Method and apparatus for supporting slice association

Abstract

The present disclosure provides a communication technique and system that combines a 5G communication system to support a higher data transmission rate than the 4G system with IoT technology. [Solution] The present disclosure can be applied to intelligent services (e.g., smart homes, smart buildings, smart cities, smart or connected cars, healthcare, digital education, retail, security and safety related services, etc.) based on 5G communication technology and IoT related technology. The present disclosure relates to a method and apparatus for providing service continuity when multiple wireless communication technologies are diverted to another wireless access network in an interoperable system.

Description

[Technical field]

[0001] The present disclosure relates to wireless communication systems, and more particularly to a method and apparatus for providing service continuity when switching to another wireless access network in a system in which multiple wireless communication technologies are interoperable. [Background technology]

[0002] Efforts are being made to develop improved 5G or pre-5G communication systems to meet the increasing demand for wireless data traffic since the commercialization of the 4G communication system. For this reason, 5G or pre-5G communication systems are referred to as Beyond 4G Network or Post-LTE systems. The 5G communication system defined by 3GPP is referred to as the New Radio (NR) system.

[0003] To achieve high data transmission rates, 5G communication systems are expected to be implemented in ultra-high frequency (mmWave) bands (such as the 60 GHz band). To mitigate the path loss of propagation in ultra-high frequency bands and increase the propagation distance, beamforming, massive MIMO, Full Dimensional MIMO (FD-MIMO), array antennas, analog beam-forming, and large scale antenna technologies have been discussed in 5G communication systems and applied to NR systems.

[0004] Furthermore, to improve the system's network, technologies being developed for the 5G communication system include advanced small cells, improved small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device to device communication (D2D), wireless backhaul, moving networks, cooperative communication, CoMP (Coordinated Multi-Points), and receive interference cancellation.

[0005] In addition, advanced coding modulation (ACM) methods such as FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding) as well as advanced connection technologies such as FBMC (Filter Bank Multi Carrier), NOMA (non orthogonal multiple access), and SCMA (sparse code multiple access) are being developed for the 5G system.

[0006] Meanwhile, the Internet is evolving from a human-centered connection network where humans generate and consume information to an IoT (Internet of Things) network that exchanges and processes information between distributed components such as things. IoE (Internet of Everything) technology is also emerging, combining big data processing technology through connection to cloud servers with IoT technology. To realize IoT, technological elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required, and recently technologies such as sensor networks for connecting things, machine to machine (M2M), and MTC (Machine Type Communication) are being researched. In the IoT environment, intelligent IT (Internet Technology) services can be provided that collect and analyze data generated by connected things to create new value in human life. IoT can be applied to fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services through the fusion and integration of existing IT (Information Technology) and various industries.

[0007] Accordingly, various attempts are being made to apply 5G communication systems to IoT networks. For example, 5G communications such as sensor networks, machine to machine (M2M), and machine type communication (MTC) are being realized using techniques such as beamforming, MIMO, and array antennas. The application of cloud radio access network (cloud RAN) as the big data processing technology mentioned above is also an example of the fusion of 5G technology and IoT technology.

[0008] Meanwhile, with the recent development of various IT (information technology) technologies, network equipment has evolved into a virtualized network function (NF) by applying virtualization technology, and the virtualized NF can be embodied in software form free from physical constraints and installed / operated in various types of clouds or data centers (DCs). In particular, NFs can be freely expanded or contracted, or initiated or terminated, depending on service requirements, system capacity, and network load. It should be noted that even if such NFs are embodied in software form, they must be operated on a physical configuration, for example, on a specific device, so a physical configuration is not excluded. Also, NFs can be embodied in a simple physical configuration, i.e., only hardware.

[0009] In order to support various services in such various network structures, network slicing technology has been introduced. Network slicing is a technology that logically configures a network by a collection of network functions (NFs) to support specific services and separates them from other slices. One terminal can connect to two or more slices when receiving various services. Summary of the Invention [Problem to be solved by the invention]

[0010] An objective of the present disclosure is to provide a method and apparatus for providing service continuity when switching to another wireless access network in a system in which multiple wireless communication technologies are interoperable.

[0011] More specifically, when a network that supports network slicing technology is linked to a network that supports an existing wireless access technology that does not support network slicing technology, a method and apparatus are provided for supporting network slicing technology even in the existing network that does not support network slicing technology. [Means for solving the problem]

[0012] According to an embodiment of the present disclosure for solving the above-mentioned problems, in a wireless communication system, a method performed by a first network function entity (SMF+PGW-C) including a session management function (SMF) and a control plane function (PGW-C) of a packet data network gateway (PGW) includes the steps of receiving a first message requesting establishment of a packet data network (PDN) connection from a mobility management entity (MME), selecting a network slice associated with the PDN connection establishment, and selecting a network slice connection. The method includes the steps of: sending a second message to a second network function entity that manages a PDN admission status (PDN admission status) to request confirmation of the availability of the network slice; receiving a third message including information on the availability of the network slice from the second network function entity; and sending a fourth message including a response to the PDN connection establishment based on the third message to the MME, wherein the second message includes a terminal ID of a terminal requesting the PDN connection establishment, and the availability of the network slice is confirmed based on the terminal ID, the number of terminals registered in the network slice, and the number of current PDU sessions of the network slice.

[0013] In the method, the step of selecting a network slice associated with the PDN connection establishment may further include a step of determining whether the selected network slice is connected to and controlled by the second network function entity based on information configured in the first network function entity.

[0014] Furthermore, if the terminal ID is not registered in the network slice and the number of registered terminals and the current number of PDU sessions are smaller than the maximum number of terminals and the maximum number of PDU sessions of the network slice, the terminal ID is registered in the network slice, the number of registered terminals and the current number of PDU sessions are increased by 1, and the third message may include information that the network slice is available.

[0015] In addition, if the terminal ID is already registered in the network slice and the current PDU session number is less than the maximum PDU session number of the network slice, the current PDU session number is increased by 1, and the third message may include information that the network slice is available.

[0016] According to another embodiment of the present disclosure, in a wireless communication system, a method performed by a second network function entity for managing network slice admission includes: receiving a first message requesting confirmation of availability of a network slice from a first network function entity (SMF+PGW-C) including a session management function (SMF) and a control plane function (PGW-C) of a packet data network gateway (PGW); confirming the availability of the network slice based on a terminal ID, a number of terminals registered in the network slice, and a current number of PDU sessions of the network slice included in the first message; and transmitting a second message including information on the availability of the network slice to the first network function entity, wherein the network slice receives a packet data entry (PDN) from a mobility management entity (MME). In relation to a PDN connection establishment request, the terminal ID included in the first message is a terminal ID of a terminal requesting the PDN connection establishment, and the PDN connection between the first network function entity and the MME can be established based on the second message.

