Methods and devices for supporting dynamic policies in wireless communication systems

Abstract

This disclosure relates to 5G or 6G communication systems for supporting higher data transmission rates. Specifically, this disclosure provides a method performed by a Session Management Policy Control Function (SM PCF) entity in a wireless communication system, comprising receiving an SM policy control update request message from the Session Management Function (SMF) entity, including information for identifying an alternative network slice and information related to whether to retain a Protocol Data Unit (PDU) session; identifying network slice replacement based on the received SM policy control update request message; and sending an event exposure notification message to at least one Network Function (NF) entity, including at least one of the information for identifying the alternative network slice or information related to the occurrence of network slice replacement.

Description

Technical Field

[0001] This disclosure generally relates to a wireless communication system, and more specifically, to a method and apparatus for supporting dynamic strategies in a wireless communication system. Background Technology

[0002] 5G mobile communication technology defines a wide frequency band to enable high transmission rates and new services. It can be implemented not only in "sub-6 GHz" bands such as 3.5 GHz, but also in "above 6 GHz" bands, including 28 GHz and 39 GHz, known as mmWave. Furthermore, it is envisioned that 6G mobile communication technology (called Beyond 5G systems) be implemented in terahertz (THz) bands (e.g., the 95 GHz to 3 THz band) to achieve transmission rates 50 times faster than 5G and ultra-low latency only one-tenth that of 5G.

[0003] In the early stages of 5G mobile communication technology development, to provide service support and meet the performance requirements associated with enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC), the following were continuously standardized: beamforming and massive multiple-input multiple-output (MIMO) to mitigate radio wave path loss and increase radio wave transmission distance; support parameter sets (numerology) for efficient utilization of millimeter wave resources and dynamic operation of time slot formats (e.g., operating multiple subcarrier spacings); initial access technologies supporting multi-beam transmission and broadband; definition and operation of BWP (bandwidth portion); novel channel coding methods, such as low-density parity-check codes (LDPC) for large-volume data transmission and polar codes for highly reliable control information transmission; L2 preprocessing; and network slicing to provide dedicated networks for specific services.

[0004] Currently, discussions are underway regarding improvements and performance enhancements to the initial 5G mobile communication technology in relation to services supported by 5G mobile communication technology. Physical layer standardization has been achieved for various technologies, such as V2X (Vehicle-to-Everything) technology, which helps autonomous vehicles make driving decisions based on vehicle location and status information transmitted by the vehicle and enhances user convenience; NR-U (New Radio Unlicensed), which aims to enable system operation in unlicensed frequency bands in compliance with various regulatory requirements; NR UE power saving; and Non-Terrestrial Network (NTN), which enables direct communication between the UE and satellites to provide coverage in areas where terrestrial network communication is not possible.

[0005] Furthermore, standardization of air interface architectures / protocols has been ongoing, such as for the Industrial Internet of Things (IIoT) to support new services through interoperability and integration with other industries; IAB (Integrated Access and Backhaul) for nodes that provide 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 two-step random access (NR two-step RACH) for simplifying random access procedures. In addition, standardization of system architectures / services has been ongoing for: 5G baseline architectures that combine Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies (e.g., service-based architectures or service-based interfaces); and mobile edge computing (MEC) for receiving UE location-based services.

[0006] With the commercialization of 5G mobile communication systems, an exponentially growing number of interconnected devices will be connected to the communication network. Therefore, enhancing the functionality and performance of 5G mobile communication systems and the integrated operation of interconnected devices is essential. To this end, new research has been planned in conjunction with: extended reality (XR) to effectively support AR (augmented reality), VR (virtual reality), MR (mixed reality), etc.; improving 5G performance and reducing complexity by leveraging artificial intelligence (AI) and machine learning (ML); AI service support; metaverse service support; and drone communication.

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

[0008] Solution to the problem

[0009] This disclosure has been made to address at least the aforementioned problems and / or disadvantages, and to provide at least the following advantages.

[0010] Therefore, one aspect of this disclosure is to provide a method and apparatus for improving the process of supporting dynamic strategies.

[0011] One aspect of this disclosure is to provide a method for receiving information from a new slice to determine a policy for a terminal when replacing a network slice.

[0012] One aspect of this disclosure is to provide a method and apparatus for deriving the optimal AM strategy in the case of network slice replacement by updating subscription information for AM PCF.

[0013] According to one aspect of this disclosure, a method performed by a Session Management Policy Control Function (SM PCF) entity in a wireless communication system includes: receiving from the Session Management Function (SMF) entity an SM policy control update request message including information for identifying an alternative network slice and information related to whether a Protocol Data Unit (PDU) session is retained; identifying a network slice replacement based on the received SM policy control update request message; and sending to at least one Network Function (NF) entity an event exposure notification message including at least one of information for identifying an alternative network slice or information related to the occurrence of a network slice replacement.

[0014] According to one aspect of this disclosure, a method performed by a network function (NF) entity in a wireless communication system includes: receiving an event exposure notification message from a session management policy control function (SM PCF) entity, comprising at least one of information for identifying an alternative network slice or information related to the occurrence of a network slice replacement, wherein the event exposure notification message is based on an SM policy control update request message, and

[0015] The SM policy control update request message includes information for identifying alternative network slices and information related to whether to retain Protocol Data Unit (PDU) sessions.

[0016] According to one aspect of this disclosure, a Session Management Policy Control Function (SM PCF) entity in a wireless communication system includes: a transceiver; and a controller coupled to the transceiver, wherein the controller is configured to receive from the Session Management Function (SMF) entity an SM policy control update request message including information for identifying an alternative network slice and information related to whether to retain a Protocol Data Unit (PDU) session, identify network slice replacement based on the received SM policy control update request message, and send an event exposure notification message to at least one Network Function (NF) entity including at least one of the information for identifying an alternative network slice or information related to the occurrence of network slice replacement.

[0017] According to one aspect of this disclosure, a network function (NF) entity in a wireless communication system includes: a transceiver; and a controller coupled to the transceiver, wherein the controller is configured to receive from a session management policy control function (SM PCF) entity an event exposure notification message including at least one of information for identifying an alternative network slice or information related to the occurrence of a network slice replacement, wherein the event exposure notification message is based on an SM policy control update request message, and wherein the SM policy control update request message includes information for identifying an alternative network slice and information related to whether to retain a Protocol Data Unit (PDU) session. Attached Figure Description

[0018] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 The structure of a 5G system according to an embodiment is shown;

[0020] Figure 2 The process for retaining Protocol Data Unit (PDU) sessions and updating subscription requests based on notifications from the Binding Support Function (BSF) according to an embodiment is illustrated.

[0021] Figure 3 The process for retaining a PDU session and updating a subscription request using a notification based on an SM PCF, according to an embodiment, is illustrated.

[0022] Figure 4 The process for reconstructing a PDU session and updating a subscription request using a BSF-based notification, according to an embodiment, is illustrated.

[0023] Figure 5 The structure of the UE according to an embodiment is shown;

[0024] Figure 6 The structure of a base station according to an embodiment is shown; and

[0025] Figure 7 The structure of a network entity according to an embodiment is shown. Detailed Implementation

[0026] The following description, provided with reference to the accompanying drawings, is intended to aid in a full understanding of this disclosure. It includes various specific details to aid understanding, but these are merely examples. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of this disclosure. For clarity and brevity, descriptions of well-known functions and structures may be omitted.

