Method and apparatus for controlling network slicing in wireless communication system

Abstract

The present disclosure relates to a 5th-Generation (5G) or 6th-Generation (6G) communication system for supporting higher data transmission rates. A method of a network entity in a wireless communication system includes, based on at least one packet data unit (PDU) session or packet data network (PDN) connection established on a network slice, determining whether to transmit an update request message for the number of at least one user equipment (UE) having the at least one PDU session or PDN connection established on the network slice; sending the update request message to a network slice admission control function (NSACF) entity; and receiving an update response message from the NSACF entity, the update response message indicating whether the number of at least one UE having at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs for the network slice.

Description

Technical Field

[0001] The present disclosure generally relates to a method and apparatus for controlling network slices in a wireless communication system, and more particularly, to a method and apparatus for managing network slice quotas based on the number of user equipments (UEs) of actual usage data in a wireless communication system. Background Art

[0002] The fifth-generation (5G) mobile communication technology defines a wide frequency band, enabling high transmission rates and new services, and can be implemented not only in frequency bands below 6 gigahertz (GHz) such as 3.5 GHz, but also in frequency bands above 6 GHz, known as millimeter wave (mmWave) frequency bands (including 28 GHz and 39 GHz). In addition, the implementation of the sixth-generation (6G) mobile communication technology (referred to as the super 5G system) in the terahertz (THz) frequency band (95 GHz to 3 THz frequency band) has been considered to achieve a transmission rate fifty times faster than that of the 5G mobile communication technology and an ultra-low latency one-tenth of that of the 5G mobile communication technology.

[0003] In the initial stage of the development of 5G mobile communication technology, in order to support services and meet the performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine type communication (mMTC), the ongoing standardization work includes: beamforming and massive MIMO for reducing radio wave path loss in millimeter waves and increasing radio wave transmission distance, parameter set support for effectively utilizing millimeter wave resources and dynamic operation of time slot formats (e.g., operating multiple subcarrier spacings), initial access technology for supporting multi-beam transmission and broadband, definition and operation of bandwidth part (BWP), new channel coding methods (such as low-density parity-check (LDPC) codes for large data transmission and polar codes for highly reliable transmission of control information), L2 preprocessing, and network slices for providing dedicated networks dedicated to specific services.

[0004] In view of the services supported by 5G mobile communication technology, discussions on the improvement and performance enhancement of the initial 5G mobile communication technology continue, and the existing physical layer standardization work involves technologies such as vehicle-to-everything (V2X) technology for assisting autonomous driving vehicles to make assisted driving decisions based on information about the position and status of the vehicle transmitted by the vehicle and improving user convenience, new radio unlicensed (NR-U) technology for system operation aiming to comply with various regulatory requirements in unlicensed frequency bands, NR UE energy-saving technology, non-terrestrial network (NTN) technology as UE-satellite direct communication for providing coverage in areas where ground network communication is unavailable, and positioning technology.

[0005] In addition, the air interface architecture / protocol is being continuously standardized, involving technologies such as: Industrial Internet of Things (IIoT) technology for supporting new services through interoperability and integration with other industries, Integrated Access and Backhaul (IAB) technology for providing nodes for the expansion of the network service area by supporting wireless backhaul links and access links in an integrated manner, mobility enhancement technologies including conditional handover and Dual-Active Protocol Stack (DAPS) handover, and two-step random access (2-step RACH for NR) technology for simplifying the random access process. Standardization work is also ongoing in the system architecture / service aspect, involving technologies such as: 5G service-based architectures or interfaces for combining Network Function Virtualization (NFV) and Software Defined Network (SDN) technologies, and Mobile Edge Computing (MEC) for receiving UE location-based services.

[0006] With the commercialization of 5G mobile communication systems, the exponentially growing connected devices will be connected to the communication network. Therefore, it is envisioned that the functions and performance of 5G mobile communication systems and the integrated operation of connected devices will need to be enhanced. For this purpose, the new research planned involves: effectively supporting Extended Reality (XR) such as Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR); improving 5G performance and reducing complexity by leveraging Artificial Intelligence (AI) and Machine Learning (ML); AI service support; Metaverse service support; and drone communication.

[0007] This development of 5G mobile communication systems will not only lay the foundation for the development of the following technologies: new waveform technologies for providing coverage in the terahertz band of 6G mobile communication technologies; multi-antenna transmission technologies such as Full-Dimensional Multiple-Input Multiple-Output (FD-MIMO), array antennas, and large antennas; metamaterial-based lenses and antenna technologies for improving the coverage range of THz band signals; high-dimensional spatial multiplexing technologies using Orbital Angular Momentum (OAM); and Reconfigurable Intelligent Surface (RIS) technologies; but also lay the foundation for the development of the following technologies: full-duplex technologies for increasing the frequency efficiency of 6G mobile communication technologies and improving the system network; AI-based communication technologies for achieving system optimization by leveraging satellites and AI from the design stage and internalizing end-to-end AI support functions; and next-generation distributed computing technologies for achieving complexity levels beyond the UE operation capacity limit by leveraging ultra-high-performance communication and computing resources.

[0008] Generally, the network slice quota management method is a solution that counts the number of UEs registered to any network slice to control the number of UEs to be less than the preset maximum number of registered UEs of the S-NSSAI. However, there may be UEs that are registered to the slice but do not send user data to the data plane (hereinafter referred to as inactive UEs). Therefore, if multiple inactive UEs occupy quotas, the conventional network slice quota control scheme based on the maximum number of registered UEs may be inefficient in terms of slice resource utilization.

[0009] Therefore, there is a need in the art for a network slice quota management method that takes into account UEs with actual sessions to improve the efficiency of the network slice control scheme. Summary of the Invention

[0010] Technical Solution

[0011] This disclosure is to at least solve the above problems and / or disadvantages, and at least provide the following advantages.

[0012] Therefore, one aspect of this disclosure provides a network slice quota management method based on the number of UEs with actual usage data and sessions, so as to improve the network slice resource utilization rate in this network slice quota management method.

[0013] Another aspect of this disclosure provides a method for controlling the number of active UEs registered to any network slice and having at least one session to exceed the maximum number of registered UEs (having at least one packet data unit (PDU) session for the UE with the S-NSSAI of the UE) set for the corresponding slice.

[0014] According to one aspect of this disclosure, a method for a network entity in a wireless communication system may include: determining whether to send an update request message for the number of at least one UE having at least one PDU session or packet data network (PDN) connection established on a network slice based on the at least one PDU session or PDN connection established on the network slice; sending the update request message to a network slice admission control function (NSACF) entity; and receiving an update response message from the NSACF entity, where the update response message indicates whether the number of at least one UE having at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs of the network slice.

[0015] According to one aspect of the present disclosure, a method for an NSACF entity in a wireless communication system may include: receiving, from a network entity, an update request message for the number of at least one UE having at least one PDU session or PDN connection established on the network slice, based on the at least one PDU session or PDN connection established on the network slice; and sending an update response message to the network entity, the update response message indicating whether the number of the at least one UE having at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs of the network slice.

[0016] According to one aspect of the present disclosure, a network entity in a wireless communication system may include: a transceiver; and at least one processor coupled to the transceiver and configured to: determine whether to send an update request message for the number of at least one UE having at least one PDU session or PDN connection established on the network slice, based on the at least one PDU session or PDN connection established on the network slice; send the update request message to the NSACF entity; and receive an update response message from the NSACF entity, the update response message indicating whether the number of the at least one UE having at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs of the network slice.