[0017] According to another embodiment of the present disclosure, in a wireless communication system, a first network function entity (SMF+PGW-C) including a session management function (SMF) and a control plane function (PGW-C) of a packet data network gateway (PGW) includes a transceiver unit for transmitting and receiving signals, and a controller connected to the transceiver unit, wherein the controller receives a first message requesting establishment of a packet data network (PDN) connection from a mobility management entity (MME), selects a network slice associated with the PDN connection establishment, and performs a network slice connection. The MME is configured to: send a second message to a second network function entity that manages a PDN admission to the MME, requesting confirmation of the availability of the network slice; receive a third message including information on the availability of the network slice from the second network function entity; and send a fourth message to the MME, the fourth message including a response to the PDN connection establishment based on the third message, wherein the second message includes a terminal ID of a terminal requesting the PDN connection establishment, and the availability of the network slice can be confirmed based on the terminal ID, the number of terminals registered in the network slice, and the number of current PDU sessions of the network slice.

[0018] According to another embodiment of the present disclosure, in a wireless communication system, a second network function entity that manages network slice admission includes a transceiver unit that transmits and receives signals, and a control unit connected to the transceiver unit, wherein the control unit is configured to receive a first message requesting confirmation of availability of a network slice from a first network function entity (SMF+PGW-C) including a session management function (SMF) and a control plane function (PGW-C) of a packet data network gateway (PGW), confirm the availability of the network slice based on a terminal ID, the number of terminals registered in the network slice, and the number of current PDU sessions of the network slice included in the first message, and transmit a second message including information on the availability of the network slice to the first network function entity, wherein the network slice receives a packet data entry (PDN) from a mobility management entity (MME), In relation to a PDN connection establishment request, the terminal ID included in the first message is a terminal ID of a terminal requesting the PDN connection establishment, and the PDN connection between the first network function entity and the MME can be established based on the second message. Effect of the Invention

[0019] According to one embodiment of the present disclosure, even in a radio access network that does not support network slicing, it is possible to support service continuity between terminals and networks that support different radio access technologies by providing protocols and operations of a radio access network that supports slicing in conjunction with each other. [Brief description of the drawings]

[0020] [Figure 1]1 is a diagram illustrating a wireless communication system in accordance with various embodiments of the present disclosure. [Diagram 2] 1 is a diagram showing a structure for providing services by interlocking 5G and 4G (LTE) according to an embodiment of the present disclosure. [Diagram 3] 13 is a diagram showing a control procedure taking into account a slice quota when connecting to a 4G network according to an embodiment of the present disclosure. [Figure 4] 13 is a diagram showing a control procedure taking into account a slice quota when connecting to a 4G network according to an embodiment of the present disclosure. [Diagram 5] 13 is a diagram showing a control procedure taking into account a slice quota when connecting to a 4G network according to an embodiment of the present disclosure. [Figure 6] 13 is a diagram showing a control procedure taking into account a slice quota when connecting to a 4G network according to an embodiment of the present disclosure. [Figure 7] 1 is a diagram illustrating a terminal device according to an embodiment of the present disclosure. [Figure 8] 1 is a diagram illustrating a base station device according to an embodiment of the present disclosure. [Figure 9] 1 is a diagram illustrating a NF device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. At this time, it should be noted that the same components in the accompanying drawings are represented by the same reference numerals as much as possible. Also, detailed description of known functions and configurations that may obscure the gist of the present disclosure will be omitted.

[0022] In describing the examples in this specification, technical content that is widely known in the technical field to which the present disclosure pertains and is not directly related to the present disclosure will be omitted in order to more clearly convey the gist of the present disclosure by omitting unnecessary explanations.

[0023] For the same reason, in the accompanying drawings, some components are exaggerated, omitted, or illustrated in a schematic manner, and the size of each component does not reflect the actual size. The same reference numerals are given to the same or corresponding components in each drawing.

[0024] The advantages and features of the present disclosure, and the methods for achieving them, will become clear from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, and may be embodied in various different forms, and the embodiments are provided solely to make the disclosure of the present disclosure complete and to fully teach the scope of the disclosure to those skilled in the art to which the present disclosure pertains, and the present disclosure is only defined by the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

[0025] At this time, it can be understood that each block of the process flow diagram and the combination of the diagrams of the flow diagrams can be implemented by computer program instructions. These computer program instructions can be loaded into a processor of a general purpose computer, a special purpose computer, or other programmable data processing equipment, such that the instructions executed by the processor of the computer or other programmable data processing equipment will generate means for performing the functions described in the flow diagram blocks. These computer program instructions can be stored in a computer usable or computer readable memory that can direct the computer or other programmable data processing equipment to implement the functions in a particular manner, such that the instructions stored in the computer usable or computer readable memory can produce an article of manufacture that includes instruction means for performing the functions described in the flow diagram blocks. The computer program instructions may be embodied on a computer, or other programmable data processing device, such that a sequence of operational steps are performed on the computer, or other programmable data processing device, to generate a computer implemented process, and the instructions that cause the computer, or other programmable data processing device, to provide steps for performing the functions described in the flow diagram blocks.

[0026] Also, each block may represent a module, segment, or portion of code that includes one or more executable instructions for performing a specified logical function. It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of sequence. For example, two blocks shown one after the other may be performed substantially simultaneously, or the blocks may sometimes be performed in reverse order depending on the corresponding functions.

[0027] In this embodiment, the term "module" refers to software or hardware components such as FPGA or ASIC, and the "module" performs any function. However, the "module" is not limited to software or hardware. The "module" can be configured to reside on an addressable storage medium and can be configured to execute one or more processors. Thus, by way of example, the "module" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The components and functions provided in the "module" can be combined into a smaller number of components and "modules" or further separated into additional components and "modules". The components and "modules" can also be embodied to execute one or more CPUs in a device or a security multimedia card.

[0028] The terms used in this disclosure are merely used to describe a particular embodiment and may not be intended to limit the scope of other embodiments. A singular expression may include a plural expression unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by a person of ordinary skill in the art described in this disclosure. Among the terms used in this disclosure, terms defined in a general dictionary may be interpreted to have the same or similar meaning as the meaning in the context of the related art, and unless clearly defined in this disclosure, they are not interpreted to have an ideal or overly formal meaning. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude an embodiment of the present disclosure.

[0029] In the various embodiments of the present disclosure described below, a hardware approach will be described as an example, but since the various embodiments of the present disclosure include techniques using both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0030] The present disclosure relates to a method and apparatus for supporting various services in a wireless communication system. Specifically, the present disclosure describes a technique for supporting various services by supporting terminal mobility in a wireless communication system.

