Method and apparatus for managing network slice

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Provided is a method for managing a network slice by means of a session management function plus a packet data network gateway control plane function (SMF+PGW-C). The method may comprise the steps of: receiving a request message for a packet data network (PDN) connection associated with a user equipment (UE) from a mobility management entity (MME); determining single-network slice selection assistance information (S-NSSAI) for the PDN connection; when the request message for the PDN connection includes information indicating that the UE supports network slice replacement, transmitting a subscription request for network slice availability information to a policy control function (PCF); and transmitting a message including the determined S-NSSAI for the PDN connection to the MME.

Description

Method and device for managing network slices

[0001] The present disclosure relates to a method and device for managing network slices in a wireless communication system. More specifically, the present disclosure relates to a method and device for replacing a network slice.

[0002] 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

[0003] In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

[0004] Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

[0005] In addition, standardization of wireless interface architecture / protocols is in progress for technologies such as intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) that simplifies random access procedures. Standardization is also in progress for system architecture / services such as 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal.

[0006] Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

[0007] In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

[0008] In mobile communication systems, network slicing technology enables the provision of various virtual networks capable of delivering specialized services. Meanwhile, when a network slice becomes unavailable, it is crucial to ensure service continuity by migrating terminals or sessions currently using that network slice to another slice. The present invention proposes a method for replacing network slices in a 4G system, where network slicing technology is applicable, using network functions that can be integrated with 5G systems.

[0009] The 5G mobile communication network consists of 5G User Equipment (UE), 5G Radio Access Network (RAN), and 5G core network. The 5G core network is composed of various network functions (NFs), such as Access and Mobility Management Function (AMF) that provides UE mobility management function, Session Management Function (SMF) that provides session management function, User Plane Function (UPF) that performs data transfer role, Policy Control Function (PCF) that provides policy control function, Unified Data Management (UDM) that provides data management function such as subscriber data and policy control data, and Unified Data Repository (UDR) that stores data of various network functions (NFs) such as UDM.

[0010] In 5G systems, network slicing technology refers to the technology and architecture that enables multiple virtualized, independent logical networks within a single physical network. Network operators configure virtual end-to-end networks called network slices to provide services to meet the specialized requirements of services and applications. Network slices are identified by an identifier called Single-Network Slice Selection Assistance Information (S-NSSAI), and network operators provide network slice(s) to terminals to enable them to receive services.

[0011] Specifically, in a 5G system, when a terminal registers a network, the terminal transmits identifier information for network slices it wishes to request (i.e., Requested S-NSSAIs) to the AMF, and the AMF provides the terminal with information (Allowed NSSAI) about network slices that the terminal can use, taking into account the Requested S-NSSAIs and subscriber information. Even if the terminal does not provide information about slices requested by the terminal, the AMF may provide Allowed NSSAI to the terminal, and at this time, Allowed NSSAI may include information about default configured slices (Default Configured NSSAI) and information about slices set as default among the subscribed slices included in the terminal subscriber information (i.e., Default Subscribed S-NSSAIs).

[0012] If no slices can be included in the Allowed NSSAI (e.g., if the Default Configured NSSAI and Default Subscribed S-NSSAIs are missing or unavailable), the AMF sends the UE a Network Registration Reject message containing a cause code indicating that the registration was rejected due to no available slices.

[0013] Meanwhile, when an S-NSSAI (i.e., a network slice) becomes unavailable, it is important to provide service continuity by migrating terminals or sessions currently using the network slice to another slice. The present invention proposes a method for replacing network slices using network functions that can be interoperable with 5G systems in a 4G system to which network slicing technology is applicable.

[0014] The present invention proposes a method for replacing a network slice through a network function or network entity (specifically, SMF+PGW-C) that can be interoperated with a 5G system in a 4G system to which network slice technology is applicable.

[0015] According to one embodiment, a method for managing a network slice by a network entity is provided. The method may include: receiving a request message for a packet data network (PDN) connection associated with a user equipment (UE) from a mobility management entity (MME); determining single-network slice selection assistance information (S-NSSAI) for the PDN connection; transmitting a subscription request for network slice availability information to a policy control function (PCF) when the request message for the PDN connection includes information indicating that the UE supports network slice replacement; and transmitting a message including the determined S-NSSAI for the PDN connection to the MME.

