5GS, or when it is necessary to move the corresponding PDN connection to 5GS, the stored NSSAI can be used to determine the requested NSSAI during the registration process.

[0102] According to an embodiment of the present disclosure, the NSSAI included in the registration request message sent after the user equipment moves to 5GS can be a union of the NSSAIs received for all created PDN connections. When two or more S-NSSAIs are stored for the corresponding PDN connection, the user equipment can apply a method for selecting the S-NSSAI when creating a PDU session in 5GS, and include the stored S-NSSAI in the PDU session request message to be sent to 5GS, and send it. In addition, according to an embodiment of the present disclosure, among the allowed NSSAIs included in the registration accept message received from the AMF when moving to 5GS, only those S-NSSAIs that overlap with the S-NSSAI stored for the corresponding PDN connection can be included in the PDU session request message and sent.

[0103] Figure 5 A method for sending NW slice information in a 5G-4G intercommunication environment according to an embodiment of the present disclosure is shown.

[0104] In operation 501, a process for establishing a PDN connection in an EPS (e.g., a 4G network) may be performed based on a request from a user equipment. Operation 501 may be combined with an Attach request from the user equipment. In operation 501, the user equipment may include the APN in the request message, which the PDN connection will be established using.

[0105] According to an embodiment of the present disclosure, the request sent by the user equipment may include information indicating whether two or more S-NSSAIs can be received through a protocol configuration option (PCO or ePCO). This information may be indicated as a capability or a separate indicator in a NAS message sent by the user equipment, or may be included in part of a PCO (protocol option, etc.). The present disclosure is not limited to the above example, and the method of transmitting the information indicating whether two or more S-NSSAIs can be received is not limited.

[0106] According to an embodiment of the present disclosure, a NAS-level PDN connection establishment request message sent by a user equipment is sent to the MME via the base station, and the MME can select the SGW or PGW to establish the PDN connection based on the request from the user equipment and the subscription information of the user equipment. The MME can send a request message (Create Session Request) to create a session to the SGW, and the message to create the session can include the identifier (IMSI) of the UE / user as the target of the PDN connection, the APN, and the PCO. The SGW can send a request message (Create Session Request) to create a session to the PGW-C, and the message to create the session can include the identifier (IMSI) of the UE / user as the target of the PDN connection, the APN, and the PCO.

[0107] In operation 502, the PGW-C may support interworking with 5GS and may include the functionality of an SMF. When the user equipment includes a PDU session ID in the PCO included in the create session request received in operation 501, the PGW-C may determine that the PDN connection is the target of interworking, and when the create session request received in operation 501 is targeted at 5GS interworking, the PGW-C may send a request to receive NW slice information of the 5GS for the corresponding user (requested APN) to the NF storing the user information. The NF may be one of UDM, HSS, UDR, and the service requested by the PGW-C may be a slice selection subscription data retrieval request. The slice selection subscription data retrieval request includes an identifier of the target user (SUPI, the user ID received in operation 501 may be used), and the APN for the current session may be sent here in addition.

[0108] In operation 503, the NF storing the user information may send slice information about the user in response to the request from the PGW-C. The NF may be one of the UDM, HSS, and UDR, and the response service may be a slice selection subscription data retrieval response. The response message may include the user's subscribed NSSAI (one or more subscribed S-NSSAIs).

[0109] When the NSSAI of the user's subscription includes two or more S-NSSAIs, the NF may additionally include information for determining the default S-NSSAI of the corresponding user in the response message. When the request received in operation 502 includes an APN, the request may include information that can be used to determine the single network slice selection assistance information (S-NSSAI) to be applied as the default relative to the APN. Alternatively, the NF may determine the priority between the S-NSSAIs of the user's subscription in the response message, and configure information that allows determination of the priority of each S-NSSAI to be responded to. The priority may explicitly inform the corresponding priority value of the S-NSSAI, or a list including a set order of priorities may be included in the response message. However, the present disclosure is not limited to the above examples.

[0110] In operation 504, when the subscribed NSSAI received in operation 503 includes two or more S-NSSAIs, or when more accurate slice selection is required, the PGW-C may provide information related to the slice or request a service from the NF providing the slice selection function. That is, the PGW-C may request a service from an NF such as a network slice selection function (NSSF). This example is not limited thereto, and another PGW-C may request a service from an NF other than the NSSF.