[0027] The terms described below are defined with reference to the functionality of 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.

[0028] In the accompanying drawings, some components are exaggerated, omitted, or shown schematically. The size of each component does not perfectly reflect its actual size. The same reference numerals are used for the same or corresponding components in each drawing.

[0029] In the following description, this disclosure will be based on a hardware-based approach. However, this disclosure may also be based on techniques using both hardware and software, and therefore, a software perspective is not excluded from this disclosure.

[0030] For ease of description, terms referring to device elements (e.g., control unit, processor, AI model, encoder, decoder, autoencoder (AE), and neural network (NN) model) and terms referring to data (e.g., signal, feedback, report, message, parameter, value, bit, and codeword) are used by way of example. Therefore, this disclosure is not limited to the terms used below, and other terms with equivalent technical meanings may be used.

[0031] The terminology used in 3GPP will be used to describe this disclosure, but it is for illustrative purposes only and can be readily applied to other communication systems by modification.

[0032] Throughout the specification, the same or similar reference numerals denote the same or similar elements.

[0033] In this document, for ease of description, the terms and names defined in the 3GPP LTE or NR standards are used. However, this disclosure is not limited to these terms and names and can be similarly applied to systems conforming to other standards.

[0034] A base station (BS) is an entity that allocates resources to terminals and can be at least one of a radio access network (RAN) node, a next-generation node B (gNode B, gNB), an evolved Node B (eNode B, eNB), a node B, a radio access unit, a base station controller, and a node on a network. For ease of description, the term eNB is used interchangeably with the term gNB. That is, a base station described as an eNB can refer to a gNB.

[0035] The terminal may include, but is not limited to, a UE, a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions.

[0036] Specifically, this disclosure can be applied to 3GPP NR and to smart services based on 5G communication technology and IoT-related technologies (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail businesses, security and safety-related services, etc.). The term "terminal" can refer not only to mobile phones, NR-IoT devices, and sensors, but also to any other wireless communication device.

[0037] Wireless communication systems are evolving towards broadband wireless communication systems that utilize communication standards such as High-Speed ​​Packet Access (HSPA) of the 3rd Generation Partnership Project (3GPP), Long Term Evolution (LTE) or Evolved Universal Terrestrial Radio Access (E-UTRA), LTE-Advanced (LTE-A), LTE-Pro, High-Speed ​​Packet Data (HRPD) of 3GPP2, Ultra Mobile Broadband (UMB), IEEE 802.16e, and typical voice-based services to provide high-speed and high-quality packet data services.

[0038] As an example of a broadband wireless communication system, the LTE system employs Orthogonal Frequency Division Multiplexing (OFDM) in the downlink (DL) and Single-Carrier Frequency Division Multiple Access (SC-FDMA) in the uplink (UL). The uplink refers to the radio link through which a terminal (or UE) transmits data or control signals to a base station (BS) (or eNB or gNB), and the downlink refers to the radio link through which the base station transmits data or control signals to the terminal. These multiple access schemes establish orthogonality by allocating and manipulating time-frequency resources for transmitting data or control information to each user, thus avoiding overlap.

[0039] As a post-LTE communication system, 5G communication systems must freely reflect the various requirements of users, service providers, etc., and therefore must support services that meet diverse needs. Services considered in 5G communication systems include eMBB, mMTC, and URLLC.

[0040] Specifically, eMBB aims to provide data rates higher than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in 5G communication systems, eMBB must provide a peak data rate of 20 gigabits per second (Gbps) in the downlink and 10 Gbps in the uplink for a single base station. 5G communication systems must provide increased user-aware data rates to the UE, as well as maximum data rates. To meet these requirements, improved transmit / receive technologies, including further enhanced MIMO transmission techniques, are needed. The data rates required by 5G communication systems can be achieved using frequency bandwidths greater than 20 MHz in the 3 to 6 GHz band or 6 GHz or higher, instead of using transmission bandwidths of up to 20 MHz in the 2 GHz band used in LTE.

[0041] Furthermore, mMTC is being considered to support application services such as IoT in 5G communication systems. mMTC may have requirements such as supporting a large number of UEs in a cell, enhanced UE coverage, improved battery life, and reduced UE cost to effectively deliver IoT. Since IoT provides communication capabilities while being provided to various sensors and devices, it must support many UEs in a cell (e.g., 1,000,000 UEs / km²). UEs supporting mMTC may require wider coverage than other services provided by 5G communication systems because UEs may be located in shaded areas, such as basements of buildings, which are not covered by the cell due to the nature of the service. UEs supporting mMTC must be configured to be inexpensive and may require very long battery life, such as 10 to 15 years, because it is difficult to frequently replace UE batteries.

[0042] URLLC, as a cellular-based mission-critical wireless communication service, can be used for remote control of robots or machines, industrial automation, unmanned aerial vehicles, remote healthcare, emergency alarms, and more. Therefore, URLLC must provide communication with ultra-low latency and ultra-high reliability. For example, services supporting URLLC must meet an air interface latency of less than 0.5 milliseconds (ms) and may also require a packet error rate of 10⁻⁵ or less. Consequently, for services supporting URLLC, 5G systems must provide shorter Transmission Time Intervals (TTIs) than other services and may also require designs that allocate significant resources in the frequency band to ensure the reliability of the communication link.

[0043] eMBB, URLLC, and mMTC can be multiplexed and transmitted within a single system. In this case, different send / receive technologies and send / receive parameters can be used across services to meet their varying requirements. However, the mMTC, URLLC, and eMBB described above are merely examples of different types of services.

[0044] This document describes LTE, LTE-A, LTE Pro, 5G (or NR), or 6G systems by way of example; however, this disclosure can also be applied to other communication systems with similar technical backgrounds or channel types. Furthermore, based on the assessment of those skilled in the art, this disclosure can be applied to other communication systems with modifications without significantly departing from its scope.

[0045] In the following description, "a / b" may refer to "a" and / or "b".

[0046] Figure 1 The structure of a 5G system according to an embodiment is shown.

[0047] refer to Figure 1 The 5G mobile communication network includes 5G user equipment (UE, terminal), 5G radio access network (RAN) 110, base stations, 5G nodeB (gNB), evolved nodeB (eNB), etc., and the 5G core network. The 5G core network may include network functions (NFs), such as Access and Mobility Management Function (AMF) 120 providing mobility management functions for UE 100, Session Management Function (SMF) 135 providing session management functions, User Plane Function (UPF) 130 for transmitting data, Policy Control Function (PCF) 140 providing policy control functions, Unified Data Management (UDM) 145 providing functions for managing data such as subscriber data and policy control data, and Unified Data Repository (UDR) storing data from various NFs such as UDM. The 5G core network may include additional NFs, such as Network Slice Selection Function (NSSF) 160, Network Data Analysis Function (NWDAF) 151, Application Function (AF) 170, Data Network (DN) 175, and Network Slice Admission Control Function (NSACF) 180.

[0048] In the 3GPP system, the conceptual link connecting the NF in a 5G system is defined as a reference point. Below, we provide a list of reference points included in the 5G system architecture. Some of these are... Figure 1 As described in the text.

[0049] N1 is the reference point between UE and AMF.

[0050] N2 is the reference point between (R)AN and AMF.