[0031] In the following description, terms for identifying a connection node, terms indicating a network object (or network entity) or a network function (NF), terms indicating a message, terms indicating an interface between network objects, terms indicating various identification information, etc. are provided as examples for the convenience of description. Therefore, the present disclosure is not limited to the terms described later, and other terms indicating objects having equivalent technical meanings may be used.

[0032] For convenience of explanation, the present disclosure uses terms and names defined in 3GPP LTE (3rd generation partnership project long term evolution) and 5G standards. However, the present disclosure is not limited to the terms and names and can be equally applied to systems conforming to other standards.

[0033] For convenience of explanation, hereinafter, the objects exchanging information for connection control and state management will be collectively referred to as NF. The NF can be, for example, at least one of an Access and Mobility Management Function (AMF) device, a Session Management Function (SMF) device, and a Network Slice Selection Function (NSSF) device. However, the embodiments of the present disclosure can be equally applied to the case where the NF is actually embodied as an instance (an AMF instance, an SMF instance, an NSSF instance, etc.).

[0034] In the present disclosure, an instance may mean a state in which a specific NF exists in the form of software code and is allocated physical or / and logical resources from a computing system to perform the function of an NF in a physical computing system, for example, a specific computing system existing on a core network, and can be executed. Therefore, an AMF Instance, an SMF Instance, and an NSSF Instance may mean that physical or / and logical resources are allocated and available for AMF, SMF, and NSSF operations from a specific computing system existing on the core network, respectively. As a result, when physical AMF, SMF, and NSSF devices exist, the AMF Instance, the SMF Instance, and the NSSF Instance that are allocated and use physical or / and logical resources for AMF, SMF, and NSSF operations from a specific computing system existing on the network can perform the same operation. Therefore, matters described as NFs (AMF, SMF, UPF, NSSF, NRF, SCP, etc.) in the embodiments of the present disclosure can be replaced with NF instances, or conversely, matters described as NF instances can be replaced with NFs and applied. Similarly, matters described as a NW slice in the embodiments of the present disclosure may be replaced with a NW slice instance, or conversely, matters described as a NW slice instance may be replaced with a NW slice and applied.

[0035] FIG. 1 illustrates a wireless communication system in accordance with various embodiments of the present disclosure.

[0036] 1, a base station (radio access node, RAN) 110 and a terminal (user equipment, UE) 120 are illustrated as some of the nodes using a wireless channel in a wireless communication system. Although FIG. 1 illustrates only one base station 110 and one terminal 120, other base stations identical to or similar to the base station 110 may be further included. Also, FIG. 1 illustrates a case where only one terminal 120 communicates within one base station 110. However, it is obvious that multiple terminals can actually communicate within one base station 110.

[0037] The base station 110 is a network infrastructure that provides wireless connectivity to the terminal 120. The base station 110 has a coverage defined as a certain geographical area based on the distance over which a signal can be transmitted (not shown in FIG. 1). The base station 110 may be referred to as an "access point (AP)", "eNodeB (eNB)", "5G node (5th generation node)", "next generation NodeB (gNB)", "wireless point", "transmission / reception point (TRP)", or other term having an equivalent technical meaning, in addition to a base station.

[0038] The terminal 120 is a device used by a user and communicates with the base station 110 via a wireless channel. In some cases, the terminal 120 may be operated without the involvement of a user. For example, the terminal 120 may be a device that performs machine type communication (MTC) and may not be carried by a user. The terminal 120 illustrated in FIG. 1 may include at least one user-carried device and may include at least one MTC. The terminal 120 in FIG. 1 may be referred to as a "terminal," "mobile station," "subscriber station," "remote terminal," "wireless terminal," or "user device," or other terms having equivalent technical meanings.

[0039] The AMF device 131 can be a network entity that manages wireless network access and mobility management for the terminal 120. The SMF device 132 can be a network entity that manages a packet data network connection to provide packet data to the terminal 120. The connection between the terminal 120 and the SMF 132 can be a PDU (protocol data unit) session.

[0040] A User Plane Function (UPF) device 133 can be a gateway that transfers packets transmitted and received by the terminal 120, or a network entity that performs the role of a gateway. The UPF 133 is connected to a data network (DN) 140 connected to the Internet, and can provide a path for data transmission and reception between the terminal 120 and the DN 140. Thus, the UPF 133 can route data to be transmitted to the Internet among packets transmitted by the terminal 120 to the Internet data network.

[0041] The network slice selection function (NSSF) device 134 may be a network entity that performs the network selection operations described in this disclosure, such as selecting a network slice. The operation of the NSSF device 134 is described in more detail in the figures described below.

[0042] An AUSF (Authentication Server Function) device 151 can be a device (network entity) that provides a service for subscriber authentication processing.

[0043] The Network Exposure Function (NEF) device 152 can access information that manages the terminal 120 in a 5G network, and can be a network entity that can subscribe to Mobility Management events for the terminal, subscribe to Session Management events for the terminal, request session-related information, set charging information for the terminal, request a PDU session policy change for the terminal, and transmit small data to the terminal.

[0044] A Network Repository Function (NRF) device 153 may be a network entity (NF) that stores state information of NFs and has the function of processing requests for other NFs to find connectable NFs.

[0045] A Policy and Charging Function (PCF) device 154 can be a network entity that applies the service policy, charging policy, and policy of a mobile communication operator to the terminal 120 for a PDU session.

[0046] A Unified Data Management (UDM) device 155 can be a network entity that stores information for subscribers and / or terminals 120 .

[0047] An Application Function (AF) device 156 can be a network entity (NF) having a function of providing services to users in conjunction with a mobile communication network.

[0048] The Service Communication Proxy (SCP) device 157 is an NF (network entity) that provides functions such as NF discovery for communication between NFs and message transfer between NFs. The SCP 157 may operate in a form integrated with the NRF 153 at the operator's discretion, in which case the SCP 157 may include the functionality of the NRF 153, or conversely, the NRF 153 may include the functionality of the SCP 157.

[0049] The AMF device 131, SMF device 132, UPF device 133, NSSF device 134, AUSF device 151, NEF device 152, NRF device 153, PCF device 154, UDM device 155, AF device 156, and SCP device 157 described above may be in the form of software or firmware that runs in at least one or more devices and / or systems. Also, the devices 131, 132, 133, 134, 151, 152, 153, 154, 155, 156, and 157 may be embodied in the form of hardware, if necessary. In the following description, the term "device" will be omitted for convenience of description. For example, the AMF device 131 will be described as AMF 131, and the SMF device 132 will be described as SMF 132.

