Method and apparatus for notifying application server of IMS session-related information

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates. According to one embodiment of the present disclosure, a method for a network entity related to user data management operating in a wireless communication system may comprise the steps of: receiving, from a network exposure function (NEF), a subscription request message for an IP multimedia subsystem (IMS)-related event; determining at least one IMS application server (AS) to perform a subscription request on the basis of the subscription request message; and transmitting, to the determined at least one IMS AS, a message for subscription to an IMS service-related event related to the subscription request message.

Description

Method and device for notifying IMS session-related information to an application server

[0001] The present disclosure relates to a method and device for controlling a data channel session for supporting an IMS DC (IP multimedia subsystem data channel) service in a DC AS (data channel application server) based on event information related to a bootstrap or application data channel session in which a terminal requests a connection through a data channel server.

[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] The IMS system is a system for transmitting IP-based multimedia, and various services such as VoLTE and VoNR are provided through existing IMS networks linked to LTE or 5G networks. The purpose of the IMS data channel service is to provide various value-added services such as user location information transmission and screen sharing using separate applications in addition to existing voice or video-based services by using the data channel linked to IMS, i.e., the IMS-DC service, in addition to existing RTP-based voice, video, and text services. In order to use these value-added services using the data channel within the IMS data network or services through a standalone IMS data channel, the terminal can transmit a signaling message containing a request for data channel applications and related configuration information for data channel-based services to the network through a bootstrap data channel setup signaling process. The IMS data channel network that receives the signaling message can transmit application or application list information to the terminal based on the user or service provider's settings and request information received from the terminal, thereby transmitting information so that the user terminal can download applications for the data channel service. Based on application or application list information received from the network, the terminal can select an appropriate data channel application based on its capabilities and user preferences and request the appropriate data channel application. Furthermore, the network can allocate a separate media function entity within the network during the bootstrap data channel setup process to support the download of a specific application requested by the terminal.The media function entity can receive data channel application-related information (Replacement HTTP URL representing the application list offered via the MDC1 interface) that can be converted into data channel application information through the media resource management service operation during the bootstrap data channel setup process. Afterwards, the media function entity can receive specific data channel application information selected and requested by the terminal through the Mb interface, and then convert the data channel application download request information into HTTP URL information that can be recognized by the IMS data channel network (e.g., DSCF) to perform application download support operation for the terminal. Multiplexed data streams can be supported depending on the type of service provided by the IMS system. The terminal can receive each data channel application through the bootstrap connection process and simultaneously receive data channel application-related information. Thereafter, the terminal can perform the application data channel setup signaling operation for the data channel connection request of the received data channel application. The application data channel setup signaling message can be transmitted together with application binding information including configuration information for supporting a specific application. Based on the above information received from the terminal, the network can perform at least one application data channel connection operation among three types of application data channel connections: terminal to terminal (P2P Application Data Channel Setup), terminal to application server (P2A Application Data Channel Setup), or terminal to terminal connection via application server (P2A2P Application Data Channel Setup).When connecting to the above IMS DC service, a bootstrap or application data channel connection operation for a standalone IMS data channel service connection, rather than an IMS data channel service in the form of a supplementary service based on existing IMS sessions (e.g. audio / video / messaging), may be requested or performed. In addition, when a terminal uses a standalone IMS data channel service, a bootstrap data channel session connection may be performed first, and a bootstrap data channel session may not always be open when the terminal uses the IMS data channel service. For example, a terminal may request an application data channel connection request to the network directly using a native application without downloading the data channel application and related configuration information through a separate bootstrap data channel session connection by using a data channel application (e.g. native application) pre-configured by the service provider.

[0009] If the service provider providing the IMS DC service is a third-party service provider other than the network operator, the service provider can use a separate contract and service, such as an SLA (Service Level Agreement) with the network operator, to receive IMS DC service-related event information from the network entity supporting the data channel service (e.g., DCSF or IMS AS) and use the event-related reporting information to provide appropriate IMS DC services to terminals. To this end, the DC AS can make a request to the IMS AS to subscribe to an IMS call session-related event or an IMS data channel-related event. Through such a subscription request, the DC AS can receive event-related reporting information directly or through the DCSF when each event occurs in the IMS AS. In addition, the DC AS can make a request to the DCSF to subscribe to an IMS data channel-related event, and through such a subscription, can receive event-related reporting information when a data channel event occurs in the DCSF. The event-related reporting information can be delivered to the DC AS through the DC3 or DC4 interface that constitutes the IMS DC service.

[0010] The present disclosure provides a method and device for supporting a bootstrap or application data channel-related event subscription request from a DC AS to an IMS AS to provide an appropriate IMS data channel service based on call-related event or data channel-related event information occurring in an IMS session. In addition, the present disclosure provides a method and device for event reporting operation for transmitting IMS call session or data channel session-related event information occurring in an IMS AS to a DC AS.

[0011] According to one embodiment of the present disclosure, a method of a network entity related to user data management operating in a wireless communication system may include: receiving a subscription request message for an IMS (IP multimedia subsystem) related event from a network exposure function (NEF); determining at least one IMS application server (AS) to perform the subscription request based on the subscription request message; and transmitting a message for subscribing to an IMS service related event related to the subscription request message to the determined at least one IMS AS.

[0012] The above IMS service related events may be related to at least one user.

[0013] The above subscription request message may include a notification target address.

[0014] The method of the above network entity may further include the step of receiving a reporting message regarding the occurrence of an event from at least one IMS AS.

[0015] The above at least one IMS AS may be classified as a dedicated application server (DAS) or a telephony application server (TAS).

[0016] According to one embodiment of the present disclosure, a method of a network exposure function (NEF) operating in a wireless communication system may include the steps of: receiving, from an application function (AF), a subscription request for an IMS (IP multimedia subsystem) related event; transmitting, to a network entity related to user data management, a subscription request message for the IMS related event when the subscription request relates to an IMS event related to a specific user; and determining, when the subscription request relates to an IMS event not related to the specific user, at least one IMS application server (AS) to perform the subscription request, and transmitting, to the determined IMS AS, a message for subscribing to an IMS related event related to the subscription request message.

[0017] A method and device according to one embodiment of the present disclosure may support an operation of performing a subscription request for transmitting IMS session-related event information from a DC AS. An NEF that has received an event information transmission request from a DC AS may receive subscription data for discovering an appropriate NF for each IMS session from a UDM / HSS or transmit an event subscription request to the UDM / HSS, thereby allowing an appropriate NF to receive a request for IMS session-related event information and supporting a terminal to receive event reporting from the corresponding NF when an IMS session-related event occurs.

[0018] FIG. 1 is a diagram illustrating a network structure and interface of a 5G system according to one embodiment of the present disclosure.

[0019] FIG. 2 is an example of an IMS-DC (IP (internet protocol) multimedia subsystem data channel) structure that provides a data channel service based on an IMS (IP (internet protocol) multimedia subsystem) service according to one embodiment of the present disclosure.

[0020] FIG. 3a is a flowchart of operations related to selecting and registering an IMS AS that supports a terminal's service based on the terminal's Capability information, etc. during an IMS registration procedure of a terminal according to one embodiment of the present disclosure.

[0021] FIG. 3b is a flowchart of operations related to selecting and registering a DCSF that supports an IMS DC service based on capability information of a terminal, etc. during an IMS registration procedure of a terminal according to one embodiment of the present disclosure.

[0022] FIG. 4a is a flowchart illustrating an operation process in which an NEF, having received a request for IMS session-related event reporting from a DC AS according to one embodiment of the present disclosure, selects an appropriate NF that provides IMS services per user or per user group based on subscription data received from a UDM and an HSS, and requests IMS session-related event reporting to the selected NF.

[0023] FIG. 4b is a flowchart illustrating an operation process in which an NEF, having received an operation requesting IMS session-related event reporting from a DC AS according to one embodiment of the present disclosure, selects an appropriate NF that provides IMS services per user or per user group based on the selection of an HSS and subscription data received from the HSS through an NRF, and requests IMS session-related event reporting to the selected NF.

[0024] FIG. 5 is a flowchart illustrating an operation process in which an NEF, having received an IMS session-related event reporting request operation from a DC AS according to one embodiment of the present disclosure, selects an appropriate NF that provides IMS services per user or per user group using an Event Exposure service request operation of a UDM and an HSS, and requests IMS session-related event reporting to the selected NF.

[0025] FIGS. 6A and 6B are flowcharts illustrating an IMS session-related event reporting operation that occurs during a bootstrap data channel connection process at the request of a terminal in order to use an IMS data channel service according to one embodiment of the present disclosure.

[0026] FIG. 7 is a diagram illustrating the structure of a terminal according to one embodiment of the present invention.

[0027] FIG. 8 is a diagram illustrating a network entity according to one embodiment of the present invention.

[0028] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the attached drawings.

[0029] In describing this disclosure, descriptions of technical details that are well-known in the technical field to which this disclosure pertains and are not directly related to this disclosure will be omitted. This is to avoid obscuring the gist of this disclosure by omitting unnecessary explanations and to convey it more clearly. Furthermore, the terms described below are defined based on their functions in this disclosure and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the contents of this specification as a whole.

[0030] 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.