[0051] N3 is the reference point between (R)AN and UPF.

[0052] N4 is the reference point between SMF and UPF.

[0053] N5 is the reference point between PCF and AF.

[0054] N6 is the reference point between UPF and DN.

[0055] N7 is the reference point for SMF and PCF.

[0056] N8 is the reference point between UDM and AMF.

[0057] N9 is the reference point between the two core UPFs.

[0058] N10 is the reference point between UDM and SMF.

[0059] N11 is the reference point between AMF and SMF.

[0060] N12 is the reference point between AMF and AUSF.

[0061] N13 is the reference point between UDM and Authentication Server Functionality (AUSF).

[0062] N14 is the reference point between the two AMFs.

[0063] N15 serves as a reference point between the PCF and AMF in non-roaming scenarios, and between the PCF and AMF in the surveyed network in roaming scenarios.

[0064] In 5G systems, network slicing refers to the architecture and technology that enables the virtualization of multiple independent logical networks within a single physical network. To meet the specific requirements of services / applications, network operators provide services by configuring virtual end-to-end networks known as network slices. In this context, network slices are distinguished by an identifier called Single Network Slice Selection Auxiliary Information (S-NSSAI). During the UE registration process, the network sends the UE a set of allowed slices (e.g., allowed NSSAIs), and the UE sends and receives application data through a PDU session generated via one S-NSSAI (i.e., a network slice) from the set of allowed slices.

[0065] The Radio Access Type (RAT) / Frequency Selection Priority (RFSP) index is a parameter applied to each UE and is also a parameter for applying Radio Resource Management (RRM) policies that enable the use of specific RATs (e.g., E-UTRA or NR), frequency bands, etc., for the UE. The RFSP index is determined by the 5G core network and then sent to the RAN (Radio Area Network). When the RAN receives the RFSP index for the UE, it can apply the specific RRM policies used for the RFSP index based on internally defined configuration information.

[0066] Service Area Restrictions (SARs) can include permitted areas within a specific region that allow service to the UE, and non-permitted areas that do not allow service. The Activated Facilitation Controller (AMC) can send SARs to the UE and the RAN. When the UE receives an SAR including permitted areas, the UE can perform actions to receive service only within those permitted areas. When the UE receives an SAR including non-permitted areas, the UE can choose not to receive service in those non-permitted areas. Upon receiving an SAR, the RAN can perform target cell selection based on the SAR during handover (e.g., during Xn-based (interface between base stations) handover or N2-based handover) (e.g., selecting a cell included in the permitted area or not selecting a cell included in the non-permitted area).

[0067] In addition, in order to dynamically determine access and mobility-related policy information (e.g., RFSP indexes or service area restrictions), the Access and Mobility (AM) PCF can send a subscription message to the BSF or Session Management (SM) PCF, which requests notification of the establishment and release of the SM policy association between the Data Network Name (DNN) and S-NSSAI.

[0068] When a network slice has been replaced from S-NSSAI to an alternative S-NSSAI or vice versa, there is a need in the art for an AM PCF to receive establishment / release information of SM policy associations for the alternative S-NSSAI (or S-NSSAI).

[0069] Figure 2 The process for retaining PDU sessions and updating subscription requests using BSF-based notifications, according to an embodiment, is illustrated.

[0070] refer to Figure 2 The scheme of notification via BSF is disclosed as a method for updating subscription requests for the establishment / termination of SM policy associations to the replaced S-NSSAI when replacing network slices.

[0071] In this disclosure, the PCF of the UE can refer to both the AM PCF and the UE PCF.

[0072] The PCF used for PDU sessions can be used to refer to the SM PCF.

[0073] refer to Figure 2 In step 200, the UE registration process is performed. The UE sends a registration request to the AMF via the RAN. The AMF receives the UE's subscription information (e.g., RFSP index and SAR) from the UDM. Then, in order to obtain the UE's AM policy, the AMF sends a message to the AMPCF requesting the AM policy. The request message sent by the AMF to the AMPCF may include the RFSP index and SAR information received from the UDM. When the message received from the AMF includes RFSP index and SAR information, the AMPCF can determine the RFSP index or SAR to be applied based on this information, and then add it to the response message sent to the AMF.

[0074] In this scenario, when access and mobility-related policy information (e.g., RFSP index or SAR) changes depending on the application in use, the AM PCF can send a subscription request message to the SM PCF via the BSF or the AMF and SMF, based on the AM PCF's operator policy. This request message is used to request notification from the AM PCF when a UE and the S-NSSAI / DNN are associated with establishing or terminating a session policy (e.g., in the case of the BSF or when a new SM PCF is registered for a Subscription Permanent Identifier (SUPI) (or UE identifier information), S-NSSAI, or DNN).

[0075] When the AM PCF has determined to send a subscription request message to the BSF requesting notification to the AM PCF regarding the association of the UE with the S-NSSAI / DNN for establishing or terminating the session policy, the AM PCF may send a request message including the following information, but this disclosure is not limited thereto.

[0076] SUPI

[0077] DNN / S-NSSAI: DNN / S-NSSAI pair. AM PCF can add DNN / S-NSSAI pairs stored as configuration information for each application or identified by information received from a third party (e.g., Application Function (AF)).

[0078] Address information used to receive notifications (e.g., callback URI)

[0079] Registration or deregistration instructions: When the AM PCF determines, based on a notification sent by the BSF, that access and mobility-related policy information can be changed when establishing and terminating SM policy associations for DNNs and S-NSSAIs, the AM PCF may add a registration or deregistration instruction for each DNN / S-NSSAI to the message sent to the BSF. The BSF reports SM PCF registration when establishing the first SM policy association for S-NSSAIs and DNNs, and reports SM PCF deregistration when terminating the last SM policy association for S-NSSAIs and DNNs.

[0080] However, the information to be included is not limited to this. When S-NSSAI is replaced for a UE (i.e., when a network slice replacement for a UE occurs), the AM PCF can send a request to the SM PCF via the AMF and SMF to notify the AM PCF of the replacement information.

[0081] The message may include an event ID that indicates a notification of network slice replacement.

[0082] When the SM PCF receives a message containing both S-NSSAI and the alternative S-NSSAI, the SM PCF can add the Network Slice Replacement Indication and the alternative S-NSSAI to a notification (or report) message sent to the AM PCF.

[0083] AMF sends a registration acceptance message to UE via RAN.

[0084] exist Figure 2 In step 201, when a PDU session is needed to send application services, the UE can send a PDU session establishment request message to the AMF via the RAN.

[0085] AMF establishes a PDU session via an S-NSSAI determined by itself or an S-NSSAI included in a message received from the UE.

[0086] In step 202, when a message indicating that S-NSSAI is unavailable is received from OAM, NSSF or AM PCF, AMF can determine to replace S-NSSAI with the UE's alternative S-NSSAI.

[0087] If the mapping of the alternative S-NSSAI (i.e., information indicating that the alternative S-NSSAI should be used instead of the S-NSSAI) and the alternative S-NSSAI are not included in the allowed NSSAI (i.e., information including the allowed network slice identifier) ​​and / or the configured NSSAI (i.e., information including the configured network slice identifier), then the AMF may send the allowed NSSAI and / or the configured NSSAI, including the alternative S-NSSAI, to the UE respectively.