[0016] According to one embodiment, a device for a network entity for managing a network slice may be provided. The device may include a transceiver and a controller connected to the transceiver. The controller may be configured to receive a request message for a packet data network (PDN) connection associated with a user equipment (UE) from a mobility management entity (MME); determine single-network slice selection assistance information (S-NSSAI) for the PDN connection; transmit a subscription request for network slice availability information to a policy control function (PCF) when the request message for the PDN connection includes information indicating that the UE supports network slice replacement; and transmit a message including the determined S-NSSAI for the PDN connection to the MME.

[0017] Embodiments of the present disclosure may provide a novel process for replacing a network slice, with respect to the availability of the network slice.

[0018] Figure 1 illustrates the architecture of an exemplary 5G system.

[0019] FIG. 2 illustrates a flowchart of a process for managing a network slice according to one embodiment of the present disclosure.

[0020] FIG. 3 illustrates a flowchart of a process for managing a network slice according to one embodiment of the present disclosure.

[0021] FIG. 4 illustrates a flowchart of a process for managing a network slice according to one embodiment of the present disclosure.

[0022] FIG. 5 illustrates a block diagram of a device for an entity according to embodiments of the present disclosure.

[0023] The operating principles of the present invention will be described in detail below with reference to the attached drawings. In the following description of the present invention, detailed descriptions of known functions or components will be omitted if they are deemed to unnecessarily obscure the gist of the invention. Furthermore, the terms described below are defined based on their functions in the present invention and may vary depending on the intentions or practices of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

[0024] The terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, and terms referring to various identification information are provided for convenience of explanation. Therefore, the present invention is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0025] For convenience of explanation, the present invention uses terms and names defined in the 5GS and NR standards, which are the most recent standards defined by the 3rd Generation Partnership Project (3GPP) among the existing communication standards. However, the present invention is not limited to the above terms and names and can be equally applied to wireless communication networks that follow other standards. The present invention can be applied to the 3GPP 5GS / NR (5th generation mobile communication standard).

[0026] The 5G mobile communication network is composed of 5G UE (user equipment, terminal), 5G RAN (radio access network, base station, gNB (5g nodeB), eNB (evolved nodeB, etc.), and 5G core network. The 5G core network is composed of network functions such as AMF (access and mobility management function) that provides UE mobility management function, SMF (session management function) that provides session management function, UPF (user plane function) that performs data transfer role, PCF (policy control function) that provides policy control function, UDM (unified data management) that provides data management function such as subscriber data and policy control data, and UDR (unified data repository) that stores data of various network functions such as UDM.

[0027] In the 3GPP system, a conceptual link connecting NFs within a 5G system is defined as a reference point. The following illustrates a reference point included in the 5G system architecture depicted in Figure 1.

[0028] - N1: Reference point between UE and AMF

[0029] - N2: Reference point between (R)AN and AMF

[0030] - N3: Reference point between (R)AN and UPF

[0031] - N4: Reference point between SMF and UPF

[0032] - N5: Reference point between PCF and AF

[0033] - N6: Reference point between UPF and DN

[0034] - N7: Reference point between SMF and PCF

[0035] - N8: Reference point between UDM and AMF

[0036] - N9: Reference point between two core UPFs

[0037] - N10: Reference point between UDM and SMF

[0038] - N11: Reference point between AMF and SMF

[0039] - N12: Reference point between AMF and AUSF

[0040] - N13: Reference point between UDM and authentication server function (AUSF)

[0041] - N14: Reference point between two AMFs

[0042] - N15: Reference point between PCF and AMF for non-roaming scenarios, reference point between PCF and AMF in visited network for roaming scenarios.

[0043] FIG. 2 illustrates a flowchart of a process for managing network slices according to one embodiment of the present disclosure. More specifically, FIG. 2 illustrates a method for notifying terminals using a slice in an evolved packet system (EPS) when an unavailable network slice occurs, and a method for replacing a network slice.