[0017] According to one aspect of the present disclosure, an NSACF entity in a wireless communication system may include: a transceiver; and at least one processor coupled to the transceiver and configured to: receive, from a network entity, an update request message for the number of at least one UE having at least one PDU session or PDN connection established on the network slice, based on the at least one PDU session or PDN connection established on the network slice; and send an update response message to the network entity, the update response message indicating whether the number of the at least one UE having at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs of the network slice. Description of the Drawings

[0018] Through the following description with reference to the drawings, the above and other aspects, features, and effects of certain embodiments of the present disclosure will become more apparent, in which:

[0019] Figure 1 A 5G system architecture to which the present disclosure can be applied is shown;

[0020] Figure 2 A method for controlling a network slice according to an embodiment is shown;

[0021] Figure 3 Shows a method for registering an NSACF according to an embodiment;

[0022] Figure 4 Shows a method for discovering an NSACF according to an embodiment;

[0023] Figure 5 Shows a method for controlling network slices during a UE registration process according to an embodiment;

[0024] Figure 6 Shows a method for controlling network slices during a PDU session creation process according to an embodiment;

[0025] Figure 7 Shows another method for controlling network slices during a PDU session creation process according to an embodiment;

[0026] Figure 8 Shows the structure of a consumer NF according to an embodiment;

[0027] Figure 9 Shows the structure of an NSACF according to an embodiment; and

[0028] Figure 10 Shows the structure of a UE according to an embodiment. Detailed Description

[0029] The following description with reference to the accompanying drawings is provided to facilitate a comprehensive understanding of the embodiments of the present disclosure. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. For the sake of clarity and conciseness, descriptions of well-known functions and configurations may be omitted.

[0030] It should be understood that the embodiments of the present disclosure and the terms used herein do not intend to limit the technical features described herein to specific embodiments, and include various changes, equivalents or alternatives corresponding to the embodiments. Regarding the description of the drawings, like reference numerals may be used to refer to like or related elements. It will be understood that unless the relevant context clearly indicates otherwise, the singular form of a noun corresponding to an item may include one or more of the things. As used herein, each of the phrases such as "A or B", "at least one of A and B", "at least one of A or B", "A, B or C", "at least one of A, B and C", and "at least one of A, B or C" may include any one or all possible combinations of the items enumerated together with the corresponding one of the phrases. As used herein, terms such as "first" and "second" or "1st" and "2nd" may be used to simply distinguish corresponding components from another component, and do not limit the components in other respects (e.g., importance or order). It will be understood that if an element (e.g., a first element) is referred to as "coupled to", "coupled with", "connected to" or "connected with" another element (e.g., a second element), with or without the terms "operatively" or "communicatively", this means that the element can be coupled to the other element directly (e.g., wired), wirelessly or via a third element.

[0031] Figure 1 The 5G system architecture to which the present disclosure can be applied is shown.

[0032] The 5G mobile communication network may include a UE (e.g., a terminal) 100, a 5G RAN 110 (e.g., a base station, a gNB (5G node B), an evolved node B (eNB), etc.), and a 5G core network. Here, the UE may also be referred to as a terminal. The 5G core network may include network function (NF) entities, such as an Access and Mobility Management Function (AMF) 120 that provides a mobility management function for the UE, a Session Management Function (SMF) 135 that provides a session management function, a User Plane Function (UPF) 130 that performs a data delivery role, a Policy Control Function (PCF) 140 that provides a policy control function, a Unified Data Management (UDM) 145 that provides a data management function for subscriber data, policy control data, etc., a Unified Data Repository (UDR) that stores data of various network functions (NFs) such as the UDM 145, a Network Slice Admission Control Function (NSACF) 180, and a Network Repository Function (NRF). In addition, the 5G core network may include network function (NF) entities, such as a Network Slice Selection Function (NSSF) 160, a Network Data Analytics Function (NWDAF) 165, an Application Function (AF) 170, a Data Network (DN) 175, and an Authentication Server Function (AUSF) 180, etc.

[0033] In a communication system, a conceptual link connecting NFs in a 5G system is defined as a reference point. The following describes Figure 1 the reference points included in the 5G system architecture shown.

[0034] N1: Reference point between the UE and the AMF

[0035] N2: Reference point between the (R)AN and the AMF

[0036] N3: Reference point between the (R)AN and the UPF

[0037] N4: Reference point between the SMF and the UPF

[0038] N5: Reference point between the PCF and the AF

[0039] N6: Reference point between the UPF and the DN

[0040] N7: Reference point between the SMF and the PCF

[0041] N8: Reference point between the UDM and the AMF

[0042] N9: Reference point between two core UPFs

[0043] N10: Reference point between the UDM and the SMF

[0044] N11: Reference point between the AMF and the SMF

[0045] N12: Reference point between AMF and AUSF

[0046] N13: Reference point between UDM and the Authentication Server Function (AUSF)

[0047] N14: Reference point between two AMFs

[0048] N15: Reference point between the PCF and the AMF for non - roaming scenarios, and reference point between the PCF in the visited network and the AMF for roaming scenarios

[0049] In a 5G communication system, network slicing technology enables multiple virtualized and independent logical networks to be implemented in a physical network. To meet the special requirements of services / applications, network operators provide services by configuring virtual end - to - end networks called network slices (or slices). A network slice is identified by an identifier called a single network slice selection assistance information (S - NSSAI). The network sends a set of slices (e.g., permitted NSSAI) that the UE is allowed to use to the UE during the UE registration process, and the UE can send and receive application data through a protocol data unit (PDU) session created via an S - NSSAI (i.e., a network slice) within these slices.

[0050] In this document, AMF 120 or SMF 135 may store information about slices (S - NSSAI that may be subject to slice remapping), and may obtain alternative slice information for each slice from PCF 140 or UDM 145 in advance. When a slice that needs to be remapped appears among the slices that may be subject to slice remapping, the corresponding information is used to determine a new slice, or when a slice that needs to be remapped appears among the slices that may be subject to slice remapping, a new slice (selected S - NSSAI) is determined by requesting a new slice from PCF 140 for the slice that needs to be remapped.

[0051] When the new slice of the slice that needs to be remapped is determined, AMF 120 or SMF 135 may perform the process of obtaining the PDU session to the new slice according to the service session continuity (SSC) mode of each PDU session in the PDU session of the slice that needs to be remapped.

[0052] Additionally, when the new slice of the slice that needs to be remapped is determined, AMF 120 or SMF 135 may, when the UE 100 requests to create a PDU session for the slice that needs to be remapped, create a PDU session based on the identifier information of the new slice rather than the identifier information of the slice that needs to be remapped, and notify the UE 100 of the identifier information of the created PDU session.

[0053] The present disclosure discloses a control method for ensuring that the number of active UEs in any network slice does not exceed the maximum number of UEs set for the corresponding slice, that is, a network slice admission control (NSAC) method based on the number of active UEs. A discovery method of an NSACF (an entity that supports NSAC based on the number of active UEs in a network slice), a method for determining an NSAC method for a network slice (for example, an NSAC method based on the number of active UEs, an NSAC method based on the number of registered UEs, etc.), and a method for providing the number of active UEs in each network slice to a third party are disclosed.