[0111] According to an embodiment of the present disclosure, the service request message sent by the PGW-C (SMF) may include an identifier of the user (a user permanent identifier (SUPI) or an IMSI), the subscribed NSSAI received in operation 503, and the APN (DNN) received from the user equipment. In addition, the service request message may include information that explicitly indicates that the slice selection or slice information request is a session establishment procedure considering 5G-4G interworking or slices in EPS.

[0112] In operation 505, after receiving the slice information from PGW-C (SMF), NF can select S-NSSAI taking into account the information included in the request (user identity, subscribed NSSAI, APN, etc.) and the fact that the PDN connection can be moved from the current EPS to 5GS in the future.

[0113] In operation 506, the PGW-C (or SMF or PGW-C, SMF combination node) may receive a response message from the NF. The NF may select only one S-NSSAI, or may select two or more S-NSSAIs. When the NF selects two or more S-NSSAIs, information for determining which S-NSSAI is the default S-NSSAI may be additionally included. Alternatively, when two or more S-NSSAIs are selected, the NF may determine the priority between the S-NSSAIs of the user's subscription in the response message, and configure information that allows determination of the priority of each S-NSSAI to be responded to. The priority may explicitly inform the corresponding priority value of the S-NSSAI, or a list including a set order of priorities may be included in the response message.

[0114] In operation 507, the PGW-C may notify the user equipment of the selected S-NSSAI. When the NSSAI in the response message includes only one S-NSSAI, the user equipment may be notified of the selected S-NSSAI. When the NSSAI in the response message includes two or more S-NSSAIs and a default S-NSSAI is specified in the response, the PGW-C may prioritize the selected S-NSSAI. Alternatively, when the NSSAI in the response message includes two or more S-NSSAIs and the priority between the S-NSSAIs can be determined based on the response, the PGW-C may prioritize the S-NSSAI with a higher priority.

[0115] The PGW-C may notify the user equipment of a selected S-NSSAI, and the S-NSSAI notified to the user equipment may use a PCO or an ePCO. That is, the PGW-C may create a PCO including at least one S-NSSAI to be notified to the user equipment. When two or more S-NSSAIs can be notified to the user equipment, but two or more S-NSSAIs cannot be received, only one S-NSSAI may be selected and sent, taking into account the information received in operation 501 about whether the corresponding function is supported by the user equipment. The PCO may be included in the create session response message in response to the SGW and the MME and sent.

[0116] In operation 508, the MME may include the PCO including the slice information (one or more S-NSSAIs) received from the PGW-C or SGW in the NAS response message sent to the user equipment.

[0117] In operation 509, the user equipment stores the NSSAI received from the MME as information (context) of the corresponding PDN connection. When the user equipment moves to 5GS, or when it is necessary to move the corresponding PDN connection to 5GS, the stored NSSAI can be used to determine the requested NSSAI during the registration process.

[0118] According to an embodiment of the present disclosure, the NSSAI included in the registration request message sent after the user equipment moves to 5GS can be a union of the NSSAIs received for all created PDN connections. When two or more S-NSSAIs are stored for the corresponding PDN connection, the user equipment can apply a method for selecting the S-NSSAI when creating a PDU session in 5GS, and include the stored S-NSSAI in the PDU session request message to be sent to 5GS, and send it. In addition, according to an embodiment of the present disclosure, among the allowed NSSAIs included in the registration accept message received from the AMF when moving to 5GS, only those S-NSSAIs that overlap with the S-NSSAI stored for the corresponding PDN connection can be included in the PDU session request message and sent.

[0119] Figure 6 is a flowchart of a communication method performed by a user equipment according to an embodiment of the present disclosure.

[0120] In operation 601, the user equipment may send a PDN connection request message including information about a specific APN to the MME. The user equipment supports 5G capabilities (N1 capabilities) and, when the corresponding PDN connection requires 5G interworking, the user equipment may generate a PDU session ID and include it in the PCO or ePCO included in the PDN connection request.

[0121] According to the embodiment of the present disclosure, the process of establishing a PDN connection can be performed together with the Attach operation. In addition, the APN in the PDN connection request message can be the APN with which the user equipment intends to establish a connection.

