Method and apparatus for controlling network slice access in a wireless communication system

Abstract

This disclosure relates to 5G or 6G communication systems for supporting higher data transmission rates. This disclosure provides a method for network slice access control in a wireless communication system, performed by a network function (NF). The method includes sending an event exposure subscription message to a Network Slice Admission Control Function (NSACF) including information about the status of a single network slice selection assistance information (S-NSSAI); receiving an event exposure subscription response message from the NSACF indicating the result of the subscription; and receiving an event exposure notification message from the NSACF including information about the event.

Description

Technical Field

[0001] This disclosure generally relates to wireless communication systems, and more specifically, to methods and apparatus for network slicing access in wireless communication systems. Background Technology

[0002] 5G mobile communication technology defines a wide frequency band, enabling high transmission rates and new services. It can be implemented not only in the "sub-6GHz" band, such as 3.5GHz, but also in the "above-6GHz" band, including 28GHz and 39GHz, known as millimeter waves. Furthermore, 6G mobile communication technology (referred to as "super 5G systems") is being considered in terahertz bands (e.g., the 95GHz to 3THz band) to achieve transmission rates fifty times faster than 5G and ultra-low latency one-tenth that of 5G.

[0003] At the outset of 5G mobile communication technology development, standardization was underway regarding beamforming and massive MIMO to support services and meet performance requirements associated with enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC). This standardization aimed to mitigate radio wave path loss in millimeter waves and increase radio wave transmission distance, support parameter sets for dynamic operation (e.g., operating multiple subcarrier spacings) for efficient utilization of millimeter wave resources and time slot formats, initial access technologies to support multi-beam transmission and broadband, the definition and operation of BWP (bandwidth portion), new channel coding methods such as LDPC (low-density parity-check) codes for large-volume data transmission and polar codes for highly reliable transmission of control information, layer 2 (L2) preprocessing, and network slicing for providing dedicated networks for specific services.

[0004] Currently, given the services that 5G mobile communication technology needs to support, discussions are underway regarding improvements and performance enhancements to the initial 5G mobile communication technology. Physical layer standardization already exists for technologies such as V2X (Vehicle-to-Everything), NR-U (New Radio Unlicensed), NR User Equipment (UE) power saving, Non-Terrestrial Network (NTN), and positioning. Among these, V2X (Vehicle-to-Everything) is used to assist autonomous vehicles in making driving decisions and enhance user convenience based on vehicle location and status information sent by the vehicle. NR-U (New Radio Unlicensed) aims to comply with the system operation requirements related to various regulations in unlicensed frequency bands. Non-Terrestrial Network (NTN) is UE-satellite direct communication used to provide coverage in areas where communication with terrestrial networks is not possible.

[0005] In addition, standardization is underway for air interface architectures / protocols such as those for supporting new services through interoperability and convergence with other industries in the Industrial Internet of Things (IIoT); for providing nodes for network service area extension by supporting wireless backhaul and access links in an integrated manner; mobility enhancements including conditional handover and DAPS (Dual Active Stack) handover; and for two-step random access (2-step RACH for NR) to simplify the random access process. Standardization is also underway for 5G baseline architectures (e.g., service-based architectures or service-based interfaces) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and for system architectures / services for Mobile Edge Computing (MEC) based on UE location reception services.

[0006] With the commercialization of 5G mobile communication systems, the number of connected devices will increase exponentially, necessitating enhanced functionality and performance of 5G mobile communication systems, as well as integrated operation of connected devices. To this end, new research related to extended reality (XR) is being undertaken to effectively support AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality), and other technologies by leveraging artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, and drone communication, while also improving 5G performance and reducing complexity.

[0007] Furthermore, this development of 5G mobile communication systems will not only serve as the foundation for developing new waveforms for providing coverage in the terahertz band for 6G mobile communication technologies, such as full-dimensional MIMO (FD-MIMO), multi-antenna transmission technologies like array antennas and massive MIMO, metamaterial-based lenses and antennas for improving terahertz band signal coverage, and high-dimensional spatial multiplexing technologies using OAM (orbital angular momentum) and RIS (reconfigurable smart surfaces), but will also serve as the foundation for developing full-duplex technologies to improve the frequency efficiency of 6G mobile communication technologies and enhance system networks, AI-based communication technologies to achieve system optimization and internalize end-to-end AI support functions by leveraging satellites and AI (artificial intelligence) from the design stage, and next-generation distributed computing technologies to achieve services with complexity exceeding the operational capabilities of UEs by utilizing ultra-high-performance communication and computing resources.

[0008] The 3rd Generation Partnership Project (3GPP), which controls the standardization of cellular mobile communications, has named the new CN architecture the 5G Core (5GC) and standardized it to facilitate the evolution from legacy 4G LTE systems to 5G systems. Compared to the Evolved Packet Core (EPC), the legacy network core of 4G, the 5GC supports the following differentiated features.

[0009] 5GC employs network slicing functionality. As a requirement of 5G systems, 5GC can support various types of terminals and services, such as eMBB, URLLC, and mMTC. Terminals / services have different requirements for the network slicing (CN). For example, eMBB services require high data rates, while URLLC services require high stability and low latency. Network slicing is a publicly disclosed technology designed to meet these requirements.

[0010] In wireless communication systems, network slicing technology enables the provision of various virtual networks that can offer dedicated services. When a new UE or Protocol Data Unit (PDU) session attempts to access a network slice via network slice access control, the wireless communication system can perform access control based on the usage of each network slice. There is a need in the art for greater efficiency in network slicing technology and for a method to reduce signaling overhead when performing network slice access control in a wireless communication system. Summary of the Invention

[0011] Technical issues

[0012] This disclosure has been made to address at least the aforementioned problems and / or disadvantages, and to provide at least the following advantages.

[0013] Technical solution

[0014] According to one aspect of this disclosure, a method for network slice access control in a wireless communication system, performed by an Access and Mobility Management Function (AMF), includes: receiving from a UE a first Protocol Data Unit (PDU) session establishment request message including information about a network slice; sending a first generation request message for a PDU session to a first network entity managing the UE's PDU sessions; receiving from the first network entity a response message including information indicating that PDU session generation has failed, in response to the first generation request message; and sending to the UE a first PDU session establishment rejection message including information about a backoff timer, in response to the first PDU session establishment request message. The backoff timer indicates the time until the UE sends a second PDU session establishment request.