[0054] Figure 2 A method for controlling a network slice according to an embodiment is shown.

[0055] In step S201, the consumer NF (or network entity) 210 may determine whether to perform an update on the number of UEs (terminals) for each slice. For example, the consumer NF may be an AMF, an SMF, or another NSACF (for example, a primary NSACF (the higher-layer NSACF in a hierarchical NSACF structure)). The SMF may support the PGW-C function at the same time, in which case the SMF corresponds to SMF+PGW-C. Several schemes for updating the number of UEs in each slice will now be described.

[0056] It may include an update scheme based on the number of slice-registered UEs (a scheme for updating the number of UEs registered to a network slice). In this scheme, if a network slice that requires NSAC is included in or removed from the allowed slices (allowed NSSAI) of a UE, the consumer NF 210 (for example, AMF) may request the NSACF 220 to perform a process of updating the number of UEs in each slice. In the request message for updating the number of UEs, the update flag may be set to increase or decrease for each case.

[0057] It may include an update scheme based on the number of active UEs on a network slice (i.e., a scheme for updating the number of UEs with at least one PDU session). For a network slice that requires NSAC, if a UE with one or more PDU sessions (or PDN connections) for the corresponding slice appears (e.g., if the UE requests to establish the first PDU session (or PDN connection) for an S-NSSAI), for a network slice serving NSAC, if a UE without a PDU session (or PDN connection) for the corresponding slice appears (e.g., if the UE releases the last PDU session (or PDN connection) for an S-NSSAI), or if the network slice serving NSAC is removed from the allowed slices, the update process of the number of active UEs can be performed for the corresponding slice. In the request message for updating the number of active UEs, the update flag can be set to increase or decrease for each case. The update scheme based on the number of active UEs can use the number of UEs with at least one PDU session.

[0058] If the consumer NF 210 supports at least one of the above schemes for updating the number of UEs per slice, the consumer NF 210 can determine the scheme for updating the number of UEs per slice in the slices that require NSAC based on the information about the scheme for updating the number of UEs per slice or all slices stored in the configuration information, the UE context information within the AMF, and the information about the scheme for updating the number of UEs per slice received from the UDM or another NF.

[0059] In step S202, the consumer NF 210 can send a request message for updating the number of UEs to the NSACF 220.

[0060] If in step S201 the consumer NF 210 determines to perform the update according to the update scheme based on the number of active UEs (i.e., the NSAC scheme based on the number of UEs with at least one PDU session / PDN connection) (e.g., if the consumer NF is set to the NSAC scheme based on the number of UEs with at least one PDU session / PDN connection), the consumer NF 210 can use the same request message as the update scheme based on the number of slice-registered UEs (e.g., the Nnsacf_NSAC_NumOfUEsUpdate_Request message). In this case, the request message can include an active UE count indicator indicating the update scheme based on the number of active UEs. When the consumer NF 210 performs the update scheme based on the number of active UEs, the request message sent by the consumer NF 210 to the NSACF 220 can be a separate message defined for updating the number of active UEs.

[0061] The request message may include a UE identifier (UE ID), a slice identifier and an identifier of the slice for which the number of UEs to be updated is requested (S-NSSAI), an active UE count indicator for the update scheme of the number of UEs to be updated being an update scheme based on the number of active UEs (however, if a message separately defined for updating the number of active UEs is used, the active UE count indicator may not be included), information for determining the access type of the UE (e.g., 3rd Generation Partnership Project (3GPP) access or non-3GPP access) or whether the access of the UE requires NSAC (access type), and an update flag. If, for the corresponding slice, there is a UE having at least one PDU session (or PDN connection) with a network slice that requires NSAC (e.g., if the UE requests to establish the first PDU session or PDN connection for the S-NSSAI), the update flag may be set to increase, and if, for the corresponding slice, there is a UE having no PDU session or PDN connection with a network slice that requires NSAC (e.g., if the UE releases the last PDU session or PDN connection for the S-NSSAI), or if the network slice that requires NSAC is deleted from the allowed slices, the update flag may be set to decrease.

[0062] In step S203, the NSACF 220 may check the availability of the number of UEs having at least one PDU session for each network slice and update the number of UEs. That is, the NSACF 220 determines whether the access type in the message received in step S202 is an access that requires NSAC based on the configuration information, and if the access type is an access that does not require NSAC, the update request is accepted without increasing or decreasing the number of UEs (that is, the response message sent to the consumer NF 210 in step S204 may include a result indicating approval).

[0063] If the request message received in step S202 includes an active UE count indicator, or if the request message received in step S202 is a message separately defined for active UE counting, and if the update flag in the request message received in step S202 is set to increase, the NSACF 220 may operate as follows.

[0064] If the UE ID included in the request message is already included in the active UE list for the S-NSSAI indicated in the request message received in step S202, the NSACF 220 maintains the number of active UEs for the corresponding S-NSSAI without increasing or decreasing the number of active UEs. If the UE ID included in the request message does not exist in the active UE list for the S-NSSAI indicated in the request message received in step S202, the NSACF 220 counts the current number of active UEs for the corresponding S-NSSAI and determines whether the current number of active UEs for the corresponding S-NSSAI has reached the preset maximum number of active UEs for the network slice. If the current number of active UEs counted for the corresponding S-NSSAI does not reach the maximum number of active UEs, the NSACF 220 adds the corresponding UE ID to the active UE list and increases the current number of active UEs for the corresponding slice. If it is determined that the current number of active UEs for the corresponding S-NSSAI has reached the maximum number of active UEs, the NSACF 220 may set a result value indicating that the corresponding slice has reached the maximum number of active UEs and include this result value in the response message.

[0065] In step S204, the NSACF 220 may send a response message to the consuming NF 210 for the request message in step S202. This response message may include information indicating the result of updating the number of UEs for each slice (e.g., the result for each S-NSSAI). If the update request message in step S202 is a request message for updating the UE number according to an update scheme based on the number of active UEs, the information indicating the update result (the result for each S-NSSAI) may include information indicating "has reached the maximum number of UEs with at least one PDU session or PDN connection" (i.e., indicating that the number of UEs with at least one PDU session or PDN connection has reached the maximum number) or "has not reached the maximum number of UEs with at least one PDU session or PDN connection" (i.e., indicating that the number of UEs with at least one PDU session or PDN connection has not reached the maximum number).

[0066] If the consuming NF 210 is the AMF, the request message in step S202 indicates to update the number of UEs according to an update scheme based on the number of active UEs, and the information indicating the update result (the result for each S-NSSAI) indicates that the number of UEs having at least one PDU session or PDN connection has reached the maximum number. Then, the consuming NF 210 (e.g., the AMF) that receives the response message may send a message to the SMF to release the PDU sessions connected to the corresponding S-NSSAI. The corresponding message may include information indicating that "the maximum number of UEs having at least one PDU session or PDN connection has been reached" (i.e., indicating that the number of UEs having at least one PDU session or PDN connection has reached the maximum number) as the cause. Thereafter, the SMF may include the cause indicating that "the maximum number of UEs having at least one PDU session or PDN connection has been reached" (i.e., indicating that the number of UEs having at least one PDU session or PDN connection has reached the maximum number) in the NAS message sent to the UE for releasing the PDU session.