[0031] Hereinafter, a base station (BS) 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 an xNode B (where x is an alphabet including g or e)), a wireless access unit, a base station controller, a satellite, an airborn, or a node on a network. A user equipment (UE) may include a mobile station (MS), a vehicle, a satellite, an airborn, a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, a downlink (DL) is a wireless transmission path of a signal transmitted from a base station to a terminal, and an uplink (UL) is a wireless transmission path of a signal transmitted from a terminal to an air station. Additionally, a sidelink (SL) may exist, which means a wireless transmission path of a signal transmitted from a terminal to another terminal.

[0032] In addition, although LTE, LTE-A, or 5G systems may be described below as examples, embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, this may include 5G-Advance or NR-Advance, or 6th generation mobile communication technology (6G) developed after 5G mobile communication technology (or new radio, NR), and the 5G described below may also include existing LTE, LTE-A, and other similar services. In addition, the present disclosure may be applied to other communication systems with some modifications within a range that does not significantly deviate from the scope of the present disclosure, as determined by a person having skilled technical knowledge.

[0033] 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).

[0034] 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.

[0035] Here, the term '~ part' used in this 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 or 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.

[0036] 3GPP, responsible for cellular mobile communications standards, is standardizing a new core network architecture called 5G Core (5GC) to facilitate the evolution of 4G LTE systems to 5G systems. Compared to the Evolved Packet Core (EPC), the network core for 4G, 5GC supports the following differentiated features:

[0037] 5GC introduces the Network Slice feature. As a requirement of 5G, 5GC must support a variety of terminal types and services, such as enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine Type Communications (mMTC). These terminals and services each have different requirements for the core network. For example, eMBB services may require high data rates, while URLLC services may require high reliability and low latency. To meet these diverse service requirements, Network Slice technology has been proposed.

[0038] Network slicing can refer to a method of virtualizing a single physical network to create multiple logical networks (e.g., network slices). An activated network slice can be called a network slice instance, and each network slice instance (NSI) can have different characteristics. By configuring a network function (NF) for each NSI according to its characteristics, mobile carriers can satisfy various service requirements according to terminals / services. For example, mobile carriers can efficiently support various 5G services (e.g., eMBB, URLLC, or mMTC) by allocating an NSI that matches the characteristics of the service required for each terminal.

[0039] 5GC can easily support the network virtualization paradigm by separating mobility management functions from session management functions. In 4G LTE, all terminals can receive services from the network through signaling exchanges with a single core entity called the mobility management entity (MME), which is responsible for registration, authentication, mobility management, and session management. In 5G, the number of terminals (including MTC terminals) will explode, and the mobility and traffic / session characteristics that must be supported depending on the terminal type will become more specialized. Therefore, supporting all functions from a single entity (such as the MME) will inevitably reduce scalability by adding entities for each required function. Therefore, various functions are being developed based on a structure that separates mobility management and session management functions to improve scalability in terms of functional / implementation complexity and signaling load of the core entity responsible for the control plane.

[0040] FIG. 1 is a diagram illustrating a network structure and interface of a 5G system according to one embodiment of the present disclosure.

[0041] A network entity included in the network structure of the 5G system of Fig. 1 may include a network function (NF) depending on the system implementation.

[0042] Referring to FIG. 1, the network structure of a 5G system may include various network entities. For example, the 5G system may include an authentication server function (AUSF) entity (108), an access and mobility management function (AMF) entity (103), a session management function (SMF) entity (105), a policy control function (PCF) entity (106), an application function (AF) entity (107), a unified data management (UDM) entity (109), a data network (DN) (110), a network exposure function (NEF) entity (111), a network slicing selection function (NSSF) entity (114), a network repository function (NRF) entity (115), a network data analytics function (NWDAF), and an edge application service domain repository (EDS). It may include a domain repository (EDR), an edge application server (EAS), an EAS discovery function (EASDF), a user plane function (UPF) entity (104), a (radio) access network ((R)AN) (102), and a terminal, for example, a user equipment (UE) (101).

[0043] Each NF entity of the 5G system (100) supports the following functions.

[0044] AUSF (108) processes and stores data for authentication of UE (101).

[0045] AMF (103) provides functions for access and mobility management per UE, and one UE can be connected to one AMF by default. Specifically, the AMF (103) provides signaling between CN nodes for mobility between 3GPP access networks, termination of a radio access network (RAN) CP interface (i.e., N2 interface), termination of non-access stratum (NAS) signaling (N1), NAS signaling security (NAS ciphering and integrity protection), AS security control, registration management (registration area management), connection management, idle mode UE reachability (including control and performance of paging retransmission), mobility management control (subscription and policy), intra-system mobility and inter-system mobility support, support for network slicing, SMF selection, lawful intercept (for AMF events and interfaces to the LI system), provision of forwarding of session management (SM) messages between UE and SMF, transparent proxy for SM message routing, access authentication, access authorization including roaming authorization check. It supports functions such as authorization, provision of SMS message transmission between UE and SMSF, security anchor function (SAF) and / or security context management (SCM). Some or all of the functions of an AMF entity (103) may be supported within a single instance of an AMF entity.

[0046] DN (110) refers to, for example, an operator service, Internet access, or a third-party service. DN (110) transmits a downlink protocol data unit (PDU) to the UPF entity (104) or receives a PDU transmitted from the UE (101) from the UPF entity (104).

[0047] The PCF entity (106) receives information about packet flows from the application server and provides a function to determine policies such as mobility management and session management. Specifically, the PCF entity (106) supports functions such as supporting a unified policy framework for controlling network operations, providing policy rules so that control plane function entity(ies) (e.g., AMF entity, SMF entity, etc.) can enforce the policy rules, and implementing a front end for accessing related subscription information for policy determination within a user data repository (UDR).

[0048] The SMF entity (105) provides a session management function, and when the UE (101) has multiple sessions, each session can be managed by a different SMF entity. Specifically, the SMF entity (105) is responsible for session management (e.g., session establishment, modification, and termination, including tunnel maintenance between the UPF entity (104) and the (R)AN (102) node), UE IP address allocation and management (optionally including authentication), selection and control of UP functions, setting up traffic steering to route traffic from the UPF entity (104) to the appropriate destination, termination of the interface to policy control functions, enforcement of the control portion of policy and quality of service (QoS), lawful intercept (for SM events and interfaces to the LI system), termination of the session management (SM) portion of NAS messages, downlink data notification, initiation of AN (access network) specific SM information (delivered to the (R)AN (102) via N2 via the AMF entity (103)), determination of the session and service continuity (SSC) mode of the session, and roaming. Supports functions such as functions, etc. Some or all of the functions of an SMF entity (105) can be supported within a single instance of an SMF entity.

[0049] The UDM entity (109) stores user subscription data, policy data, etc. The UDM entity (109) includes two parts: an application front end (FE) and a user data repository (UDR).

[0050] The FE (front end) includes the UDM FE, which is responsible for location management, subscription management, and credential processing, and the PCF entity, which is responsible for policy control. The UDR stores the data required for the functions provided by the UDM-FE and the policy profiles required by the PCF entity. The data stored in the UDR includes user subscription data and policy data, including subscription identifiers, security credentials, access and mobility-related subscription data, and session-related subscription data. The UDM-FE accesses the subscription information stored in the UDR and supports functions such as authentication credential processing, user identification handling, access authentication, registration / mobility management, subscription management, and SMS management.

[0051] The UPF entity (104) forwards the downlink PDU received from the DN (110) to the UE (101) via the (R)AN (102), and forwards the uplink PDU received from the UE (101) via the (R)AN (102) to the DN (110). Specifically, the UPF entity (104) supports functions such as an anchor point for intra / inter RAT mobility, an external PDU session point for interconnection to the Data Network, a user plane part of packet routing and forwarding, packet inspection and policy rule enforcement, an uplink classifier to support lawful intercept, traffic usage reporting, routing of traffic flows to the Data Network, a branching point to support multi-homed PDU sessions, QoS handling for the user plane (e.g., packet filtering, gating, uplink / downlink rate enforcement), uplink traffic validation (service data flow (SDF) to QoS flow mapping), transport level packet marking in uplink and downlink, downlink packet buffering and downlink data notification triggering. Some or all of the functions of a UPF entity (104) may be supported within a single instance of a UPF.

[0052] The AF entity (107) interacts with the 3GPP core network to provide services (e.g., supporting functions such as application impact on traffic routing, access to network capability exposure, and interaction with the policy framework for policy control).

[0053] (R)AN(102) is a general term for a new radio access network that supports both evolved E-UTRA, an evolved version of 4G radio access technology, and new radio (NR) (e.g., gNB).

[0054] The gNB provides functions for radio resource management (i.e., radio bearer control, radio admission control, connection mobility control, dynamic allocation of resources to the UE in uplink / downlink (i.e., scheduling), IP (internet protocol) header compression, encryption and integrity protection of user data streams, selection of an AMF upon attachment of the UE if routing to the AMF is not determined from the information provided to the UE, routing of user plane data to UPF(s), routing of control plane information to the AMF, connection setup and teardown, scheduling and transmission of paging messages (originating from the AMF), scheduling and transmission of system broadcast information (originating from the AMF or operating and maintenance (O&M)), measurement and measurement reporting setup for mobility and scheduling, transport level packet marking in uplink, session management, support for network slicing, and QoS flows. It supports features such as mapping to management and data radio bearers, support for UEs in inactive mode, distribution of NAS messages, NAS node selection, radio access network sharing, dual connectivity, and tight interworking between NR and E-UTRA.

