Method and device for providing synchronization service in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. The present disclosure relates to a method performed by a terminal in a wireless communication system. The terminal according to an embodiment of the present disclosure may: transmit, to a base station, a registration message including terminal capability information; receive, from the base station, an SIB including a reference identifier for performing synchronization and a domain identifier for grouping a plurality of terminals; and update a synchronization state on the basis of the reference identifier and the domain identifier.

Description

Method and device for providing synchronization service in a wireless communication system

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method for providing time synchronization between wireless terminals using the 3GPP 5GS (5G System). In particular, the present disclosure relates to a method for providing time synchronization between base station-based wireless terminals to multiple groups of terminals.

[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] As a result of the development of wireless communication systems and the aforementioned advancements in technology, various services have become available, and methods for effectively providing these services are required. In particular, methods for efficiently transmitting real-time media, such as voice and video calls, are required.

[0009] When a 3GPP network (5GS) serves as a synchronization source and provides time synchronization services to terminals, it can provide time synchronization between base station-based wireless terminals to multiple groups of terminals. To ensure the accuracy of the sync service provided by the base station, the 3GPP network can provide the terminals with a sync status. While terminals in the Connected state can check their sync status through signaling between the individual terminals and the base station, Idle terminals broadcast a reference ID (Reference ID) indicating whether there has been a change in the sync status from the base station. Individual terminals compare this with their own status and, if they determine that an update is necessary, transition to the Connected state and check their sync status. The current method only determines whether Idle terminals have changed their sync status and transitions to the Connected state. This approach does not assess the accuracy of the sync service for each terminal, which can result in unnecessary transitions to the Connected state. Furthermore, if Idle terminals all transition to the Connected state simultaneously, it can cause congestion at the base station.

[0010] According to the present disclosure, a method for a terminal to perform communication may include transmitting a registration message including terminal capability information to a base station. The method may receive a synchronization information block (SIB) from the base station, the SIB including a reference identifier for performing synchronization and a domain identifier for grouping multiple terminals. The method may perform a synchronization status update based on the reference identifier and the domain identifier.

[0011] According to the present disclosure, a method for a base station to perform communication may include receiving a registration message including terminal capability information from a terminal. The method may transmit an SIB including a reference identifier for performing synchronization and a domain identifier for grouping multiple terminals to the terminal. The method may perform a synchronization status update of the terminal based on the reference identifier and the domain identifier.

[0012] According to the present disclosure, a terminal for performing communication in a wireless communication system may be provided, and the terminal may include a transceiver and at least one processor connected to the transceiver. The at least one processor may transmit a registration message including terminal capability information to a base station. The at least one processor may receive an SIB including a reference identifier for performing synchronization and a domain identifier for grouping a plurality of terminals from the base station. The at least one processor may perform a synchronization status update based on the reference identifier and the domain identifier.

[0013] When 5GS becomes a Sync (Synchronization) Source and provides Sync services to UEs, it can prevent idle terminals from unnecessarily transitioning to Connected status to check for Sync Status changes. This can reduce battery consumption. It can also prevent congestion at the base station caused by idle terminals transitioning to Connected status all at once.

[0014] FIG. 1 is a diagram illustrating a method for providing 5GS Sync through a 3GPP network according to one embodiment of the present disclosure.

[0015] FIG. 2 is a diagram illustrating a method for transmitting an Event ID to an Idle UE when providing 5GS Sync through a 3GPP network according to one embodiment of the present disclosure.

[0016] FIG. 3 is a diagram illustrating a method for providing multiple domain 5GS Sync through a 3GPP network according to one embodiment of the present disclosure.

[0017] FIG. 4 is a diagram illustrating a method for transmitting an Event ID to an Idle UE when providing multiple domain 5GS Sync through a 3GPP network according to one embodiment of the present disclosure.

[0018] FIG. 5 is a diagram illustrating a method for transmitting an Event ID to an Idle UE when providing multiple domain 5GS Sync through a 3GPP network according to one embodiment of the present disclosure, in which a carrier / AF sets a domain according to a Sync Threshold to reduce congestion.

[0019] FIG. 6 is a diagram illustrating a method for transmitting an Event ID to an Idle UE when providing multiple domain 5GS Sync through a 3GPP network according to one embodiment of the present disclosure, in which a user / operator / AF sets a domain according to service subscription information to reduce battery consumption of a terminal.

[0020] FIG. 7a is a diagram illustrating a method of additionally considering a domain when changing a Sync Status according to one embodiment of the present disclosure, and illustrates that a UE that has confirmed the same Reference ID for the same Domain does not perform a separate Sync Status Update.

[0021] FIG. 7b is a diagram illustrating a method of additionally considering a domain when changing a Sync Status according to one embodiment of the present disclosure, and is a diagram illustrating a process in which a UE that has confirmed a new Reference ID for the same Domain performs a separate Sync Status Update.

[0022] The operating principles of the present disclosure are described in detail below with reference to the attached drawings. In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, the terms described below are defined based on the functions of the present disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the overall content of this specification.

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

[0024] For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size. Identical or corresponding components in each drawing are assigned the same reference numbers.

[0025] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the present disclosure is complete and to fully inform those skilled in the art of the scope of the invention, and the present disclosure is defined solely by the scope of the claims. Like reference numerals designate like elements throughout the specification.

[0026] At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

[0027] Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

[0028] Here, the term '~ part' used in the present embodiment means software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and the '~ part' performs certain roles. However, the '~ part' is not limited to software or hardware. The '~ part' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Therefore, as an example, the '~ part' includes components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ parts' may be combined into a smaller number of components and '~ parts' or further separated into additional components and '~ parts'. Additionally, the components and '~parts' may be implemented to activate one or more CPUs within a device or secure multimedia card. In addition, in an embodiment, the '~parts' may include one or more processors.

[0029] In the following description of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Embodiments of the present disclosure will be described below with reference to the attached drawings.

[0030] 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 as examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms referring to objects with equivalent technical meanings may be used.

[0031] For convenience of explanation, this disclosure uses terms and names defined in the 5GS and NR standards, the most recent standards defined by the 3rd Generation Partnership Project (3GPP) among the existing communication standards. However, this disclosure is not limited to the above terms and names and can be equally applied to wireless communication networks conforming to other standards. In particular, this disclosure can be applied to 3GPP 5GS / NR (5th generation mobile communication standards).