[0067] If the consuming NF 210 is the SMF, the request message in step S202 is a request message for updating the number of UEs according to an update scheme based on the number of active UEs, and the information indicating the update result (the result for each S-NSSAI) indicates that the number of UEs having at least one PDU session or PDN connection has reached the maximum number. Then, the SMF may perform a process for releasing the PDU session or rejecting the PDU session establishment request. The SMF may include the cause indicating that "the maximum number of UEs having at least one PDU session or PDN connection has been reached" (i.e., indicating that the number of UEs having at least one PDU session or PDN connection has reached the maximum number) in the NAS message sent to the UE for releasing the PDU session or rejecting the PDU session establishment request.

[0068] Figure 3 A method for registering the NSACF according to an embodiment is shown.

[0069] In step S301, if the NSACF 220 supports the method for updating the number of active UEs, the NSACF 220 may include information indicating that the NSACF 220 supports active UE counting (i.e., supports active UE counting) in the registration request message sent to the Network Repository Function (NRF) 230. Alternatively, if the NSACF 220 supports the method for updating the number of active UEs, the NSACF 220 may include the information indicating that the NSACF 220 supports active UE counting in the NSAC service capabilities included in the registration request message sent to the NRF 230.

[0070] The registration request message sent from the NSACF 220 to the NRF 230 may include the type of network function (NF type), the network function instance identifier (NF instance ID), the fully qualified domain name (FQDN) or IP address of the NF, the domain address or IP address of the network function, the public land mobile network (PLMN) ID: PLMN identifier, the slice identifier information (S-NSSAI and NSACF SA), and the NSAC service capability including information indicating whether the NSACF supports the active UE count (e.g., supports the active UE count).

[0071] In step S302, when receiving the request message from the NSACF 220, the NRF 230 may determine whether the registration of the network function can be performed and perform the registration. If the registration can be performed, the NRF 230 may include the information indicating that the registration has been performed in the response message and send the response message to the NSACF 220. If the registration cannot be performed, the NRF 230 may send a response message for notifying that the registration cannot be performed.

[0072] Figure 4 A method for discovering the NSACF according to an embodiment is shown.

[0073] In step S401, if the consumer NF 210 wishes to know the NF profile including information related to the NSACF that supports updating the number of active UEs (e.g., the address (IP address and domain address) of the NSACF, etc.), the consumer NF 210 may send a discovery request (e.g., NF discovery request) to the NRF 230. The discovery request message may include information about the type of the NF to be targeted (which may be the NSACF) (target NF type), information indicating the type of the requesting consumer NF 210 (consumer NF type), S-NSSAI, the access type of the UE (access type), the NSAC service capability (if the consumer NF 210 wishes to find the NSACF that supports the scenario of updating the number of UEs based on the number of active UEs, the information indicating that the consumer NF 210 supports the scenario of updating the number of UEs based on the number of active UEs may be included in the NSAC service capability), and the support for active UE count (if the consumer NF 210 wishes to find the NSACF that supports the scenario of updating the number of UEs based on the number of active UEs and the information indicating that the consumer NF 210 supports the scenario of updating the number of UEs based on the number of active UEs is not included in the NSAC service capability, the support for active UE count may be included).

[0074] In step S402, if the information indicating that the consumer NF 210 supports the solution of updating the UE count based on the number of active UEs is included in the NSAC service capabilities included in the discovery request message received in S401, or the support for active UE counting is included in the discovery request message, the NRF 230 may support the active UEs and include the NF profile of the NSACF for the S-NSSAI and access type within the discovery request message in the discovery response message sent to the consumer NF 210.

[0075] Figure 5 A method for controlling network slices during UE registration according to an embodiment is shown.

[0076] In step S501, the UE 510 may send a registration request message to the AMF 520. The registration request message may include information about the requested slice (requested S-NSSAI) that the UE 510 wishes to use.

[0077] In step S502, the AMF 520 may send a message requesting the UE subscription information of the UE 510 to the UDM 540. The message may include the identifier (UE ID) of the UE 510 for which registration is requested.

[0078] In step S503, the UDM 540 may include the subscriber information related to the UE ID included in the message received in S502 in the response message and send the response message to the AMF 520. The subscriber information may include information about the subscribed slice (subscribed S-NSSAI), information about the slice that requires NSAC (S-NSSAI that requires NSAC), and information indicating the solution for supporting the update of the UE count for each slice (UE count update method for each S-NSSAI). The information indicating the solution for supporting the update of the UE count for each slice may indicate at least one of the method based on the number of active UEs and the method based on the number of registered UEs. If the slice information is not included in the information indicating the solution for supporting the update of the UE count for each slice, the same method may be applied to all subscribed S-NSSAIs.

[0079] In step S504, the AMF 520 may store the information included in the response message received in step S503 in the UE context.

[0080] In step S505, if a UE with at least one PDU session (or PDN connection) corresponding to the network slice that requires NSAC appears in the corresponding slice (for example, in an Evolved Packet System (EPS), if a UE with a PDN connection for the S-NSSAI that requires NSAC requests registration for the corresponding slice in the S-NSSAI that requires NSAC included in the requested NSSAI, if a UE with a PDU session for the S-NSSAI that requires NSAC requests registration for the corresponding slice in another PLMN (i.e., the S-NSSAI that requires NSAC included in the requested NSSAI), and if the UE sends a request to establish a first PDU session (or PDN connection) for the corresponding S-NSSAI that requires NSAC, etc.), the AMF 520 may determine whether to perform the UE count update for each slice for the corresponding slice and request the NSACF 530 to update the UE count. The AMF 520 may determine the scheme for updating the UE count for each slice in the slice that requires NSAC based on the information about the scheme for updating the UE count for each slice or all slices stored in the configuration information, the UE context information in the AMF 520, and the information about the method for updating the UE count for each slice received from the UDM or another NF. If the AMF 520 determines to perform the update according to the scheme for updating the UE count based on the active UE count, the same request message as the update scheme based on the slice-registered UE count may be used. In this case, the request message may include an active UE count indicator. If the AMF 520 performs the scheme for updating the UE count based on the active UE count, the request message sent from the AMF 520 to the NSACF 530 may be a separate message defined for updating the active UE count. The request message may include the UEID, S-NSSAI, active UE count indicator (unless a message separately defined for updating the active UE count is used), access type, and update flag, as previously described herein.

[0081] In step S506, the NSACF 530 determines based on the configuration information whether the access type in the update request message received in step S505 requires NSAC. If the access type does not require NSAC, the NSACF 530 may accept the update request without increasing or decreasing the UE count (i.e., the response message sent to the AMF 520 may include a result value indicating acceptance).

[0082] If the received update request message includes an active UE count indicator, or if the update request message is separately defined for the active UE count, and if the update flag in the received update request message is set to increase, the NSACF 530 may operate as follows.