[0055] UE (101) refers to a user equipment. The user equipment may be referred to by terms such as terminal, mobile equipment (ME), or mobile station (MS). Furthermore, the user equipment may be a portable device such as a laptop, mobile phone, personal digital assistant (PDA), smartphone, or multimedia device, or may be a non-portable device such as a personal computer (PC) or vehicle-mounted device.

[0056] The NEF (111) provides a means to securely expose services and capabilities provided by 3GPP network functions, for example, for third parties, internal exposure / re-exposure, application functions, and edge computing. The NEF (111) receives information from other NF (s) (based on the exposed capability(s) of other NF (s)). The NEF (111) can store the received information as structured data using a standardized interface to a data storage network function. The stored information can be re-exposed to other NF entity(s) and AF entity(s) by the NEF entity (111) and used for other purposes, such as analysis.

[0057] EASDF is an NF that can add an ECS (EDNS (extension mechanisms for DNS) client subnet) option that can be expressed as the address of a DNS server to which a DNS (domain name system) request of a terminal is forwarded, and an IP subnet address to be added when forwarding a DNS request of a terminal, for each FQDN (fully qualified domain name). EASDF receives EAS (exchange active sync) domain configuration information from EDR, and processes a DNS request message received from a terminal according to the received information. In addition, EASDF is an NF that receives a terminal IP address, location information of the terminal within 3GPP, DNS message processing rules, and DNS message reporting rules from an SMF (105), processes a DNS Query message received from a terminal, a DNS response message received from a DNS server, and transmits information in a DNS message and statistical information processed therefrom to the SMF (105) according to the DNS message reporting rules.

[0058] NRF (115) supports service discovery. It receives NF discovery requests from NF instances and provides information about discovered NF instances to the NF instances. It also maintains available NF instances and the services they support.

[0059] Meanwhile, for convenience of explanation, FIG. 1 illustrates a reference model for a case where a UE (101) accesses one DN (110) using one PDU session, but the present disclosure is not limited thereto.

[0060] A UE (101) can access two (i.e., local and central) data networks simultaneously using multiple PDU sessions. In this case, two SMFs can be selected for different PDU sessions. However, each SMF can have the ability to control both the local UPF and the central UPF within the PDU session.

[0061] Additionally, the UE (101) may simultaneously access two (i.e., local and central) data networks provided within a single PDU session.

[0062] In the 3GPP system, a conceptual link connecting NFs within a 5G system is defined as a reference point. For example, the reference point(s) included in the 5G system (100) of FIG. 1 are as follows.

[0063] - N1: Reference point between UE (101) and AMF (103)

[0064] - N2: Reference point between (R)AN(102) and AMF(103)

[0065] - N3: Reference point between (R)AN(102) and UPF(104)

[0066] - N4: Reference point between SMF (105) and UPF (104)

[0067] - N5: Reference point between PCF (106) and AF (107)

[0068] - N6: Reference point between UPF (104) and DN (110)

[0069] - N7: Reference point between SMF (105) and PCF (106)

[0070] - N8: Reference point between UDM (109) and AMF (103)

[0071] - N10: Reference point between UDM (109) and SMF (105)

[0072] - N11: Reference point between AMF (103) and SMF (105)

[0073] - N12: Reference point between AMF (103) and AUSF (108)

[0074] - N13: Reference point between UDM (109) and AUSF (108)

[0075] - N14: Reference point between two AMFs (103)

[0076] - N15: Reference point between PCF and AMF in non-roaming scenario, reference point between PCF and AMF in visited network in roaming scenario.

[0077] - Nx: Reference point between SMF(105) and EASDF

[0078] - Ny: Reference point between NEF (EDF) (111) and EASDF

[0079] FIG. 2 is an example of an IMS-DC (IP (internet protocol) multimedia subsystem data channel) structure that provides a data channel service based on an IMS (IP (internet protocol) multimedia subsystem) service according to one embodiment of the present disclosure.

[0080] In the above structure, the terminal can transmit a SIP (session initiation protocol) INVITE message to an existing CSCF, such as a P-CSCF (proxy - call session control function) and an S-SCSF (serving - call session control function), to request a call session connection. The SIP INVITE message can include media-related parameters and multiplexing-related requirement information in the SDP (Session Description Protocol). In addition, the terminal can transmit an SDP offer including bootstrap information together with an SDP offer for connecting an existing video or audio session, etc., in the SIP INVITE message in order to use an IMS data channel service.

[0081] The S-CSCF, which receives the SIP INVITE including the above SDP information, can forward the contents of the bootstrap data channel SDP offer to the IMS AS if the SIP INVITE contains a bootstrap data channel SDP offer for a data channel service connection request. At this time, the S-CSCF can check whether the terminal or network supports IMS-DC based on the contents of the received bootstrap-related SDP offer, and if both sides support the data channel, it can decide to forward the information for the bootstrap data channel connection to the IMS AS. The IMS AS, which receives the bootstrap-related SDP offer message from the S-CSCF, can first check with the HSS (home subscriber server) whether the corresponding UE or subscriber can use the corresponding data channel service. If the corresponding user cannot use the data channel based on the corresponding user profile, the MMTel (multimedia telephony) session setup operation can be performed without connecting the data channel through the general IMS process. Additionally, if the user cannot use a data channel-based service, the IMS AS can update the SIP INVITE message received from the S-CSCF by deleting the DC (data channel)-related media information in the SIP INVITE message, and then forward the updated SIP INVITE message to the S-CSCF.

[0082] If the service user can use the service based on the IMS data channel, the IMS AS can perform data channel bootstrapping through a data channel call request to the Data Channel Signaling Function (DCSF). The IMS AS can perform discovery and selection of a DCSF instance through NRF based on the network operator's local configuration or information transmitted from the terminal. The IMS AS can transmit a session event control notification (SessionEventControl_Notify) message containing information such as SessionEstablishmentRequestEvent, Session ID, CallingID, CalledID, SessionCase, Event initiator, MediaInfoList, and DC Stream ID to the DCSF selected through the above process.

[0083] Upon receiving a DC control request from the IMS AS, the DCSF can make policy decisions on how to create a bootstrap data channel based on the relevant parameters in the DC control request message. The DCSF can also determine MDC1 media information to enable the UE to download applications via the MF or MRF.

[0084] Based on the above decision information, DCSF can forward a MediaControl_MediaInstruction message containing information such as SessionID and MediaInstructionSet to the IMS AS. DCSF can also forward the MediaInstructionSet to the IMS AS, including the MDC1 media endpoint address, DC stream ID, and alternative information for the URL of the application list transmitted on the MDC1 interface. Based on this, DCSF can provide the IMS AS with a policy on how to create a bootstrap data channel using MF on the originating and terminating sides.

[0085] IMS AS can select MF through a process of searching and selecting MF instance or enhanced MRF supporting local configuration or DC media capabilities using NRF.

[0086] The IMS AS can forward a list of Media Termination Descriptors to the MF selected in the above process via the Nmf_MRM_Create message. The IMS AS can request the creation of two different Media Terminations. One Media Termination may represent local bootstrap media-related information, and the other may represent remote bootstrap media-related information to be provided to a remote UE. Each Media Termination may include resource allocation request information for the Mb and MDC1 interfaces. The MF may forward the results of the negotiation of the corresponding data channel media resource information to the IMS AS.

[0087] An IMS AS may send a response to a MediaInstruction request received from the DCSF. The response message may include information regarding the result of the above operation and information regarding negotiation of MDC1 data channel media resource information.

[0088] DCSF can store media resource information in a response message to a MediaInstruction request received from an IMS AS, and forward a response message related to a data channel connection notification (SessionEventControl_Notify) request received from an IMS AS to the IMS AS.

[0089] The IMS AS can forward a SIP INVITE message containing an updated SDP offer with media information from the MF or enhanced MRF to the S-CSCF. The S-CSCF can forward the SIP INVITE message containing the received updated SDP offer to the remote network and UE#2.

[0090] UE#2 and the terminating network can forward the SDP response related to the bootstrap data channel to the originating network in an 18X response message. Based on the received SDP response message, the MF or enhanced MRF can update the data channel media resource information of UE#2. Afterwards, UE#2 and the terminating network can send a 200 OK response message indicating the successful completion of the request.

[0091] The IMS AS can notify the DCSF of successful session connection-related event information by sending a SessionEventControl Notify message containing SessionEstablishmentSuccessEvent, SessionID, and MediaInfoList. After receiving a response message for the successful session connection event notification from the DCSF, the IMS AS can send a 200 OK message to UE#1, indicating that the bootstrap data channel has been connected. This allows the bootstrap data channel connection to be established between UE#1, UE#2, and the originating MF or enhanced MRF. Afterwards, UE#1 and UE#2 can request data channel applications by sending an Application Request message to the MF or enhanced MRF. If multiple DC applications are supported, UE#1 and UE#2 can request a list of applications from the MF or enhanced MRF. The MF or MRF can change the root URL to application-related URL information based on the replacement URL information received from the DCSF. Afterwards, the MF can forward the application request message received from the UE to the DCSF. DCSF can provide a list of applications or appropriate data applications to UE#1 and UE#2, depending on the UE's data channel processing capabilities and selection. Depending on the MF's location, when using terminating MF or MRF, the UE can perform the above process through terminating DCSF and download the appropriate data channel application.

[0092] After the IMS session and bootstrap data channel connection and data channel application are downloaded to UE#1 and UE#2, UE#1 can send a SIP reINVITE message containing the updated SDP to the IMS AS. The updated SDP may include not only bootstrap data channel information, but also application data channel request and related DC application binding information.