[0032] When used for applications such as smart grids, accurate time synchronization between terminals is required. Sync services can only be provided in certain areas. Outside of these areas, services may not be available, or a different type of sync service may need to be applied. Accurate time synchronization between terminals is also required for factory automation. Audio / video sharing applications also require accurate time synchronization between terminals. Financial applications also require this. For example, stock trading terminals must perform buys and sells based on accurate time synchronization.

[0033] In this disclosure, AF (Application Function) is responsible for the control plane function within the network and can perform the role of providing application services.

[0034] In the present disclosure, the Network Exposure Function (NEF) can perform the role of exchanging information with and controlling external applications.

[0035] In this disclosure, TSN (Time Sensitive Networking) may refer to a set of standards designed to enhance the real-time properties of Ethernet networks.

[0036] In the present disclosure, SFM (Session Management Function) can perform a role of providing connection between a terminal and an external data network.

[0037] In the present disclosure, AMF (Access and Mobility management Function) can serve as a passage for a terminal to access a network.

[0038] In this disclosure, the Policy Control Function (PCF) may be responsible for governing integrated policies for network-wide operations and communicating policies to other entities.

[0039] In this disclosure, Unified Data Management (UDM) can perform the role of providing essential services to various network functions on a request basis.

[0040] In the present disclosure, UDR (User Data Repository) may mean a centralized database that stores and manages user-related information and data in a communication network.

[0041] In the present disclosure, PTP (Precision Time Protocol) may mean a protocol that enables hardware-based time stamping.

[0042] In the present disclosure, RRC (Radio Resource Control) may refer to a radio resource control protocol corresponding to a control plane, which is one of the protocols used when a terminal and a base station communicate.

[0043] In the present disclosure, SIB (System Information Block) may mean a grouping of system information elements of the same characteristics.

[0044] In this disclosure, AS (Access Stratum) may refer to communication between a terminal and a RAN that focuses on wireless-related functions and signaling.

[0045] In the present disclosure, NAS (Non Access Stratum) may mean a functional layer for exchanging signaling and traffic messages between a terminal and a core network in a UMTS protocol stack.

[0046] In this disclosure, a Data Network Name (DNN) may mean a point at which a device connects to the Internet.

[0047] In the present disclosure, a base station is an entity that performs resource allocation of a terminal, and may be at least one of a gNode B, an eNode B, a Node B (or, x Node B (where x is an alphabet including g and e)), a BS (Base Station), a wireless access unit, a base station controller, a satellite, an airborne vehicle, or a node on a network, but is not limited thereto. The base station in the present disclosure may mean the base station itself, a Cell, or an RU depending on the interpretation, and the target that exchanges messages with the UE may be a DU or a CU depending on the structure.

[0048] Additionally, in the present disclosure, user equipment (UE) may include a mobile station (MS), a cellular phone, a smartphone, a computer, a vehicle, a satellite, or a multimedia system capable of performing a communication function.

[0049] FIG. 1 is a diagram illustrating a method for providing 5GS Sync through a 3GPP network according to one embodiment of the present disclosure.

[0050] 5GS (5G System) can provide synchronization service to terminals upon request from AF. 5GS interacts with external AF (Application Function) through TSCTSF (Time Sensitive Communications and Time Synchronization Function) / NEF (network exposure function). In this case, TSCTSF / NEF can exchange management information with NW-TT (Network Side TSN Translator) and DS-TT (Device Side TSN Translator). NW-TT can periodically generate sync messages to synchronize and transmit them to DS-TT including time information. In addition, TSCTSF / NEF can interact with SMF (Session Management Function), AMF (Access and Mobility Management Function), PCF (Policy Control Function), UDM / UDR, etc. to transmit 5GS information to external AF or apply external AF requests to the 5GS System. In particular, TSCTSF / NEF stores the necessary information in UDR and, through the notification process, can deliver updated information to UDM (Unified Data Management) / UDR (user data repository) or PCF (policy control function) via notification. This method can be called a (g)PTP-based sync method.

[0051] It is also possible to support time synchronization between terminals by adjusting RRC (Radio Resource Control) or SIB (System Information Block) by transmitting it to the RAN (Radio Access Network) of 5G that applies the AF request. This method can be called AS (Access Stratum)-based sync method or base station-based sync method. The AS-based sync method can increase the RRC (Radio Resource Control) / SIB (System Information Block) transmission frequency for transmitting time information to a level that satisfies the accuracy. That is, the base station can adjust the time synchronization accuracy by measuring the precise delay time by adjusting the cycle of exchanging messages for measuring the delay time between a specific terminal and the base station using RRC. In addition, the base station can adjust the time synchronization accuracy by adjusting the cycle of including time information in the information broadcast to all terminals using SIB.

[0052] AF's sync request is either (g)PTP-based or AS-based, but AF does not know the internal status of 5GS, such as the supported sync accuracy, the number of corresponding UEs, and whether the corresponding UEs are idle or active. Therefore, even if AF makes a (G)PTP-based request, it may need to be processed as AS-based 5GS sync. Even if AF makes an AS-based request, it may need to be processed as (G)PTP-based 5GS sync. Or, even if AF makes an NAS- or AS-based request, it may need to be processed as both AS-based 5GS sync and (G)PTP-based 5GS sync.

[0053] 5GS sync provisioning may be based on subscription data in the UDM. In addition to conditions such as sync service subscription status for each UE and sync error budget, coverage conditions may also be included.

[0054] At this time, in order for the 3GPP network to guarantee the accuracy level of the sync service provided by the base station, the sync status can be provided to the terminals. The terminal in the connected state can check the sync status through signaling between the development terminal and the base station, but the terminal in the idle state broadcasts a reference ID (Reference ID) indicating whether there has been a change in the sync status from the base station. If individual terminals compare their own status and determine that an update is necessary, they switch to the connected state and check the sync status.

[0055] 5GS broadcasts a reference ID indicating a sync status update (Sync Status Update) for each cell to the UE by including it in the SIB. At this time, the reference ID is composed of a sync scope ID and an event ID, and the sync scope ID is an ID assigned to each unit that maintains the same sync status within the base station. When a UE in RRC_Idle state moves between cells, it can only refer to the reference ID of the sync status broadcast in the SIB. If this value is the same, there is no need to perform a separate sync status update signaling. Conversely, if this value is different from the value previously known to the UE, the UE performs sync status update signaling (Sync Status Update signaling) to check the new sync status.