[0088] In step 203, when there is a PDU session associated with the UE’s S-NSSAI, the AMF can send a message to the SMF responsible for the PDU session that includes a replacement S-NSSAI, S-NSSAI and SM context ID (i.e., the context information identifier of the PDU session) (e.g., Nsmf_UpdateSMcontext request or Nsmf_ReleaseSMcontext request).

[0089] In step 204, after receiving the message from step 203, the SMF can determine whether to retain the PDU session or rebuild the PDU session for network slice replacement.

[0090] The SMF can send a message to the SM PCF used for the PDU session, including the UE address, SUPI, DNN, alternative S-NSSAI, S-NSSAI, SM policy context ID (i.e., the SM policy identifier used for the PDU session), and a retention indication (indicating that the PDU session or SM policy associated information will be retained) (this information can be included when the SMF determines to retain the PDU session) or a non-retention indication (indicating that the PDU session or SM policy associated information will be released) (this information can be included when the SMF determines to rebuild the PDU session).

[0091] When the SM PCF receives the message from step 204 from the SMF, it can determine that the S-NSSAI used for the PDU session has been replaced by the alternative S-NSSAI.

[0092] When the SM PCF receives a subscription request for a network slice replacement event from the AM PCF in step 200 or step 201, the SM PCF may send a message to the AM PCF in step 204a that includes a network slice replacement occurrence indication (i.e., an indication that a network slice change has occurred) and one or more of the following: replacement S-NSSAI, S-NSSAI, SUPI, UE address, and notification relevance information.

[0093] When the message in step 204a includes a network slice replacement indication and a replacement S-NSSAI, the AM PCF can identify the replaced S-NSSAI in step 205 (e.g., the S-NSSAI that notifies of the relevance information or the S-NSSAI included in step 204a).

[0094] When a subscription to an SM policy association related to a replacement S-NSSAI exists for the BSF (e.g., when the AM PCF has already sent a subscription request for the replacement S-NSSAI to the BSF in step 200 or step 201, or when a subscription association ID for the replacement S-NSSAI exists for the BSF), the AM PCF can cancel the subscription and make a new subscription request, or perform a subscription update via a new subscription request.

[0095] When AM PCF cancels its subscription, AM PCF can send an Nbsf_Management_Unsubscribe request (subscription-related ID) to BSF.

[0096] AM PCF can send a subscription request message to BSF that includes the following information.

[0097] SUPI

[0098] DNN / S-NSSAI: A DNN / S-NSSAI pair. The AM PCF can add DNN / S-NSSAI pairs stored as configuration information for each application or identified by information received from the AF. In this case, when the AM PCF receives information indicating that S-NSSAI has been replaced by a substitute S-NSSAI, the AM PCF can add a substitute S-NSSAI instead of S-NSSAI.

[0099] Address information used to receive notifications (e.g., callback URI)

[0100] Registration or deregistration instructions: When the AM PCF determines, based on a notification sent by the BSF, that access and mobility-related policy information can be changed when establishing and terminating SM policy associations for DNNs and S-NSSAIs, the AM PCF may add a registration or deregistration instruction for each DNN / S-NSSAI to the message sent to the BSF. The BSF reports SM PCF registration when establishing the first SM policy association for S-NSSAIs and DNNs, and reports SM PCF deregistration when terminating the last SM policy association for S-NSSAIs and DNNs.

[0101] The SM PCF may send the message of step 206a or the message of step 206b only if the message of step 204 includes a reservation instruction.

[0102] The SM PCF may send the message of step 206a or the message of step 206b only if the message of step 204 does not include a non-retention instruction.

[0103] When the message from step 204 is received, in step 206a, the SM PCF can send a message to the BSF for registering or updating binding information.

[0104] The message may include one or more of the following: UE address, SUPI, DNN, alternative S-NSSAI, S-NSSAI, and PCF address.

[0105] When a message is received, the BSF can generate binding information including the UE address, SUPI, DNN, and alternative S-NSSAI, S-NSSAI, or PCF address.

[0106] Alternatively, upon receiving the message from step 204, in step 206b, the SM PCF may send a message to the BSF to update the binding information.

[0107] The message may include one or more of the following: UE address, binding identifier, alternative S-NSSAI, and network slice addition indication (i.e., an indication that an alternative S-NSSAI will be added to the binding information).

[0108] When the BSF receives a subscription request message including the replacement S-NSSAI from the AM PCF in step 205, if binding information including the replacement S-NSSAI is generated in step 206a or step 206b, the BSF may send a message to the AMPCF in step 207 to notify of network slice replacement, SM PCF registration, and / or SM PCF deregistration.

[0109] The message may include DNN, alternative S-NSSAI, UE address, SUPI, registration notification (i.e., information indicating that the SM PCF has registered with DNN and alternative S-NSSAI) and PCF address, but this disclosure is not limited thereto.

[0110] When the message from step 207 is received, the AM PCF can update the RFSP index or SAR in step 208.

[0111] In step 209, when the AM PCF determines to update the RFSP index, the AM PCF can send the updated RFSP index to the RAN via the AMF. Upon receiving the updated RFSP index, the RAN can send the corresponding cell reselection priority to the UE.

[0112] In step 210, when the AM PCF determines that the SAR needs to be updated, the AM PCF can send the updated SAR to the UE via the AMF and RAN.

[0113] Figure 3The procedure for retaining a PDU session and updating a subscription request using SM PCF-based notifications, according to an embodiment, is illustrated.

[0114] refer to Figure 3 The notification scheme via SM PCF is disclosed as a method for updating the SM policy association establishment / termination subscription request for the S-NSSAI used for replacement when a network slice is replaced.

[0115] In step 300, the UE registration process is performed. The UE sends a registration request to the AMF via the RAN. The AMF receives the UE's subscription information (e.g., which may include RFSP indexes and SARs) from the UDM. Then, in order to obtain the UE's AM policy, the AMF sends a message to the AM PCF requesting the AM policy. The request message sent by the AMF to the AM PCF may include the RFSP index and SAR information received from the UDM. When the message received from the AMF includes RFSP index and SAR information, the AM PCF can determine the RFSP index or SAR to be applied based on this information, and then add it to the response message sent to the AMF.

[0116] In this scenario, when access and mobility-related policy information (e.g., RFSP index or SAR) changes depending on the application in use, the AM PCF can send a subscription request message to the SM PCF via the BSF or the AMF and SMF, based on the AM PCF's operator policy. This request message is used to request notification when establishing or terminating session policy associations for the UE and for the S-NSSAI / DNN (e.g., in the case of the BSF or when registering a new SMPCF for the SUPI (or UE address), S-NSSAI, or DNN).

[0117] When the AM PCF has determined to send a subscription request message for requesting notification to the UE and for S-NSSAI / DNN to associate the establishment or termination of a session policy, the AM PCF may send a request message to the SM PCF via the AMF and SMF, including one or more of the following information (i.e., the request message may be delivered sequentially from the AM PCF to the AMF, SMF, and SM PCF). However, this disclosure is not limited thereto.

[0118] Event ID: Includes an event identifier that indicates the session policy associated with the establishment / termination event.

[0119] SUPI

[0120] DNN / S-NSSAI: DNN / S-NSSAI pair. AM PCF can add DNN / S-NSSAI pairs stored as configuration information for each application or DNN / S-NSSAI pairs identified by information received from AF to the request message.