[0093] Based on user subscription data information, the IMS AS can determine whether to notify the DCSF of a media change request event. If the IMS AS decides to notify the DCSF of the event, it can forward a SessionEventControl_Notify message containing the MediaChangeRequest Event, Session ID, Event Direction, Event Initiator, and Media Info List to the DCSF.

[0094] After receiving the session event notification message, the DCSF can determine how to handle the application data channel connection request based on the relevant parameters conveyed in the notification message and the network operator's policy. The DCSF can decide to add the application data channel media descriptor to the SDP offer if UE#2 is the target endpoint and does not require an anchor of the local MF or enhanced MRF. If the MF or enhanced MRF is required as the anchor of the application data channel, the DCSF can forward the Nimsas_MediaControl message to the IMS AS to instruct the IMS AS to perform the allocation of data channel media resources of the MF or enhanced MRF.

[0095] DCSF can forward a response to the Session Event Notification message to the IMS AS. The IMS AS can then forward a SIP reINVITE message to the originating S-CSCF, which can then forward it to the terminating network and UE#2.

[0096] UE#2 and the terminating network can forward the 200 OK response to the originating network within the SDP response related to the application data channel. Afterwards, the IMS AS, which receives the SDP offer response message including the 200 OK response from the terminating network, can notify the DCSF that the data channel change has been successfully performed. The DCSF will send a response to the notification to the IMS AS, and the IMS AS can then forward the 200 OK response to UE#1 through the originating S-CSCF and P-CSCF. At this time, the P-CSCF of the originating network can perform the QoS procedure of the application data channel media based on the SDP response information including the 200 OK response. UE#1 can send an ACK to the terminating network. Through the above process, the application data channel connection operation between UE#1 and UE#2 can be performed.

[0097] FIG. 3a is a flowchart of operations related to selecting and registering an IMS AS that supports a terminal's service based on the terminal's Capability information, etc. during an IMS registration procedure of a terminal according to one embodiment of the present disclosure.

[0098] In Step 1, the terminal can transmit a registration request (SIP REGISTER) message to the P-CSCF to register with the IMS network. The terminal can use a media feature tag in the registration request message header to convey capability information related to the service requested by the terminal or the service supported by the terminal.

[0099] In step 2, the P-CSCF can forward the registration request message requested by the terminal to the I-CSCF (Interrogating-CSCF).

[0100] In step 3, the I-CSCF can determine which S-CSCF can process the registration request message based on the HSS data information and forward it to the appropriate S-CSCF.

[0101] In steps 4 and 5, the S-CSCF transmits a 401 response message including nonce information for performing authentication operations with the terminal to the terminal through the P-CSCF, and the terminal transmits related information such as Shared Secret Data to the S-CSCF through a registration request message to perform an IMS network registration procedure for the terminal in order to perform the authentication procedure, and transmits the related result to the terminal to complete the registration procedure.

[0102] In step 6, the S-CSCF initiates a third-party registration (3-party registration) with the IMS AS based on the Initial Filter Criteria information in the user profile received from the HSS and the service-related information in the registration request message received from the terminal. rdThe service provider can decide whether to perform a party registration (AP) operation and can generate a new registration request message to perform the registration procedure in the IMS AS based on the IMS AS information supporting each service determined through the IFC (Initial Filter Criteria) operation process. The IFC information can include priority, trigger point, and application server-related information.

[0103] In steps 7 to 9, the S-CSCF can obtain information on an IMS AS (TAS) that supports additional IMS data channel services based on existing IMS sessions based on the media capability tag information in the registration request message header of the terminal. Thereafter, the S-CSCF can transmit a registration request message to the IMS AS for a service that supports additional IMS data channel services based on existing IMS sessions and perform related authentication procedures with the HSS to complete the registration procedure with the IMS AS that supports the additional IMS data channel services.

[0104] In steps 10 to 12, the S-CSCF can obtain information on an IMS AS (DAS) supporting a standalone IMS data channel service connection through an IFC operation if the header of the registration request message of the terminal includes media capability tag information related to a service supporting a standalone IMS data channel service without an existing IMS session. Thereafter, the S-CSCF transmits a registration request message for third-party registration to the IMS AS supporting a service supporting the standalone IMS data channel service, and the IMS AS receiving the registration request message can perform a related authentication procedure with the HSS to complete the registration procedure with the IMS AS supporting the standalone IMS data channel service.

[0105] FIG. 3b is a flowchart of operations related to selecting and registering a DCSF that supports an IMS DC service based on capability information of a terminal during an IMS registration or session connection procedure of a terminal according to an embodiment of the present disclosure.

[0106] As in the embodiment of the above drawing 3a, after completing the selection and registration procedure of the IMS AS supporting the selected data channel service through the three-party registration procedure when registering the terminal with the IMS, the IMS AS can perform the discovery of the DCSF supporting the data channel service and the operation for session connection between the IMS AS and the DSCF during the IMS registration procedure or session connection procedure.

[0107] In steps 1a and 1b, the IMS AS for which the three-party registration procedure of FIG. 3a has been completed can request information for selecting a DCSF from the HSS. If DCSF-related subscription information has been registered in the HSS in advance during the registration process of the NF in the 5GC of the DCSF to support the service of the IMS data channel of a specific user and a specific user group, the IMS AS can receive DCSF information for supporting the service of the IMS data channel of a specific user and a specific user group from the HSS. An IMS AS (e.g., TAS and / or DAS) that has received the previously registered DCSF-related subscription data information from the HSS can omit steps 2a to 2d. When requesting DCSF information for supporting the service of the IMS data channel of a specific user and a specific user group from the HSS, the IMS AS can request DCSF information based on user identification information such as IMPIs (IMS private identity), IMPUs (IMS public identity), PSI (Public Service Identity), and MSISDN (Mobile Station International Subscriber Directory Number).

[0108] If the IMS AS does not receive DCSF information supporting the service of the IMS data channel of a specific user and a specific user group from the HSS in the above step, the IMS AS can perform the operation of receiving a DCSF Discovery service request and related information from the NRF through steps 2a to 2d.

[0109] In step 2a, the IMS AS (TAS, telephony application server) sends the Nnrf_NFDiscovery_Request message to the NRF, which includes user information such as IMPIs (IMS private identity), IMPUs (IMS public identity), PSI (Public Service Identity), MSISDN (Mobile Station International Subscriber Directory Number), and data channel information such as DC stream ID, to select a DCSF that supports the IMS data channel service, so that the IMS AS (TAS) can request information on connectable DCSFs for the service of the IMS data channel for a specific user and a specific user group.

[0110] In step 2b, NRF can forward appropriate DCSF information to IMS AS in the Nnrf_NFDiscovery_Request response message based on the information passed by IMS AS.

[0111] In step 2c, the IMS AS (DAS, dedicated application server) forwards the Nnrf_NFDiscovery_Request message to the NRF, which includes user information such as IMPIs (IMS private identity), IMPUs (IMS public identity), PSI (Public Service Identity), MSISDN (Mobile Station International Subscriber Directory Number), and data channel information such as DC stream ID, to select a DCSF that supports the IMS data channel service, so that the IMS AS (TAS) can request information on connectable DCSFs for the service of the IMS data channel for a specific user and a specific user group.

[0112] In step 2d, NRF can forward appropriate DCSF information to IMS AS in the Nnrf_NFDiscovery_Request response message based on the information passed by IMS AS.

[0113] In steps 3a and 3b, each IMS AS may forward the Ndcsf_sessioneventcontrol_create request message to the DCSF to request a session connection between the IMS AS and the DCSF based on the appropriate DCSF information received from the HSS or NRF in the above steps. At this time, the DCSF to which each IMS AS requests a session connection may be the same or different depending on the data channel service served by the DCSF or a specific user or specific user group. Through the above steps, the IMS AS may request a DC1 interface connection between the IMS AS and the DCSF.

[0114] In steps 4a and 4b, the DCSF can determine whether to accept the request for session connection based on the request information received from the HSS and IMS AS, and whether to accept the data channel service request of a specific user or user group. Based on information such as the specific user or user group information requested by the DCSF, the HSS can perform an operation to store data channel service-related information, including the specific user or user group information provided by the DSCF, in the subscription data within the HSS.

[0115] In steps 5a and 5b, if the DCSF can accept the DC1 interface connection request based on the session connection request message received from the IMS AS, the DCSF can forward response information including DC1 resource information on the DCSF side to the IMS AS.

[0116] In steps 6a and 6b, the DCSF may forward a session event related reporting request to the IMS AS via a Nimsas_sessioneventcontrol_subscribe request message to receive IMS data channel related event information delivered to the IMS AS.

[0117] In steps 7a and 7b, the IMS AS may transmit response information to the DCSF, including a Subscription ID for transmission of IMS data channel-related events, which are transmitted based on information such as specific user or user group information.

[0118] Afterwards, when a data channel session connection request, etc. is transmitted from the terminal to the IMS AS, the IMS AS can distinguish the data channel or call-related session event information based on the user information, such as the Subscription ID, and transmit the information to the DCSF that transmitted the reporting request.