[0015] According to one aspect of this disclosure, an AMF in a wireless communication system includes a transceiver and a processor. The processor is configured to receive, via the transceiver, a first Protocol Data Unit (PDU) session establishment request message including information about network slicing from a UE; send via the transceiver a first generation request message for a PDU session to a first network entity managing the UE's PDU sessions; receive via the transceiver a response message from the first network entity in response to the first generation request message, including information indicating that PDU session generation has failed; and send via the transceiver a first PDU session establishment rejection message to the UE in response to the first PDU session establishment request message, including information about a backoff timer. The backoff timer indicates the time until the UE sends a second PDU session establishment request.

[0016] Technical effect

[0017] Therefore, one aspect of this disclosure is to provide a method and apparatus for efficiently performing network slice access control in a wireless communication system.

[0018] One aspect of this disclosure is to provide a method and apparatus for reducing signaling overhead during network slice access control in a wireless communication system. Attached Figure Description

[0019] The above and other aspects, features, and advantages of certain embodiments of this disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0020] Figure 1 The network structure of a 5G system according to an embodiment is shown;

[0021] Figure 2A and Figure 2B A network slice access control method in a wireless communication system according to an embodiment is shown;

[0022] Figure 3A and Figure 3B A network slice access control method in a wireless communication system according to an embodiment is shown;

[0023] Figure 4 A network slicing access control method in a wireless communication system according to an embodiment is shown; and

[0024] Figure 5 The configuration of network entities in a wireless communication system according to an embodiment is shown. Detailed Implementation

[0025] In the following, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be noted that in the drawings, the same or similar elements are preferably represented by the same or similar reference numerals. For clarity and brevity, detailed descriptions of known functions or configurations that might obscure the subject matter of this disclosure will be omitted.

[0026] The terms described below are defined with reference to the functionality in this disclosure and may vary depending on the intent or practice of the user and provider. Therefore, they should be defined based on the entire contents of this specification.

[0027] In the accompanying drawings, some components are exaggerated, omitted, or shown schematically. The dimensions of the components do not perfectly reflect their actual dimensions. The same reference numerals are used for identical or equivalent components in all drawings.

[0028] The embodiments of this disclosure complete the disclosure, and these embodiments are provided to fully inform those skilled in the art to which this disclosure pertains of the scope of the disclosure.

[0029] Throughout the specification, the same reference numerals refer to the same parts.

[0030] For ease of description, terms are provided to indicate network entities or network functions and entities of an edge computing system, as well as terms to indicate messages and identification information used in this disclosure. Therefore, this disclosure is not limited to the terms described below, and other terms indicating objects with equivalent technical meanings may be used.

[0031] 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” can include all possible combinations of items listed together in the corresponding phrase. As used herein, terms such as “first” and “second” or “first” and “second” can be used simply to distinguish the corresponding component from another component without limiting the components in terms of importance or order.

[0032] As used herein, for ease of description, terms are provided as examples for identifying access nodes and representing network entities, messages, interfaces between network entities, and various identifying information. Therefore, this disclosure is not limited to these terms, and these terms may be replaced by other terms representing objects having equivalent technical concepts.

[0033] For ease of description, this document uses the terms and names defined in the 3GPP 5G and NR standards of current communications standards. However, this disclosure is not limited to these terms and names and can be equally applied to wireless communication systems conforming to other standards such as 3GPP GS / NR (the fifth-generation mobile communication standard).

[0034] In the following text, a base station can be an entity that allocates resources to a terminal, and can be at least one of an eNodeB, Node B, base station (BS), radio access network (RAN), access network (AN), RAN node, radio access unit, base station controller, or node on a network. A UE can be at least one of a terminal capable of performing communication functions, a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia device. In this disclosure, downlink (DL) refers to the radio transmission path of a signal transmitted from the BS to the terminal, and uplink (UL) refers to the radio transmission path of a signal transmitted from the terminal to the BS. Although LTE or LTE-A systems have been described in conjunction with embodiments, by way of example, embodiments can also be applied to other communication systems with similar technical backgrounds or channel configurations. Embodiments can be modified within the scope of this disclosure without significantly departing from the determination of those skilled in the art, and such modifications can be applied to other communication systems.

[0035] Figure 1 The network structure of a 5G system according to an embodiment is shown.

[0036] refer to Figure 1 Network technology can refer to relevant standards defined by the International Telecommunication Union (ITU) or 3GPP, and includes... Figure 1 Each component in the network architecture can refer to a physical entity or software, or hardware combined with software, that performs a separate function. The reference numerals shown as N1, N2, N3, ..., Nxxx indicate known interfaces between NFs in the 5G CN.

[0037] Figure 1The 5G system may include a 5G CN (5GC), a BS 120, and a UE 110. The 5GC may include an Access and Mobility Management Function (AMF) 150 for managing the mobility of the UE 110, a Session Management Function (SMF) 160 for managing sessions, a User Plane Function (UPF) 130 for connecting to a Data Network (DN) 140 to perform data transmission functions, a Network Slice Selection Function (NSSF) 190 for selecting network slices to serve the UE 110, an Authentication Server Function (AUSF) 151 for authenticating network entities in the 5G system, a Network Exposure Function (NEF) (not shown) for sending or receiving events and support capabilities occurring in the 5G system to external entities, a Network Repository Function (NRF) (not shown) for managing registration information about NFs, a Policy Control Function (PCF) 180 for providing policy control functions for network operators, and a User Data Management (UDM) 153 for providing data management functions such as subscriber data and policy control data. The Unified Data Storage Library (UDR) (not shown) that stores data for various NFs such as UDM 153 and the Application Function (AF) 130 that provides application services can communicate with the 5GC.

[0038] The conceptual link connecting NFs in a 5G system is defined as a reference point. (Including...) Figure 1 The following are example reference points in the 5G system architecture as shown in the diagram.

[0039] N1 is the reference point between UE 110 and AMF 150.

[0040] N2 is the reference point between (R)AN 120 and AMF 150.

[0041] N3 is the reference point between (R)AN 120 and UPF 130.