[0050] Meanwhile, in Fig. 1, the symbols between the connected lines between each network entity, the terminal 120 and the RAN 110, may represent the interfaces of each entity. For example, this may mean that an N1 interface is used between the terminal 120 and the AMF 131, an N2 interface is used between the RAN 110 and the AMF 131, and an N3 interface is used between the RAN 110 and the UPF 133. Similarly, an N4 interface is used between the SMF 132 and the UPF 133, an N9 interface is used between or inside the UPF 133, and an N6 interface is used between the UPF 133 and the DN 140.

[0051] Meanwhile, to provide true 5G services to users, 5G cells must be provided in full coverage and terminals must be connected to the 5G network anywhere. However, in the early stages of 5G services, the coverage may be limited as 5G cells are only partially introduced. Therefore, 5G networks can overcome such limitations by being provided in conjunction with existing 4G (LTE) networks to ensure service continuity.

[0052] FIG. 2 is a diagram showing a structure for providing services by linking 5G (new radio, NR) and 4G (LTE).

[0053] In order to control the same subscriber, the unified data management (UDM) 210 and home subscriber subsystem (HSS) must be linked to each other, and in order to support session continuity (such as IP address maintenance), the SMF 220 and UPF 225 must support the functions of the packet data network gateway (PGW, PDN-GW). In this case, the control plane function (PGW-C) of the PGW can be supported by the SMF 220, and the user plane function (PGW-U) of the PGW can be supported by the UPF 225. In addition, the policy and charging function (PCF) 230 must be linked to the policy control and charging rules function (PCRF) to manage the service policy, charging policy, and quality of service (QoS) of the mobile communication operator for the terminal.

[0054] In this way, a network entity that combines a 5G network entity and a 4G network entity can be referred to as an NF (network entity) that supports multiple radio access technologies (RATs), a combined network entity, an interworking network entity, or a combi node.

[0055] Alternatively, each network entity may be understood to support multiple RATs to support an interwalking system. That is, the above-mentioned UDM 210, SMF 220, UPF 225, and PCF 230 may be understood to include the functions of HSS, PGW-C (PGW-control plane), PGW-U (PGW-user plane), and PCRF, respectively, and to share the 5G network and the 4G network. In this specification, the interlocked / shared network entities may be indicated as interlocked / shared by a "+" sign or a " / " sign. For example, an entity in which an SMF is interlocked with the function of a PGW-C and shared with a 4G network may be expressed as PGW-C / SMF, PGW-C+SMF, or SMF+PGW-C, or may simply be expressed as SMF.

[0056] In addition, the AMF and a mobility management entity (MME), which is a node for mobility management in a 4G network, can exchange information for terminal mobility support between 5G and 4G via the N26 interface.

[0057] A communication system (including a terminal, a base station, and a core network (CN)) that is the subject of the present disclosure may operate based on a network slice. A network slice may be considered as a logically separated network and may be composed of a collection of NFs for supporting network functions. When a network is operated based on a network slice, each network slice may operate with different capacity, settings, and policies. In the present disclosure, a quota may be introduced for each network slice, and the quota may include a maximum number of terminals that can be simultaneously connected to the slice, a maximum number of sessions (PDU Sessions or PDN (packet data network) Connections) that can be simultaneously generated, and a maximum transmission rate (Data Rate) that a subscriber can use for each slice, but is not limited thereto, and may include other types of parameters necessary for network operation, and the spirit, operation, and configuration of the present invention may be extended to cover these.

[0058] When network slicing is used, it is necessary to consider the interoperability between 5G networks that explicitly support the concept of network slicing through standardized protocols and operations and 4G networks that do not. In particular, as mentioned above, when the whole or part of the network equipment (NF) is shared to ensure service continuity between 5G and 4G networks, the slice quota should be applied not only to 5G but also to 4G connections, and it should be possible to consider the mobile status of the terminal between 5G and 4G. Such operations can be selectively applied to users who subscribe to 5G services using terminals that can support 5G.

[0059] Figure 3 shows a control procedure that takes into account the slice quota when connecting to a 4G network.

[0060] Step 1. After connecting to a 4G radio network (RAN), the terminal may perform an Attach process to receive 4G services, or a process to create a PDN connection if already registered 301. The terminal may also perform an operation for establishing a PDN connection during the Attach process. The terminal may include a desired access point name (APN) in a non-access stratum (NAS) request message sent to the MME to distinguish the service to be the target of session creation.

[0061] Step 2. The MME may perform a process for creating a session according to the information received from the terminal. If the terminal explicitly includes an APN in the message of step 1, the MME may determine whether the APN requested by the terminal is permitted based on the subscription information received from the HSS / UDM. If the terminal does not explicitly include an APN, the MME may use a default APN included in the subscription information received from the HSS / UDM or set in the MME. The MME selects a gateway (GW; SGW, PGW) to process the session considering the determined APN and other parameters, and the MME transmits a request message for session creation to the PGW-C+SMF (hereinafter referred to as SMF) 302, which may be delivered to the SMF via the SGW. The Create Session Request message transmitted by the MME may include the determined APN and the subscriber identity (international mobile subscriber identity, IMSI) of the terminal.

[0062] Step 3. The SMF determines whether the APN can be supported via the received APN, and may perform procedures to receive and apply session-related policies with the PCF (PCRF) if necessary. The SMF selects a slice (single-network slice selection assistance information, S-NSSAI) mapped to the APN, and may also perform slice selection via the NSSF during this process 303.

[0063] Step 4. If the quota for the network slice should be considered, the following steps can be performed. This can be determined based on information configured in the SMF, a policy received from the PCF, or subscription information received from the UDM. This can be applied exclusively to a specific subscriber, or exclusively to a specific S-NSSAI or APN. The SMF checks the status of the slice quota in an NF for slice quota management (referred to as a Counting NF in this disclosure, or the name can be Network Slice Quota Management Function, etc., or among NFs that previously provided other functions, PCF, UDM, UDR (unified data repository), etc. can include the corresponding function) and transmits a request message to check whether a user / session can be added to the slice, or can call a request service 304. At this time, the request message sent by the SMF may include the selected S-NSSAI, the radio access technology (RAT) type to which the current terminal is connected, the subscriber's ID, the selected APN, a Session ID, etc. The RAT to which the current terminal is connected may be indirectly indicated by other information included in the request message sent by the SMF. For example, if the request message sent by the SMF contains a subscriber ID, the Counting NF that receives it can determine that the RAT to which the subscriber is connected is 4G / LTE and take appropriate action.