[0119] FIG. 4A is a flowchart illustrating an operation process in which an NEF, having received a request for IMS session-related event reporting from a DC AS according to an embodiment of the present disclosure, selects an appropriate NF that provides IMS services per user or per user group based on subscription data received from a UDM and an HSS, and requests IMS session-related event reporting to the selected NF. The operation of requesting IMS event reporting according to an embodiment of the present disclosure may be to perform an event reporting forwarding request operation based on IMS entity information in which a corresponding user is registered if the terminal is registered in an IMS network, or to perform an event reporting forwarding request operation for a specific user and user group regardless of whether the terminal is registered in the IMS network. The operation request for requesting IMS event reporting according to an embodiment of the present disclosure may be to perform an IMS event reporting request operation to the DCSF and / or IMS AS by utilizing the preset information if a connection between the DCSF and the DC AS is pre-established or the DCAS can perform a connection request operation between the DCSF and the DCAS based on information registered in the NRF or HSS. If there is no separate connection between DCSF and DCAS, after the IMS entity supporting data channel services such as DCSF is determined through a data channel session request from the terminal, etc., and a connection request to DC AS is performed through DCSF, etc., that is, after a data channel session (DC3 or DC4) is connected between DCSF and DCAS, an IMS event reporting request operation can be requested and performed from DC AS.

[0120] In step 1, the AF (DC AS) may transmit IMS session-related event request information to the NEF via the Nnef_EventExposure_Subscribe message to request IMS session-related event information. The IMS session-related request information may include IMS user-related information such as Target of Event Reporting (GPSI, SUPI, UE IPv4 address(es), UE IPv6 prefix(es), External Group Identifier, S-NSSAI, Internal Group Identifier, UE addressing information (IP or MAC address), or indication that any UE is targeted), External Application Identifier(s), Notification Target Address, Event Reporting Information, NF information requesting transmission of IMS session-related event information (e.g. NF type info), and IMS session-related event requirement information such as reporting cycle.

[0121] In step 2, NEF may request IMS DC service-related Subscription Data from UDM via Nudm_SDM_Get request message to perform IMS session-related event request operation in AF. The request message may include information such as NF ID, Subscription data type(s), Key for each Subscription data type(s).

[0122] In step 3, the UDM determines that the NEF requests IMS DC service-related subscription data based on the information in the subscription data request message received from the NEF, and transmits the Nhss_ImsSDM_Get request message to the HSS to request transmission of IMS DC service-related subscription data from the HSS. The IMS DC service-related subscription data request message may include information such as NF ID, subscription data type(s), and key for each subscription data type(s).

[0123] In step 4, the HSS can forward the IMS DC service-related subscription data requested from the UDM to the UDM via the Nhss_ImsSDM_Get response message.

[0124] In step 5, UDM can forward a Nudm_SDM_Get response message including the IMS DC service related Subscription Data requested by NEF in step 402 to NEF.

[0125] In step 6, the NEF can find NF information to transmit the IMS session-related event reporting request requested by the AF (DC AS) based on the IMS DC service-related Subscription Data transmitted from the UDM. In step 1, the NEF can find an NF that can provide the corresponding reporting information based on the IMS session-related event reporting information if there is specific NF information in the IMS session-related event reporting requirement transmitted from the DC AS. If the NEF receives separate NF information from the DC AS but cannot find NF information to request event reporting based on the event reporting information requested by the DC AS, the NEF can first transmit IMS session-related event reporting requirement information for the IMS session-related event reporting request to the DCSF, and the DCSF that receives the IMS session-related event reporting requirement can additionally perform an operation of requesting specific IMS session-related event reporting to an IMS entity such as the IMS AS.

[0126] In step 7a, the NEF may transmit to DCSF, via an Ndcsf_EventExposure_Subscribe request message, requirement information requesting event reporting related to a data channel within an IMS session, which was received from the DC AS. The requirement requesting event reporting related to the IMS data channel may include at least one or more event reporting-related information, such as specific event reporting information, an event reporting cycle, and an event reporting condition. If in step 6, the NEF does not have Subscription data received from the UDM or NF information requesting separate event reporting from the AF, the NEF may transmit, to DCSF, an Ndcsf_EventExposure_Subscribe request message including requirement information requesting events related to a data channel and a call session within an IMS session. If there is event reporting information to be transmitted from the IMS AS in the Ndcsf_EventExposure_Subscribe request message received by the DCSF, the DCSF can transmit a separate event reporting request message to the IMS AS to receive IMS data channel event reporting information or IMS call-related event reporting information that can be provided by the IMS AS.

[0127] In step 7b, DCSF may transmit the result of the IMS data channel related event reporting operation to NEF by transmitting an Ndcsf_EventExposure_Subscribe response message including event reporting information that DCSF can provide based on the information in the IMS data channel related event reporting request message requested from NEF.

[0128] In step 7c, the NEF may transmit requirement information requesting event reporting related to data channels within an IMS session received from the DC AS to the IMS AS via a Nimsas_EventExposure_Subscribe request message. The requirement requesting event reporting related to the IMS data channel may include at least one or more event reporting-related information, such as specific event reporting information (e.g., MF profile information, DC routing information, results of data channel-related request information transmitted to the IMS AS), event reporting cycle, and event reporting conditions.

[0129] In step 7d, the IMS AS may transmit the result of the IMS data channel related event reporting operation to the NEF by transmitting a Nimsas_EventExposure_Subscribe response message including event reporting information that can be provided by the IMS AS based on the information in the IMS data channel related event reporting request message requested from the NEF.

[0130] In step 7e, the NEF may request data channel and call-related event reporting within the IMS session received from the DC AS, or may transmit requirement information requesting data channel or call-related event reporting to the IMS AS (TAS) via a Nimsas_EventExposure_Subscribe request message. The requirement requesting IMS data channel-related event reporting may include at least one or more event reporting-related information, such as specific event reporting information, an event reporting cycle, and an event reporting condition. For example, if a call connection including data channel information is transmitted to the IMS AS or a data channel connection request comes in during an IMS call session connection, the corresponding event occurrence information may be requested to be event reported to the DC AS. In addition, if a data channel connection request is added during an IMS call session connection but is rejected based on the capability information of the originating or terminating terminal, the event reporting may be requested to the DC AS, including the occurrence information of the rejection event and the information on which terminal did not have the data channel-related capability and thus rejected the data channel connection request.

[0131] In step 7f, the IMS AS (TAS) may convey the result of the IMS data channel related event reporting operation by sending a Nimsas_EventExposure_Subscribe response message to the NEF, including event reporting information that can be provided by the IMS AS, based on the information in the IMS data channel or IMS call related event reporting request message requested by the NEF.

[0132] In step 8, the NEF may respond to the IMS service-related event reporting request requested by the AF (DC AS) via the Nnef_EventExposure_Subscribe response message. The response message may include at least one of the following information: Subscription correlation ID, Expire Time, and Accepted IMS event exposure information for a specific user or user group requested by the AF.

[0133] In step 9a, when the DCSF satisfies the event reporting conditions related to the IMS data channel service occurring in the DCSF based on the event reporting requirements received from the NEF in step 7a, the DCSF can immediately transmit the event reporting when the event occurs or perform the event reporting operation after a certain period of time. The IMS data channel event reporting conditions can be set to at least one event occurring in the DCSF, such as the occurrence of a session connection / update / termination event related to a data channel within an IMS session, a request for a media resource update event, etc.

[0134] In step 10a, DCSF may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to NEF using the Ndcsf_EventExposure_Notify message.

[0135] In step 9b, the IMS AS (DAS) can transmit the event report immediately when an event occurs or perform the event reporting operation after a certain period of time when the IMS data channel service-related event reporting condition that occurs in the IMS AS (DAS) is satisfied based on the event reporting requirement received from the NEF in step 7c.

[0136] In step 10b, the IMS AS (DAS) may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to the NEF using the Ndcsf_EventExposure_Notify message.

[0137] In step 9c, based on the event reporting requirements received from the NEF in step 7e, the IMS AS (TAS) can immediately transmit the event reporting when an event occurs and / or an event reporting condition related to an IMS data channel service and / or an IMS video / audio / messaging service occurring in the IMS AS (TAS) is satisfied, or can perform the event reporting operation after a certain period of time.

[0138] At step 10c, the IMS AS (TAS) may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to the NEF using the Ndcsf_EventExposure_Notify message.

[0139] The above event reporting operation may be to transmit IMS session-related event reporting information from at least one IMS entity among DCSF, IMS AS (DAS), and IMS AS (TAS) to NEF according to the information in the subscription data of a specific user or user group received from the HSS in step 6 and the IMS event-related information requirements requested by AF (DC AS).

[0140] In step 11, NEF can periodically or aperiodically forward IMS session event reporting information forwarded to NEF from at least one IMS entity among DCSF, IMS AS (DAS), and IMS AS (TAS) based on IMS session-related event reporting requirement information forwarded from AF (DC AS).

[0141] FIG. 4b is a flowchart illustrating an operation process in which an NEF, having received an operation requesting IMS session-related event reporting from a DC AS according to one embodiment of the present disclosure, selects an appropriate NF that provides IMS services per user or per user group based on the selection of an HSS and subscription data received from the HSS through an NRF, and requests IMS session-related event reporting to the selected NF.

[0142] An operation for requesting IMS event reporting according to an embodiment of the present disclosure may be to perform an event reporting forwarding request operation based on IMS entity information in which the user is registered when the terminal is registered in the IMS network, or to perform an event reporting forwarding request operation for a specific user or user group regardless of whether the terminal is registered in the IMS network. An operation request for requesting IMS event reporting according to an embodiment of the present disclosure may be to perform an IMS event reporting request operation to the DCSF and / or IMS AS by utilizing the preset information when a connection between the DCSF and the DC AS is pre-established or the DCAS can perform a connection request operation between the DCSF and the DCAS based on information registered in the NRF or HSS. If there is no separate connection between the DCSF and the DCAS, an IMS event reporting request operation may be received and performed from the DC AS after an IMS entity supporting a data channel service such as the DCSF is determined through a data channel session request from the terminal, etc., and a connection request is made to the DC AS through the DCSF, etc., that is, after a data channel session (DC3 or DC4) is connected between the DCSF and the DCAS.