[0042] N4 is the reference point between SMF 160 and UPF 130.

[0043] N5 is the reference point between PCF 180 and AF 170.

[0044] N6 is the reference point between UPF 130 and DN 140.

[0045] N7 is the reference point between SMF 160 and PCF 180.

[0046] N8 is the reference point between UDM 153 and AMF 150.

[0047] N9 is the reference point between the two core UPF 130s.

[0048] N10 is the reference point between UDM 153 and SMF 160.

[0049] N11 is the reference point between AMF 150 and SMF 160.

[0050] N12 is the reference point between AMF 150 and AMF 151.

[0051] N13 is the reference point between UDM 153 and the Authentication Server Function (AUSF 151).

[0052] N14 is the reference point between the two AMF 150s.

[0053] N15 serves as a reference point between PCF 180 and AMF 150 in non-roaming scenarios and between PCF 180 and AMF 150 in the surveyed network in roaming scenarios.

[0054] N22 is the reference point between AMF 150 and NSSF 190.

[0055] Figure 1 This is a view showing an example of the network architecture of a 5G system.

[0056] AMF 150 is the entity used to manage the access and mobility of UE 110. As an example, AMF 150 can perform network functions such as UE 110 registration, connection, reachability, mobility management, access identification / authentication, and mobility event generation. SMF 160 can perform management functions for UE 110's PDU sessions. For example, SMF 160 can perform network functions such as establishing, modifying, or releasing sessions and maintaining the tunnel between UPF 130 and BS 120, as well as allocating and managing UE 110's IP address, user plane selection, and control. UPF 130 can perform data processing functions, transmitting data sent by UE 110 to DN 140 (which is an external network) or transmitting data received from DN 140 to UE 110. UPF 130 can perform network functions such as acting as an anchor point between Radio Access Technologies (RATs), providing connectivity with PDU sessions and AF 170, packet routing and forwarding, packet inspection, application of user plane policies, and creating traffic usage reports or buffers.

[0057] PCF 180 can manage operator policy information used to provide services in 5G systems, and UDM 153 can perform functions such as generating authentication information for 3GPP security, managing a list of network functions (NFs) supporting UE 110, and managing subscription information. 5G systems support a technology called Session and Service Continuity (SSC) mode, which supports session continuity to improve user quality of experience (QoE) or support mission-critical services.

[0058] exist Figure 1 When UE 110 registers with the network, UE 110 can send identification information about the network slice to be requested (i.e., the requested S-NSSAI) to AMF 150, and AMF 150 can consider the requested S-NSSAI and subscriber information to provide UE 110 with information about the network slices that UE 110 can use (the allowed NSSAI). In order to send data to and receive data from a specific data network (DN) 140 through the allowed network slice (the allowed NSSAI), UE 110 can select one of the allowed network slices, request the data network name (DNN) of the network slice to generate a PDU session, and send and receive data through the generated PDU session.

[0059] In 5G systems, network slicing is a technology and architecture that implements several virtualized, independent logical networks within a single physical network. Network operators can configure virtual end-to-end networks, called network slices, and provide services to meet specified service / application requirements. Network slices are identified by an identifier called Single Network Slice Selection Auxiliary Information (S-NSSAI), and network operators provide network slices to UEs to allow them to receive services.

[0060] When a UE registers in the network, it sends identifier information about the network slice it requests (i.e., the requested S-NSSAI) to the AMF. The AMF then considers the requested S-NSSAI and subscriber information to provide the UE with information about the network slices the UE can use (the allowed NSSAI). Even if the UE does not provide information about the network slice it requests, the AMF can still provide the allowed NSSAI. In this case, the allowed NSSAI may include information about the default network slice (the default configured NSSAI) included in the UE's subscriber information and information about the network slice set as the default (i.e., the default subscribed S-NSSAI) from the information about the subscribed network slices.

[0061] When a new UE or PDU session attempts to access a network slice via the network slice admission control function in a wireless communication system (e.g., when the AMF receives a requested NSSAI from the UE), the network slice admission control function (NSACF) can perform access control based on the usage of each network slice. In this case, the following methods can be used for each network slice.

[0062] When the number of currently registered UEs in a network slice reaches the maximum number of registered UEs for that network slice, the NSACF can reject new UEs' access to the corresponding network slice. When the maximum number of registered UEs has not been reached, access to the corresponding network slice can be allowed. When a new UE requests access to a new network slice, the AMF can send a request message to inquire with the NSACF whether access is permitted.

[0063] NSACF can perform access control based on the number of UEs that have at least one or more PDU sessions or PDN connections when registering to a network slice (i.e., the number of registered UEs with at least one PDU session / PDN connection per S-NSSAI).

[0064] When the number of currently registered UEs with at least one PDU session / PDN connection per S-NSSAI of a network slice reaches the maximum number of registered UEs with at least one PDU session / PDN connection per S-NSSAI of a network slice, the NSACF may deny new UEs access to the corresponding network slice. When the maximum number has not been reached, access to the corresponding network slice may be allowed.

[0065] A network node (NF) or network entity can simultaneously support different network systems, and such an NF, network node, or network entity can be referred to as a combined node, combined NF, merged node, merged NF, interconnected node, or interconnected NF as previously described. The functionality of an NF exemplified as a combined node can be achieved through interconnection between two or more network entities. For example, the symbols "+" or " / " can be used to indicate an NF that simultaneously supports different network systems. For instance, when the 5GS SMF and the Evolved Packet System (EPS) Packet Data Network Gateway Control (PGW-C) are configured as a combined node, the combined node can be represented as, for example, PGW-C / SMF, PGW-C+SMF, SMF / PGW-C, or SMF+PGW-C. When a new UE sends a PDU session establishment request for a new network slice, SMF+PGW-C can send a request message to inquire whether the NSACF allows access to the new network slice. When the NSACF sends a message indicating rejection, the SMF (or SMF+PGW-C) can reject the PDU session establishment request for the corresponding UE.

[0066] When the current number of PDU sessions in a network slice (i.e., the number of PDU sessions per S-NSSAI) reaches the maximum number of PDU sessions per S-NSSAI for the corresponding network slice, the NSACF may refuse access to the corresponding network slice for a new UE. When the maximum number of sessions has not been reached, the NSACF may allow access to the corresponding network slice. When a new UE sends a PDU session establishment request for a new network slice, the SMF may send a request message to inquire whether the NSACF allows access. When the NSACF sends a message indicating rejection, the SMF may reject the PDU session establishment request for the corresponding UE.