[0044] Step 1. The UE can send a request to establish a packet data network (PDN) connection to the mobility management entity (MME) through the RAN.

[0045] The message may include the APN (access point name) associated with the UE, the PDU (protocol data unit) Session ID, and Support of Network Slice Replacement (i.e., whether the UE supports network slice replacement). The PDU session ID and the Support of network slice replacement information may be included in the PCO (protocol configuration option) and passed to the SMF+PGW-C (session management function plus packet data network gateway control plane function). The SMF+PGW-C may also be simply referred to as any network entity or any NF.

[0046] Step 2. When the MME receives the request of step 1 from the UE, it sends a request message for PDN connection to the SMF+PGW-C.

[0047] The message may include one or more of a PDU Session ID, an APN, and a UE ID. The message may include a PCO received from the UE.

[0048] Step 3. SMF+PGW-C determines S-NSSAI (i.e., slice identifier information) for PDN Connection based on APN for PDN Connection, S-NSSAI information supported by SMF_PGW-C, subscription S-NSSAI information for UE, etc. SMF+PGW-C may send a subscription request for network slice availability information (e.g., slice availability) to PCF. SMF+PGW-C may send a subscription request for slice availability information only if the PCO of the message received in Step 2 includes an indication of support of Network Slice Replacement (i.e., if the UE supports Network Slice Replacement).

[0049] The subscription request may include one or more of an event ID indicating slice availability, a subscription S-NSSAI for the terminal, a UE ID, a PDU Session ID, and a notification address.

[0050] When PCF receives a subscription request, it creates a subscription based on the information contained in the request.

[0051] Meanwhile, even if PCF receives a message other than a separate subscription request from SMF_PGW-C, it may consider the message as an implicit subscription request for a slice availability event for one or more S-NSSAIs and generate a subscription for the slice availability event for one or more S-NSSAIs for the corresponding SMF+PGW-C.

[0052] Step 4. PCF sends a response message to SMF+PGW-C.

[0053] Step 5. SMF+PGW-C can include S-NSSAI and PLMN information for PDN Connection in PCO and transmit it to MME.

[0054] Step 6. If the message received from the SMF-PGW-C includes a PCO, the MME includes it in the message sent to the UE via the RAN. The message sent by the MME to the UE may include information indicating that a PDN Connection has been established.

[0055] If a message received by the UE through the RAN includes a PCO and the PCO includes an S-NSSAI and a PLMN ID, the UE stores the S-NSSAI and PLMN ID as the S-NSSAI and PLMN ID values ​​corresponding to the PDU Session ID.

[0056] Step 7a. If the S-NSSAI is unavailable and there is an SMF+PGW-C that has requested subscription for the slice availability event of the S-NSSAI, or there is an SMF+PGW-C that is responsible for the UE using the unavailable S-NSSAI (i.e., the PCF knows about the SMF+PGW-C), the PCF can send a notification message to the SMF+PGW-C. The message includes the following information:

[0057] -S-NSSAI: Indicates an unavailable S-NSSAI (or an S-NSSAI that needs to be replaced). If S-NSSAI availability exists, it can indicate an available S-NSSAI if S-NSSAI availability indicates availability.

[0058] -S-NSSAI availability: May contain information indicating the availability of the slice. It may indicate unavailable or available (i.e., an S-NSSAI that was unavailable has become available).

[0059] -Alternative S-NSSAI: Indicates S-NSSAI information that should replace the unavailable S-NSSAI.

[0060] -Transaction ID (or PDU session ID): You can include the Transaction ID (or PDU session ID or UE ID) corresponding to the PDU session that has subscribed to the slice availability change.

[0061] If there is no Alternative S-NSSAI in the message received in step 7a, SMF+PGW-C may determine another S-NSSAI, other than the unavailable S-NSSAI received in step 7a, as the Alternative S-NSSAI among the network slices supported by SMF+PGW-C.