[0143] In step 1, the AF (DC AS) may transmit IMS session-related event request information to the NEF via the Nnef_EventExposure_Subscribe message to request IMS session-related event information. The IMS session-related request information may include IMS user-related information such as Target of Event Reporting (GPSI, SUPI, UE IPv4 address(es), UE IPv6 prefix(es), External Group Identifier, S-NSSAI, Internal Group Identifier, UE addressing information (IP or MAC address), or indication that any UE is targeted), External Application Identifier(s), Notification Target Address, Event Reporting Information, NF information requesting transmission of IMS session-related event information (e.g. NF type info), and IMS session-related event requirement information such as reporting cycle.

[0144] In step 2, NEF may send NRF an Nnrf_NFDiscoveery request message to request HSS information for requesting IMS DC service-related Subscription Data to perform an IMS session-related event request operation in AF. The request message may include specific user-specific or user-group-specific information, such as IMPI / IMPU ranges.

[0145] In step 3, NRF may forward HSS information, including HSS instances and / or any HSS Group IDs registered within the operator network, to NEF.

[0146] In step 4, the NEF can select the HSS that has the corresponding user information based on the HSS information transmitted from the NRF. Thereafter, the NEF can transmit an Nhss_ImsSDM_Get request message including at least one of NF Type, IMS Subscriber data type(s), Key for each IMS Subscriber data type(s), and Application Service Identity to the HSS in order to receive IMS session-related event information. The NF Type information may be information on an IMS entity transmitted from the AF in order to receive the corresponding IMS session event. The IMS Subscriber data type may be Repository Data or Non-Transparent Data that can be provided by an IMS AS or DCSF as IMS session event-related data. The Application Service Identity may be information for distinguishing services as session-related application information such as a call session or a data channel session.

[0147] In step 5, the HSS may forward an Nhss_ImsSDM_Get response message to the NEF containing Subscription Data related to the IMS DC services that are supported per user or per user group as requested by the NEF in step 402.

[0148] In step 6, the NEF can find NF information to transmit the IMS session-related event reporting request requested by the AF (DC AS) based on the IMS DC service-related Subscription Data transmitted from the HSS. In step 1, the NEF can find an NF that can provide the corresponding reporting information based on the IMS session-related event reporting information if there is specific NF information in the IMS session-related event reporting requirement transmitted from the DC AS. If the NEF receives separate NF information from the DC AS but cannot find NF information to request event reporting based on the event reporting information requested by the DC AS, the NEF can first transmit IMS session-related event reporting requirement information for the IMS session-related event reporting request to the DCSF, and the DCSF that receives the IMS session-related event reporting requirement can additionally perform an operation of requesting specific IMS session-related event reporting to an IMS entity such as the IMS AS.

[0149] In step 7a, the NEF may transmit to DCSF, via an Ndcsf_EventExposure_Subscribe request message, requirement information requesting event reporting related to a data channel within an IMS session, which was received from the DC AS. The requirement requesting event reporting related to the IMS data channel may include at least one or more event reporting-related information, such as specific event reporting information, an event reporting cycle, and an event reporting condition. If in step 6, the NEF does not have Subscription data received from the HSS or NF information requesting separate event reporting from the AF, the NEF may transmit, to DCSF, an Ndcsf_EventExposure_Subscribe request message including requirement information requesting events related to a data channel and a call session within an IMS session. If there is event reporting information to be transmitted from the IMS AS in the Ndcsf_EventExposure_Subscribe request message received by the DCSF, the DCSF can transmit a separate event reporting request message to the IMS AS to receive IMS data channel event reporting information or IMS call-related event reporting information that can be provided by the IMS AS.

[0150] In step 7b, DCSF may transmit the result of the IMS data channel related event reporting operation to NEF by transmitting an Ndcsf_EventExposure_Subscribe response message including event reporting information that DCSF can provide based on the information in the IMS data channel related event reporting request message requested from NEF.

[0151] In step 7c, the NEF may transmit requirement information requesting event reporting related to data channels within an IMS session received from the DC AS to the IMS AS via a Nimsas_EventExposure_Subscribe request message. The requirement requesting event reporting related to the IMS data channel may include at least one or more event reporting-related information, such as specific event reporting information (e.g., MF profile information, DC routing information, results of data channel-related request information transmitted to the IMS AS), event reporting cycle, and event reporting conditions.

[0152] In step 7d, the IMS AS may transmit the result of the IMS data channel related event reporting operation to the NEF by transmitting a Nimsas_EventExposure_Subscribe response message including event reporting information that can be provided by the IMS AS based on the information in the IMS data channel related event reporting request message requested from the NEF.

[0153] In step 7e, the NEF may request data channel and call-related event reporting within the IMS session received from the DC AS, or may transmit requirement information requesting data channel or call-related event reporting to the IMS AS (TAS) via a Nimsas_EventExposure_Subscribe request message. The requirement requesting IMS data channel-related event reporting may include at least one or more event reporting-related information, such as specific event reporting information, an event reporting cycle, and an event reporting condition. For example, if a call connection including data channel information is transmitted to the IMS AS or a data channel connection request comes in during an IMS call session connection, the corresponding event occurrence information may be requested to be event reported to the DC AS. In addition, if a data channel connection request is added during an IMS call session connection but is rejected based on the capability information of the originating or terminating terminal, the event reporting may be requested to the DC AS, including the occurrence information of the rejection event and the information on which terminal did not have the data channel-related capability and thus rejected the data channel connection request.

[0154] In step 7f, the IMS AS (TAS) may convey the result of the IMS data channel related event reporting operation by sending a Nimsas_EventExposure_Subscribe response message to the NEF, including event reporting information that can be provided by the IMS AS, based on the information in the IMS data channel or IMS call related event reporting request message requested by the NEF.

[0155] In step 8, the NEF may respond to the IMS service-related event reporting request requested by the AF (DC AS) via the Nnef_EventExposure_Subscribe response message. The response message may include at least one of the following information: Subscription correlation ID, Expire Time, and Accepted IMS event exposure information for a specific user or user group requested by the AF.

[0156] In step 9a, based on the event reporting requirements received from the NEF in step 7a, when an event reporting condition related to an IMS data channel service occurring in the DCSF is satisfied, the DCSF can immediately transmit the event reporting when the event occurs or perform the event reporting operation after a certain period of time. The IMS data channel event reporting condition can be set to at least one event occurring in the DCSF, such as an event of a data channel-related session connection / update / termination within an IMS session, a request for a media resource update event, etc.

[0157] In step 10a, DCSF may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to NEF using the Ndcsf_EventExposure_Notify message.

[0158] In step 9b, the IMS AS (DAS) can transmit the event report immediately when an event occurs or perform the event reporting operation after a certain period of time when the IMS data channel service-related event reporting condition that occurs in the IMS AS (DAS) is satisfied based on the event reporting requirement received from the NEF in step 7c.

[0159] In step 10b, the IMS AS (DAS) may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to the NEF using the Ndcsf_EventExposure_Notify message.

[0160] In step 9c, the IMS AS (TAS) can, based on the event reporting requirements received from the NEF in step 7e, immediately forward the event reporting when an event occurs and / or an event reporting condition related to an IMS data channel service and / or an IMS video / audio / messaging service occurring in the IMS AS (TAS) is satisfied, or perform the event reporting operation after a certain period of time.

[0161] At step 10c, the IMS AS (TAS) may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to the NEF using the Ndcsf_EventExposure_Notify message.

[0162] The above event reporting operation may be to transmit IMS session-related event reporting information from at least one IMS entity among DCSF, IMS AS (DAS), and IMS AS (TAS) to NEF according to the information in the subscription data of a specific user or user group received from the HSS in step 6 and the IMS event-related information requirements requested by AF (DC AS).

[0163] In step 11, NEF can periodically or aperiodically forward IMS session event reporting information forwarded to NEF from at least one IMS entity among DCSF, IMS AS (DAS), and IMS AS (TAS) based on IMS session-related event reporting requirement information forwarded from AF (DC AS).

[0164] FIG. 5 is a flowchart illustrating an operation process in which an NEF, having received an IMS session-related event reporting request operation from a DC AS according to one embodiment of the present disclosure, selects an appropriate NF that provides IMS services per user or per user group using an Event Exposure service request operation of a UDM and an HSS, and requests IMS session-related event reporting to the selected NF.

[0165] In step 1, the AF (DC AS) may transmit IMS session-related event request information to the NEF via the Nnef_EventExposure_Subscribe message to request IMS session-related event information. The IMS session-related request information may include IMS user-related information such as Target of Event Reporting (GPSI, SUPI, UE IPv4 address(es), UE IPv6 prefix(es), External Group Identifier, S-NSSAI, Internal Group Identifier, UE addressing information (IP or MAC address), or indication that any UE is targeted), External Application Identifier(s), Notification Target Address, Event Reporting Information, NF information requesting transmission of IMS session-related event information (e.g. NF type info), and IMS session-related event requirement information such as reporting cycle.