[0067] exist Figure 1 In the NSACF process, the NSACF can manage the following quotas for each network slice through the NSAC procedure. For example, it can manage quotas such as the number of registered UEs per network slice, the number of PDU sessions established per network slice, and the number of registered UEs per network slice with at least one PDU session / PDN connection. In the NSACF process for the number of registered UEs per network slice, the AMF can include an increase or decrease request indicator for the number of registered UEs for the corresponding network slice in each message sent to the NSACF when registering or deregistering a UE in a network slice. The NSACF can count the number of registered UEs per network slice and reject requests from the AMF to increase the number of UEs for the corresponding network slice when the number of registered UEs per network slice reaches a predetermined maximum value. In the NSACF process for the number of PDU sessions per network slice, the SMF can request the NSACF to increase or decrease the number of PDU sessions per network slice when creating or releasing a PDU session for each network slice. NSACF can count the number of PDU sessions per network slice, and when the number of PDU sessions per network slice reaches a predetermined maximum value, it will reject requests from SMF to increase the number of PDU sessions for the corresponding network slice.

[0068] During the NSACF process for determining the number of registered UEs with at least one PDU session or PDN connection per network slice, the SMF may include an increase or decrease request indicator for the number of registered UEs for the corresponding network slice in each message sent by the UE to the NSACF during the first PDU session generation or the last PDU session release for each network slice. The NSACF may count the number of registered UEs with at least one PDU session or PDN connection per network slice, and when the number of registered UEs with at least one PDU session or PDN connection per network slice reaches a predetermined maximum value, it will reject requests from the SMF to increase the number of UEs for the corresponding network slice.

[0069] Figure 2A and Figure 2B A network slice access control method in a wireless communication system according to an embodiment is shown. Figure 2A and 2B The example illustrates the NSAC method based on the number of registered UEs with at least one PDU session / PDN connection per network slice (per S-NSSAI).

[0070] Reference Figure 2A In step 201, the UE can send a registration request message to the AMF via the RAN. The registration request message may include information about the network slice (one or more) used for the registration request (e.g., the requested NSSAI).

[0071] In step 202, the AMF may include permitted network slice information (e.g., permitted NSSAI) in the registration acceptance message sent to the UE via the RAN.

[0072] In step 203, the UE may send a PDU session establishment request message that includes the S-NSSAI (e.g., one of the S-NSSAIs included in the allowed NSSAIs received in step 202) and the PDU session ID.

[0073] In step 204, the AMF can select SMF+PGW-C. The AMF can send an SM context generation request for the PDU session to the selected SMF+PGW-C. The SM context generation request message may include the PDU session ID and S-NSSAI received in step 203.

[0074] In step 205, when the S-NSSAI received in step 204 is the target of EPC counting, the SMF+PGW-C, or information indicating whether it is the NSAC target for each S-NSSAI in the EPC, can be included in the configuration information. In an S-NSSAI that is the NSAC target in the EPC, the SMF+PGW-C can perform the NSAC procedure when the UE accesses through the EPC. In an S-NSSAI that supports interoperability, whether the S-NSSAI supports interoperability (i.e., whether it can be used in the EPC) can be stored in the configuration information. When the SMF+PGW-C is set as the NSAC based on the number of registered UEs with at least one PDU session / PDN connection per S-NSSAI, it can operate as follows.

[0075] Specifically, when the UE establishes the first PDU session / PDN connection associated with the corresponding S-NSSAI, the SMF+PGW-C can send an update request message related to network slice access control to the NSACF. The corresponding update request message may include at least one of the information in 1-1) to 1-4).

[0076] 1-1) UE ID: may include UE identifier.

[0077] 1-2) S-NSSAI: may include the S-NSSAI to be updated.

[0078] 1-3) NF ID: can include the ID of SMF+PGW-C.

[0079] 1-4) - Flag: Can be set to "Increase".

[0080] In step 206, when the flag is set to, for example, "add" in the update request message received in step 205, NSACF can operate as follows.

[0081] When the UE ID, S-NSSAI, and NF ID received in step 205 have been stored, the NSACF may include a result indication in the update response message related to network slice access control sent to the SMF+PGW-C. This result indication indicates that the maximum number of UEs per S-NSSAI or the maximum number of UEs with at least one PDU session / PDN connection per S-NSSAI has not been reached.

[0082] In step 206, when the UE ID, S-NSSAI, and NF ID received in step 205 are not stored in NSACF, NSACF can identify whether the number of registered UEs with at least one PDU session / PDN connection per S-NSSAI of the corresponding S-NSSAI reaches the maximum value of the number of registered UEs with at least one PDU session / PDN connection per S-NSSAI of the corresponding S-NSSAI.

[0083] When the maximum value has been reached, in step 206, the NSACF may deny new UE access to the corresponding network slice. In this case, the NSACF may include an indication in the response message related to network slice access control sent to the SMF+PGW-C that the maximum number of UEs per S-NSSAI has been reached, or the maximum number of UEs per S-NSSAI with at least one PDU session / PDN connection has been reached.

[0084] When the maximum value is not reached, the NSACF may allow access to the corresponding network slice in step 206. In this case, the NSACF may include a result indication in the response message sent to SMF+PGW-C indicating that the maximum number of UEs per S-NSSAI (or the maximum number of UEs with at least one PDU session / PDN connection per S-NSSAI) has not been reached. The NSACF may store the S-NSSAI, NF ID, and UE ID included in the message received in step 205, and for the corresponding S-NSSAI, increment the current number of registered UEs with at least one PDU session / PDN connection per S-NSSAI by 1.

[0085] In step 207, when the result indication received from the NSACF in step 206 indicating that the maximum number of UEs per S-NSSAI (or the maximum number of UEs with at least one PDU session / PDN connection per S-NSSAI) has not been reached, the SMF+PGW-C may send an SM context response message to the AMF including information indicating that the SM context generation request in step 204 was successful.