[0062] Step 8. If the message received in Step 7a contains an unavailable S-NSSAI (or an S-NSSAI that requires replacement), SMF+PGW-C may perform S-NSSAI replacement for the PDN Connection corresponding to the Transaction ID (or UE ID or PDU Session ID) of the message received in Step 7a.

[0063] If a message from PCF contains an unavailable S-NSSAI (or an S-NSSAI that requires replacement) and an Alternative S-NSSAI, the Alternative S-NSSAI contained in the message from PCF may be used as an S-NSSAI that replaces the unavailable S-NSSAI (or the S-NSSAI that requires replacement).

[0064] If the message from the PCF includes an unavailable S-NSSAI (or an S-NSSAI that needs to be replaced) but does not include an Alternative S-NSSAI, the SMF+PGW-C can determine an S-NSSAI (i.e., an Alternative S-NSSAI) that replaces the unavailable S-NSSAI (or the S-NSSAI that needs to be replaced) based on configuration information and subscription slice information for the terminal.

[0065] SMF+PGW-C transmits a message including a PCO (message format transmitted to the UE) to the MME responsible for the PDN Connection (or UE) corresponding to the Transaction ID (or UE ID or PDU Session ID), and the PCO may include an Alternative S-NSSAI, a PDU Session ID, and a mapping of the Alternative S-NSSAI.

[0066] Mapping of Alternative S-NSSAI indicates mapping information between the existing S-NSSAI and the Alternative S-NSSAI (i.e., information indicating that the Alternative S-NSSAI is used instead of the existing S-NSSAI).

[0067] Step 9. If a PCO exists in the message received from SMF-PGW-C, the MME transmits it to the UE through the RAN.

[0068] Step 10. If the message received by the UE through the RAN includes a PCO and the PCO includes an Alternative S-NSSAI and a PDU Session ID, the UE changes the S-NSSAI corresponding to the PDU Session ID to the S-NSSAI value included in the Alternative S-NSSAI.

[0069] Step 11. SMF+PGW-C may send a message to PCF indicating the result of the network slice replacement. The message may include the Transaction ID (or PDU Session ID), the result of the network slice replacement (e.g., success if processable, failure if not), and the Alternative S-NSSAI (if SMF+PGW-C has decided on an Alternative S-NSSAI, it may be included).

[0070] If network slice replacement is not possible for the PDN Connection (e.g., SMF+PGW-C determines that the maximum number of sessions has been reached for the Alternative S-NSSAI determined by PCF), SMF+PGW-C may transmit the result of performing network slice replacement indicating failure and cause information (e.g., maximum number of sessions reached).

[0071] Step 12. If the UE has moved to 5GS (5th generation system), and if the message received by the UE in step 9 includes Mapping of Alternative S-NSSAI and if the information indicates to use Alternative S-NSSAI instead of S-NSSAI, the UE may include Alternative S-NSSAI instead of S-NSSAI in the PDU Session Establishment Request message sent to the AMF.

[0072] FIG. 3 illustrates a flowchart of a process for managing network slices according to one embodiment of the present disclosure. More specifically, FIG. 3 illustrates a method for notifying when an unavailable network slice becomes available and a method for replacing a network slice.

[0073] Step 1. If SMF+PGW-C supports Network Slice Replacement and is configured to perform Network Slice Replacement using the network slicing selection function (NSSF), SMF+PGW-C can send a subscription request for slice availability to NSSF.

[0074] The subscription request may include one or more of an event ID indicating slice availability, an S-NSSAI(s), and a notification address.

[0075] At this time, S-NSSAI(s) may be composed of some or all of the S-NSSAIs supported by SMF+PGW-C.

[0076] Step 2. When NSSF receives a subscription request, it creates a subscription based on the information contained in the request.

[0077] Meanwhile, even if NSSF receives a message other than a separate subscription request from SMF_PGW-C, it may consider the message as an implicit subscription request for a slice availability event for one or more S-NSSAIs and generate a subscription for the slice availability event for one or more S-NSSAIs for the corresponding SMF+PGW-C.