[0056] FIG. 2 is a diagram illustrating a method for transmitting an event ID to an idle UE when providing 5GS sync through a 3GPP network according to one embodiment of the present disclosure.

[0057] UE1, UE2, and UE3 are the sync service precision requirements that ensure that the base station-based sync service has a sync error budget less than or equal to Threshold 1.

[0058] For UE4, UE5, and UE6, the accuracy requirement for the sync service is to ensure that the base station-based sync service has a sync error budget of Threshold 2 or less.

[0059] UE7, UE8, and UE9 are the sync service precision requirements that ensure that the base station-based sync service has a sync error budget of Threshold 3 or less.

[0060] UE10, UE11, and UE12 are the accuracy requirements for the sync service, which ensures that the base station-based sync service has a sync error budget of Threshold 4 or less.

[0061] When the sync status changes from Threshold 4 or higher to Threshold 3 or higher, the base station broadcasts this status change to SIB with Event ID1 and notifies the terminals with the Reference ID. The Reference ID is composed of a sync scope ID and an event ID, and the Sync Scope ID is an ID assigned to each unit that maintains the same sync status within the base station. At this time, since the sync status has changed from Threshold 3 or lower to Threshold 3 or higher, UE7 to 9 are the terminals that must check the sync status. However, at this time, all UE1 to UE12 switch from the idle state to the connected state and check the sync status.

[0062] When the sync status changes from Threshold 3 or higher to Threshold 1 or higher, the base station broadcasts this status change to SIB with Event ID2 and notifies the terminals with Reference ID. At this time, since the sync status has changed from Threshold 2 or lower to Threshold 2 or higher, and from Threshold 1 or lower to Threshold 1 or higher, UE4~6 and UE1~3 are the terminals that must check the sync status. However, at this time, all UE1~UE12 switch from idle to connected state and check the sync status.

[0063] When the sync status changes from Threshold 1 or higher to Threshold 1 or lower, the base station broadcasts this status change via SIB with Event ID3 and notifies the terminals with the Reference ID. At this time, since the sync status has changed from Threshold 1 or higher to Threshold 1 or lower, UE1 to UE3 are the terminals that must check the sync status. However, at this time, UE1 to UE12 all transition from the idle state to the connected state and check the sync status.

[0064] When the sync status changes from Threshold 2 or higher to Threshold 4 or lower, the base station broadcasts this status change to SIB with Event ID4 and notifies the terminals with Reference ID. At this time, since the sync status has changed from Threshold 2 or higher to Threshold 2 or lower, from Threshold 3 or higher to Threshold 3 or lower, and from Threshold 4 or higher to Threshold 4 or lower, UE4~6, UE7~9, and UE10~12 are the terminals that must check the sync status. However, at this time, all UE1~UE12 switch from idle to connected state and check the sync status.

[0065] As described above, unnecessary connection state transitions between terminals can occur. Furthermore, since idle terminals are simultaneously transitioning to a connected state, congestion can occur at the base station.

[0066] FIG. 3 is a diagram illustrating a method for providing multiple domain 5GS sync through a 3GPP network according to one embodiment of the present disclosure.

[0067] 5GS (5G System) can provide synchronization service to terminals upon request from AF. 5GS interacts with external AF (Application Function) through TSCTSF (Time Sensitive Communications and Time Synchronization Function) / NEF (network exposure function). In this case, TSCTSF / NEF can exchange management information with NW-TT (Network Side TSN Translator) and DS-TT (Device Side TSN Translator). NW-TT can periodically generate sync messages to synchronize and transmit them to DS-TT, including time information. In addition, TSCTSF / NEF can interact with SMF (Session Management Function), AMF (Access and Mobility Management Function), PCF (Policy Control Function), UDM / UDR, etc. to transmit 5GS information to external AF or apply external AF requests to the 5GS System. In particular, TSCTSF / NEF stores the necessary information in UDR and, through the notification process, can deliver updated information to UDM (Unified Data Management) / UDR (user data repository) or PCF (policy control function) through notification. This method can be called a (g)PTP-based sync method.

[0068] It is also possible to support time synchronization between terminals by adjusting RRC (Radio Resource Control) or SIB (System Information Block) by transmitting it to the RAN (Radio Access Network) of 5G that applies the AF request. This method can be called an AS (Access Stratum)-based synchronization method. The RRC (Radio Resource Control) / SIB (System Information Block) transmission frequency for transmitting time information can be increased to a level that satisfies accuracy. The base station can adjust the time synchronization accuracy by measuring the precise delay time by adjusting the cycle of exchanging messages for measuring the delay time between a specific terminal and the base station through RRC. In addition, the base station can adjust the time synchronization accuracy by adjusting the cycle of including time information in the information broadcast to all terminals through SIB.

[0069] AF's sync request is either (g)PTP-based or AS-based, but AF does not know the internal status information of 5GS such as the sync accuracy that can be supported, the number of corresponding UEs, and whether the corresponding UE is idle or active. Therefore, even if AF makes a (G)PTP-based request, it may need to be processed as AS-based 5GS sync. Even if AF makes an AS-based request, it may need to be processed as (G)PTP-based 5GS sync. Alternatively, even if AF makes an NAS- or AS-based request, it may need to be processed as both AS-based 5GS sync and (G)PTP-based 5GS sync. In this case, it is possible to add a domain ID to indicate which group among multiple terminals it belongs to.

[0070] 5GS sync provisioning can also be based on subscription data in the UDM. In addition to conditions such as each UE's sync service subscription and sync error budget, coverage conditions can also be included. In this case, the domain ID can be used to indicate which group a terminal belongs to.

[0071] At this time, the 3GPP network can provide the sync status to terminals to ensure the accuracy of the sync service provided by the base station. Connected terminals can check their sync status through signaling between the development terminal and the base station, but idle terminals broadcast a Reference ID indicating whether there has been a change in the sync status from the base station. Individual terminals compare their status with their own status and, if they determine that an update is necessary, switch to the connected state to check their sync status. At this time, the domain ID can be added to indicate which group the terminal belongs to among multiple groups.

[0072] 5GS broadcasts a Reference ID indicating a Sync Status Update for each cell in the SIB and delivers it to the UE. At this time, the Reference ID is composed of a Sync Scope ID and an Event ID, and the Sync Scope ID is an ID assigned to each unit that maintains the same Sync Status within the base station. When a UE in RRC_Idle state moves between cells, it can only refer to the Reference ID of the Sync Status broadcast in the SIB. If this value is the same, there is no need to perform a separate Sync Status Update signaling. Conversely, if this value is different from the value previously known to the UE, the UE performs Sync Status Update signaling to check the new Sync Status.