[0122] In addition, according to an embodiment of the present disclosure, the user equipment may transmit information indicating whether the user equipment is capable of receiving two or more S-NSSAIs through the PCO to the MME. The information indicating whether the user equipment is capable of receiving two or more S-NSSAIs through the PCO may be indicated as a capability or a separate indicator in the transmitted NAS message, or may be included in a portion of the PCO (protocol options, etc.).

[0123] In operation 603, the user equipment may receive a response message including at least one network slice information corresponding to the APN from the MME.

[0124] According to an embodiment of the present disclosure, the user equipment may include slice information (at least one S-NSSAI) received from the PGW (or SGW) in the NAS response message received from the MME, and the slice information may be included in the PCO.

[0125] In operation 605, the user equipment may store at least one network slice information of the response message.

[0126] According to an embodiment of the present disclosure, the user equipment may store the NSSAI received from the MME as information (context) of the corresponding PDN connection. When the user equipment moves from the EPS to the 5GS, the user equipment may send a PDU session request message to the 5GS by including at least one stored S-NSSAI in the PDU session request message.

[0127] According to an embodiment of the present disclosure, when a user equipment stores multiple S-NSSAIs, all of the multiple S-NSSAIs may be sent via a PDU session request message, or at least one of the multiple S-NSSAIs may be selected and sent via the PDU session request message. For example, the user equipment may include in the PDU session request message only the S-NSSAI corresponding to the allowed NSSAI included in the registration accept message among the multiple stored S-NSSAIs, and send it.

[0128] Figure 7 4 is a flow chart of a communication method of a PGW according to an embodiment of the present disclosure.

[0129] In operation 701, the PGW may receive a PDN connection request message including specific APN information from the MME through the SGW. When the PDU session ID generated by the user equipment is included in the PCO or ePCO included in the received request message, the PGW may determine that the corresponding PDN connection can be a target for 5G interworking.

[0130] According to the embodiment of the present disclosure, the process of establishing a PDN connection can be performed together with the Attach operation. In addition, the APN in the PDN connection request message can be the APN with which the user equipment intends to establish a connection.

[0131] In addition, according to an embodiment of the present disclosure, the PGW may receive information indicating whether the user equipment is capable of receiving two or more S-NSSAIs through the PCO. The information indicating whether the user equipment is capable of receiving two or more S-NSSAIs through the PCO may be indicated as a capability or a separate indicator in the transmitted NAS message, or may be included in a portion of the PCO (protocol options, etc.). The PGW may not receive the information indicating whether the user equipment is capable of receiving two or more S-NSSAIs through the PCO, and only the MME may receive this information.

[0132] In operation 703, the PGW may request slice information from the NF storing user information based on the APN information.

[0133] According to an embodiment of the present disclosure, the PGW can support interworking with the 5GS and include the functionality of the SMF. The PGW can send a request to the NF storing the user information to receive the NW slice information of the 5GS corresponding to the user of the user equipment and the requested APN.

[0134] According to an embodiment of the present disclosure, the NF storing user information may be one of UDM, HSS, and UDR, and the service requested by the PGW may be a slice selection subscription data retrieval request. The slice selection subscription data retrieval request includes an identifier of the target user (SUPI, which may use the user ID received in operation 501), and the APN for the current session may be additionally sent here.

[0135] In operation 705, the PGW may receive a response message including network slice information corresponding to the APN from the NF storing the user information.

[0136] According to an embodiment of the present disclosure, the response message may be a slice selection subscription data retrieval response. The response message may include the user's subscribed NSSAI (one or more subscribed S-NSSAIs).

[0137] According to an embodiment of the present disclosure, when multiple network slice identification information (e.g., multiple S-NSSAIs) are included in a response message, the PGW may select at least one S-NSSAI and notify the user equipment of the selected at least one S-NSSAI.

[0138] For example, when a default S-NSSAI is specified in the response message, the PGW may prioritize the default S-NSSAI. In addition, when information about the priority of the S-NSSAI is included in the response message, the PGW may select at least one S-NSSAI based on the information about the priority.