[0086] When an update response message is received in step 206, including an indication of the maximum number of UEs reaching each S-NSSAI (or the maximum number of UEs with at least one PDU session / PDN connection reaching each S-NSSAI), the SMF+PGW-C may send an SM context response message to the AMF in step 204, indicating that the SM context generation request failed. For example, the SM context response message may include at least one of the information in 2-1) to 2-4).

[0087] 2-1) Result indication: may include result indication indicating that the SM context failed to generate the request.

[0088] 2-2) Reasons: may include one of the following: a reason value indicating S-NSSAI congestion, a reason value indicating S-NSSAI resource shortage, or a reason value indicating S-NSSAI rejection due to NSAC.

[0089] 2-3) Backoff timer for AMF: This may include a backoff timer that can be used by the AMF. This value may be the same as the backoff timer included in the N1 SM container.

[0090] 2-4) N1 SM container (PDU session rejected (reason, backoff timer))

[0091] Reference Figure 2BIn step 208a, when the SM context response message received in step 207 includes an N1SM container (e.g., an N1 SM container including PDU session rejection), the AMF can send a PDU session establishment rejection message to the UE via the RAN, including information indicating PDU session rejection (reason, backoff timer). When the SM context response message received in step 207 does not include a backoff timer, the AMF can include the backoff timer in the PDU session rejection message based on configuration information. In this case, the AMF can set the backoff timer to be included in the session establishment rejection message based on the backoff timer for the AMF included in the SM context response message in step 207 or the backoff timer included in the configuration information (e.g., a timer selected from at least one timer value that can be set to a backoff timer for the UE or a backoff timer for the AMF).

[0092] In step 208a, the UE may receive a message including information indicating PDU session rejection, and when the corresponding message includes a backoff timer, start the backoff timer and may not send the PDU session establishment request message associated with the corresponding S-NSSAI until the backoff timer expires. If the corresponding backoff timer expires (i.e., if the received backoff timer time has elapsed), the UE may send the PDU session establishment request message associated with the corresponding S-NSSAI.

[0093] In step 208b, when the SM context response message received in step 207 includes at least one of the following: a result indication of failure, a cause value indicating S-NSSAI congestion, a shortage of S-NSSAI resources, or S-NSSAI rejection due to NSAC, and when the SM context response message in step 207 does not include a backoff timer for the AMF, the AMF may start a timer where the backoff timer stored as configuration information for the corresponding S-NSSAI (e.g., the S-NSSAI for the message in step 204 or step 207) is set to its expiration value. When the SM context response message in step 207 includes a backoff timer for the AMF, the AMF may set the value of the backoff timer for the AMF, instead of the backoff timer stored in the configuration information, to the timer's expiration value and start the corresponding timer.

[0094] In steps 209a and 209b, when the S-NSSAI timer (i.e., the AMF's backoff timer) started by the AMF in step 208b has not expired, and when a PDU session establishment request message including the corresponding S-NSSAI is received from the UE, the AMF may send a PDU session establishment rejection message to the UE and may not send an SM context generation request message to the SMF+PGW-C. In this case, the PDU session establishment rejection message may include the reason and backoff timer information as in step 208a. In this case, the AMF may set the backoff timer to be included in the session establishment rejection message based on the backoff timer for the AMF included in the SM context response message in step 207 or the backoff timer included in the configuration information (e.g., a timer selected from at least one timer value that can be set as a backoff timer for the UE or a backoff timer for the AMF). In step 210, the timer started by the AMF in step 208b may expire.

[0095] In step 211a, step 211b is executed at the AMF when the timer for S-NSSAI started by the AMF in step 208b expires, and when a PDU session establishment request message including the corresponding S-NSSAI is received from the UE. Specifically, a series of operations can be performed in steps 204 to 207, in which the AMF sends an SM context generation request message and receives an SM context response message in response (i.e., the AMF sends a create SM context message to the SMF+PGW-C). The AMF can send a PDU session establishment acceptance or PDU session establishment rejection to each UE based on the message received from the SMF+PGW-C.

[0096] Figure 3A and Figure 3B A network slice access control method in a wireless communication system according to an embodiment is shown. Figure 3A and Figure 3B The example illustrates the NSAC method based on the number of PDU sessions per S-NSSAI.

[0097] Reference Figure 3A In step 301, the UE can send a registration request message to the AMF via the RAN. The registration request message may include information about one or more network slices(s) for which registration is requested (e.g., the requested NSSAI).

[0098] In step 302, the AMF may include permitted network slice information (e.g., permitted NSSAI) in the registration acceptance message sent to the UE via the RAN.

[0099] In step 303, the UE may send a PDU session establishment request message to the AMF, including an S-NSSAI (e.g., one of the S-NSSAIs included in the allowed NSSAIs received in step 302) and a PDU session ID.

[0100] In step 304, the AMF can select an SMF. The AMF can send an SM context generation request for the PDU session to the selected SMF. The SM context generation request message may include the PDU session ID and S-NSSAI.

[0101] In step 305, when the S-NSSAI received in step 304 is set to NSAC based on the number of PDU sessions per S-NSSAI, the SMF can operate as follows.

[0102] Specifically, when a UE establishes a PDU session associated with the corresponding S-NSSAI, the SMF can send an update request message related to network slice access control to the NSACF. The corresponding update request message may include at least one of the information in 3-1) to 3-4).

[0103] 3-1) UE ID: may include UE identifier.

[0104] 3-2) S-NSSAI: may include the S-NSSAI to be updated.

[0105] 3-3) NF ID: can include the ID of SMF.

[0106] 3-4) Flag: can be set to "Add".

[0107] In step 306, when the flag is set to, for example, "add" in the update request message received in step 305, NSACF can operate as follows.

[0108] When the UE ID, S-NSSAI, and NF ID received in step 305 are already stored, the NSACF may include a result indication in the update response message related to network slice access control sent to the SMF, indicating that the maximum number of PDU sessions per S-NSSAI has not been reached.

[0109] In step 306, when the UE ID, S-NSSAI and NF ID received in step 305 are not stored in NSACF, NSACF can identify whether the current number of PDU sessions per network slice corresponding to S-NSSAI has reached the number of PDU sessions per S-NSSAI corresponding to S-NSSAI.