[0073] FIG. 4 is a diagram illustrating a method for transmitting an event ID to an idle UE when providing multiple domain 5GS sync through a 3GPP network according to one embodiment of the present disclosure.

[0074] UE1, UE2, and UE3 are the sync service precision requirements that ensure that the base station-based sync service has a sync error budget less than or equal to Threshold 1.

[0075] For UE4, UE5, and UE6, the accuracy requirement for the sync service is to ensure that the base station-based sync service has a sync error budget of Threshold 2 or less.

[0076] UE7, UE8, and UE9 are the sync service precision requirements that ensure that the base station-based sync service has a sync error budget of Threshold 3 or less.

[0077] UE10, UE11, and UE12 are the accuracy requirements for the sync service, which ensures that the base station-based sync service has a sync error budget of Threshold 4 or less.

[0078] Also, UE1 and UE2 belong to Domain1, UE7, UE8, and UE9 belong to Domain2. The remaining UEs, UE3~6 and UE10~12, belong to Domain0 or the default domain.

[0079] When the Sync Status changes from Threshold 4 or higher to Threshold 3 or higher, the base station broadcasts this status change via SIB with Event ID1, notifying the terminals with the Reference ID and the target domain. In this case, D2, E1, Domain2, and Event ID1 are included in the SIB and broadcast. At this time, since the Sync Status has changed from Threshold 3 or lower to Threshold 3 or higher, UE7~9 are the terminals that must check the Sync Status. Since Domain2 is designated as the target, only UE7~9 transition from Idle to Connected to check the Sync Status. When 5GS becomes a Synchronization Source and provides Sync Service to UEs, it can prevent idle terminals from unnecessarily transitioning to Connected to check for the Sync Status change. This can reduce battery consumption of the terminals. In addition, it can prevent the base station from being congested by idle terminals transitioning to Connected status all at once.

[0080] When the sync status changes from Threshold 3 or higher to Threshold 1 or higher, the base station broadcasts this status change as an SIB with Event ID2 and notifies the terminals with the Reference ID along with the target domain. In this case, D0, E2 and D1, E2, i.e., Domain0 (default domain) and Domain1, and Event ID2 are included in the SIB and broadcast. At this time, since the sync status has changed from Threshold 2 or lower to Threshold 2 or higher, and from Threshold 1 or lower to Threshold 1 or higher, UE4~6 and UE1~3 are the terminals that must check the sync status. UE1~2 of the target Domain1 and UE3~UE6 and UE10~12 of Domain0 (default domain) all switch from the idle state to the connected state to check the sync status. It can prevent the terminals (UE7~9) belonging to Domain2 from unnecessarily switching from the idle state to the connected state to check the sync status change. This can reduce the battery consumption of the terminals. Additionally, it is possible to prevent congestion at the base station by having idle terminals switch to a connected state all at once.

[0081] When the sync status changes from Threshold 1 or higher to Threshold 1 or lower, the base station broadcasts this status change with Event ID3 in SIB, notifying the terminals with the Reference ID and the target domain. In this case, D1, E3, i.e., Domain 1 and Event ID3, are included in the SIB and broadcast. At this time, since the sync status has changed from Threshold 1 or higher to Threshold 1 or lower, UE1 to 3 are the terminals that must check the sync status. UE1 to 2, which are terminals in the target Domain 1, and UE3 to UE6 and UE10 to 12, which are terminals in Domain 0 (default Domain), all transition from the idle state to the connected state to check the sync status. This can prevent terminals belonging to Domain 2 (UE7 to 9) from unnecessarily transitioning from the idle state to the connected state to check the sync status change. This can reduce the battery consumption of the terminals. In addition, it can prevent the base station from being congested by the idle terminals transitioning to the connected state all at once.

[0082] When the sync status changes from Threshold 2 or higher to Threshold 4 or lower, the base station broadcasts this status change as an SIB with Event ID4 and notifies the terminals with the Reference ID and the target domain. In this case, D0, E4 and D2, E4, that is, Domain0 (default domain) and Domain2, and Event ID4 are included in the SIB and broadcast. At this time, since the sync status has changed from Threshold 2 or higher to Threshold 2 or lower, from Threshold 3 or higher to Threshold 3 or lower, and from Threshold 4 or higher to Threshold 4 or lower, UE4~6, UE7~9, and UE10~12 are the terminals that must check the sync status. Since Domain2 is specified as the target, UE7~9 terminals switch from idle state to connected state and check the sync status. In addition, since Domain0 is also specified, UE3~6 and UE10~12 also switch from idle state to connected state and check the sync status. Domain 1 terminals (UE1-2) can be prevented from unnecessarily switching from idle to connected mode to check for sync status changes. This can reduce terminal battery consumption. Furthermore, it can prevent congestion at the base station caused by idle terminals simultaneously switching to connected mode.

[0083] FIG. 5 illustrates a method for transmitting an event ID to an idle UE when providing multiple domain 5GS sync through a 3GPP network according to one embodiment of the present disclosure, in which a carrier / AF sets a domain according to a sync threshold for reducing congestion.

[0084] Operators or AFs can assign domains to UEs for the purpose of grouping and dispersing UEs to prevent congestion at base stations. In this case, UEs can be divided and assigned to the same domain based on the thresholds of the sync error budget for which event IDs are generated. For example, UE1, UE2, and UE3 based on Threshold 1 can be assigned to Domain 1, and UE7, UE8, and UE9 based on Threshold 3 can be assigned to Domain 2. The remaining thresholds, UE4~6 and UE10~12 based on Threshold 2 or Threshold 4, can be assigned to Domain 0 or the default domain.

[0085] UE1, UE2, and UE3 are the sync service precision requirements that ensure that the base station-based sync service has a sync error budget less than or equal to Threshold 1.

[0086] For UE4, UE5, and UE6, the accuracy requirement for the sync service is to ensure that the base station-based sync service has a sync error budget of Threshold 2 or less.

[0087] UE7, UE8, and UE9 are the sync service precision requirements that ensure that the base station-based sync service has a sync error budget of Threshold 3 or less.