[0064] Step 5. The Counting NF may determine whether the request received in step 4 can be accepted 305. At this time, the Counting NF may perform a process of comparing the quota (maximum number of terminals, maximum number of sessions) set for each current slice with the actual number of terminals and number of sessions collected to date. If slice use is permitted, the NF may update the terminal / session status for each slice. As an example of such a status update, if the connection of the corresponding slice is the first for the corresponding terminal / subscriber (i.e., if the first session is generated), the number of terminals may be incremented by 1. If a new session is generated for the corresponding slice, the number of sessions may be incremented by 1. If a new session is added for the corresponding slice but there is an existing session generated, only the number of sessions may be incremented by 1. If a new session is added for the corresponding slice but there is an existing session generated, the number of terminals may not be incremented.

[0065] Step 6 / 7. If slice-related state information should be stored in a separate NF or storage, the counting NF sends a request for updating / storing state information to the NF providing the corresponding function 306, and this message may include slice-specific information (maximum / current quota information) and information on the currently targeted terminal / subscriber / session. In this case, the separate NF or storage may be a UDM or UDR, or a network entity (NF) having slice state information. The separate NF receiving the message may return a response to the updating / storing of the state information to the counting NF 307. According to one embodiment, if the NF providing the function is a UDM, the counting NF may send a request message to the UDM 306. If necessary, the UDM may store slice-specific information and / or information on the currently targeted terminal / subscriber / session in the UDR. According to another embodiment, if the NF providing the function is a UDR, the counting NF may send a request message to the UDR, which may be transferred to the UDR via the UDM 306.

[0066] Step 8. The Counting NF sends a response that the slice is available, and may also convey information about the current slice at this time 308.

[0067] Step 9. The SMF can finally determine the S-NSSAI to transmit to the terminal 309.

[0068] Step 10. The SMF sends a Create Session Response to the MME, which may include the selected S-NSSAI in a protocol configuration option (PCO) 310. This message may be sent to the MME via the SGW.

[0069] Step 11. The MME sends an accept message to the terminal informing it that the Attach or session creation is permitted, and may include the previously received PCO at this time (311).

[0070] Through the above process, the terminal finally receives the S-NSSAI, and this information can be used for the registration process and other session processing when the terminal moves to a 5G network in the future.

[0071] Figure 4 shows a control procedure that takes into account the slice quota when connecting to a 4G network.

[0072] Step 1. After connecting to a 4G radio network (RAN), the terminal may perform an Attach process to receive 4G services, or a process to create a PDN connection if already registered 401. The terminal may also perform an operation for establishing a PDN connection during the Attach process. The terminal may include a desired APN in an NAS request message sent to the MME to distinguish a service to be the target of session creation.

[0073] Step 2. The MME may perform a process for creating a session according to the information received from the terminal. If the terminal explicitly includes an APN in the message of step 1, the MME may determine whether the APN requested by the terminal is permitted based on the subscription information received from the HSS / UDM. If the terminal does not explicitly include an APN, the MME may use a default APN included in the subscription information received from the HSS / UDM or configured in the MME. The MME selects a GW (SGW, PGW) to process the session considering the determined APN and other parameters, and the MME transmits a request message for session creation to the PGW-C+SMF (hereinafter referred to as SMF) 402, which may be delivered to the SMF via the SGW. The Create Session Request message transmitted by the MME may include the determined APN and the subscriber ID (IMSI) of the terminal.

[0074] Step 3. The SMF determines whether the APN can be supported via the received APN, and may perform procedures to receive and apply session-related policies with the PCF (PCRF) if necessary. The SMF selects the APN and the mapped slice (S-NSSAI), and may also perform slice selection via the NSSF during this process 403.

[0075] Step 4. If the quota for the network slice should be considered, the following steps can be performed. This can be determined based on information configured in the SMF, a policy received from the PCF, or subscription information received from the UDM. This can be applied exclusively to a specific subscriber, or exclusively to a specific S-NSSAI or APN. The SMF can check the status of the slice quota in an NF for slice quota management (referred to as a Counting NF in this disclosure, or the name can be Network Slice Quota Management Function, etc., or among NFs that already provide other functions, PCF, UDM, UDR, etc. can include the corresponding function) and call a request service to check whether a user / session can be added to the slice 404. At this time, the request message sent by the SMF can include the selected S-NSSAI, the RAT Type to which the current terminal is connected, the subscriber's ID, the selected APN, the Session ID, etc.

[0076] Step 5. The Counting NF may perform a process for grasping the status information of the current slice in a separate NF or storage as necessary 405. At this time, the separate NF or storage may be a UDM or UDR, or may be a network entity (NF) having the status information of the slice. The status information may include a quota (maximum number of terminals, maximum number of sessions) set for each slice, and the actual number of terminals and number of sessions collected up to now. According to one embodiment, if the NF providing the function is a UDM, the counting NF may send a request message to the UDM. If necessary, the UDM may store the status information in the UDR. According to another embodiment, if the NF providing the function is a UDR, the counting NF may send a request message to the UDR, which may be transferred to the UDR via the UDM.

[0077] Step 6. The Counting NF can check the quota set for each slice to determine whether the request received in step 4 can be accepted 406. At this time, the Counting NF can perform a process of comparing the quota (maximum number of terminals, maximum number of sessions) set for the current slice with the actual number of terminals and number of sessions collected up to now. If the current slice situation reaches or exceeds the upper limit of the quota, it cannot connect a new terminal or session.

[0078] Step 7. If the current slice status reaches or exceeds the quota limit as determined in step 6, the Counting NF sends a response 407 that the slice cannot be used, and informs the cause (whether it is due to a limit on the number of terminals or a limit on the number of sessions). In addition, if it is desired to limit the terminal request for a specific time, a back-off timer value can be transmitted together. The back-off timer can have separate values ​​for limiting the number of terminals (Mobility Management) and limiting the number of sessions (Session Management), and can be transmitted together with the cause so that the two can be distinguished.

[0079] Step 8. The SMF may finally determine the reason for rejection of the Create Session request to inform the MME and set the back-off timer value taking into account the previously received timer 408.

[0080] Step 9. The SMF sends a Create Session Response to the MME 409, including a cause indicating that the request was rejected. It may also include a back-off timer value. This message may be sent to the MME via the SGW. In this case, the Response may be a Reject message.

[0081] Step 10. The MME can determine whether attach is possible even if session creation is rejected based on the message received from the SMF, and can determine the setting value of the back-off timer from among the MM (mobility management) back-off timer and the SM (session management) back-off timer depending on whether the setting value is due to a limit on the number of terminals in the slice quota or a limit on the number of sessions in the slice quota 410.