[0110] When the maximum value has been reached, in step 306, the NSACF may deny new UE access to the corresponding network slice. In this case, the NSACF may include a result indication that the number of PDU sessions per network slice has reached the maximum value in the response message related to network slice access control sent to the SMF.

[0111] When the maximum value is not reached, the NSACF can allow access to the corresponding network slice in step 306. In this case, the NSACF can include a result indication in the response message sent to the SMF indicating that the maximum number of PDU sessions per S-NSSAI has not been reached. The NSACF can store the S-NSSAI, NF ID, and UEID included in the message received in step 305, and increment the current number of PDU sessions per network slice corresponding to the S-NSSAI by 1.

[0112] In step 307, when the result indication received from NSACF in step 306 indicating that the maximum number of PDU sessions per S-NSSAI has not been reached, SMF may send an SM context response message to AMF including information indicating that the SM context generation request in step 304 was successful.

[0113] When an update response message including a result indication indicating that the maximum number of PDU sessions per S-NSSAI has been reached is received in step 306, the SMF may send an SM context response message to the AMF in step 304 indicating that the SM context generation request failed. For example, the SM context response message may include at least one of the information in 4-1) to 4-4).

[0114] 4-1) Result indication: may include result indication of failure.

[0115] 4-2) Reasons: may include one of the following: S-NSSAI congestion, S-NSSAI resource shortage, and S-NSSAI being rejected due to NSAC.

[0116] 4-3) Backoff timer for AMF: This may include a backoff timer that can be used by the AMF. This value may be the same as the backoff timer included in the N1 SM container.

[0117] 4-4) N1 SM container (PDU session rejected (reason, backoff timer))

[0118] Reference Figure 3BIn step 308a, when the SM context response message received in step 307 includes an N1SM container (e.g., an N1 SM container including PDU session rejection), the AMF can send a PDU session establishment rejection message to the UE via the RAN, including information indicating PDU session rejection (reason, backoff timer). When the SM context response message received in step 307 does not include a backoff timer, the AMF can include the backoff timer in the PDU session rejection message based on configuration information. In this case, the AMF can set the backoff timer to be included in the session establishment rejection message based on the backoff timer for the AMF included in the SM context response message in step 307 or information stored in the configuration information (e.g., a timer selected from at least one timer value that can be set to a backoff timer for the UE or a backoff timer for the AMF).

[0119] In step 308a, the UE may receive a message including information indicating PDU session rejection, and when the corresponding message includes a backoff timer, start the backoff timer and may not send the PDU session establishment request message associated with the corresponding S-NSSAI until the backoff timer expires. If the corresponding backoff timer expires (i.e., if the received backoff timer time has elapsed), the UE may send the PDU session establishment request message associated with the corresponding S-NSSAI.

[0120] In step 308b, when the SM context response message received in step 307 includes a result indication of failure or a reason value indicating that S-NSSAI is congested, S-NSSAI resources are insufficient, or S-NSSAI has been rejected due to NSAC, and when the SM context response message in step 307 does not include a backoff timer for the AMF, the AMF may start a timer where the backoff timer stored as configuration information for the corresponding S-NSSAI (e.g., the S-NSSAI for the message in step 304 or step 307) is set to its expiration value. When the SM context response message in step 307 includes a backoff timer for the AMF, the AMF may set the value of the backoff timer for the AMF, instead of the backoff timer stored in the configuration information, to the timer's expiration value and start the corresponding timer.

[0121] In steps 309a and 309b, when the timer for the S-NSSAI initiated by the AMF in step 308b has not expired, and when a PDU session establishment request message including the corresponding S-NSSAI is received from the UE, the AMF may send a PDU session establishment rejection message to the UE and may not send an SM context generation request message to the SMF+PGW-C. In this case, the PDU session establishment rejection message may include the reason and backoff timer information as in step 208a. In this case, the AMF may set the backoff timer to be included in the session establishment rejection message based on the backoff timer for the AMF included in the SM context response message in step 307 or the backoff timer included in the configuration information (e.g., a timer selected from at least one timer value that can be set to the backoff timer for the UE or the backoff timer for the AMF).

[0122] In step 310, the timer started by AMF in step 308b can expire.

[0123] In step 311a, step 311b is executed when the timer for S-NSSAI started by the AMF in step 308b expires, and when a PDU session establishment request message including the corresponding S-NSSAI is received from the UE. Specifically, a series of operations can be performed in steps 304 to 307, in which the AMF sends an SM context generation request message and receives an SM context response message in response (i.e., the AMF sends a create SM context message to the SMF). The AMF can send a PDU session establishment acceptance or PDU session establishment rejection to each UE based on the message received from the SMF.

[0124] Figure 4 A network slice access control method in a wireless communication system according to an embodiment is shown. Figure 4 The example illustrates an AMF-based PDU session rejection method that is subscribed to via NSACF events.

[0125] refer to Figure 4 In step 400a, the AMF may send a subscription request message for the S-NSSAI status information to the NSACF. The corresponding subscription request message may include at least one of the information in 5-1) to 5-4).

[0126] 5-1) Event ID: may include one or more of the following: the number of UEs registered to the network slice, the number of registered UEs with at least one PDU session / PDN connection to the network slice, and the number of PDU sessions established on the network slice.

[0127] 5-2) Event Filter: This may include the target S-NSSAI that is to receive status information (e.g., the number of registered UEs, the number of sessions) notifications.

[0128] 5-3) Event reporting information: can indicate threshold-based notifications or periodic notifications.

[0129] 5-4) Notification Thresholds: When event reporting information is based on thresholds, a threshold may be included. The threshold can be a numerical value or a percentage. When expecting to receive notifications about when the number of registered UEs with a network slice has reached a specific value, the AMF may set the threshold to the corresponding value. When expecting to receive notifications about when the number of registered UEs with a network slice has reached a maximum value, the AMF may set the threshold to the maximum value, or set the threshold to a predefined value indicating the maximum value. When expecting to receive notifications about when the number of registered UEs with at least one PDU session / PDN connection with a network slice has reached a specific value, the AMF may set the threshold to the corresponding value. When expecting to receive notifications about the number of registered UEs with at least one PDU session / PDN connection with a network slice, the AMF may set the threshold to the maximum value, or set the threshold to a predefined value indicating the maximum value.