[0088] UE10, UE11, and UE12 are the accuracy requirements for the sync service, which ensures that the base station-based sync service has a sync error budget of Threshold 4 or less.

[0089] When the sync status changes from Threshold 4 or higher to Threshold 3 or higher, the base station broadcasts this status change via SIB with Event ID1, notifying the terminals with the Reference ID and the target domain. In this case, D2, E1, Domain2, and Event ID1 are included in the SIB and broadcast. At this time, since the sync status has changed from Threshold 3 or lower to Threshold 3 or higher, UE7~9 are the terminals that must check the sync status. Since Domain2 is designated as the target, only UE7~9 transition from the idle state to the connected state to check the sync status. When 5GS becomes a synchronization source and provides sync services to the UE, it can prevent idle terminals from unnecessarily transitioning to the connected state to check the sync status change. This can reduce the battery consumption of the terminals. It can also prevent the base station from being congested by idle terminals transitioning to the connected state all at once.

[0090] When the sync status changes from Threshold 3 or higher to Threshold 1 or higher, the base station broadcasts this status change as an SIB with Event ID2 and notifies the terminals with the Reference ID along with the target domain. In this case, D0, E2 and D1, E2, i.e., Domain0 (default domain) and Domain1, and Event ID2 are included in the SIB and broadcast. At this time, since the sync status has changed from Threshold 2 or lower to Threshold 2 or higher, and from Threshold 1 or lower to Threshold 1 or higher, UE4~6 and UE1~3 are the terminals that must check the sync status. UE1~3 of the target Domain1 and UE4~UE6 and UE10~12 of Domain0 (default domain) all switch from idle to connected state to check the sync status. It can prevent the terminals (UE7~9) belonging to Domain2 from unnecessarily switching from idle to connected state to check the sync status change. This can reduce the battery consumption of the terminals. Additionally, it is possible to prevent congestion at the base station by having idle terminals switch to a connected state all at once.

[0091] When the sync status changes from Threshold 1 or higher to Threshold 1 or lower, the base station broadcasts this status change with Event ID3 in SIB, notifying the terminals with the Reference ID and the target domain. In this case, D1, E3, i.e., Domain 1, and Event ID3 are included in the SIB and broadcast. At this time, since the sync status has changed from Threshold 1 or higher to Threshold 1 or lower, UE1 to 3 are the terminals that must check the sync status. UE1 to 3, which are the terminals of the target Domain 1, switch from the idle state to the connected state and check the sync status. This can prevent the terminals belonging to Domain 2 (UE7 to 9) from unnecessarily switching from the idle state to the connected state to check the sync status change. This can reduce the battery consumption of the terminals. In addition, it can prevent the base station from being congested by the terminals in the idle state switching to the connected state all at once.

[0092] When the sync status changes from Threshold 2 or higher to Threshold 4 or lower, the base station broadcasts this status change as an SIB with Event ID4 and notifies the terminals with the Reference ID and the target domain. In this case, D0, E4 and D2, E4, that is, Domain0 (default domain) and Domain2, and Event ID4 are included in the SIB and broadcast. At this time, since the sync status has changed from Threshold 2 or higher to Threshold 2 or lower, from Threshold 3 or higher to Threshold 3 or lower, and from Threshold 4 or higher to Threshold 4 or lower, UE4~6, UE7~9, and UE10~12 are the terminals that must check the sync status. Since Domain2 is specified as the target, UE7~9 terminals switch from idle state to connected state and check the sync status. In addition, since Domain0 is also specified, UE3~6 and UE10~12 also switch from idle state to connected state and check the sync status. This prevents terminals (UE1-3) in Domain 1 from unnecessarily switching from idle to connected mode to check for sync status changes. This reduces battery consumption. Furthermore, it prevents congestion at the base station caused by idle terminals simultaneously switching to connected mode.

[0093] FIG. 6 is a diagram illustrating a method for transmitting an event ID to an idle UE when providing multiple domain 5GS sync through a 3GPP network according to one embodiment of the present disclosure, in which a user / operator / AF sets a domain according to service subscription information to reduce battery consumption of the UE.

[0094] Operators or AFs can group UEs and assign domains to provide additional services that reduce battery consumption of terminals by preventing unnecessary transitions from idle to connected states for sync status checks for synchronization services. In this case, assignment to domains can be based on whether or not the UEs subscribe to the corresponding service. For example, among terminals based on Threshold 1, UE1 and UE2 subscribed to the battery saving service can be assigned to Domain 1, and among terminals based on Threshold 3, UE7 and UE8 subscribed to the battery saving service can be assigned to Domain 2. The remaining terminals, UE3~6 and UE9~12, can be assigned to Domain 0 or the default domain.

[0095] UE1, UE2, and UE3 are the sync service precision requirements that ensure that the base station-based sync service has a sync error budget less than or equal to Threshold 1.

[0096] For UE4, UE5, and UE6, the accuracy requirement for the sync service is to ensure that the base station-based sync service has a sync error budget of Threshold 2 or less.

[0097] UE7, UE8, and UE9 are the sync service precision requirements that ensure that the base station-based sync service has a sync error budget of Threshold 3 or less.

[0098] UE10, UE11, and UE12 are the accuracy requirements for the sync service, which ensures that the base station-based sync service has a sync error budget of Threshold 4 or less.

[0099] When the sync status changes from Threshold 4 or higher to Threshold 3 or higher, the base station broadcasts this status change as an SIB with Event ID1, notifying the terminals with the Reference ID and the target domain. In this case, D2, E1, and D0, E1, that is, Domain2, Domain0, and Event ID1, are included in the SIB and broadcast. Alternatively, D0 can be omitted by including only D2 and E1, and it can be assumed that D0 is always included in the target. At this time, since the sync status has changed from Threshold 3 or lower to Threshold 3 or higher, UE7~9 are the terminals that must check the sync status. Since Domain2 is designated as the target, UE7~8 transition from idle to connected state and check the sync status. In addition, UE9~12 and UE3~6, which are terminals in Domain0, transition from idle to connected state and check the sync status. When 5GS becomes a synchronization source and provides sync service to the UE, UE1~2, which are terminals in Domain 1, can prevent idle terminals from unnecessarily switching to a connected state to check for a change in sync state.