[0121] Address information used to receive notifications

[0122] When S-NSSAI is replaced for a UE (i.e., when a network slice replacement occurs for a UE), the AM PCF can send a request to the SM PCF via the AMF and SMF to notify the AM PCF of the replacement information.

[0123] The message may include an event ID that indicates a notification of network slice replacement.

[0124] When the SM PCF receives a message containing both S-NSSAI and the alternative S-NSSAI, the SM PCF can add the Network Slice Replacement Indication and the alternative S-NSSAI to a notification (or report) message sent to the AM PCF.

[0125] When the AM PCF determines, based on notifications sent by the BSF, that access and mobility-related policy information can be changed when establishing and terminating SM policy associations for DNNs and S-NSSAIs, the PCF can add a registration or deregistration instruction for each DNN / S-NSSAI to the message sent to the BSF. When establishing the first SM policy association, the BSF can report PCF registration for the PDU session, and when terminating the last SM policy association for a DNN and S-NSSAI, the BSF can report PCF deregistration for the PDU session.

[0126] AMF sends a registration acceptance message to UE via RAN.

[0127] exist Figure 3 In step 301, when a PDU session is needed to send application services, the UE can send a PDU session establishment request message to the AMF via the RAN.

[0128] AMF establishes a PDU session via an S-NSSAI determined by itself or an S-NSSAI included in a message received from the UE.

[0129] In step 302, when a message indicating that S-NSSAI is unavailable is received from OAM, NSSF or AM PCF, AMF can determine to replace S-NSSAI with the UE's alternative S-NSSAI.

[0130] If the mapping of the alternative S-NSSAI (i.e., information indicating that the alternative S-NSSAI should be used instead of the S-NSSAI) and the alternative S-NSSAI are not included in the allowed NSSAI (i.e., information including the allowed network slice identifier) ​​and / or the configured NSSAI (i.e., information including the configured network slice identifier), then the AMF may send the allowed NSSAI and / or the configured NSSAI, including the alternative S-NSSAI, to the UE respectively.

[0131] In step 303, when there is a PDU session associated with the UE’s S-NSSAI, the AMF can send a message to the SMF responsible for the PDU session that includes a replacement S-NSSAI, S-NSSAI and SM context ID (i.e., the context information identifier of the PDU session) (e.g., Nsmf_UpdateSMcontext request or Nsmf_ReleaseSMcontext request).

[0132] In step 304, after receiving the message from step 303, the SMF can determine whether to retain the PDU session or rebuild the PDU session for network slice replacement.

[0133] The SMF can send a message to the SM PCF used for the PDU session, including the UE address, SUPI, DNN, alternative S-NSSAI, S-NSSAI, SM policy context ID (i.e., the SM policy identifier used for the PDU session), and a retention indication (indicating that the PDU session or SM policy associated information will be retained) (this information can be included when the SMF determines to retain the PDU session) or a non-retention indication (indicating that the PDU session or SM policy associated information will be released) (this information can be included when the SMF determines to rebuild the PDU session).

[0134] When the SM PCF receives the message from step 304 from the SMF, it can determine that the S-NSSAI used for the PDU session has been replaced by the alternative S-NSSAI.

[0135] When the SM PCF receives a subscription request for a network slice replacement event from the AM PCF in step 300 or 301, the SM PCF may send a message to the AM PCF in step 304a. This message includes a network slice replacement occurrence indication (i.e., an indication that a network slice change has occurred) and one or more of the following: replacement S-NSSAI, S-NSSAI, SUPI, UE address, and notification relevance information.

[0136] When the message in step 304a includes a network slice replacement indication and a replacement S-NSSAI, the AM PCF can identify the replaced S-NSSAI in step 305 (e.g., the S-NSSAI that notifies of the relevance information or the S-NSSAI included in step 304a).

[0137] When a subscription to an SM policy associated with a replacement S-NSSAI exists for the SM PCF (e.g., when the AM PCF has already sent a subscription request for the replacement S-NSSAI to the SM PCF via the AMF and SMF in step 300 or 301, or when a notification related ID for the replacement S-NSSAI exists for the SM PCF), the AM PCF can cancel the subscription and issue a new subscription request, or perform a subscription update via the new subscription request.

[0138] When AM PCF unsubscribes, AM PCF can send an Npcf_EventExposure_Unsubscribe request (notifying the relevance ID) to SM PCF.

[0139] AM PCF can send a subscription request message to SM PCF including the following information. Step 305 indicates the logical flow, in which the information sent from AM PCF to SM PCF is first sent from AM PCF to AMF, from AMF to SMF, and then from SMF to SM-PCF.

[0140] Event ID: Includes an event identifier that indicates the session policy associated with the establishment / termination event.

[0141] SUPI

[0142] DNN / S-NSSAI: A DNN / S-NSSAI pair. The AM PCF can add DNN / S-NSSAI pairs stored as configuration information for each application or identified by information received from the AF. In this case, when the AM PCF receives information indicating that S-NSSAI has been replaced by a substitute S-NSSAI, the AM PCF can add a substitute S-NSSAI instead of S-NSSAI.

[0143] Address information used to receive notifications

[0144] The SM PCF may send the message of step 306a or the message of step 306b only if the message of step 304 includes a reservation instruction.

[0145] The SM PCF may send the message of step 306a or the message of step 306b only if the message of step 304 does not include a non-retention instruction.

[0146] When the message from step 304 is received, in step 306a, the SM PCF can send a message to the BSF for registering or updating binding information.

[0147] The message may include one or more of the following: UE address, SUPI, DNN, alternative S-NSSAI, S-NSSAI, and PCF address.

[0148] When a message is received, the BSF can generate binding information including the UE address, SUPI, DNN, and alternative S-NSSAI, S-NSSAI, or PCF address.

[0149] Alternatively, upon receiving the message from step 304, in step 306b, the SM PCF may send a message to the BSF to update the binding information.

[0150] The message may include one or more of the following: UE address, binding identifier, alternative S-NSSAI, and network slice addition indication (i.e., an indication that an alternative S-NSSAI will be added to the binding information).

[0151] When the SM PCF receives a subscription request message that includes a replacement S-NSSAI from the AM PCF (via the SMF) in step 305, if a new SM policy association including the replacement S-NSSAI is established in step 306a or 306b, or if the S-NSSAI in an existing SM policy association is changed to the replacement S-NSSAI, the SM PCF may send a message to the AM PCF in step 307 to notify of the changed S-NSSAI.

[0152] The message may include DNN, alternative S-NSSAI, UE address, SUPI and registration notification (i.e., information indicating that an SM policy association has been established with DNN and alternative S-NSSAI), but this disclosure is not limited thereto.

[0153] When the message from step 307 is received, the AM PCF can update the RFSP index or SAR in step 308.

[0154] In step 309, when the AM PCF determines to update the RFSP index, the AM PCF can send the updated RFSP index to the RAN via the AMF. Upon receiving the updated RFSP index, the RAN can send the corresponding cell reselection priority to the UE.

[0155] In step 310, when the AM PCF determines that the SAR needs to be updated, the AM PCF can send the updated SAR to the UE via the AMF and RAN.

[0156] Figure 4 The process for reconstructing a PDU session and updating a subscription request using a BSF-based notification, according to an embodiment, is illustrated.