[0130] When the AMF expects to receive notifications about when the number of PDU sessions for a network slice has reached a specific value, it can set the threshold to that value. When the AMF expects to receive notifications about when the number of PDU sessions for a network slice has reached a maximum value, it can set the threshold to the maximum value, or set the threshold to a predefined value that indicates the maximum value.

[0131] In step 400b, the NSACF may send a response message to the AMF in response to the subscription request message of step 400a. The corresponding response message may include information indicating the result (e.g., success or failure in the subscription request) and notification correlation information (i.e., it may include, for example, identification information used to identify the subscription information generated by the subscription request message sent by the AMF in step 400a). The notification correlation information indicates correlation information regarding the notification.

[0132] In step 401, when a request for a threshold-based notification regarding the number of registered UEs with at least one PDU session / PDN connection having S-NSSAI is received from the AMF in step 400a, the NSACF may send a notification message to the AMF indicating the threshold-based notification when the threshold is received, and when the number of registered UEs with at least one PDU session / PDN connection reaches the corresponding threshold (e.g., a threshold indicating a percentage of the current value relative to the maximum value or a threshold indicating the current value). The corresponding notification message may include at least one of the information in 6-1) to 6-4).

[0133] 6-1) Event ID: This may include the event ID corresponding to the notification in the information that is the same as the event ID included in the message of step 400a. For example, the event ID may include a value indicating the number of registered UEs or the number of PDU sessions.

[0134] 6-2) Event filters: can include S-NSSAI for application notifications.

[0135] 6-3) Event reporting information: This may include network slice status information. When information on the number of registered UEs with at least one PDU session / PDN connection is included, this may include an indication of that number.

[0136] 6-4) Notification-related information: This may include associated information used for notification.

[0137] When the message sent from NSACF to AMF in step 401 is a notification message sent due to a threshold-based notification, and the threshold is set to a predefined value indicating a maximum value (e.g., the maximum number of registered UEs with at least one PDU session / PDN connection when the event ID is the number of registered UEs and the notification information includes an indication of the number of registered UEs with at least one PDU session / PDN connection), NSACF may include information indicating that the threshold has reached its maximum value, or may include a predefined value indicating the maximum value or the maximum value itself.

[0138] The notification association information contained in the response message sent by NSACF to AMF in step 400b can also be included in the notification message in step 401.

[0139] In steps 402a and 402b, the AMF may receive the notification message from step 401, and when the corresponding notification message includes information indicating that the number of registered UEs with at least one PDU session / PDN connection for S-NSSAI has reached a maximum value or 100% (or a predefined threshold), or includes information indicating that the number of PDU sessions for S-NSSAI has reached a maximum value or 100% (or a predefined threshold), if a PDU session establishment request for the corresponding S-NSSAI is subsequently received from the UE, the AMF may send a message including a PDU session establishment rejection message for the corresponding UE. The corresponding PDU session establishment rejection message may include a reason (e.g., reaching (or exceeding) the maximum number of UEs with at least one PDU session / PDN connection, reaching (or exceeding) the maximum number of PDU sessions) and a backoff timer. The AMF may perform the corresponding determination based on the operator's policy or configuration information.

[0140] In step 403, when the number of registered UEs with at least one PDU session / PDN connection for S-NSSAI decreases to below a maximum value or 100% (or a lower threshold), the NSACF may send a notification message to the AMF. This notification message includes information indicating that the corresponding value has not reached the maximum value or threshold, or information indicating that the corresponding percentage value has not reached 100% or the threshold. If the notification message sent by the NSACF to the AMF in step 401 includes information indicating that the number of PDU sessions for S-NSSAI has reached the maximum value or 100% (or a lower threshold), and if the number of PDU sessions for the corresponding S-NSSAI subsequently decreases to below the maximum value or 100% (or a lower threshold), the NSACF may send a notification message to the AMF including information indicating that the corresponding value has not reached the maximum value or threshold, or information indicating that the corresponding percentage value has not reached 100% or the threshold. In this case, the lower threshold can be received from the AMF, or it can be a threshold set by the user.

[0141] Subsequently, in steps 404a to 404c, if in step 401 a message indicating that the number of registered UEs with at least one PDU session / PDN connection for S-NSSAI has reached a maximum value or 100% (or the threshold) or an information indicating that the number of PDU sessions for S-NSSAI has reached a maximum value or 100% (or the threshold) is received, or if in step 403 a message indicating that the number of registered UEs with at least one PDU session / PDN connection for S-NSSAI has not reached the threshold or maximum value, or a message indicating that the number of PDU sessions for S-NSSAI has not reached the threshold or maximum value is received, and after the self-set timer value for the corresponding S-NSSAI expires, a PDU session establishment request for the corresponding S-NSSAI is received from the UE, then the AMF can send an SM context generation request message to the SMF. Afterwards, the remaining PDU session establishment process can be performed.

[0142] Figure 5 The configuration of network entities in a wireless communication system according to an embodiment is shown.

[0143] Figure 5 Network entities can be combined as follows Figures 1 to 4 The embodiments described are one of the network entities of NSACF, SMF+PGW-C, SMF, AMF and UE.

[0144] like Figure 5 As shown, the network entity may include a processor 501, a transceiver 503, and a memory 505. The processor 501, transceiver 503, and memory 505 of the network entity can be configured according to the above combination. Figures 1 to 4The network entity operates according to the communication method described in the embodiments. However, the components of the network entity are not limited thereto. For example, the network entity may include more or fewer components than those described above. The processor 501, transceiver 503, and memory 505 may be implemented as a single chip.

[0145] Transceiver 503 is collectively referred to as a receiver and transmitter for a network entity, and can send and receive signals to / from a UE or another network entity. The transmitted / received signals may include at least one of control information and data. For this purpose, transceiver 503 may include wired / wireless transceivers and may include various components for sending / receiving signals. Transceiver 503 can receive signals through a predetermined communication interface, output signals to processor 501, and transmit signals output from processor 501. Figure 5 When the network entity is a UE, transceiver 503 may include an RF transmitter for up-converting and amplifying the transmitted signal, and an RF receiver for low-noise amplification of the received signal and down-converting the frequency of the received signal. Transceiver 503 can receive communication signals and output them to processor 501, and transmit signals output from processor 501 to the UE or another network entity via the network. Memory 505 can store information according to... Figures 1 to 4 The memory 505 stores the programs and data required for the operation of at least one network entity in the embodiments. The memory 505 may store control information or data included in signals obtained by the network entity. The memory 505 may include storage media such as ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

[0146] Processor 501 can control a series of processes, enabling network entities to... Figures 1 to 4 The method may operate in at least one of the embodiments described in the specification. Processor 501 may include at least one processor. The method according to the embodiments described in the specification may be implemented in hardware, software, or a combination of hardware and software. When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions that enable the electronic device to perform the method according to the embodiments described in the specification.