[0082] Step 11. The MME sends a message to the UE informing it that the Attach or session creation has been rejected 411, and may include a cause indicating whether the reason is due to a slice quota limit on the number of UEs (Mobility Management) or due to a slice quota limit on the number of sessions (Session Management). It may also include a back-off timer determined in step 10. In addition, if the UE did not explicitly request an APN in step 1, the MME may explicitly notify the UE of the APN selected and rejected.

[0083] Step 12. If the connection request is rejected and the terminal receives the back-off timer, the terminal starts the back-off timer and must not send a request while the timer is running 412. If the terminal explicitly requests an APN in step 1 and receives a rejection for the request, the terminal cannot send a request for the APN before the back-off timer expires. If the terminal does not explicitly request an APN, and receives an APN through the message of step 11, the terminal cannot send a session management request for the APN before the back-off timer expires. If the terminal does not request / receive an APN or receives an APN due to a mobility management rejection for the Attach request, the terminal may not send a mobility management request before the back-off timer expires. The terminal's back-off timer may be applied as is even when the terminal changes cell, mobility, or RAT (e.g., moves to a 5G network).

[0084] Figure 5 shows a control procedure that takes into account the slice quota when connecting to a 4G network.

[0085] Step 1. After connecting to a 4G radio network (RAN), the terminal may perform an Attach process to receive 4G services, or a process to create a PDN connection if already registered 501. The terminal may also perform an operation for establishing a PDN connection during the Attach process. The terminal may include a desired APN in an NAS request message sent to the MME to distinguish a service to be the target of session creation.

[0086] Step 2. The MME may perform a process for creating a session according to the information received from the terminal. If the terminal explicitly includes an APN in the message of step 1, the MME may determine whether the APN requested by the terminal is permitted based on the subscription information received from the HSS / UDM. If the terminal does not explicitly include an APN, the MME may use a default APN included in the subscription information received from the HSS / UDM or set in the MME. The MME selects a GW (SGW, PGW) to process the session considering the determined APN and other parameters, and the MME transmits a request message for session creation to the PGW-C+SMF (hereinafter referred to as SMF) 502, which may be delivered to the SMF via the SGW. The Create Session Request message transmitted by the MME may include the determined APN and the subscriber ID (IMSI) of the terminal.

[0087] Step 3. The SMF determines whether the APN can be supported via the received APN, and may perform procedures to receive and apply session-related policies with the PCF (PCRF) if necessary. The SMF selects the APN and the mapped slice (S-NSSAI), and may also perform slice selection via the NSSF during this process 503.

[0088] Step 4. If the quota for the network slice should be considered, the following steps can be performed. This can be determined based on information set in the SMF, or a policy received from the PCF, or subscription information received from the UDM. This can be applied exclusively to a specific subscriber, or exclusively to a specific S-NSSAI or APN. The SMF can check the status of the slice quota in an NF for slice quota management (referred to as a Counting NF in this disclosure, or the name can be Network Slice Quota Management Function, etc., or among NFs that already provide other functions, PCF, UDM, UDR, etc. can include the corresponding function) and call a request service to check whether a user / session can be added to the slice 504. At this time, the request message sent by the SMF can include the selected S-NSSAI, the RAT Type to which the current terminal is connected, the subscriber's ID, the selected APN, the Session ID, etc.

[0089] Step 5. The Counting NF may perform a process for grasping the status information of the current slice in a separate NF or storage as necessary 505. At this time, the separate NF or storage may be a UDM or UDR, or may be a network entity (NF) having the status information of the slice. The status information may include a quota (maximum number of terminals, maximum number of sessions) set for each slice, and the actual number of terminals and number of sessions collected up to now. According to one embodiment, if the NF providing the function is a UDM, the counting NF may send a request message to the UDM. If necessary, the UDM may store the status information in the UDR. According to another embodiment, if the NF providing the function is a UDR, the counting NF may send a request message to the UDR, which may be transferred to the UDR via the UDM.

[0090] Step 6. The Counting NF can check the quota set for each slice to determine whether the request received in step 4 can be accepted 506. At this time, the Counting NF can perform a process of comparing the quota (maximum number of terminals, maximum number of sessions) set for the current slice with the actual number of terminals and number of sessions collected up to now. If the current slice situation reaches or exceeds the upper limit of the quota, it cannot connect a new terminal or session.

[0091] Step 7. If the current slice status reaches or exceeds the quota limit as determined in step 6, the Counting NF sends a response 507 that the slice cannot be used, along with the cause (whether it is due to a limit on the number of terminals or a limit on the number of sessions). If the terminal is to be switched to another slice or APN, the NF can instead inform the SMF of the selected APN information if the service can be provided.

[0092] Step 8. If APN replacement is possible, the SMF may determine the APN to be replaced 508. At this time, the SMF's internal settings, subscription information received from the UDM / HSS, or APN policy received from the PCF, and the APN information received in step 7 may be used.

[0093] Step 9. The SMF sends a Create Session Response to the MME 509, which may include a reason indicating that the request was rejected. If an alternative APN has been determined, the SMF may notify the MME of this. This message may be sent to the MME via the SGW.

[0094] Step 10. The MME knows that the request has been rejected and can decide whether to provide service through APN replacement 510. This can be decided using the MME's internal configuration, subscription information received from the UDM / HSS, or information received in step 9. If the APN has been replaced, the MME can again send a Create Session Request to the SMF to request session creation, in which case the procedure from step 2 302 in FIG. 3 can be repeated. In this case, the S-NSSAI for the APN replaced by the MME is selected by the SMF and transmitted to the terminal via the PCO. Also, the network may not explicitly inform the terminal of the replaced APN.

[0095] Meanwhile, APN replacement may be applied by the decision of the MME even if the Counting NF notifies the APN to be replaced in step 7 or the SMF does not notify the APN to be replaced in step 8. In this case, if the session creation request is rejected through step 8, the MME may decide to replace the APN and select an APN to make a session creation request.

[0096] Figure 6 shows a control procedure that takes into account the slice quota when connecting to a 4G network.

[0097] Step 1. The UE may perform a PDN connection creation process for connecting to a 4G network or an Attach process incorporating a PDN connection creation request 601. This corresponds to steps 1 to 3 in FIG. 3 described above.

[0098] Step 2. The SMF that has received the session creation request determines whether a slice connection or session creation is possible for the terminal according to the above embodiment, and if possible, can determine a per slice aggregated maximum bit rate (per slice AMBR) for the terminal 602. At this time, the maximum transmission rate for each slice indicates the maximum transmission rate of data that one terminal can transmit and receive through one slice. At this time, the SMF can immediately calculate the AMBR for each APN if it can be determined. If two or more PDN connections are generated for one slice and APN and the Per Slice Session AMBR can be determined for each Session / Connection similar to 5G, the SMF can determine the Per Slice APN-AMBR as the sum of the AMBRs of the sessions belonging to the same slice. If one slice is supported by two or more SMFs or the SMFs of each session are different, the above calculation can be performed by the PCF instead of the SMF.