[0100] When the sync status changes from Threshold 3 or higher to Threshold 1 or higher, the base station broadcasts this status change as SIB with Event ID2 and notifies the terminals with the Reference ID along with the target domain. In this case, D0, E2 and D1, E2, that is, Domain0 (default domain) and Domain1 and Event ID2 are included in the SIB and broadcast. Alternatively, it can operate as if D0 is always included in the target by omitting D0 by including only D1 and E2. At this time, since the sync status has changed from Threshold 2 or lower to Threshold 2 or higher, and from Threshold 1 or lower to Threshold 1 or higher, UE4~6 and UE1~3 are the terminals that must check the sync status. UE1~2 of the target Domain1 and UE3~UE6 and UE9~12 of Domain0 (default Domain) all switch from idle to connected state to check the sync status. This can prevent terminals (UE7-8) belonging to Domain 2 from unnecessarily switching from idle to connected state to check for sync status changes. This can reduce terminal battery consumption.

[0101] When the sync status changes from Threshold 1 or higher to Threshold 1 or lower, the base station broadcasts this status change as SIB with Event ID3 and notifies the terminals with Reference ID along with the target domain (Domain0). In this case, D1, E3 and D0, E3, that is, Domain1, Domain0, and Event ID3, are included in the SIB and broadcast. Alternatively, it may operate as if D0 is always included in the target by omitting D1 and E2. At this time, since the sync status has changed from Threshold 1 or higher to Threshold 1 or lower, UE1 to 3 are the terminals that must check the sync status. UE1 to 2, which are the terminals of the target Domain1, switch from the idle state to the connected state and check the sync status. In addition, UE3 to UE6 and UE9 to 12 of Domain0 (default Domain) all switch from the idle state to the connected state and check the sync status. It can prevent the terminals (UE7 to 8) belonging to Domain2 from unnecessarily switching from the idle state to the connected state to check the sync status change. This can save the battery of the terminal. It can reduce consumption.

[0102] When the sync status changes from Threshold 2 or higher to Threshold 4 or lower, the base station broadcasts this status change as an SIB with Event ID4, notifying the terminals with the Reference ID and the target domain. In this case, D0, E4, and D2, E4, that is, Domain0 (default domain), Domain2, and Event ID4 are included in the SIB and broadcast. Alternatively, D0 can be omitted by including only D1 and E2, and it can operate as if D0 is always included in the target. At this time, since the sync status has changed from Threshold 2 or higher to Threshold 2 or lower, from Threshold 3 or higher to Threshold 3 or lower, and from Threshold 4 or higher to Threshold 4 or lower, UE4~6, UE7~9, and UE10~12 are the terminals that must check the sync status. Since Domain2 is designated as the target, UE7~8 terminals switch from the idle state to the connected state and check the sync status. Additionally, since Domain 0 is also designated, UEs 3-6 and UEs 9-12 also transition from the idle state to the connected state to check the sync status. This prevents the terminals belonging to Domain 1 (UEs 1-2) from unnecessarily transitioning from the idle state to the connected state to check the sync status change. This can reduce the terminal's battery consumption.

[0103] FIG. 7a illustrates a method of additionally considering a domain when changing a sync status according to one embodiment of the present disclosure, and shows that a UE that has confirmed the same reference ID for the same domain does not perform a separate sync status update.

[0104] In step 0, the terminal (UE) sends registration information including UE capability information indicating that it can receive the 5GS synchronization service. At this time, it may include the Cell ID, RAN ID, TA ID, and SA ID where the UE is located. The RAN ID, TA ID, or SA ID can also be derived from the Cell ID. At this time, the UDM can check whether the UE has a service subscription to receive the 5GS synchronization service. The subscription information can include requirements such as the UE, sync error bound, and coverage conditions. In addition, the AMF can check whether the UDM / UDR and the target UE have subscribed to the sync service. At this time, the subscription information can include the sync error budget and domain.

[0105] In step 1, the AF can send a 5GS sync request for the target UEs to the Time Sensitive Communications and Time Synchronization Function (TSCTSF) / Network Exposure Function (NEF). This request includes the required synchronization accuracy as the sync error budget. It can also specify the coverage to which the sync service should be applied, either in the form of a location or a range. The target UEs can be identified by a list of UE IDs, a group ID, or a data network name (DNN) / single network slice selection assistance information (S-NSSAI). In addition, the domain for the synchronization service can be specified.

[0106] In step 1a, TSCTSF / NEF can check whether UDM / UDR and target UE are subscribed to sync service. At this time, sync service subscription information received from UDM / UDR may include sync error budget and domain. It can compare the sync error budget requested by AF with the sync error budget allowed by UDM to determine whether to allow AF's request. In addition, it can compare the domain requested by AF with the sync domain allowed by UDM to determine whether to allow AF's request or map it to a new sync domain to apply service later.

[0107] In Step 2, TSCTSF / NEF can request AMF to report location and range information for target UEs. At this time, the location / range can be converted to RAN ID, TA ID, SA ID, or Cell ID as known from 3GPP.

[0108] In step 3, AMF can notify the location and range information of the UE to TSCTSF / AMF.

[0109] In step 4, the TSCTSF / NEF can report the location and range information of the corresponding UE to the AF. This may include the result of comparing the sync error budget requested by the AF with the sync error budget allowed by the UDM, as confirmed in step 1a, to determine whether to grant the AF's request. Furthermore, this may include the result of comparing the domain requested by the AF with the sync domain allowed by the UDM, as confirmed in step 1a, to determine whether to grant the AF's request, or the result of mapping to a new sync domain.

[0110] In Step 4a, AF can verify that the terminal's location information meets its requirements. It can also store newly allocated domain information in 5GS for future use.

[0111] In step 4b, AF can send a 5GS sync request for the terminal to TSCTSF / NEF.

[0112] In step 5, TSCTSF / NEF can check whether the terminal's location information meets the requirements.

[0113] In step 6, TSCTSF / NEF can receive input of sync status change from RAN / CN / OAM and determine whether sync status update is required. Sync status change input may occur in RAN due to congestion in a specific area, or sync status change input may occur from CN to update sync status of a specific UE through a report from UPF after interaction between UE and UPF. Sync status change input may also occur from OAM to request sync status change when OAM detects a status abnormality in a specific RAN or CN. TSCTSF / NEF can synthesize these inputs to determine whether sync status update is required.

[0114] In step 6a, TSCTSF / NEF can notify the AF of the current status by reflecting the changed sync status in the AF.