[0157] refer to Figure 4 The scheme of notification via BSF is disclosed as a method for updating the SM policy association establishment / termination subscription request of the replaced S-NSSAI when rebuilding the replacement network slice via PDU session.

[0158] In step 400, the UE registration process is performed. The UE sends a registration request to the AMF via the RAN. The AMF receives the UE's subscription information (e.g., which may include RFSP indexes and SARs) from the UDM. Then, in order to obtain the UE's AM policy, the AMF sends a message to the AM PCF requesting the AM policy. The request message sent by the AMF to the AM PCF may include the RFSP index and SAR information received from the UDM. When the message received from the AMF includes RFSP index and SAR information, the AM PCF can determine the RFSP index or SAR to be applied and then add it to the response message sent to the AMF.

[0159] In this scenario, when access and mobility-related policy information (e.g., RFSP index or SAR) changes depending on the application in use, the AM PCF can send a subscription request message to the SM PCF via the BSF or the AMF and SMF, based on the AM PCF's operator policy. This request message is used to request notification when establishing or terminating session policy associations for the UE and for the S-NSSAI / DNN (e.g., in the case of the BSF or when registering a new SMPCF for the SUPI (or UE address), S-NSSAI, or DNN).

[0160] When the AM PCF has determined to send a subscription request message for requesting notification to the UE and for S-NSSAI / DNN to associate with the establishment or termination of session policies, the AM PCF may send a request message to the BSF including the following information. However, this disclosure is not limited thereto.

[0161] SUPI

[0162] DNN / S-NSSAI: DNN / S-NSSAI pair. AM PCF can add DNN / S-NSSAI pairs stored as configuration information for each application or DNN / S-NSSAI pairs identified by information received from AF to the request message.

[0163] Address information used to receive notifications (e.g., callback URI)

[0164] Registration or deregistration instructions: When the AM PCF determines, based on a notification sent by the BSF, that access and mobility-related policy information can be changed when establishing and terminating SM policy associations for DNNs and S-NSSAIs, the AM PCF may add a registration or deregistration instruction for each DNN / S-NSSAI to the message sent to the BSF. When establishing the first SM policy association for the corresponding S-NSSAI and DNN, the BSF reports SM PCF registration, and when terminating the last SM policy association for the corresponding S-NSSAI and DNN, the BSF reports SM PCF deregistration.

[0165] When S-NSSAI is replaced for a UE (i.e., when a network slice replacement occurs for a UE), the AM PCF can send a request to the SM PCF via the AMF and SMF to notify the AM PCF of the replacement information.

[0166] The message may include an event ID that indicates a notification of network slice replacement.

[0167] When the SM PCF receives a message containing both S-NSSAI and the alternative S-NSSAI, the SM PCF can add the Network Slice Replacement Indication and the alternative S-NSSAI to a notification (or report) message sent to the AM PCF.

[0168] AMF sends a registration acceptance message to UE via RAN.

[0169] In step 401, when a PDU session is needed to send application services, the UE can send a PDU session establishment request message to the AMF via the RAN.

[0170] AMF establishes a PDU session via an S-NSSAI determined by itself or an S-NSSAI included in a message received from the UE.

[0171] In step 402, when a message indicating that S-NSSAI is unavailable is received from OAM, NSSF or AM PCF, AMF can determine to replace S-NSSAI with the UE's alternative S-NSSAI.

[0172] If the mapping of the alternative S-NSSAI (i.e., information indicating that the alternative S-NSSAI should be used instead of the S-NSSAI) and the alternative S-NSSAI are not included in the allowed NSSAI (i.e., information including the allowed network slice identifier) ​​and / or the configured NSSAI (i.e., information including the configured network slice identifier), then the AMF may send the allowed NSSAI and / or the configured NSSAI, including the alternative S-NSSAI, to the UE respectively.

[0173] In step 403, when a PDU session associated with the UE’s S-NSSAI exists, the AMF can send a message to the SMF responsible for the PDU session that includes a replacement S-NSSAI, S-NSSAI and SM context ID (i.e., the context information identifier of the PDU session) (e.g., Nsmf_UpdateSMContext request or Nsmf_ReleaseSMContext request).

[0174] In step 404, after receiving the message from step 403, the SMF can determine whether to retain the PDU session or rebuild the PDU session for network slice replacement.

[0175] The SMF can send a message to the SM PCF used for the PDU session, including the UE address, SUPI, DNN, alternative S-NSSAI, S-NSSAI, SM policy context ID (i.e., the SM policy identifier used for the PDU session), and a retention indication (indicating that the PDU session or SM policy associated information will be retained) (this information can be included when the SMF determines to retain the PDU session) or a non-retention indication (indicating that the PDU session or SM policy associated information will be released) (this information can be included when the SMF determines to rebuild the PDU session).

[0176] When the SM PCF receives the message of step 404 from the SMF, it can determine that the S-NSSAI used for the PDU session has been replaced by the alternative S-NSSAI.

[0177] When the SM PCF receives a subscription request for a network slice replacement event from the AM PCF in step 400 or 401, the SM PCF may send a message to the AM PCF in step 404a that includes a network slice replacement occurrence indication (i.e., an indication that a network slice change has occurred) and one or more of the following: replacement S-NSSAI, S-NSSAI, SUPI, UE address, and notification relevance information.

[0178] When the message in step 404a includes a network slice replacement indication and a replacement S-NSSAI, the AM PCF can identify the replaced S-NSSAI in step 405 (e.g., the S-NSSAI that notifies of the relevance information or the S-NSSAI included in step 404a).

[0179] When a subscription to an SM policy associated with a replacement S-NSSAI exists for the BSF (e.g., when the AM PCF has already sent a subscription request for the replacement S-NSSAI to the BSF in step 400 or operation 1, or when a subscription-related ID for the replacement S-NSSAI exists for the BSF), the AM PCF can cancel the subscription and make a new subscription request, or perform a subscription update via a new subscription request.

[0180] When AM PCF cancels its subscription, AM PCF can send an Nbsf_Management_Unsubscribe request (subscription-related ID) to BSF.

[0181] AM PCF can send a subscription request message to BSF that includes the following information.

[0182] SUPI

[0183] DNN / S-NSSAI: A DNN / S-NSSAI pair. The AM PCF can add DNN / S-NSSAI pairs stored as configuration information for each application or identified by information received from the AF. In this case, when the AM PCF receives information indicating that S-NSSAI has been replaced by a substitute S-NSSAI, the AM PCF can add a substitute S-NSSAI instead of S-NSSAI.

[0184] Address information used to receive notifications (e.g., callback URI)

[0185] Registration or deregistration instructions: When the AM PCF determines, based on a notification sent by the BSF, that access and mobility-related policy information can be changed when establishing and terminating SM policy associations for DNNs and S-NSSAIs, the AM PCF may add a registration or deregistration instruction for each DNN / S-NSSAI to the message sent to the BSF. When establishing the first SM policy association for the corresponding S-NSSAI and DNN, the BSF reports SM PCF registration, and when terminating the last SM policy association for the corresponding S-NSSAI and DNN, the BSF reports SM PCF deregistration.

[0186] The SM PCF may send the message of step 406a or the message of step 406b only if the message of step 404 includes a reservation instruction.

[0187] The SM PCF may send the message of step 406a or the message of step 406b only if the message of step 404 does not include a non-retention instruction.