[0099] Step 3. The SMF transmits the calculated per slice APN-AMBR to the UPF via a PFCP message 603. If the 4G network does not support an explicit per slice APN-AMBR, the calculated per slice APN-AMBR may be substituted for the APN-AMBR and transmitted.

[0100] Step 4. The SMF may convey the calculated per slice APN AMBR to the MME via the Allowed APN-AMBR field of the Create Session Response message 604. This message may be conveyed to the MME via the SGW.

[0101] Step 5. The MME may store the received APN-AMBR and include it in a NAS response message sent to the terminal. The MME may also update the UE-AMBR with the received APN-AMBR 605.

[0102] Step 6. The MME may send a response message to the terminal informing it that the Attach or PDN connection creation request has been accepted 606. This message may include the S-NSSAI inserted by the SMF into the PCO, and the APN-AMBR calculated taking into account the slice-specific quota for the created session.

[0103] Meanwhile, in the description of the embodiment, it has been described that the NAS response message to the terminal request includes information related to the slice, but this can be expressed in the form of a message requested by the NW rather than a response message. More specifically, in the embodiment included in Fig. 3, the response message of step 11 to the terminal's session creation request in step 1 can be seen as a response message from the terminal's perspective, but can actually be delivered in the form of a network-triggered request for creating a default bearer when the session creation is in progress in the network.

[0104] FIG. 7 is a diagram illustrating a structure of a terminal according to an embodiment of the present disclosure.

[0105] 7, the terminal may include a transceiver 710, a terminal controller 720, and a memory unit 730. In the present disclosure, the terminal controller 720 may be defined as a circuit, an application specific integrated circuit, or at least one processor.

[0106] The transceiver 710 may transmit and receive signals to and from other network entities, such as receiving system information from a base station, a synchronization signal or a reference signal, or control information and data for a terminal.

[0107] The terminal controller 720 may control the overall operation of the terminal according to the embodiment proposed in the present disclosure. For example, the terminal controller may control the signal flow between each block to perform the operations according to the above-mentioned drawings and flowcharts. Specifically, the terminal controller may operate according to a control signal from a base station and transmit and receive messages or signals with the terminal and / or network entity.

[0108] The storage unit 730 can store at least one of information transmitted and received via the transmission / reception unit 710 and information generated via the terminal control unit.

[0109] FIG. 8 is a diagram illustrating a structure of a base station according to an embodiment of the present disclosure.

[0110] 8, the base station may include a transceiver unit 810, a base station controller 820, and a memory unit 830. In the present disclosure, the base station controller 820 may be defined as a circuit, or an application specific integrated circuit, or at least one processor.

[0111] The transceiver 810 may transmit and receive signals to and from other network entities. The transceiver may transmit, for example, system information, a synchronization signal, or a reference signal, or control information and data for the terminal to the terminal, and may transmit and receive control information and data for providing services to the terminal from the NF.

[0112] The base station controller 820 may control the overall operation of the base station according to the embodiment proposed in the present disclosure. For example, the base station controller may control the signal flow between each block to perform the operations according to the above-mentioned drawings and flowcharts. Specifically, the base station controller may transmit and receive messages or signals to and from terminals, base stations, and / or network entities.

[0113] The storage unit 830 can store at least one of information transmitted and received via the transceiver unit and information generated via the base station control unit.

[0114] FIG. 9 is a diagram illustrating a structure of an NF (including an NF instance) according to one embodiment of the present disclosure.

[0115] The NF illustrated in Fig. 9 may mean at least one of the above-mentioned MME, AMF, SMF, counting NF, UDM, and PCF, and is not limited to a specific NF. In addition, the NF may be provided in the form of an instance, and when provided as an instance, the NF exists in the form of software code, and in a physical computing system, for example, in a specific computing system existing on a core network, the NF may be allocated physical or / and logical resources from the computing system to perform the function of the NF, and may be executable. Therefore, the structure of Fig. 9 may mean a physical division or a logical division.

[0116] Referring to FIG. 9, the NF may include a transceiver unit 910, an NF control unit 920, and a memory unit 930.

[0117] The transceiver 910 may transmit and receive signals to and from other network entities. The transceiver may transmit and receive system information to, for example, other network entities (NFs) or base stations (RANs), and may transmit and receive control information and data for a terminal.

[0118] The NF control unit 920 can control the overall operation of the NF according to the embodiment proposed in this disclosure.

[0119] The storage unit 930 can store at least one of information transmitted and received via the transceiver unit and information generated via the NF control unit.

[0120] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0121] In the case of a software implementation, a computer-readable storage medium may be provided that stores one or more programs (software modules). The one or more programs stored in the computer-readable storage medium may be configured for execution by one or more processors in an electronic device. The one or more programs may include instructions that cause the electronic device to perform a method according to the embodiments described in the claims or specification of the present disclosure.

[0122] Such programs (software modules, software) can be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc-ROM (CD-ROM), digital versatile discs (DVDs), other forms of optical storage, magnetic cassette, or in a memory configured by a combination of some or all of these. Also, each of the configuration memories can be included in multiple numbers.

[0123] The program may be stored in an attachable storage device accessible via a communication network such as the Internet, an Intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device that performs the embodiments of the present disclosure via an external port. Also, a separate storage device on the communication network may be connected to a device that performs the embodiments of the present disclosure.

[0124] In the above-described specific embodiments of the present disclosure, the elements included in the disclosure are expressed in the singular or plural form according to the specific embodiments presented. However, the expressions singular or plural are selected to fit the presented situation for the convenience of explanation, and the present disclosure is not limited to the singular or plural elements, and even if an element is expressed in the plural form, it may be constituted in the singular form, and even if an element is expressed in the singular form, it may be constituted in the plural form.

[0125] Meanwhile, although the detailed description of the present disclosure has been given with respect to specific embodiments, it goes without saying that various modifications can be made without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by equivalents to the scope of the claims.