[0115] In step 6b, the domain requested by the AF is compared with the sync domain allowed by the UDM to determine whether to allow the AF's request, or to map it to a new sync domain for future service application. In this step, the UE stores its sync domain and uses it to check the sync status later.

[0116] In step 7, the TSCTSF / NEF can forward a 5GS Sync Request for the UE to the PCF. This request includes the required synchronization accuracy as a Sync Error Budget. It can also specify the coverage area to which the Sync service should be applied, using either a Location or Range. The Sync Request can also include a Reference ID (e.g., #1) indicating the point in time or event of the Sync status transfer. The Sync Request can also include a Sync Domain.

[0117] In step 8, the PCF can forward a 5GS Sync Request to the PCF for a UE that satisfies the location or range conditions in the AMF. The request includes the required synchronization accuracy as a sync error budget. It can also specify the coverage to which the sync service should be applied, based on location or range. The Sync Request can include a Reference ID (e.g., #1) that indicates the point in time or event of sync status transmission. This Reference ID can be received from the TSCTSF or generated by the PCF. The Sync Request can also include a sync domain.

[0118] In step 8a, AMF can check whether the terminal's location information meets the requirements.

[0119] In step 9, the AMF requests the gNB to apply synchronization accuracy to UEs that meet the conditions. The synchronization accuracy is included in the sync error budget. The request is simultaneously sent to all gNBs that meet the coverage conditions, i.e., gNB1 and gNB2. The request may include a Reference ID (e.g., #1) indicating the timing or event of sync status transfer. This Reference ID may be received from the TSCTSF or generated by the PCF. The request may also include a sync domain.

[0120] At this stage, each gNB can increase / decrease the SIB (System Information Block) period based on the Sync Error Budget information transmitted in 5GC or increase / decrease the delay time measurement period between the base station and the terminal to measure the RRC (Radio Resource Control) TA (Timing Advance) value with each terminal to satisfy the time synchronization accuracy requirements of the terminal.

[0121] Additionally, each gNB can store a Reference ID (e.g., #1) indicating the point in time or event of sync status transmission, or directly generate and store a Reference ID based on the point in time when the information was received. Each gNB then periodically broadcasts this Reference ID by including it in an SIB. Each gNB can also create a reference ID including the group ID by having gNBs with the same sync status have the same group ID, and periodically broadcast it by including it in an SIB. In addition, at this time, the gNB can include the sync domain in the information it broadcasts. The method of generating the domain and Reference ID is the same as the examples of FIGS. 4, 5, and 6.

[0122] In step 10, the UE receives a SIB from the gNB it is camping on. At this point, it confirms that Reference ID #1 included in the SIB is a new value. The UE can store multiple, most recent Reference IDs and use them for comparison. The SIB may also include a sync domain.

[0123] In step 10a, the gNB can transmit sync state change information to the TSCTSF via the AMF and PCF. The sync state change information may include a sync domain.

[0124] In step 10b, TSCTSF / NEF may also report information received in step 10a to AF.

[0125] In step 11, the UE performs RRC signaling with the gNB to receive detailed sync status information. This RRC signaling may include a sync domain. The UE stores #1, the Reference ID of the most recently performed sync status update. The UE may also store this domain. Afterwards, if there is no traffic for a certain period of time, the UE transitions to the RRC_Idle state.

[0126] In step 12, the UE receives a SIB from the gNB it is camping on. When the domain included in the SIB matches its own domain, Reference ID #1 included in the SIB is identical to the previously stored value, so no separate sync status update is performed. When using the domain configuration method as shown in Fig. 6, depending on the configuration, the UE in Domain 0 may always check whether Reference ID #1 included in the SIB is identical to the previously stored value, even if the domain is not included in the SIB.

[0127] In step 12a, the gNB can transmit sync state change information to the TSCTSF via the AMF and PCF. The sync state change information may include a sync domain.

[0128] In step 12b, TSCTSF / NEF may also report information received in step 12a to AF.

[0129] FIG. 7b illustrates a method of additionally considering a domain when changing a sync status according to one embodiment of the present disclosure, and illustrates a process in which a UE that has confirmed a new Reference ID for the same domain performs a separate sync status update.

[0130] In step 13, the gNB reflects the change in sync status by generating a new Reference ID for the target domains and broadcasting it to the SIB. The method for generating the domain and Reference ID is the same as the examples in Figures 4, 5, and 6.

[0131] The UE receives a SIB from a gNB it is camping on. If the domain included in the SIB does not match its own domain, it compares the Reference ID #2 included in the SIB with the previously stored value, and does not perform a separate sync status update even if the value is new. When using the domain configuration method as shown in Fig. 6, depending on the configuration, the UE in Domain 0 may always check whether the Reference ID #2 included in the SIB is identical to the previously stored value, even if the domain is not included in the SIB.

[0132] In step 13a, the gNB can transmit sync state change information to the TSCTSF via the AMF and PCF. The sync state change information may include a sync domain.

[0133] In step 13b, TSCTSF / NEF may also report the information received in step 13a to AF.

[0134] In step 14, the gNB reflects the change in sync status by generating a new Reference ID for the target domains and broadcasting it to the SIB. The method for generating the domain and Reference ID is the same as the examples in Figures 4, 5, and 6.

[0135] The UE receives a SIB from a gNB on which it is camping. When the domain included in the SIB matches its own domain, the Reference ID #3 included in the SIB is compared to the previously stored value and is a new value, so the UE switches to the RRC_Connected state to perform a sync status update. When using the domain configuration method as shown in Fig. 6, depending on the configuration, the UE of Domain 0 may always check whether the Reference ID #3 included in the SIB is the same as the previously stored value even if the domain is not included in the SIB.

[0136] In step 14a, the gNB can transmit sync state change information to the TSCTSF via the AMF and PCF. The sync state change information may include a sync domain.

[0137] In step 14b, TSCTSF / NEF may also report the information received in step 13a to AF.

[0138] In step 15, the UE performs RRC signaling with the gNB to receive detailed sync status information. This may include a sync domain. The UE stores #3, the Reference ID of the most recently performed sync status update. The terminal may also store this domain. After this, if there is no traffic for a certain period of time, the UE transitions to the RRC_Idle state.

[0139] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0140] 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 disclosure.

[0141] 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.

[0142] 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 performing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device performing an embodiment of the present disclosure.

[0143] In the specific embodiments of the present disclosure described above, components included in the disclosure 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 disclosure is not limited to singular or plural components. Components expressed in the plural form may be composed of singular elements, or components expressed in the singular form may be composed of plural elements.