[0147] The program (software module or 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), disk storage devices, optical disc ROM, digital versatile optical disc (DVD), or other types of optical storage devices or magnetic tape cartridges. Alternatively, the program can be stored in a memory comprising all or some of these components. Multiple such components may be present. The program can be stored in an attachable storage device accessible via a communication network, such as the Internet, intranet, local area network (LAN), wide area network (WAN), or storage area network (SAN), or a combination thereof. The storage device can be connected to the device implementing the embodiment via an external port. Individual storage devices on the communication network can be connected to the device implementing the embodiment.

[0148] It should be understood that the boxes and combinations of flowcharts in each flowchart in this document can be executed by computer program instructions.

[0149] Each box may represent a module, segment, or portion of code comprising one or more executable instructions for performing a specified logical function. In some embodiments, the functions mentioned in the boxes may occur in different orders. For example, depending on the respective function, two consecutively shown boxes may be executed substantially simultaneously or in reverse order.

[0150] As used herein, the term "unit" refers to a software element or hardware element, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). A unit plays a specific role. However, units are not limited to software or hardware and can be configured in a storage medium that can be addressed or configured to execute one or more processors. Thus, by way of example, units include elements (such as software elements, object-oriented software elements, class elements, and task elements), processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data schemas, tables, arrays, and variables. The functionality provided within components and units can be combined into a smaller number of components and units, or further divided into additional components and units. Components and units can be implemented as one or more CPUs in an execution device or secure multimedia card. According to embodiments, a unit may include one or more processors.

[0151] Although this disclosure has been described with reference to various embodiments, various changes may be made without departing from the spirit and scope of this disclosure, which is not limited by the detailed description and embodiments, but by the appended claims and their equivalents.

Claims

1. A method for network slice access control in a wireless communication system, executed by a network function (NF), the method comprising: Send an event exposure subscription message to the Network Slice Admission Control Function (NSACF) containing information about the status of Single Network Slice Selection Assistance Information (S-NSSAI). Receive an event exposure subscription response message from NSACF indicating the outcome of the subscription; Receive an event exposure notification message from NSACF that includes information about the event.

2. The method of claim 1, wherein, The event exposure notification message includes at least one of the following: event ID, event filter, or event report information.

3. The method of claim 1, wherein, The event exposure notification message includes information about the number of UEs with at least one PDU session or PDN connection.

4. The method according to claim 1, further comprising: Receives a first Protocol Data Unit (PDU) session establishment request message from the UE, which includes information about network slicing; Send a first generation request message for the PDU session to the first network entity that manages the PDU session of the UE; Receive a response message from the first network entity in response to the generation request message, the response message including information indicating that the generation of the PDU session failed; and In response to the first PDU session establishment request message, a first PDU session establishment rejection message including information about the backoff timer is sent to the UE. The backoff timer indicates the time until the UE sends a PDU session establishment request again.

5. The method of claim 4, wherein, Each of the response message and the PDU session establishment rejection message includes one of the following reasons: indicating S-NSSAI congestion, indicating S-NSSAI resource shortage, and indicating S-NSSAI rejection due to Network Slice Access Control (NSAC).

6. The method of claim 4, wherein, In the first PDU session establishment rejection message, the backoff timer is set based on the backoff timer information included in the response message or the configuration information about the NF.

7. The method according to claim 4, further comprising: Start the backoff timer; and When a second PDU session establishment request message is received from the UE at the same time the backoff timer is activated, a second PDU session establishment rejection message is sent to the UE.

8. The method according to claim 4, further comprising: Start the backoff timer; and When a second PDU session establishment request message is received from the UE after the backoff timer expires, a second generation request message for the PDU session is sent to the first network entity.

9. The method of claim 4, wherein, The first network entity is SMF+PGW-C or the SMF, wherein the SMF+PGW-C is a combined node of the Session Management Function (SMF) of the 5G system 5GS and the Packet Data Network Gateway Control (PGW-C) of the Evolved Packet System (EPS).

10. A network function NF in a wireless communication system, comprising: transceiver; and Processor, the processor being configured to: The transceiver sends an event exposure subscription message, including information about the status of individual network slice selection assistance information (S-NSSAI), to the network slice admission control function (NSACF). The transceiver receives an event exposure subscription response message from NSACF indicating the result of the subscription. Receive event exposure notification messages from NSACF via transceiver, which include information about the event.

11. The NF of claim 10, wherein, The event exposure notification message includes at least one of the following: event ID, event filter, or event report information.

12. The NF of claim 10, wherein, The event exposure notification message includes information about the number of UEs with at least one PDU session or PDN connection.

13. The NF according to claim 10, further comprising: The transceiver receives a first Protocol Data Unit (PDU) session establishment request message from the UE, which includes information about network slices. The transceiver sends a first generation request message for the PDU session to a first network entity that manages the PDU session of the UE. The transceiver receives a response message from the first network entity in response to the generation request message, the response message including information indicating that the generation of the PDU session has failed; and In response to the first PDU session establishment request message, the transceiver sends a first PDU session establishment rejection message, including information about the backoff timer, to the UE. The backoff timer indicates the time until the UE sends a PDU session establishment request again.

14. The NF according to claim 13, wherein, Each of the response message and the PDU session establishment rejection message includes one of the following reasons: indicating S-NSSAI congestion, indicating S-NSSAI resource shortage, and indicating S-NSSAI rejection due to Network Slice Access Control (NSAC).

15. The NF according to claim 13, wherein, The processor is configured to set the backoff timer in the first PDU session establishment rejection message based on the backoff timer information included in the response message or the configuration information about the NF.

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