[0083] If the UE ID included in the request message is already included in the active UE list of the S-NSSAI indicated by the received request message, the NSACF 530 may maintain the number of active UEs of the corresponding S-NSSAI without increasing or decreasing the number. If the UE ID included in the request message does not exist in the active UE list of the S-NSSAI indicated by the received update request message, the NSACF 530 may count the current number of active UEs of the corresponding S-NSSAI and determine whether the current number of active UEs of the corresponding S-NSSAI has reached a preset maximum number of active UEs (i.e., the maximum number of active UEs of the network slice). If the current number of active UEs counted for the corresponding S-NSSAI has not reached the maximum number of active UEs, the NSACF 530 may add the corresponding UE ID to the active UE list and increase the current number of active UEs of the corresponding slice. If it is determined that the current number of active UEs of the corresponding S-NSSAI has reached the maximum number of active UEs, the NSACF 530 may set a result value indicating that the corresponding slice has reached the maximum number of active UEs and include the result value in the response message.

[0084] In step S506, the NSACF 530 may send a response message to the AMF 520 for the request message in step S505. The response message may include information indicating the result of updating the number of active UEs for each slice (e.g., the result for each S-NSSAI). If the request message is an update request message for updating the number of active UEs, the information indicating the update result (the result for each S-NSSAI) may include information indicating "the maximum number of UEs with at least one PDU session or PDN connection has been reached" (i.e., indicating that the number of UEs with at least one PDU session or PDN connection has reached the maximum number) or "the maximum number of UEs with at least one PDU session or PDN connection has not been reached" (i.e., indicating that the number of UEs with at least one PDU session or PDN connection has not reached the maximum number).

[0085] For an S-NSSAI (network slice) for which the maximum number of active UEs has been reached, the NSACF 530 may include, in a response message (sent to the AMF 520) to the request message of step S505, the result of each S-NSSAI indicating the update result of "the maximum number of UEs with at least one PDU session or PDN connection has been reached" (i.e., indicating that the number of UEs with at least one PDN session or PDN connection has reached the maximum number) and the fallback timer information for the corresponding slice, and send the response message. The fallback timer information for each slice includes time information and indicates that requests for the corresponding slice should not be performed during the corresponding time period. The access type information may be provided together with the fallback timer information for each slice and may indicate that requests for the corresponding slice of the corresponding access type should not be performed during the corresponding time period.

[0086] In step S507, the AMF 520 may send a registration response message (registration acceptance) in response to the registration request message to the UE 510. If the information indicating the result of updating the number of active UEs for each slice (i.e., the result of each S-NSSAI) included in the update response message received in step S506 indicates that "the maximum number of UEs with at least one PDU session or PDN connection has been reached", the AMF 520 may include the corresponding slice in the rejected NSSAI included in the registration acceptance message and may include a cause value indicating that "the maximum number of UEs with at least one PDU session or PDN connection has been reached" for the corresponding slice (i.e., the reason for slice registration rejection). The cause for each slice may be included in the rejected NSSAI, or may not be included in the rejected NSSAI but may be defined as a separate parameter. If the fallback timer information and access type information for each slice are present in the update response message received in step S506, the AMF 520 may include the fallback timer information and access type information for each slice in the registration acceptance message.

[0087] Alternatively, if the result of each S-NSSAI indicating the result of updating the number of active UEs for each slice in the update response message received in step S506 indicates that "the maximum number of UEs with at least one PDU session or PDN connection has not been reached", the AMF 520 may include the corresponding slice in the allowed NSSAI included in the registration acceptance message and may include a cause value for the slice registration acceptance indicating that "the maximum number of UEs with at least one PDU session or PDN connection has not been reached". The cause for each slice may be included in the allowed NSSAI, or may not be included in the allowed NSSAI but may be defined as a separate parameter.

[0088] If the requested S-NSSAI is included in the rejected NSSAI included in the registration acceptance message received from the AMF 520, and there is a slice in which there is a reason indicating "the maximum number of UEs with at least one PDU session or PDN connection has been reached", the UE 510 may not request the creation of a PDU session for the corresponding slice. If there is fallback timer information for a slice in the registration acceptance message, the UE 510 is not allowed to send a PDU session creation message during the time period included in the fallback timer information for the slice. If the registration acceptance message includes fallback timer information and access type information, for the corresponding access type and the slice for which there is fallback timer information, during the time period included in the fallback timer information, the UE 510 is not allowed to send a PDU session creation message. After the time included in the fallback timer information has passed, the UE 510 may perform a PDU session creation request for the corresponding slice. Alternatively, if there is fallback timer information for a slice in the registration acceptance message, the UE 510 is not allowed to include the slice in the NSSAI requested in the registration request message during the time period included in the fallback timer information. If the registration acceptance message includes access type information and fallback timer information, for the corresponding access type and the slice for which there is fallback timer information, during the time period included in the fallback timer information, the UE 510 is not allowed to include the corresponding slice in the NSSAI requested in the registration request message.

[0089] Figure 6 A method for controlling network slices during a PDU session creation process according to an embodiment is shown.

[0090] In step S601, the UE 510 may send a NAS message including a PDU session creation request message to the AMF 520. The NAS message may include an S-NSSAI, a data network name (DNN), a PDU session ID, and an N1 SM container (PDU session establishment request).

[0091] In step S602, if the S-NSSAI included in the received NAS message is a slice that requires NSAC, as determined based on configuration information or UE context information stored in the AMF 520, the AMF 520 may send a request message for updating the number of UEs for the corresponding slice to the NSACF 530. If the scheme for updating the number of UEs for the corresponding slice or all slices is set to the scheme for updating the number of UEs based on active UEs in the configuration information or UE context information stored in the AMF 520, the AMF 520 may Figure 5Send an update request message to the NSACF 530 in a similar manner to step S505 in []. If there is a UE in the corresponding slice that has at least one PDU session or PDN connection with the network slice that requires NSAC, if a UE with a PDU session for the S-NSSAI that requires NSAC requests registration for the corresponding slice in another PLMN (i.e., the requested NSSAI includes the S-NSSAI that requires NSAC), and if the UE sends a request to establish the first PDU session or PDN connection for the corresponding S-NSSAI that requires NSAC, etc., the AMF 520 can determine whether to execute the scheme of updating the number of UEs per slice for the corresponding slice and request the NSACF 530 to update the number of UEs. The AMF 520 can determine the scheme for updating the number of UEs per slice for each slice that requires NSAC based on the information about the scheme of updating the number of UEs per slice or all slices stored in the configuration information, the UE context information in the AMF 520, and the information about the scheme of updating the number of UEs per slice received from the UDM or another NF. If the AMF 520 determines to perform the update according to the scheme of updating the number of UEs based on the active UE count, the same request message as the update scheme based on the slice-registered UE count can be used. In this case, the request message can include an active UE count indicator indicating the scheme of updating the number of UEs based on the active UE count. If the AMF 520 executes the scheme of updating the number of UEs based on the active UE count, the request message sent from the AMF 520 to the NSACF 530 can be a separate message defined for updating the active UE count. The request message can include the UEID, S-NSSAI, active UE count indicator, access type, and update flag, as described previously in this document.

[0092] In step S603, the NSACF 530 determines whether the access type in the update request message received in step S602 is one that requires NSAC based on the configuration information. If the access type is one that does not require NSAC, the NSACF 530 can accept the update request without increasing or decreasing the number of UEs. That is, the response message sent to the AMF 520 can include a result value indicating acceptance.

[0093] If the received update request message includes an active UE count indicator, or if the update request message is a message separately defined for active UE counting, and if the update flag in the received update request message is set to increment, the NSACF 530 can operate as follows.