[0139] In addition, according to an embodiment of the present disclosure, the PGW may request another NF to select a network slice. For example, the NF may be an NSSF. However, the present disclosure is not limited to the above example. Figure 7 In the figure, for the convenience of description, the NF to which the PGW requests to select a network slice is described as NSSF, but is not limited to this.

[0140] According to an embodiment of the present disclosure, the PGW may request the NSSF to select network slice information. The PGW may send the user's identifier (SUPI or IMSI), the subscribed NSSAI received from the NF storing the user information, and a message requesting the selection of a network slice including the APN (DNN) received from the user equipment to the NSSF.

[0141] In addition, according to an embodiment of the present disclosure, the PGW may receive a response message to a request to select a network slice. The response message may include information about the network slice selected by the NSSF. The information about the network slice selected by the NSSF may include at least one S-NSSAI. That is, the NSSF may select only one S-NSSAI, or may select two or more S-NSSAIs. In addition, the response message received from the NSSF may include information about which S-NSSAI is the default S-NSSAI or priority information between S-NSSAIs. The priority information may be a list.

[0142] In addition, according to an embodiment of the present disclosure, the PGW may send a selected S-NSSAI to the user equipment. For example, the PGW may identify whether two or more S-NSSAIs may be notified to the user equipment and provide only one S-NSSAI to the user equipment or provide multiple S-NSSAIs to the user equipment.

[0143] In other words, the PGW may directly select the S-NSSAI, or may request the NSSF to select the S-NSSAI.

[0144] In operation 707, the PGW may send the network slice information to the MME.

[0145] When the response message received from the NSSF includes only one S-NSSAI, the user equipment may be notified of this. When the NSSAI of the response message includes two or more S-NSSAIs and a default S-NSSAI is specified in the response, the PGW may prioritize the default S-NSSAI and, when information about the priority between the S-NSSAIs is included, the PGW may select and send an S-NSSAI based on the information about the priority between the S-NSSAIs.

[0146] The PGW may also provide multiple S-NSSAIs to the user equipment. When two or more S-NSSAIs can be notified to the user equipment, the PGW may send one or two or more S-NSSAIs to the user equipment based on information about whether the user equipment is capable of receiving multiple S-NSSAIs.

[0147] In addition, according to an embodiment of the present disclosure, the PGW may use a protocol configuration option (PCO) or an ePCO to provide the S-NSSAI to be notified to the user equipment.

[0148] Figure 8 is a block diagram illustrating a structure of a user equipment according to an embodiment of the present disclosure.

[0149] like Figure 8 As shown, the user equipment 100 of the present disclosure may include a processor 830, a transceiver 810, and a memory 820. However, the components of the user equipment 100 are not limited thereto. For example, the user equipment 100 may include more or fewer components than those described above. In addition, the processor 830, the transceiver 810, and the memory 820 may be implemented in the form of a single chip.

[0150] According to an embodiment, the processor 830 may control a series of processes, wherein the user equipment 100 may operate according to the above-mentioned embodiments of the present disclosure. For example, in a wireless communication system according to an embodiment of the present disclosure, the components of the user equipment 100 may be controlled to provide a service requested by the user equipment 100. A plurality of processors 830 may be provided, and the processor 830 may execute the operation of providing the service according to the above-mentioned present disclosure by executing the program stored in the memory 820.

[0151] The transceiver 810 can transmit and receive signals to and from a base station. The signals transmitted and received to and from the base station may include control information and data. The transceiver 810 may include an RF transmitter for up-converting the frequency of transmitted signals and amplifying them, and an RF receiver for performing low-noise amplification and down-converting the frequency of received signals. This is merely an example, and the components of the transceiver 810 are not limited to an RF transmitter and an RF receiver. Furthermore, the transceiver 810 may receive signals via a wireless channel and output them to the processor 830, and transmit signals output from the processor 830 via a wireless channel.

[0152] According to an embodiment, the memory 820 may store programs and data required for the operation of the user equipment 100. In addition, the memory 820 may store control information or data included in the signal transmitted or received by the user equipment 100. The memory 820 may include a storage medium such as ROM, RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media. In addition, there may be multiple memories 820. According to an embodiment, the memory 820 may store a program for controlling the components of the user equipment to perform the method for supporting inter-system mobility according to the present disclosure.