[0188] When PDU session reconstruction is determined in step 404, the SMF may send an indication request to the UE in step 406 to request PDU session reconstruction using an alternative to S-NSSAI.

[0189] SMF can release an existing PDU session before or after it is rebuilt.

[0190] The UE can send a PDU session establishment request message to the AMF, which includes a replacement for S-NSSAI, S-NSSAI, and PDU session ID.

[0191] In step 407, the AMF may select a new SMF (SMF2) based on the alternative S-NSSAI and send an SM context creation message to the SMF including the PDU session ID, the alternative S-NSSAI, and the S-NSSAI.

[0192] Upon receiving the message from step 407, in step 408, SMF2 can select a new SM PCF and perform SM policy association establishment via the corresponding SM PCF (SM PCF2). Alternatively, SMF2 can select and use an existing SM PCF (e.g., the PCFs for S-NSSAI, DNN, and SUPI used for the message received in step 407).

[0193] In this case, when the alternative S-NSSAI and S-NSSAI are received in step 407, a message including SUPI, DNN alternative S-NSSAI and S-NSSAI can be sent to SM PCF2.

[0194] When the message received in step 408 includes both the alternative S-NSSAI and the S-NSSAI, SM PCF2 may include both the S-NSSAI and the alternative S-NSSAI in the registration message sent to BSF in step 409.

[0195] When the BSF receives a subscription request message including the alternative S-NSSAI from the AM PCF in step 405, if binding information including the alternative S-NSSAI is generated in step 409, the BSF may send a message to the AM PCF in step 410 to notify it of the generated information.

[0196] The message may include DNN, alternative S-NSSAI, UE address, SUPI, registration notification (i.e., information indicating that the SM PCF has registered with DNN and alternative S-NSSAI) and PCF address, but this disclosure is not limited thereto.

[0197] When the message from step 407 is received, the AM PCF can update the RFSP index or SAR in step 411.

[0198] In step 412, when the AM PCF determines to update the RFSP index, the AM PCF can send the updated RFSP index to the RAN via the AMF. Upon receiving the updated RFSP index, the RAN can send the corresponding cell reselection priority to the UE.

[0199] In step 413, when the AM PCF determines that the SAR needs to be updated, the AM PCF can send the updated SAR to the UE via the AMF and RAN.

[0200] Figure 5 The structure of the UE according to an embodiment is shown.

[0201] refer to Figure 5 The UE may include a controller (control unit) 530, a transceiver 510, and a storage device (memory) 520. However, the components of the UE are not limited to the examples described above. For example, the UE may include fewer or more components than those described above. The controller 530, transceiver 510, and storage device 520 may be implemented as a single chip. Figure 5 The controller 530 may include at least one processor or controller.

[0202] The controller 530 can control a series of processes that enable the UE to operate according to the embodiments of the present disclosure described above. For example, the controller 530 can control the components of the UE to perform the UE's transmission and reception methods depending on whether the base station mode is a base station power-saving mode or a base station normal mode. The controller 530 may include one or more controllers, and the controller 530 can execute a program stored in the storage device 520 to perform the UE's transmission and reception operations in the wireless communication system employing the carrier aggregation described above of the present disclosure.

[0203] Transceiver 510 can transmit / receive signals with a base station. The signals transmitted / received with the base station may include control information and data. Transceiver 510 may include an RF transmitter configured to up-convert and amplify the frequency of the transmitted signal, an RF receiver configured to perform low-noise amplification and down-convert the frequency of the received signal, etc. However, the components of transceiver 510 are not limited to RF transmitters and RF receivers. Transceiver 510 can receive signals via a radio channel, output signals to controller 530, and transmit signals output from controller 530 via a radio channel.

[0204] The memory 520 can store programs and data required for the operation of the UE. The memory 520 can store control information or data included in signals transmitted / received by the UE. The storage device 520 can include storage media such as read-only memory (ROM), random access memory (RAM), hard disk, CD-ROM, and DVD, or a combination of storage media. The storage device 520 can include multiple storage devices. The memory 520 can store programs for performing the UE's transmission and reception operations depending on whether the base station mode is a base station power-saving mode or a base station normal mode.

[0205] Figure 6 The structure of a base station according to an embodiment is shown.

[0206] refer to Figure 6 The base station disclosed herein may include a controller (control unit) 630, a transceiver 610, and a storage device (memory) 620. However, the components of the base station are not limited to the examples described above. For example, the base station may include fewer or more components than those described above. The controller 630, transceiver 610, and storage device 620 may be implemented as a single chip. Figure 6 The controller 630 may include at least one processor or controller.

[0207] The controller 630 can control a series of processes that enable the base station to operate according to the embodiments of the present disclosure described above. For example, the controller 630 can control the components of the base station to execute a UE scheduling method based on whether the base station mode is a base station power-saving mode or a base station normal mode. The controller 630 may include one or more controllers and can execute a program stored in the memory 620 to execute the UE scheduling method based on whether the base station mode is a base station power-saving mode or a base station normal mode.

[0208] Transceiver 610 can transmit / receive signals with the UE. The signals transmitted / received with the UE may include control information and data. Transceiver 610 may include an RF transmitter configured to up-convert and amplify the frequency of the transmitted signal, an RF receiver configured to amplify the received signal with low noise and down-convert its frequency, etc. However, the components of transceiver 610 are not limited to RF transmitters and RF receivers. Transceiver 610 can receive signals via a radio channel, output signals to controller 630, and transmit signals output from controller 630 via a radio channel.

[0209] The memory 620 can store programs and data required for the operation of the base station. The memory 620 can store control information or data included in signals transmitted / received by the base station. The memory 620 can include storage media or combinations of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. The storage device 620 can include multiple storage devices. The memory 620 can store programs for executing UE scheduling methods based on whether the base station mode is a base station power-saving mode or a base station normal mode.

[0210] Figure 7 The structure of a network entity according to an embodiment is shown.

[0211] refer to Figure 7 The network entity disclosed herein may include a controller 730, a transceiver 710, and a storage device (or memory) 720. However, the components of the network entity are not limited to the examples described above. For example, the network entity may include fewer or more components than those described above. The controller 730, transceiver 710, and storage device 720 may be implemented as a single chip. The network entity may refer to an NF including AMF, SMF, PCF, UDM, DN, AF, UPF, NSSF, NWDAF, NSACF, etc.

[0212] The controller 730 can control a series of processes that enable the network entity to operate according to the embodiments of the present disclosure described above. For example, the controller 730 can control components of a network entity to perform a method for providing a broadcast service according to the embodiments described above. The controller 730 can control components of a network entity to perform embodiments of the present disclosure by executing a program stored in storage device 720. The controller 730 may be an application processor (AP), a communication processor (CP), a circuit, a dedicated circuit, or at least one processor.

[0213] Transceiver 710 can transmit / receive signals with other network entities, base stations, or UEs. Signals transmitted / received with other network entities or UEs may include control information and data. Transceiver 710 may include an RF transmitter configured to up-convert and amplify the frequency of transmitted signals, an RF receiver configured to perform low-noise amplification and down-convert the frequency of received signals, etc. However, the components of transceiver 710 are not limited to RF transmitters and RF receivers. Transceiver 710 can receive signals via a radio channel, output signals to controller 730, and transmit signals output from controller 730 via a radio channel.