[0166] In step 2, the NEF may request IMS DC service-related event reporting operation requirement information from the UDM via the Nudm_EventExposure_Subscribe request message in order to perform an IMS session-related event request operation in the AF. The request message may include information such as UE(s) ID (SUPI or GPSI, Internal Group Identifier or External Group Identifier, or indication that any UE is targeted), Event filter, and Event Reporting Information.

[0167] In step 3, the UDM determines that the event reporting information is an IMS DC service-related request based on the Event filter and Event Reporting Information information in the IMS event reporting request message received from the NEF, and then determines to which NF the related IMS event reporting requirements should be forwarded to the HSS for the IMS service-related event reporting request.

[0168] In step 4, the UDM may transmit an Nhss_EE_Subscribe request message to the HSS for requesting IMS service-related event reporting. The IMS DC service-related Subscription Data transmission request message may include information such as IMSI, monitoring event type(s), notification address, IMS event reporting request subject NF information, event reporting periodicity information, and other IMS session-related event reporting requirements.

[0169] In step 5a, the HSS may transmit requirement information requesting event reporting related to a data channel within an IMS session received from the UDM to the DCSF via an Ndcsf_EventExposure_Subscribe request message. The requirement requesting event reporting related to the IMS data channel may include at least one or more event reporting-related information such as specific event reporting information, an event reporting cycle, and an event reporting condition. If the Ndcsf_EventExposure_Subscribe request message received by the DCSF contains event reporting information to be transmitted from the IMS AS, the DCSF may transmit a separate event reporting request message to the IMS AS to receive IMS data channel event reporting information or IMS call-related event reporting information that can be provided by the IMS AS.

[0170] In step 5b, the DCSF may transmit the result of the IMS data channel related event reporting operation to the HSS by transmitting an Ndcsf_EventExposure_Subscribe response message including event reporting information that can be provided by the DCSF based on the information in the IMS data channel related event reporting request message requested from the HSS.

[0171] In step 5c, the HSS may transmit the requirement information requesting event reporting related to the data channel within the IMS session received from the UDM to the IMS AS via the Nimsas_EventExposure_Subscribe request message. The requirement requesting event reporting related to the IMS data channel may include at least one or more event reporting-related information, such as specific event reporting information (e.g., MF profile information, DC routing information, results of data channel-related request information transmitted to the IMS AS), event reporting cycle, and event reporting conditions.

[0172] In step 5d, the IMS AS may transmit the result of the IMS data channel related event reporting operation to the HSS by transmitting a Nimsas_EventExposure_Subscribe response message including event reporting information that can be provided by the IMS AS based on the information in the IMS data channel related event reporting request message requested from the HSS.

[0173] In step 5e, the HSS may request event reporting related to data channels and calls within the IMS session received from the UDM, or may transmit requirement information requesting event reporting related to data channels or calls to the IMS AS (TAS) via a Nimsas_EventExposure_Subscribe request message. The requirement requesting event reporting related to the IMS data channel may include at least one or more event reporting-related information, such as specific event reporting information, an event reporting cycle, and an event reporting condition. For example, if a call connection including data channel information is transmitted to the IMS AS or a data channel connection request comes in during an IMS call session connection, the corresponding event occurrence information may be requested to be reported to the DC AS. In addition, if a data channel connection request is added during an IMS call session connection but is rejected based on the capability information of the originating or terminating terminal, the rejection event occurrence information and information on which terminal did not have the capability related to the data channel and thus rejected the data channel connection request, may be requested to be reported to the DC AS.

[0174] In step 5f, the IMS AS (TAS) may transmit the result of the IMS data channel related event reporting operation to the HSS by sending a Nimsas_EventExposure_Subscribe response message including event reporting information that can be provided by the IMS AS based on the information in the IMS data channel or IMS call related event reporting request message requested from the HSS.

[0175] In step 6, the HSS can transmit response information related to the IMS session event reporting request received from the UDM, including Result Indication, Subscription ID, and Accepted Event reporting information, to the UDM via the Nhss_EE_Subscribe response message.

[0176] In step 7, UDM can forward a Nudm_EventExposure_Subscribe response message to NEF, including Subscription Correlation ID, Expiry time, Accepted Event reporting information, etc. related to the IMS session event reporting operation request requested by NEF in step 2.

[0177] In step 8, the NEF may respond to the IMS service-related event reporting request requested by the AF (DC AS) via the Nnef_EventExposure_Subscribe response message. The response message may include at least one of the following information: Subscription correlation ID, Expire Time, and Accepted IMS event exposure information for a specific user or user group requested by the AF.

[0178] In step 9a, when the DCSF satisfies the event reporting conditions related to the IMS data channel service occurring in the DCSF based on the event reporting requirements received from the HSS in step 505a, the DCSF can immediately forward the event reporting to the NEF when the event occurs or perform the event reporting operation to the NEF after a certain period of time. The IMS data channel event reporting conditions can be set to events occurring in the DCSF, such as the occurrence of a session connection / update / termination event related to a data channel within an IMS session, or a request for a media resource update event.

[0179] In step 10a, DCSF may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to NEF using the Ndcsf_EventExposure_Notify message.

[0180] In step 9b, the IMS AS (DAS) can immediately transmit the event report when an event occurs and the IMS data channel service-related event reporting conditions occurring in the IMS AS (DAS) are satisfied based on the event reporting requirements received from the NEF in step 5c, or can perform the event reporting operation after a certain period of time.

[0181] In step 10b, the IMS AS (DAS) may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to the NEF using the Ndcsf_EventExposure_Notify message.

[0182] In step 9c, the IMS AS (TAS) can, based on the event reporting requirements received from the NEF in step 5e, immediately forward the event reporting when an event occurs and / or an IMS data channel service and / or an IMS video / audio / messaging service-related event reporting condition is satisfied in the IMS AS (TAS), or perform the event reporting operation after a certain period of time.

[0183] At step 10c, the IMS AS (TAS) may forward event reporting information related to IMS data channels that satisfy the event reporting conditions to the NEF using the Ndcsf_EventExposure_Notify message.

[0184] The above event reporting operation may be to transmit IMS session-related event reporting information from at least one IMS entity among DCSF, IMS AS (DAS), and IMS AS (TAS) to NEF according to the information in the subscription data of a specific user or user group in the HSS in step 5 and the IMS event-related information requirements requested by AF (DC AS).

[0185] In step 11, NEF can periodically or aperiodically forward IMS session event reporting information forwarded to NEF from at least one IMS entity among DCSF, IMS AS (DAS), and IMS AS (TAS) based on IMS session-related event reporting requirement information forwarded from AF (DC AS).

[0186] FIGS. 6A and 6B are flowcharts illustrating an IMS session-related event reporting operation that occurs during a bootstrap data channel connection process at the request of a terminal to use an IMS data channel service according to an embodiment of the present disclosure. For the IMS session-related event reporting operation of the IMS AS (TAS) and DCSF according to an embodiment of the present disclosure, it can be assumed that one of the IMS session-related event subscription request operations of FIGS. 4A, 4B, and 5 has already been performed during the registration process of the terminal in the IMS network. Through the above operation process, the IMS AS (TAS) and DCSF receive and set the IMS session event reporting requirement, and can perform the event reporting operation to the NEF when an IMS session event occurs according to the corresponding event reporting condition. The event reporting operation requirement information requested by the AF can be determined by the NEF through the subscription information whether to accept the transmission of some or all event reporting information within the event reporting requirement, depending on the settings of the service provider and the network provider. If the transmission of event reporting information related to one or all IMS calls or IMS data channel services within the event reporting requirements requested by the AF is rejected, the NEF may forward the rejected event information to the AF. Events related to data channel services requested by the AF may include events such as DCS selection or IMS DC-only service request generated by the IMS AS, application list information downloaded by the terminal, application information selected and downloaded by the terminal, MF allocation (selection) information and related profile information, capability information of the other terminal, successful session establishment / update / termination operation, and failure of session establishment / update / termination operation.Additionally, events related to data channel services requested by AF may include successful establishment / update / termination operations of sessions created or generated by DCSF, session establishment / update / termination, etc.

[0187] Event reporting information related to data channel services, such as DCS selection or IMS DC-only service events, application download information, and application list information occurring in the above IMS AS, may be transmitted to the DCSF by the NEF when an event reporting request operation of an IMS AS-related data channel service is transmitted to the DCSF, and event reporting request information is transmitted from the DCSF to the IMS AS, or when a subscription service for event reporting is performed or an event reporting request is directly transmitted to the IMS AS. Event reporting occurring in the IMS AS may be transmitted to the DCSF and then transmitted to the NEF through the DCSF.

[0188] In step 1, the terminal (UE#1) may determine to use additional data channel services based on the connection of video, audio, and messaging-related IMS sessions according to the policy of the service provider or network operator, and may transmit an INVITE message for the connection request. The UE#1 may forward a bootstrap data channel session connection request message including a session description protocol including data channel-related information to the S-CSCF through the P-CSCF. The S-CSCF may perform service management actions to forward the session connection request message including only data channel-related information to an appropriate IMS AS (e.g., TAS) for processing the session connection request message based on information in the session description protocol forwarded during registration with the IMS network. The S-CSCF may forward the bootstrap data channel session connection request message including a session description protocol including data channel-related information to the IMS AS.