[0144] While the detailed description of this disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be defined not only by the scope of the claims described below, but also by equivalents thereof.

[0145] According to one embodiment of the present disclosure, in a method for a terminal to perform communication 3, a registration message including terminal capability information may be transmitted to a base station. The method may receive, from the base station, a synchronization information block (SIB) including a reference identifier for performing synchronization and a domain identifier for grouping a plurality of terminals. The method may perform a synchronization status update based on the reference identifier and the domain identifier.

[0146] In one embodiment, the reference identifier may include an event identifier indicating whether an event occurred in a synchronization state and a scope identifier indicating a unit having the same synchronization state.

[0147] In one embodiment, the step of performing a synchronization status update may not perform a synchronization status update if the domain identifier is different from the domain identifier of the domain in which the terminal is included.

[0148] In one embodiment, the step of performing a synchronization status update may not perform a synchronization status update if the domain identifier is identical to the domain identifier of the domain in which the terminal is included and the reference identifier is identical to the reference identifier stored by the terminal.

[0149] In one embodiment, the step of performing a synchronization status update may perform a synchronization status update when the domain identifier is the same as the domain identifier of the domain in which the terminal is included and the reference identifier is different from the reference identifier stored by the terminal.

[0150] In one embodiment, the step of performing a synchronization status update may include transitioning to an RRC_Connected state with the base station. The method may receive an RRC message containing information regarding the synchronization status from the base station.

[0151] In one embodiment, the method may store a reference identifier and a domain identifier. The method may perform a transition between the base station and the RRC_Idle state.

[0152] According to one embodiment of the present disclosure, a method for a base station to perform communication may include receiving a registration message including terminal capability information from a terminal. The method may transmit an SIB including a reference identifier for performing synchronization and a domain identifier for grouping multiple terminals to the terminal. The method may perform a synchronization status update of the terminal based on the reference identifier and the domain identifier.

[0153] According to one embodiment of the present disclosure, a terminal for performing communication in a wireless communication system may be provided, the terminal including a transceiver and at least one processor connected to the transceiver. The at least one processor may transmit a registration message including terminal capability information to a base station. The at least one processor may receive an SIB including a reference identifier for performing synchronization and a domain identifier for grouping a plurality of terminals from the base station. The at least one processor may perform a synchronization status update based on the reference identifier and the domain identifier.

[0154] A device-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the term "non-transitory storage medium" simply means a tangible device that does not contain signals (e.g., electromagnetic waves). This term does not distinguish between cases where data is permanently stored in the storage medium and cases where data is temporarily stored. For example, a "non-transitory storage medium" may include a buffer in which data is temporarily stored.

[0155] According to one embodiment, the method according to various embodiments disclosed in the present document may be provided as included in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) through an application store or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., a downloadable app) may be temporarily stored or temporarily generated in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

Claims

1. In a method for a terminal to perform communication in a wireless communication system, A step of transmitting a registration message including terminal capability information to a base station; A step of receiving a SIB (synchronization information block) including a reference identifier for performing synchronization from the base station and a domain identifier for grouping a plurality of terminals; and A method comprising: performing a synchronization status update based on the above reference identifier and domain identifier; 2. In paragraph 1, A method wherein the above reference identifier includes an event identifier indicating whether an event has occurred in a synchronization state and a scope identifier indicating a unit having the same synchronization state.

3. In paragraph 1, The steps for performing the above synchronization status update are: A method comprising: a step of not performing the synchronization status update when the domain identifier is different from the domain identifier of the domain in which the terminal is included; 4. In paragraph 1, The steps for performing the above synchronization status update are: A method comprising: a step of not performing the synchronization status update when the domain identifier is identical to the domain identifier of the domain in which the terminal is included and the reference identifier is identical to the reference identifier stored by the terminal; 5. In paragraph 1, The steps for performing the above synchronization status update are: A method comprising: performing a synchronization status update when the domain identifier is identical to the domain identifier of the domain in which the terminal is included and the reference identifier is different from the reference identifier stored by the terminal; 6. In paragraph 1, The steps for performing the above synchronization status update are: A step of performing a transition to the RRC_Connected state with the above base station; and A method comprising: receiving an RRC message including information about a synchronization status from the base station; 7. In paragraph 6, a step of storing the above reference identifier and the above domain identifier; and A method further comprising: performing a transition to the RRC_Idle state with the base station; 8. In a method for a base station to perform communication in a wireless communication system, A step of receiving a registration message including terminal capability information from a terminal; A step of transmitting a SIB (synchronization information block) including a reference identifier for performing synchronization to the terminal and a domain identifier for grouping multiple terminals; and A method comprising: performing a synchronization status update of the terminal based on the reference identifier and the domain identifier; 9. In paragraph 8, A method wherein the above reference identifier includes an event identifier indicating whether an event has occurred in a synchronization state and a scope identifier indicating a unit having the same synchronization state.

10. In paragraph 8, The step of performing synchronization status update of the above terminal is: A method comprising: a step of not performing the synchronization status update when the domain identifier is different from the domain identifier of the domain in which the terminal is included; 11. In paragraph 8, The step of performing synchronization status update of the above terminal is: A method comprising: a step of not performing the synchronization status update when the domain identifier is identical to the domain identifier of the domain in which the terminal is included and the reference identifier is identical to the reference identifier stored by the terminal; 12. In paragraph 8, The step of performing synchronization status update of the above terminal is: A method comprising: performing a synchronization status update when the domain identifier is identical to the domain identifier of the domain in which the terminal is included and the reference identifier is different from the reference identifier stored by the terminal; 13. In paragraph 8, The step of performing synchronization status update of the above terminal is: A step of performing a transition to the RRC_Connected state with the above terminal; and A method comprising: transmitting an RRC message including information about a synchronization status to the terminal; 14. In paragraph 13, A method further comprising: a step of performing a transition to an RRC_Idle state with the terminal when the synchronization status update of the terminal is completed; 15. In a terminal performing communication in a wireless communication system, Transmitter and receiver; and At least one processor connected to the transceiver, wherein the at least one processor comprises: Transmit a registration message containing terminal capability information to the base station, Receives a SIB (synchronization information block) including a reference identifier for performing synchronization from the base station and a domain identifier for grouping multiple terminals, A method for performing a synchronization status update based on the above reference identifier and domain identifier.

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