[0078] Step 3. One or more PDN Connections managed by SMF+PGW-C can be created. The PDN Connection creation procedure is identical to steps 1, 2, 5, and 6 of Figure 2.

[0079] Step 4. If an S-NSSAI (e.g., S-NSSAI1) is unavailable, and there is an SMF+PGW-C that has a subscription for the availability event of the S-NSSAI or an SMF+PGW-C that is responsible for a UE using the S-NSSAI (i.e., the NSSF knows of the SMF+PGW-C), the NSSF may send a notification message to the SMF+PGW-C. The message includes the following information:

[0080] -S-NSSAI: Indicates an unavailable S-NSSAI (or an S-NSSAI that needs to be replaced). If S-NSSAI availability exists, it can indicate an available S-NSSAI if S-NSSAI availability indicates availability.

[0081] -S-NSSAI availability: May contain information indicating the availability of the slice. It may indicate unavailable or available (i.e., an S-NSSAI that was unavailable has become available).

[0082] -Alternative S-NSSAI: Indicates S-NSSAI information that should replace the unavailable S-NSSAI.

[0083] -UE ID, PDU Session ID(s): May contain UE ID(s) or PDU session ID(s) for which the unavailable S-NSSAI is no longer available (or for which the S-NSSAI needs to be replaced).

[0084] -Number of UEs to be replaced, percentage of UEs to be replaced: Instead of UE ID or PDU Session ID, the number or percentage (or ratio) of UEs to be replaced may be included.

[0085] -Number of PDU sessions to be replaced or percentage of PDU Sessions to be replaced: Instead of the UE ID or PDU Session ID, the number or percentage (or ratio) of PDU sessions to be replaced may be included.

[0086] Step 5. If the message received from NSSF contains an unavailable S-NSSAI (or an S-NSSAI that needs to be replaced), SMF+PGW-C may perform S-NSSAI replacement for some or all of the UEs that have a PDN Connection to the corresponding S-NSSAI.

[0087] If a message from NSSF contains an unavailable S-NSSAI (or an S-NSSAI that requires replacement) and an Alternative S-NSSAI, the Alternative S-NSSAI contained in the message from NSSF may be used as an S-NSSAI that replaces the unavailable S-NSSAI (or the S-NSSAI that requires replacement).

[0088] If the message from NSSF contains an unavailable S-NSSAI (or an S-NSSAI that needs to be replaced) but does not contain an Alternative S-NSSAI, SMF+PGW-C can determine an S-NSSAI (i.e., an Alternative S-NSSAI) that replaces the unavailable S-NSSAI (or the S-NSSAI that needs to be replaced) based on the configuration information. At this time, a different Alternative S-NSSAI may be used for each PDN Connection.

[0089] SMF+PGW-C may replace the S-NSSAI of the PDN Connections of the corresponding UEs (or the PDN Connections corresponding to the PDU Session IDs) with an Alternative S-NSSAI if the message from NSSF contains an unavailable S-NSSAI (or an S-NSSAI that needs to be replaced) and UE IDs (or contains PDU Session IDs).

[0090] When a message from NSSF contains an unavailable S-NSSAI (or an S-NSSAI that needs to be replaced) and a Number of UEs to be replaced (or a percentage of UEs to be replaced), SMF+PGW-C can perform slice replacement for PDU Sessions (or PDN Connections) of UEs that satisfy the Number of UEs to be replaced (or a percentage of UEs to be replaced) among the UEs using the S-NSSAI.

[0091] When a message from NSSF contains an unavailable S-NSSAI (or an S-NSSAI that needs to be replaced) and a Number of PDU sessions to be replaced (or percentage of PDU Sessions to be replaced), SMF+PGW-C can perform slice replacement for a number (or percentage or ratio) of PDN Connections that satisfy the Number of UEs to be replaced (or percentage of UEs to be replaced) among the PDU Sessions (or PDN Connections) that are using the S-NSSAI.

[0092] SMF+PGW_C transmits a message including a PCO (message format transmitted to the UE) to the MME responsible for the UE for each UE that performs slice replacement, and the PCO may include Alternative S-NSSAI, PDU Session ID (or PDN Connection ID), and Mapping of Alternative S-NSSAI.