[0153] Figure 9 is a block diagram illustrating the structure of a NF according to an embodiment of the present disclosure.

[0154] Figure 9 It is a block diagram showing the structure of NF (entity, core network entity) in a wireless communication system according to an embodiment of the present disclosure. Terms such as "... unit", "... module" and the like used in the present disclosure indicate a unit that processes at least one function or action, and the unit and module can be implemented by hardware or software, or by a combination of hardware and software. According to the embodiment, NF may include MME, PGW (PGW-C, PGW-U), SGW, UDM, HSS, NSSF, SMF, AMF, etc., and is not limited to the above examples, but may include all NFs that may be included in the entire core network. In addition, Figure 9 The NF may correspond to the configuration of the base station.

[0155] refer to Figure 9 , the NF may include a transceiver 910 , a memory 920 , and a processor 930 .

[0156] The transceiver 910 can provide an interface for performing communication with other devices in the network. That is, the transceiver 910 can convert a bit string sent from the NF to another device into a physical signal, and convert a physical signal received from another device into a bit string. In other words, the transceiver 910 can send or receive signals. Therefore, the transceiver 910 can be referred to as a modem, a transmitter, a receiver, a communication unit, or a communication module. Here, the transceiver 910 can allow the NF to communicate with other devices or systems via a backhaul connection (e.g., a wired backhaul or a wireless backhaul) or other connection methods or networks.

[0157] The memory 920 can store data, such as default programs, applications, or configuration information for operating the NF. The memory 920 can be configured with volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. Specifically, the memory 920 can provide the stored data based on a request from the processor 930.

[0158] The processor 930 may control the overall operation of the NF. For example, the processor 930 may transmit or receive signals via the transceiver 910. Furthermore, the processor 930 may write data to or read data from the memory 920. To this end, the processor 930 may include at least one processor. The processor 930 may control the NF to perform operations according to the above-described embodiments. For example, components of the NF may be controlled to perform the method for supporting inter-system mobility according to the present disclosure.

[0159] The methods according to the embodiments disclosed in the claims or the specification of the present disclosure may be implemented as hardware, software, or a combination of hardware and software.

[0160] When implemented in software, a computer-readable storage medium storing one or more programs (e.g., software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions that direct the electronic device to perform the method according to the embodiments of the present disclosure as described in the claims or the specification.

[0161] The program (e.g., software module or software) may be stored in random access memory (RAM), non-volatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disk storage, compact disk (CD-ROM), digital versatile disk (DVD), other optical storage device or magnetic tape. Alternatively, the program may be stored in a memory comprising a combination of some or all of the above storage media. A plurality of such memories may be included.

[0162] The program may also be stored in an attachable storage device that is accessible via a communication network (such as the Internet, an intranet, a local area network (LAN), a wireless LAN (WLAN), or a storage area network (SAN), or a combination thereof). Such a storage device may access the device executing the embodiments of the present disclosure via an external port. In addition, additional storage devices on the communication network may access the device executing the embodiments of the present disclosure.

[0163] In the above-mentioned embodiments of the present disclosure, according to the described embodiments of the present disclosure, one or more components included in the present disclosure are expressed in singular or plural form. However, the singular or plural form is appropriately selected for the convenience of description, and the present disclosure is not limited thereto. Therefore, a component expressed in plural form may also be configured as a single component, and a component expressed in singular form may also be configured as multiple components.

[0164] In the detailed description of the present disclosure, specific embodiments have been described, but various modifications may be made without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiments described herein, and should be defined by the appended claims and their equivalents. In other words, it is obvious to those skilled in the art that other modifications based on the technical spirit of the present disclosure can be implemented. In addition, when necessary, the above-mentioned corresponding embodiments may be used in combination. For example, parts of the method provided by the present disclosure may be combined with each other to enable the base station and the user equipment to operate. In addition, although the above-mentioned embodiments are proposed with reference to 5G and NR systems, other modifications based on the technical spirit of the embodiments may also be implemented in combination with other systems (such as LTE, LTE-A, and LTE-A-Pro systems).