[0094] If the UE ID included in the request message is already included in the S-NSSAI active UE list indicated by the received request message, the NSACF 530 may maintain the number of active UEs for the corresponding S-NSSAI without increasing or decreasing the number. If the UE ID included in the request message does not exist in the S-NSSAI active UE list indicated by the received update request message, the NSACF 530 may count the current number of active UEs for the corresponding S-NSSAI and determine whether the current number of active UEs for the corresponding S-NSSAI has reached the preset maximum number of active UEs for the network slice. If the current number of active UEs counted for the corresponding S-NSSAI has not reached the maximum number of active UEs, the NSACF 530 may add the corresponding UE ID to the active UE list and increase the current number of active UEs for the corresponding slice. If it is determined that the current number of active UEs for the corresponding S-NSSAI has reached the maximum number of active UEs, the NSACF 530 may set a result value indicating that the corresponding slice has reached the maximum number of active UEs and include the result value in the response message.

[0095] In step S603, the NSACF 530 may send a response message to the AMF 520 for the request message in step S602. The response message may include the result for each S-NSSAI indicating the result of updating the number of UEs for each slice. If the update request message is a request message for updating the number of active UEs, the result for each S-NSSAI indicating the update result may include information indicating "has reached the maximum number of UEs with at least one PDU session or PDN connection" (i.e., indicating that the number of UEs with at least one PDU session or PDN connection has reached the maximum number) or "has not reached the maximum number of UEs with at least one PDU session or PDN connection" (i.e., indicating that the number of UEs with at least one PDU session or PDN connection has not reached the maximum number).

[0096] When the S-NSSAI has reached the maximum number of active UEs, the NSACF 530 may include, in the response message (sent to the AMF 520) to the request message in step S602, the result of each S-NSSAI indicating that "the maximum number of UEs with at least one PDU session or PDN connection has been reached" (i.e., indicating that the number of UEs with at least one PDN session or PDN connection has reached the maximum number), the fallback timer information of the corresponding slice, and the access type information, and send the response message. The fallback timer information of each slice includes time information and indicates that requests for the corresponding slice should not be executed during the corresponding time period. The access type information may be provided together with the fallback timer information of each slice and may be included to indicate that requests for the corresponding slice of the corresponding access type should not be executed during the corresponding time period.

[0097] In step S604, the AMF 520 may send a NAS message (i.e., a PDU session acceptance message or a PDU session rejection message) to the UE 510. If the cause included in the update response message received from the NSACF 530 in step S603 indicates that "the maximum number of UEs with at least one PDU session or PDN connection has been reached", the AMF 520 may include information indicating that the PDU session creation request has been rejected and the cause indicating that "the maximum number of UEs with at least one PDU session or PDN connection has been reached" in the NAS message sent to the UE 510. If there is fallback timer information and access type information for each slice in the response message received in step S603, the AMF 520 may include the fallback timer information and access type information for each slice in the response message to the PDU session creation request.

[0098] In step S605, if the cause included in the message received from the NSACF 530 in step S603 indicates that "the maximum number of UEs with at least one PDU session or PDN connection has not been reached", the AMF 520 may perform the remaining PDU session creation process without performing step S504.

[0099] If the response message to the PDU session creation request includes a slice with fallback timer information, the UE 510 is not allowed to send a PDU session creation request message during the time period included in the fallback timer information of the slice. If the response message to the PDU session creation request also includes access type information together with the fallback timer information, for the slice with fallback timer information and the corresponding access type, the UE 510 is not allowed to send a PDU session creation request message during the time period included in the fallback timer information of the slice. After the time included in the fallback timer information has passed, the UE 510 may perform a PDU session creation request for the corresponding slice.

[0100] Figure 7 Another method for controlling network slices during the PDU session creation process according to an embodiment is shown.

[0101] In step S701, the UE 510 may send a NAS message including a PDU session creation request message to the AMF 520. The NAS message may include an S-NSSAI, a DNN, a PDU session ID, and an N1 SM container (PDU session establishment request).

[0102] In step S702, the AMF 520 may select the SMF 550 based on the S-NSSAI and DNN included in the NAS message received in step S701. The AMF 520 may send an SM context creation request message to the selected SMF 550. The message may include the S-NSSAI, DNN, PDU session ID, and PDU session request included in the NAS message received in step S701.

[0103] In step S703, the SMF 550 may send a message requesting the subscription information of the UE 510 that requests to perform a PDU session procedure to the UDM 540. The message requesting the subscription information may include the UE ID, S-NSSAI, and DNN of the requested UE 510.

[0104] In step S704, the UDM 540 may include the subscription information related to the UE ID, S-NSSAI, and DNN received in step S703 in the message sent to the SMF 550. The message may include a UE quantity update method for each S-NSSAI, and the update method is a supported UE quantity update method indicating at least one of a method for updating the UE quantity based on the active UE quantity and a method for updating the UE quantity based on the registered UE quantity. If the slice information is not included in the method for supporting the UE quantity update method for each S-NSSAI, the same method may be applied to all subscribed S-NSSAIs.

[0105] In step S705, if the S-NSSAI requires NSAC, as determined based on the configuration information or the UE context information stored in the SMF 550, the SMF 550 may send a request message to the NSACF 530 for updating the number of UEs for the corresponding slice. If the scheme for updating the number of UEs for the corresponding slice or all slices is set to the scheme for updating the number of UEs based on the active UE number in the configuration information or the UE context information stored in the SMF 550, the SMF 550 may send an update request message to the NSACF 530 in a manner similar to Figure 6 step S602 therein. If there is a UE in the corresponding slice that has at least one PDU session or PDN connection with the network slice that requires NSAC, if a UE with a PDU session for the S-NSSAI that requires NSAC requests registration for the corresponding slice in another PLMN (i.e., the requested NSSAI includes the S-NSSAI that requires NSAC), and if the UE requests to establish a first PDU session or PDN connection for the corresponding S-NSSAI that requires NSAC, the SMF 550 may determine whether to update the number of UEs for each slice of the corresponding slice and request the NSACF 530 to update the number of UEs. The SMF 550 may determine the scheme for updating the number of UEs for each slice of the slice that requires NSAC based on the information about the scheme for updating the number of UEs for each slice or all slices stored in the configuration information, the UE context information in the SMF 550, and the information about the method for updating the number of UEs received from the UDM or another NF. If the SMF 550 determines that the update is performed according to the scheme for updating the number of UEs based on the active UE number, the same request message as the update scheme based on the slice-registered UE number may be used. In this case, the request message may include an active UE count indicator indicating the scheme for updating the number of UEs based on the active UE number. If the SMF 550 performs the scheme for updating the number of UEs based on the active UE number, the request message sent from the SMF 550 to the NSACF 530 may be a separate message defined for updating the active UE number. The request message may include the UE ID, S-NSSAI, active UE count indicator, access type, and update flag, as previously described herein.

[0106] In step S706, the NSACF 530 determines based on the configuration information whether the access type in the update request message received in step S705 is one that requires NSAC. If the access type is one that does not require NSAC, the NSACF 530 may accept the update request without increasing or decreasing the number of UEs (i.e., the response message sent to the SMF 550 may include a result value indicating acceptance).

[0107] If the received update request message includes an active UE count indicator, or if the update request message is separately defined for active UE counting, and if the update flag in the received update request message is set to increment, the NSACF 530 may operate as follows.