[0093] Mapping of Alternative S-NSSAI indicates mapping information between existing S-NSSAI and Alternative S-NSSAI (i.e., information indicating that Alternative S-NSSAI is used instead of existing S-NSSAI).

[0094] Step 6. If a PCO exists in the message received from SMF-PGW-C, the MME transmits it to the UE through the RAN.

[0095] Step 7. If the message received by the UE through the RAN includes a PCO and the PCO includes an Alternative S-NSSAI and a PDU Session ID, the UE changes the S-NSSAI corresponding to the PDU Session ID to the S-NSSAI value included in the Alternative S-NSSAI.

[0096] Step 8. SMF+PGW-C may send a message to NSSF indicating the result of the network slice replacement. The message may include the Transaction ID, the result of the network slice replacement per UE ID or PDU session ID (e.g., success if processable, failure if not processable), and the Alternative S-NSSAI per UE or PDU session ID (if SMF+PGW-C has decided on an Alternative S-NSSAI, it may be included).

[0097] If network slice replacement is not possible for the PDN Connection (for example, if SMF+PGW-C determines that the maximum number of sessions has been reached for the Alternative S-NSSAI determined by PCF), SMF+PGW-C can transmit the result of performing network slice replacement indicating failure and cause information (for example, maximum number of sessions reached).

[0098] Based on the processing result included in the message received from SMF+PGW-C, NSSF can decide whether to retry the slice change with another Alternative S-NSSAI for UEs (or PDN Connections) that are still using the unavailable slice in EPS. If so, NSSF can perform the network slice change by including another Alternative S-NSSAI in the message in step 4.

[0099] Step 9. If the UE has moved to 5GS, and if the message received by the UE in step 9 includes a Mapping of Alternative S-NSSAI and if that information indicates to use Alternative S-NSSAI instead of S-NSSAI, the UE may include Alternative S-NSSAI instead of S-NSSAI in the PDU Session Establishment Request message it sends to the AMF.

[0100] FIG. 4 illustrates a flowchart of a process for managing network slices according to one embodiment of the present disclosure. More specifically, FIG. 4 illustrates a method for reusing a slice that was replaced due to unavailability when the slice becomes available again.

[0101] Step 1. SRNF (slice replacement notification function) can send a notification message to the SMF+PGW-C if the S-NSSAI (e.g., S-NSSAI1) is unavailable and there is an SMF+PGW-C that has a subscription for the availability event of the S-NSSAI or there is an SMF+PGW-C that is responsible for the UE using the S-NSSAI (i.e., the SRNF knows about the SMF+PGW-C). The SRNF can be located in one or more of PCF, UDM, OAM, and NSSF.

[0102] The message contains the following information:

[0103] -S-NSSAI: Indicates S-NSSAI with changed availability.

[0104] -S-NSSAI availability: Indicates availability or unavailability.

[0105] -UE ID, PDU Session ID(s): May contain UE ID(s) or PDU session ID(s) to notify S-NSSAI availability change (or to which slice replacement must be performed due to S-NSSAI availability change).

[0106] Step 2. If the message received from SRNF contains an S-NSSAI that has become available (i.e., if S-NSSAI availability indicates availability), SMF+PGW-C may perform S-NSSAI replacement with the available S-NSSAI for some or all of the PDN Connections for which slice replacement was performed, where the original S-NSSAI is the available S-NSSAI. If the message received in Step 1 contains a UE ID or a PDU Session ID, S-NSSAI replacement (i.e., replacement for use of the originally used S-NSSAI) may be performed for the corresponding UE ID(s) PDU Session(S).

[0107] If the message received from the SRNF contains an S-NSSAI that has become available (i.e., if the S-NSSAI availability indicates availability), the SMF+PGW_C transmits a message including a PCO (message format transmitted to the UE) to the MME responsible for the UE for each UE that is to perform slice replacement, and may include the S-NSSAI and the PDU Session ID (or PDN Connection ID) included in the message received from the SRNF in the PCO.