[0214] The memory 720 can store programs and data required for the operation of network entities. The memory 720 can store control information or data included in signals sent / received by the network entities. The storage device 720 can include storage media or combinations of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. The storage device 720 can include multiple storage devices. The storage device 720 can store programs for performing the aforementioned network slicing change support methods.

[0215] It should be noted that the above figures and embodiments can be combined as needed. For example, the methods in this disclosure can be partially combined with each other to operate network entities and terminals.

[0216] The aforementioned operations of the base station or terminal can be achieved by providing any unit of the base station or terminal equipment with a memory device that stores the corresponding program code. In other words, the controller of the base station or terminal equipment can perform the aforementioned operations by reading and executing the program code stored in the memory device using a processor or central processing unit (CPU).

[0217] Various units or modules of physical entities, base station equipment, or terminal equipment can be operated using hardware circuits such as logic circuits based on complementary metal-oxide-semiconductor, firmware, or combinations of hardware circuits such as software and / or hardware, and firmware and / or software embedded in a machine-readable medium. For example, various electrical structures and methods can be implemented using transistors, logic gates, and circuits such as application-specific integrated circuits (ASICs).

[0218] Here, each box in the flowchart illustration, and combinations of boxes in the flowchart illustration, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, create a device module for implementing the function specified in one or more flowchart boxes.

[0219] These computer program instructions may also be stored in a computer-available or computer-readable storage medium that can instruct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-available or computer-readable storage medium produce an article of manufacture including instruction means modules that implement the functions specified in one or more flowchart blocks.

[0220] Computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus, thereby producing a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in the flowchart blocks.

[0221] Furthermore, each box in the flowchart can represent a module, segment, or section of code, which includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in the boxes may occur out of order. For example, depending on the functions involved, two boxes shown consecutively may actually execute substantially simultaneously, or these boxes may sometimes execute in reverse order.

[0222] Here, the term "cell" refers to a software or hardware element, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), that performs certain functions. However, the term "cell" does not always have a meaning limited to software or hardware. A cell can be configured to be stored in addressable memory or to run one or more processors.

[0223] Therefore, this unit includes, for example, software elements, object-oriented software elements, class elements or task elements, procedures, functions, attributes, processes, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and parameters.

[0224] The elements and functions provided by the unit can be combined into a smaller number of elements or units, or divided into a larger number of elements or units. Furthermore, the elements and units can be implemented to reproduce one or more CPUs within a device or secure multimedia card. The unit in the embodiment may include one or more processors.

[0225] When the method is implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). The one or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors within an electronic device. At least one program includes instructions that cause the electronic device to execute the method according to this disclosure.

[0226] These programs (software modules or software) can be stored in non-volatile memory, including random access memory and flash memory, ROM, electrically erasable programmable read-only memory (EEPROM), disk storage devices, CD-ROMs, DVDs, or other types of optical storage devices or magnetic tape cassettes. Alternatively, any combination of some or all of them can form a memory storing programs. Multiple such memories can be included in an electronic device.

[0227] The program can be stored in an attachable storage device that can access the electronic device via a communication network such as the Internet, intranet, local area network (LAN), wide LAN (WLAN), and storage area network (SAN), or a combination thereof. Such a storage device can access the electronic device via an external port. A separate storage device on a communication network can access portable electronic devices.

[0228] 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 performed by a session management policy control function (SM-PCF) entity in a wireless communication system, comprising: receiving, from a session management function (SMF) entity, an SM policy control update request message including information for identifying a replacement network slice and information related to whether to retain a protocol data unit (PDU) session; identifying a network slice replacement based on the received SM policy control update request message; and transmitting, to at least one network function (NF) entity, an event exposure notification message including at least one of information for identifying the replacement network slice or information related to occurrence of the network slice replacement. 2.The method of claim 1, further comprising: in case that it is identified to retain the PDU session based on the information related to whether to retain the PDU session, transmitting, to a binding support function (BSF) entity, a message for updating binding information of the PDU session and the replacement network slice. 3.The method of claim 1, further comprising: in case that it is identified to release the PDU session based on the information related to whether to retain the PDU session, transmitting, to a BSF entity, a message for creating binding information of the PDU session and the replacement network slice. 4.The method of claim 2, the message for updating the binding information includes at least one of a binding identifier, an identifier of the replacement network slice, or an indicator indicating to add the replacement network slice to the binding information. wherein, 5.The method of claim 1, further comprising: receiving, from the at least one NF entity, a subscription request related to the replacement network slice. 6.A method performed by a network function (NF) entity in a wireless communication system, comprising: receiving, from a session management policy control function (SM-PCF) entity, an event exposure notification message including at least one of information for identifying a replacement network slice or information related to occurrence of a network slice replacement, wherein the event exposure notification message is based on an SM policy control update request message, and wherein the SM policy control update request message includes information for identifying the replacement network slice and information related to whether to retain a protocol data unit (PDU) session. 7.The method of claim 6, further comprising: in case that it is identified to retain or release the PDU session based on the information related to whether to retain the PDU session included in the SM policy control update request message, receiving, from a binding support function (BSF) entity, a BSF notification message including information related to the replacement network slice. 8.The method of claim 6, further comprising: transmitting, to the BSF entity, a subscription request related to the replacement network slice. 9.The method of claim 7, the BSF notification message is based on a message for creating or updating binding information, and wherein wherein the message for creating or updating the binding information includes at least one of a binding identifier, an identifier of the replacement network slice, or an indicator indicating to add the replacement network slice to the binding information. 10.The method of claim 6, further comprising: transmitting, to the SM-PCF entity, a subscription request related to the replacement network slice. ​ 11.A session management policy control function (SM PCF) entity in a wireless communication system, comprising: a transceiver; and a controller coupled to the transceiver, wherein the controller is configured to: receive, from a session management function (SMF) entity, an SM policy control update request message including information for identifying a replacement network slice and information related to whether to retain a protocol data unit (PDU) session, identify a network slice replacement based on the received SM policy control update request message, and transmit, to at least one network function (NF) entity, an event exposure notification message including at least one of information for identifying the replacement network slice or information related to occurrence of the network slice replacement. 12.The SM PCF entity of claim 11, wherein the controller is further configured to, in case that the PDU session is identified to be retained based on the information related to whether to retain the PDU session, transmit, to a binding support function (BSF) entity, a message for updating binding information of the PDU session and the replacement network slice. 13.The SM PCF entity of claim 11, wherein the controller is further configured to, in case that the PDU session is identified to be released based on the information related to whether to retain the PDU session, transmit, to a BSF entity, a message for creating binding information of the PDU session and the replacement network slice. 14.A network function (NF) entity in a wireless communication system, comprising: a transceiver; and a controller coupled to the transceiver, wherein the controller is configured to: receive, from a session management policy control function (SM PCF) entity, an event exposure notification message including at least one of information for identifying a replacement network slice or information related to occurrence of a network slice replacement, wherein the event exposure notification message is based on an SM policy control update request message, and wherein the SM policy control update request message includes information for identifying the replacement network slice and information related to whether to retain a protocol data unit (PDU) session. 15.The NF entity of claim 14, wherein the controller is further configured to, in case that the PDU session is identified to be retained or released based on the information related to whether to retain the PDU session included in the SM policy control update request message, receive, from a binding support function (BSF) entity, a BSF notification message including information related to the replacement network slice.

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