Claims

1. A method for supporting inter-system mobility of a first entity, comprising: receiving a create session request message, the create session request message including: information about an access point name APN for which the user equipment requests a packet data network PDN connection, user identification information of the user equipment, and a field indicating capability information of the user equipment regarding slice identification information; Based on the create session request message, determine whether the PDN connection needs to be moved to the 5G system 5GS; In a case where the PDN connection needs to be moved to 5GS, sending a user information request including user identification information and information about the APN to the second entity; receiving a response to the user information request from the second entity, the response including identification information of one or more subscribed network slices corresponding to the user identification information; and providing at least one identification information of the one or more subscribed network slices to the user equipment, Wherein, in the case where the response to the user information request includes two or more network slice identification information, the response to the user information request includes information for determining the default network slice, or information about the priority between the two or more network slice identification information, wherein, when the user equipment moves from an evolved packet system (EPS) to a 5GS, at least one identification information of the one or more subscribed network slices provided to the user equipment is used, and Among them, the first entity includes a combination node of the PDN gateway control PGW-C of EPS and the session management function SMF of 5GS.

2. The method according to claim 1, wherein The capability information of the user equipment regarding the slice identification information includes information indicating whether the user equipment is capable of receiving two or more network slice identification information, and Providing at least one identification information of the one or more subscribed network slices to the user equipment includes: providing one identification information or multiple network slice identification information of the one or more subscribed network slices to the user equipment based on a field of capability information of the user equipment indicating slice identification information.

3. The method according to claim 1, wherein At least one identification information of the one or more subscribed network slices provided to the user equipment is included in a specific field of the create session response message.

4. The method according to claim 1, further comprising: Sending a message to a third entity requesting selection of a network slice based on identification information of the one or more subscribed network slices; as well as receiving a response message including one or more slice identification information selected by a third entity from among the identification information of the one or more subscribed network slices, Wherein, providing at least one identification information of the one or more subscribed network slices to the user equipment includes: sending at least one of the selected slice identification information to the user equipment.

5. The method according to claim 4, wherein The second entity includes one of a unified data management UDM, a home subscriber server HSS, a unified data repository UDR, and the third entity includes a network slice selection function NSSF.

6. A first entity supporting inter-system mobility, comprising: transceiver; and a processor coupled to the transceiver and configured to: receive a create session request message, the create session request message including: information about an access point name APN for which a user equipment requests a packet data network (PDN) connection, user identification information of the user equipment, and a field indicating capability information of the user equipment regarding slice identification information; Based on the Create Session Request message, determine whether the PDN connection needs to be moved to the 5G system 5GS, In the case where the PDN connection needs to be moved to 5GS, a user information request including user identification information and information about the APN is sent to the second entity, receiving a response to the user information request from the second entity, the response including identification information of one or more subscribed network slices corresponding to the user identification information, and providing at least one identification information of the one or more subscribed network slices to the user equipment, Wherein, in the case where the response to the user information request includes two or more network slice identification information, the response to the user information request includes information for determining the default network slice, or information about the priority between the two or more network slice identification information, wherein, when the user equipment moves from an evolved packet system (EPS) to a 5GS, at least one identification information of the one or more subscribed network slices provided to the user equipment is used, and Among them, the first entity includes a combination node of the PDN gateway control PGW-C of EPS and the session management function SMF of 5GS.

7. The first entity according to claim 6, wherein: The capability information of the user equipment regarding the slice identification information includes information indicating whether the user equipment is capable of receiving two or more network slice identification information, and The processor is also configured to: provide the user equipment with one or more identification information of the one or more subscribed network slices based on the field indicating the capability information of the user equipment regarding the slice identification information.

8. The first entity according to claim 6, wherein: At least one identification information of the one or more subscribed network slices provided to the user equipment is included in a specific field of the create session response message.

9. The first entity according to claim 6, wherein: The processor is also configured to: Sending a message to a third entity requesting selection of a network slice based on identification information of the one or more subscribed network slices, receiving a response message including one or more slice identification information selected by a third entity from among the identification information of the one or more subscribed network slices, and At least one of the selected slice identification information is sent to the user equipment.

10. The first entity according to claim 9, wherein: The second entity includes one of a unified data management UDM, a home subscriber server HSS, a unified data repository UDR, and the third entity includes a network slice selection function NSSF.

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