[0108] Step 3. If a PCO exists in the message received from SMF-PGW-C, the MME transmits it to the UE through the RAN.

[0109] Step 4. If the message received by the UE through the RAN includes a PCO and the PCO includes S-NSSAI and PDU Session ID, the UE changes the S-NSSAI corresponding to the PDU Session ID to the S-NSSAI value corresponding to the S-NSSAI included in the received message.

[0110] The UE may delete the stored Mapping of Alternative S-NSSAI if there is a stored Mapping of Alternative S-NSSAI and / or if there is no Mapping of Alternative S-NSSAI in the PCO.

[0111] Mapping of Alternative S-NSSAI indicates mapping information between the existing S-NSSAI and the Alternative S-NSSAI (i.e., information indicating that the Alternative S-NSSAI is used instead of the existing S-NSSAI).

[0112] FIG. 5 illustrates a block diagram of a device for an entity according to embodiments of the present disclosure.

[0113] The device (500) may implement one of the multiple entities described herein. For example, the device may implement any one of UE (500), SMF+PGW-C, MME, PCF, NSSF, and SRNF, but is not limited thereto.

[0114] The device (500) may include a memory (530), a transceiver (520), and a controller (510).

[0115] The controller (510) can control the operations of other elements of the device (500). The operations of the device (500) can be understood to be substantially executed by the controller (510). The controller (510) can be implemented through at least one processor. The controller can execute instructions stored in the memory (530) to perform the operations of the device (500) described herein.

[0116] The transceiver (520) may be used to transmit signals from the controller (510) to other entities or to receive signals from other entities. The transceiver (520) may support communication via various radio access technologies (RATs), including, for example, Long Term Evolution (LTE), Wireless Fidelity (Wi-Fi), orthogonal frequency division multiplexing (OFDM), code division multiple access (CDMA), and Bluetooth. The RATs supported by the transceiver (520) are not limited thereto.

[0117] The memory (530) may store at least one of information transmitted and / or received via the transceiver (520) and information generated via the controller (510). The memory (530) may additionally store information / data / commands / instructions to be executed by the controller (510) to cause the device (500) to perform the operations described herein. The memory (530) may include a non-transitory computer-readable storage medium that stores instructions executable by the controller.

[0118] The methods according to the embodiments described in the claims or specification of the present invention may be implemented in the form of hardware, software, or a combination of hardware and software.

[0119] 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 for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of the present invention.

[0120] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage device, compact disc ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage device, magnetic cassette. Or, they may be stored in a memory configured as a combination of some or all of these. In addition, each configuration memory may be included in multiple numbers.

[0121] Additionally, the program may be stored in an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present invention via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present invention.

[0122] In the specific embodiments of the present invention described above, components included in the invention are expressed in the singular or plural form depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present invention is not limited to singular or plural components. Even components expressed in the plural form may be composed of singular elements, or even components expressed in the singular form may be composed of plural elements.

[0123] While the detailed description of the present invention has described specific embodiments, it is clear that various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims but also by equivalents thereof.

Claims

1. A method for managing a network slice by a network entity, A step of receiving a request message for packet data network (PDN) access related to a user equipment (UE) from a mobility management entity (MME); A step of determining single-network slice selection assistance information (S-NSSAI) for the above PDN connection; If the request message for the PDN connection includes information indicating that the UE supports network slice replacement, a step of transmitting a subscription request for network slice availability information to a policy control function (PCF); and Comprising the step of transmitting a message including the determined S-NSSAI for the PDN connection to the MME; method.

2. In paragraph 1, A step of receiving a notification of unavailability of the S-NSSAI from the PCF; A step of replacing the S-NSSAI with another S-NSSAI for the PDN connection based on receiving a notification of unavailability of the S-NSSAI; and Further comprising the step of transmitting a message related to replacement of the S-NSSAI to the MME; method.

3. In paragraph 2, The notification of unavailability of the S-NSSAI includes at least one of information indicating the S-NSSAI being unavailable, information indicating another S-NSSAI to replace the S-NSSAI, and a transaction ID associated with a protocol data unit (PDU) session associated with the PDN connection. method.