Claims

1. A method in a wireless communication system, the method being performed by a first network function entity (SMF+PGW-C) including a session management function (SMF) and a control plane function (PGW-C) of a packet data network gateway (PGW), the method comprising: receiving a first message requesting establishment of a packet data network (PDN) connection from a mobility management entity (MME); selecting a network slice associated with the PDN connection establishment based on an access point name (APN) included in the first message; Sending a second message to a second network function entity for network slice admission management to request confirmation of availability of the network slice; receiving a third message from the second network function entity, the third message including information on availability of the network slice; sending, to the MME, a fourth message comprising a response to the PDN connection establishment based on the third message; The second message includes a terminal ID and a session ID of a terminal requesting the establishment of the PDN connection, The third message includes information on a limit on the number of terminals registered in the network slice or information on a limit on the number of PDU sessions registered in the network slice, When the number of terminals registered in the network slice reaches the maximum number of terminals in the network slice, the fourth message is a PDN connection establishment rejection message including a rejection reason due to reaching the maximum number of terminals; When the number of PDU sessions registered in the network slice reaches the maximum number of PDU sessions of the network slice, the fourth message is a PDN connection establishment rejection message including a rejection reason due to reaching the maximum number of PDU sessions.

2. 2. The method of claim 1, wherein if the terminal ID is not registered in the network slice, and the number of registered terminals and the number of current PDU sessions are less than the maximum number of terminals and the maximum number of PDU sessions of the network slice, the terminal ID is registered in the network slice, the number of registered terminals and the number of current PDU sessions are increased by 1, and the third message includes information that the network slice is available.

3. 2. The method of claim 1, wherein if the terminal ID is already registered in the network slice and the current PDU session number is less than a maximum PDU session number of the network slice, the current PDU session number is increased by 1, and the third message includes information that the network slice is available.

4. A method performed by a second network function entity for managing network slice admission in a wireless communication system, comprising: receiving a second message from a first network function entity (SMF+PGW-C) including a session management function (SMF) and a control plane function (PGW-C) of a packet data network gateway (PGW), requesting confirmation of availability of a network slice; Checking availability of the network slice based on a terminal ID and a session ID included in the second message, the number of terminals registered in the network slice, and the number of current PDU sessions of the network slice; sending a third message to the first network function entity, the third message including information on availability of the network slice; The network slice is selected by the first network function entity based on an access point name (APN) in association with a packet data network (PDN) connection establishment request from a mobility management entity (MME), The terminal ID included in the second message is a terminal ID of a terminal requesting the establishment of the PDN connection, The third message includes information on a limit on the number of terminals registered in the network slice or information on a limit on the number of PDU sessions registered in the network slice, The method, characterized in that the PDN connection between the first network function entity and the MME is established based on the third message.

5. The step of checking the availability of the network slice includes: checking whether the terminal ID is registered in the network slice; Comparing the number of registered terminals and the number of current PDU sessions with a maximum number of terminals and a maximum number of PDU sessions of the network slice; If the terminal ID is not registered in the network slice and the number of registered terminals and the number of current PDU sessions are smaller than the maximum number of terminals and the maximum number of PDU sessions of the network slice, registering the terminal ID in the network slice and incrementing the number of registered terminals and the number of current PDU sessions by 1; 5. The method of claim 4, further comprising: if the terminal ID is already registered in the network slice and the current PDU session number is less than a maximum PDU session number of the network slice, increasing the current PDU session number by 1.

6. In a wireless communication system, in a first network function entity (SMF+PGW-C) including a session management function (SMF) and a control plane function (PGW-C) of a packet data network gateway (PGW), A transceiver unit for transmitting and receiving signals; A control unit connected to the transceiver unit, The control unit is Receive a first message requesting establishment of a packet data network (PDN) connection from a mobility management entity (MME); Selecting a network slice associated with the PDN connection establishment based on an access point name (APN) included in the first message; Sending a second message to a second network function entity for network slice admission management to request confirmation of availability of the network slice; receiving a third message from the second network function entity, the third message including information on availability of the network slice; configured to send, to the MME, a fourth message comprising a response to the PDN connection establishment based on the third message; The second message includes a terminal ID and a session ID of a terminal requesting the establishment of the PDN connection, The third message includes information on a limit on the number of terminals registered in the network slice or information on a limit on the number of PDU sessions registered in the network slice, When the number of terminals registered in the network slice reaches the maximum number of terminals in the network slice, the fourth message is a PDN connection establishment rejection message including a rejection reason due to reaching the maximum number of terminals; When the number of PDU sessions registered in the network slice reaches the maximum number of PDU sessions of the network slice, the fourth message is a PDN connection establishment rejection message including a rejection reason due to reaching the maximum number of PDU sessions. A first network function entity.

7. 7. The first network function entity of claim 6, wherein if the terminal ID is not registered in the network slice, and the number of registered terminals and the number of current PDU sessions are smaller than the maximum number of terminals and the maximum number of PDU sessions of the network slice, the terminal ID is registered in the network slice, the number of registered terminals and the number of current PDU sessions are increased by 1, and the third message includes information that the network slice is available.

8. 7. The first network function entity of claim 6, wherein if the terminal ID is already registered in the network slice and the current PDU session number is less than the maximum PDU session number of the network slice, the current PDU session number is increased by 1, and the third message includes information that the network slice is available.

9. In a wireless communication system, a second network function entity for managing a network slice admission includes: A transceiver unit for transmitting and receiving signals; A control unit connected to the transceiver unit, The control unit is Receive a second message from a first network function entity (SMF+PGW-C) including a session management function (SMF) and a control plane function (PGW-C) of a packet data network gateway (PGW), requesting confirmation of availability of a network slice; Confirming the availability of the network slice based on a terminal ID and a session ID included in the second message, the number of terminals registered in the network slice, and the number of current PDU sessions of the network slice; configured to send to the first network function entity a third message comprising information on availability of the network slice; The network slice is selected by the first network function entity based on an access point name (APN) in association with a packet data network (PDN) connection establishment request from a mobility management entity (MME), The terminal ID included in the second message is a terminal ID of a terminal requesting the establishment of the PDN connection, The third message includes information on a limit on the number of terminals registered in the network slice or information on a limit on the number of PDU sessions registered in the network slice, A second network function entity, characterized in that the PDN connection between the first network function entity and the MME is established based on the third message.

10. The control unit is Check whether the terminal ID is registered in the network slice; The second network function entity of claim 9, further comprising: a second network function entity configured to compare the number of registered terminals and the number of current PDU sessions with a maximum number of terminals and a maximum number of PDU sessions of the network slice.

11. The control unit is If the terminal ID is not registered in the network slice and the number of registered terminals and the number of current PDU sessions are smaller than the maximum number of terminals and the maximum number of PDU sessions of the network slice, register the terminal ID in the network slice, and increment the number of registered terminals and the number of current PDU sessions by 1; The second network function entity of claim 10, further comprising: if the terminal ID is already registered in the network slice and the current PDU session number is less than the maximum PDU session number of the network slice, the current PDU session number is configured to be increased by 1.

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