[0108] If the UE ID included in the request message is already included in the S-NSSAI active UE list indicated by the received request message, the NSACF 530 may maintain the number of active UEs for the corresponding S-NSSAI without incrementing or decrementing that number. If the UE ID included in the request message does not exist in the S-NSSAI active UE list indicated by the received update request message, the NSACF 530 may count the current number of active UEs for the corresponding S-NSSAI and determine whether the current number of active UEs for the corresponding S-NSSAI has reached the preset maximum number of active UEs for the network slice. If the current number of active UEs counted for the corresponding S-NSSAI has not reached the maximum number of active UEs, the NSACF 530 may add the corresponding UE ID to the active UE list and increment the current number of active UEs for the corresponding slice. If it is determined that the current number of active UEs for the corresponding S-NSSAI has reached the maximum number of active UEs, the NSACF 530 may set a result value indicating that the corresponding slice has reached the maximum number of active UEs and include that result value in the response message.

[0109] In step S706, the NSACF 530 may send a response message to the SMF 550 for the update request message in step S705. The response message may include the result for each S-NSSAI indicating the result of updating the number of UEs for each slice. If the update request message is for updating the active UE count, the result for each S-NSSAI indicating the update result may include information indicating "has reached the maximum number of UEs with at least one PDU session or PDN connection" (i.e., indicating that the number of UEs with at least one PDU session or PDN connection has reached the maximum number) or "has not reached the maximum number of UEs with at least one PDU session or PDN connection" (i.e., indicating that the number of UEs with at least one PDU session or PDN connection has not reached the maximum number).

[0110] When the S-NSSAI has reached the maximum number of active UEs, the NSACF 530 may include in the response message (sent to the SMF 550) to the request message in step S705 the information of the update result indicating that "the maximum number of UEs with at least one PDU session or PDN connection has been reached" (i.e., indicating that the number of UEs with at least one PDN session or PDN connection has reached the maximum number), the fallback timer information for the corresponding slice, and the access type information, and send the response message. The fallback timer information for each slice includes time information and is information used to indicate that requests for the corresponding slice should not be executed during the corresponding time period. The access type information may be provided together with the fallback timer information for each slice, and this may be included to indicate that requests for the corresponding slice of the corresponding access type should not be executed during the corresponding time period.

[0111] In step S707, the SMF 550 may send a response message to the SM context creation request message in step S702 to the AMF 520. The corresponding message may include the cause received from the NSACF 530, the SM context ID, or the N1 SM container (PDU session reject (cause)). The N1 SM container may represent the message sent to the UE 510 through the AMF 520.

[0112] If the message received by the SMF 550 in step S706 includes a cause indicating that "the maximum number of UEs with at least one PDU session or PDN connection has been reached", the SMF 550 may include in the response message sent to the AMF 520 a cause indicating that "the maximum number of UEs with at least one PDU session or PDN connection has been reached", and include the N1 SM container (PDU session reject (cause)). The cause included in the PDU session reject information may be set to the information indicating that "the maximum number of UEs with at least one PDU session or PDN connection has been reached".

[0113] If there is fallback timer information and access type information for each slice in the response message received by the SMF 550 in step S706, the SMF 550 may include the corresponding information in the N1 SM container.

[0114] If the message received by the SMF 550 in step S706 includes a cause indicating that "the maximum number of UEs with at least one PDU session or PDN connection has not been reached", and if a PDU session can be created, a cause value indicating success and the created SM context ID may be included in the message sent to the AMF 520.

[0115] In step S708a, the AMF 520 may send the N1 SM container information included in the message received from the SMF 550 in step S707 to the UE 510 via a NAS message. The UE 510 receives a PDU session rejection (cause), and if the received cause indicates "the maximum number of UEs with at least one PDU session or PDN connection has been reached", the UE 510 may not request to create a PDU session for the corresponding slice. If the slice for which the response message to the PDU session creation request includes fallback timer information, the UE 510 is not allowed to send a PDU session creation request message during the time period included in the fallback timer information for the corresponding slice. If the response message to the PDU session creation request includes access type information and fallback timer information, for the slice with fallback timer information and the corresponding access type, the UE 510 is not allowed to send a PDU session creation request message during the time period included in the fallback timer information. After the time included in the fallback timer information has passed, the UE 510 may execute a PDU session creation request for the corresponding slice.

[0116] In step S708b, if the cause in the received response message indicates "the maximum number of UEs with at least one PDU session or PDN connection has not been reached", step S708a is omitted, and the remaining part of the PDU session establishment process may be executed.

[0117] Figure 8 The structure of a consumer NF according to an embodiment is shown. The consumer NF 800 may correspond to the AMF, SMF, or NSACF, and the corresponding devices may be configured separately or combined to form one device. In Figure 8 it, the consumer NF 800 may include at least one controller (processor) 810 and a transceiver 820 including a receiver and a transmitter. The consumer NF 800 may include a memory. The transceiver 820 and the memory may be connected to at least one controller 810 such that the transceiver 820 and the memory may operate under the control of at least one controller 810.

[0118] At least one controller 810 may control a series of processes such that the operations of the consumer NF 800 (AMF, SMF, and NASCF) described in the present disclosure may be executed. The transceiver 820 may send signals to and receive signals from another NASCF entity 900 and the UE 1000. The signals may include control messages, data information, etc. Figures 1 to 7

[0119] Figure 9 Figure 9 The structure of an NSACF according to an embodiment is shown. In Figure 9In [description], the NSACF 900 may include at least one controller (processor) 910 and a transceiver 920 including a receiver and a transmitter. The NSACF 900 may include a memory. The transceiver 920 and the memory may be connected to the at least one controller 910 such that the transceiver 920 and the memory may operate under the control of the at least one controller 910.

[0120] The at least one controller 910 may control a series of processes such that the operations of the NSACF 900 described in the present disclosure may be performed. The transceiver 920 may send signals to and receive signals from the consumer NF 800 and the UE 1000. The signals may include control messages, data information, etc. Figures 1 to 7 The signal may include control messages, data information, etc.

[0121] Figure 10 The structure of a UE according to an embodiment is shown. In Figure 10 In [description], the UE 1000 may include at least one controller (or processor) 1010 and a transceiver 1020 including a receiver and a transmitter. The UE 1000 may include a memory. The transceiver 1020 and the memory may be connected to the at least one controller 1010 such that the transceiver 1020 and the memory may operate under the control of the at least one controller 1010.

[0122] The at least one controller 1010 may control a series of processes such that the operations of the UE 1000 described in the present disclosure may be performed. The transceiver 1020 may send signals to and receive signals from the consumer NF 800 and the NSACF 900. The signals may include control information, data, etc. Figures 1 to 7 The signal may include control information, data, etc.

[0123] The network entities described herein may have the same structure as the NSACF in Figure 9 and may be combined into one device or may be implemented as separate devices.

[0124] As described above, a method performed by a network entity in a wireless communication system may include: determining the number of UEs for updating a network slice based on a first scheme; sending a request message to the NSACF requesting an update to the number of UEs for the network slice; and receiving a response message from the NSACF, the response message including information indicating the result of the update to the number of UEs for the network slice.