4. In paragraph 3, If the notification of unavailability of the S-NSSAI does not include information indicating another S-NSSAI for replacing the S-NSSAI, further comprising a step of determining another S-NSSAI for replacing the S-NSSAI based on the configuration information and the subscription slice information for the UE. method.

5. In paragraph 2, A message related to replacement of the above S-NSSAI includes information indicating a transaction ID related to a protocol data unit (PDU) session associated with the PDN connection and the other S-NSSAI, and mapping information between the other S-NSSAI and the above S-NSSAI. method.

6. In paragraph 1, Comprising the step of sending a subscription request for slice availability to the Network Slice Selection Function (NSSF); A subscription request for the above slice availability includes an event ID indicating the slice availability, information indicating at least one S-NSSAI supported by the network entity, and at least one of a notification address. method.

7. In paragraph 6, A step of receiving a notification of unavailable S-NSSAI from the NSSF; and A step of performing replacement of S-NSSAI for at least one UE having PDU connection to the unavailable S-NSSAI based on receiving a notification about the unavailable S-NSSAI; and Further comprising the step of transmitting a message related to replacement of the S-NSSAI to an MME associated with each of the at least one UE; method.

8. In paragraph 7, The notification for the unavailable S-NSSAI includes at least one of information indicating the unavailable S-NSSAI, information indicating another S-NSSAI to replace the unavailable S-NSSAI, an ID of at least one UE that cannot use the unavailable S-NSSAI or at least one PDU session ID, a number or a ratio of UEs for which the S-NSSAI should be replaced, and a number or a ratio of PUD sessions for which the S-NSSAI should be replaced. method.

9. In paragraph 7, If the notification for the unavailable S-NSSAI does not include information indicating another S-NSSAI for replacing the unavailable S-NSSAI, a step of determining another S-NSSAI for replacing the unavailable S-NSSAI for each PDU session based on the configuration information is included. method.

10. In paragraph 7, The message related to the replacement of the above S-NSSAI includes information indicating another S-NSSAI that replaces the above S-NSSAI for the UE corresponding to the MME, and mapping information between the other S-NSSAI and the above S-NSSAI. method.

11. In paragraph 1, A step of receiving a message regarding a change in availability of S-NSSAI from the Slice Replacement Notification Function (SRNF); If the message about the change in availability of the above S-NSSAI indicates an S-NSSAI that has become available, a step of replacing the S-NSSAI for at least some of the PDN connections using the above S-NSSAI that has become available with the above S-NSSAI that has become available; and A method further comprising the step of transmitting a message regarding replacement of the S-NSSAI to an MME associated with the replaced S-NSSAI.

12. In paragraph 11, The message for change of availability of the above S-NSSAI includes at least one of information indicating the S-NSSAI whose availability has been changed, information indicating availability or unavailability of the S-NSSAI whose availability has been changed, at least one UE ID associated with the S-NSSAI whose availability has been changed, and at least one PDU session ID associated with the S-NSSAI whose availability has been changed. method.

13. In paragraph 12, The step of replacing S-NSSAI for at least some of the PDN connections using the above-mentioned available S-NSSAI with the above-mentioned available S-NSSAI is: If the message about the change in availability of the S-NSSAI includes information indicating at least one UE ID associated with the S-NSSAI whose availability has been changed, a step of replacing the S-NSSAI for the at least one UE ID with the S-NSSAI that has become available; or If the message about the change in availability of the S-NSSAI includes information indicating at least one PDU session ID associated with the S-NSSAI whose availability has been changed, a step of replacing the S-NSSAI for the at least one PDU session ID with the S-NSSAI that has become available is included. method.

14. In paragraph 11, The message for replacement of the above S-NSSAI includes information indicating the replaced available S-NSSAI and information indicating at least one PDU session ID. method.

15. As a device for a network entity to manage a network slice, Transmitter and receiver; and comprising a controller connected to the above transmitter and receiver; The above controller is configured to operate according to any one of the methods of claims 1 to 14. device.

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