[0125] The first scheme may be a scheme for performing an update to the number of UEs for the network slice based on the number of UEs for at least one session connected to the network slice, and the request message may include an indicator indicating the performance of the update to the number of UEs for the network slice in the first scheme.

[0126] The request message may include a flag indicating whether the number of UEs for a network slice needs to be increased or decreased.

[0127] The response message may include information indicating whether the number of UEs for at least one session connected to the network slice has reached the maximum number preset by the NSACF.

[0128] The network entity may be an Access and Mobility Management Function (AMF), a Session Management Function (SMF), or another NSACF.

[0129] As described above, a method performed by an NSACF device in a wireless communication system may include: receiving, from a network entity, a request message for updating the number of UEs for a network slice; identifying whether the request message includes an indicator indicating to perform the update of the number of UEs for the network slice in a first scenario; counting, when the request message includes the indicator, the number of UEs for at least one session connected to the network slice; and sending, to the network entity, a response message including information indicating the result of the update of the number of UEs for the network slice.

[0130] The request message may include a flag indicating whether the number of UEs for a network slice needs to be increased or decreased.

[0131] The method may further include: determining whether the counted number of UEs for at least one session connected to the network slice has reached a preset maximum number; and including, in the response message, information indicating whether the counted number of UEs for at least one session connected to the network slice has reached the preset maximum number.

[0132] The method may further include: increasing the number of UEs for the network slice when the flag included in the request message indicates that the number of UEs for the network slice needs to be increased and it is determined that the counted number of UEs for at least one session connected to the network slice has not reached the preset maximum number.

[0133] As described above, slicing can be controlled by only counting the UEs with actual sessions, thereby improving the utilization rate of network slice resources.

[0134] As used in connection with various embodiments of the present disclosure, the term "module" may include a unit implemented in hardware, software, or firmware, and may be used interchangeably with other terms (e.g., "logic", "logic block", "portion", or "circuitry"). A module may be a single integrated component or its smallest unit or portion adapted to perform one or more functions. For example, according to an embodiment, a module may be implemented in the form of an Application Specific Integrated Circuit (ASIC).

[0135] Various embodiments described herein may be implemented as software (e.g., a program) including one or more instructions readable by a machine (e.g., an electronic device) stored in a storage medium (e.g., internal memory or external memory). For example, a processor (e.g., a processor) of a machine (e.g., an electronic device) may call at least one of the one or more instructions stored in the storage medium and execute the instruction. This enables the machine to operate to perform at least one function in accordance with the at least one called instruction. The one or more instructions may include code generated by a compiler or code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Herein, the term "non-transitory" simply means that the storage medium is a tangible device and does not include signals (e.g., electromagnetic waves), but this term does not distinguish between data stored semi-permanently in the storage medium and data stored temporarily in the storage medium.

[0136] Although the present disclosure has been shown and described with reference to various embodiments of the present disclosure, those skilled in the art will understand that various changes may be made in form and detail without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method for a network entity in a wireless communication system, the method comprising: Determining whether to send an update request message for the number of at least one user equipment (UE) having at least one packet data unit (PDU) session or packet data network (PDN) connection established on the network slice, based on the at least one PDU session or PDN connection established on the network slice; Sending the update request message to a network slice admission control function (NSACF) entity; And Receiving an update response message from the NSACF entity, the update response message indicating whether the number of the at least one UE having the at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs of the network slice.

2. The method according to claim 1, wherein, Determining whether to send the update request message includes: Determining to send the update request message when a first PDU session or a first PDN connection associated with the network slice is established by the UE, or when a second PDU session or a second PDN connection associated with the network slice is released.

3. The method according to claim 1, wherein The update request message includes single network slice selection assistance information (S-NSSAI), a UE identifier, and an update flag, and Wherein, the update flag indicates whether to increase or decrease the number of the at least one UE having the at least one PDU session or PDN connection established on the network slice.

4. The method according to claim 3, wherein In the following cases, increase the number of the at least one UE having the at least one PDU session or PDN connection established on the network slice: The update flag indicates an increase in the number of the at least one UE, The UE identifier is not included in the UE list associated with the S-NSSAI, and The increased number of the at least one UE is less than the maximum number of registered UEs of the network slice.

5. The method according to claim 1, further comprising: Sending a network function discovery request message for the NSACF entity to a network repository function (NRF) entity; And Receiving a network function discovery response message from the NRF entity, the network function discovery response message including the network function profile of the NSACF entity, Wherein, the network function discovery request message includes an NSACF service capability indicator for supporting monitoring and controlling the number of at least one UE having at least one PDU session or PDN connection established on the network slice.

6. A method for a network slice admission control function (NSACF) entity in a wireless communication system, the method comprising: Receiving, from a network entity, an update request message for the number of at least one user equipment (UE) having at least one packet data unit (PDU) session or packet data network (PDN) connection established on the network slice, based on the at least one PDU session or PDN connection established on the network slice; And Send an update response message to the network entity, where the update response message indicates whether the number of at least one UE having at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs of the network slice.

7. The method according to claim 6, wherein The update request message is received when a UE establishes a first PDU session or a first PDN connection associated with the network slice, or when a second PDU session or a second PDN connection associated with the network slice is released.

8. The method according to claim 6, wherein, The update request message includes single network slice selection assistance information S-NSSAI, a UE identifier, and an update flag, and wherein the update flag indicates whether to increase or decrease the number of at least one UE having at least one PDU session or PDN connection established on the network slice.

9. The method according to claim 8, further comprising: In the following cases, increasing the number of at least one UE having at least one PDU session or PDN connection established on the network slice: The update flag indicates an increase in the number of at least one UE, The UE identifier is not included in the UE list associated with the S-NSSAI, and The increased number of at least one UE is less than the maximum number of registered UEs of the network slice.

10. The method according to claim 6, further comprising: Send a network function registration request message to a network repository function NRF entity; and Receive a network function response message from the NRF entity, wherein the network function registration message includes an NSACF service capability indicator for supporting monitoring and controlling the number of at least one UE having at least one PDU session or PDN connection established on the network slice.

11. A network entity in a wireless communication system, the network entity comprising: A transceiver; and At least one processor, the at least one processor being coupled to the transceiver and configured to: Based on at least one packet data unit PDU session or packet data network PDN connection established on a network slice, determine whether to send an update request message for the number of at least one user equipment UE having at least one PDU session or PDN connection established on the network slice; Send the update request message to a network slice admission control function NSACF entity; and Receive an update response message from the NSACF entity, the update response message indicating whether the number of at least one UE having at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs of the network slice.

12. The network entity according to claim 11, the network entity according to claim 11, wherein, The at least one processor is further configured to operate according to the method according to any one of claims 2 to 5.

13. A network slice admission control function NSACF entity in a wireless communication system, the NSACF entity comprising: A transceiver; and At least one processor, the at least one processor being coupled to the transceiver and configured to: Receive an update request message from a network entity for the number of at least one user equipment (UE) having at least one packet data unit (PDU) session or packet data network (PDN) connection established on the network slice, based on the at least one PDU session or PDN connection established on the network slice; And Send an update response message to the network entity, the update response message indicating whether the number of the at least one UE having at least one PDU session or PDN connection established on the network slice reaches the maximum number of registered UEs of the network slice.

14. The NSACF entity according to claim 13, wherein, The at least one processor is further configured to operate according to the method according to any one of claims 7 to 10.

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