[0189] In step 2, the IMS AS can select the location of an appropriate DCSF by looking at the DC Stream ID in the data channel service connection request information. For example, if a data channel session connection request with a DC Stream ID between 0 and 100 is transmitted from the terminal, the IMS AS can determine that the data channel session connection request information should be transmitted to the local (originating) DCSF and can then transmit the data channel connection request information to the local DCSF. Alternatively, if the DC Stream ID is 100 or greater, the IMS AS can determine that the data channel session connection request information received from the terminal should be transmitted to the remote (terminating) DCSF to request allocation of data channel-related media resources.

[0190] In step 2a, if the IMS AS receives at least one event reporting request with an event reporting condition, such as selecting a DCS (Local or Remote) within the IMS session event reporting requirements or whether it is an IMS DC-only service request, it can forward the event reporting information via the DCSF, to the NEF, or directly to the NEF. The event reporting can be performed immediately or periodically, depending on the information within the event reporting requirements.

[0191] In step 3, the IMS AS selects an appropriate DCS based on the DC stream ID information and then transmits a Nimsas_SessionEventControl_Notify message containing information such as SessionEstablishmentRequestEvent, SessionID, MediaInfoList, and EventInitiator to the selected DCSF to request execution of a data channel session connection request event.

[0192] In steps 4 and 5, the DCSF can determine a data channel policy based on the information received from the terminal and generate media resource information on the Originating and Terminating sides within the MF.

[0193] In Step 6, the DCSF generates a Media instruction set based on media resource allocation information within the MF and then forwards it to the IMS AS to perform a related media resource handling request. Based on the Media instruction information received from the DSCF, the IMS AS can receive information on an appropriate MF supporting the Media instructions via the NRF and then decide to forward the Media instruction set information to the selected MF.

[0194] In Step 7, the IMS AS selects an appropriate MF that supports the media information received from the DCSF and then forwards the relevant media instruction set information to the MF, allowing it to allocate media resources on the originating and terminating sides to support data channel services. The MF can then forward the results of the media resource allocation to the MF, and at this time, may additionally forward relevant information to support additional interfaces connected to the MF, such as MDC1 and MDC2.

[0195] In step 7a, if the IMS AS receives an event reporting request related to MF selection regarding which MF was selected as an event reporting condition, the IMS AS can forward the event reporting information to the NEF via the DCSF or directly to the NEF.

[0196] In step 8, the IMS AS selects an appropriate MF that supports the media information received from the DCSF through step 7, and then transfers media instruction set information related to the bootstrap data channel service to the MF to allocate media resources on the originating and terminating sides to support the data channel service. The MF can then transfer the media resource allocation result to the IMS AS. The media resource allocation result message may include additional resource information related to the MF, such as information about the MDC1 interface between the DCSF and the MF.

[0197] In step 9, the IMS AS can forward the MF-related media resource allocation information and media resource allocation result information received from the MF to the DCSF via the Nimsas_MediaControl_MediaInstrution response message.

[0198] In step 10, the DCSF may inform the IMS AS of the result of the data channel session connection request event requested from the IMS AS in step 03.

[0199] In steps 11 and 12, the IMS AS may forward a SIP INVITE message containing a modified SDP offer based on the terminating side media resource information in the MF to the terminating network and terminal.

[0200] In step 13, UE #2 determines whether to accept the relevant data channel session connection request from UE #2 based on the information in the SIP INVITE message delivered from the Originating network.

[0201] At step 14, if additional session negotiation operations related to the SIP INVIT message received from UE#1 in UE#2 and the terminating network are required, additional session negotiation operations between UE#1 and UE#2 may be performed via a PRACK message.

[0202] In step 15, if UE #2 can accept the bootstrap data channel session connection request requested by UE #1 from step 12 or step 14, it can forward a response message (200 OK) including an SDP answer including media resource information of UE #2 to the Originating Side S-CSCF.

[0203] In step 16, the Originating side S-CSCF can forward response information for the bootstrap data channel connection request received from UE #2 to the IMS AS via a 200 OK message.

[0204] In step 17, the IMS AS may forward a Nimsas_SessionEventControl_Notify message to the DCSF, including information that the bootstrap data channel connection request has been accepted by UE#2 and the terminating network, and media resource information of UE#2, based on the SDP answer information received from UE#2.

[0205] In step 17a, DCSF, which has received the bootstrap data channel connection request acceptance information including media resource information of UE#2, can report to NEF through event reporting that an IMS session-related event, such as connection / deletion / update related to the bootstrap data channel session, has occurred.

[0206] At step 18, DCSF can finally signal to IMS AS that the application data channel connection is complete via a 200 OK message.

[0207] At step 19, the IMS AS may forward a 200 OK message to UE #1 via the S-CSCF and P-CSCF indicating that the bootstrap data channel session connection is completed.

[0208] In step 20-1, UE#1 may perform a bootstrap data channel connection operation between UE#1 and the Originating MF based on the Originating side MF media resource information in the 200 Ok message transmitted from the IMS AS in step 619.

[0209] In step 20-2, UE #1 can transmit a data channel application request message to MF or MRF via the bootstrap data channel to download a data channel application. The MF or MRF, upon receiving the application request message, can convert the root URL information of the data channel application transmitted from the terminal into a replacement URL and forward it to DCSF. Based on the application request message received from the MF, DCSF can transmit an application list containing information on appropriate data channel applications to UE #1 via MF.

[0210] In step 20-2a, the DCSF may report the provided application list information to the NEF after receiving the data channel application request message requested by the terminal. Based on the application list information, the DC AS may check whether the DCSF has provided the appropriate data channel application to UE #1, and if it determines that a data channel application update is necessary, it may transmit a data channel application update request operation to the DCSF through steps 21 and 22.

[0211] In step 20-3, UE #1 can perform an appropriate application download operation considering the capability of UE #1 based on the data channel application list and related information received from DCSF in step 620-2.

[0212] In step 20-3a, the DCSF may forward the data channel application and application-related configuration information selected and downloaded by UE #1 to the NEF via an event reporting operation. Based on the event reporting information, the DC AS may receive the data channel application information and application-related configuration information selected by the UE. If the application-related configuration information is not up-to-date or the data channel application is not up-to-date, the DC AS may forward the latest data channel application and application configuration information to the UE via the DCSF.

[0213] FIG. 7 is a diagram illustrating the structure of a terminal according to one embodiment of the present invention.

[0214] Referring to FIG. 7, the terminal may include a transceiver (710), a control unit (720), and a storage unit (730). In the present invention, the control unit may be defined as a circuit or an application-specific integrated circuit or at least one processor.

[0215] The transceiver (710) can transmit and receive signals with other network entities. The transceiver (710) can receive system information from a base station, for example, and can receive a synchronization signal or a reference signal.

[0216] The control unit (720) can control the overall operation of the terminal according to the embodiment proposed in the present invention. For example, the control unit (720) can control the signal flow between each block so that the terminal transmits an INVITE message for application data channel connection to the IMS AS according to the embodiment of the present invention.

[0217] The storage unit (730) can store at least one of the information transmitted and received through the transmission and reception unit (710) and the information generated through the control unit (720). For example, the storage unit (730) can store information for a video or audio session bootstrap data channel connection.

[0218] FIG. 8 is a diagram illustrating a network entity according to one embodiment of the present invention.

[0219] The network entity illustrated in FIG. 8 may be composed of one of various types of network entities disclosed in the present invention, for example, UPF, AMF, SMF, PCF, UDM, NSSF, AUSF, IMS AS, DCSF, MF, etc.

[0220] Referring to FIG. 8, a network entity may include a transceiver (810), a control unit (820), and a storage unit (830). In the present invention, the control unit may be defined as a circuit or an application-specific integrated circuit or at least one processor.

[0221] The transceiver (810) can transmit and receive signals with other network entities. The transceiver (810) can receive, for example, request messages for various information from terminals, base stations, or other network entities.

[0222] The control unit (820) can control the overall operation of a network entity according to an embodiment proposed in the present invention. For example, the control unit (820) can cause a network entity to perform a channel establishment-related policy decision response according to an embodiment disclosed in the present invention.

[0223] The storage unit (830) can store at least one of the information transmitted and received through the transmission and reception unit (810) and the information generated through the control unit (820). For example, the storage unit (830) can store information related to media control.

[0224] 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.

[0225] 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 embodiments described in the claims or specification of the present disclosure.

[0226] These programs (software modules, software) may be stored in a non-volatile memory including random access memory, flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc ROMs (CD-ROMs), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or 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.

[0227] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wide local area network (WLAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

[0228] In the specific embodiments of the present disclosure described above, components included in the present disclosure are expressed singularly or plurally, 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 plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

[0229] 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.

Claims

1. A method of a network entity related to user data management operating in a wireless communication system, A step of receiving a subscription request message for an IMS (IP multimedia subsystem) related event from a NEF (network exposure function); A step of determining at least one IMS AS (application server) to perform a subscription request based on the subscription request message; and A method comprising the step of transmitting a message for subscription to an IMS service related event related to the subscription request message to at least one IMS AS determined.

2. In paragraph 1, A method wherein the above IMS service related event is related to at least one user.

3. In paragraph 1, A method wherein the subscription request message includes a notification target address.

4. In paragraph 1, A method further comprising the step of receiving a reporting message regarding an event occurrence from at least one IMS AS.

5. In paragraph 1, A method wherein at least one of the above IMS ASs is classified as a dedicated application server (DAS) or a telephony application server (TAS).

6. In a method of NEF (network exposure function) operating in a wireless communication system, A step of receiving a subscription request for an IMS (IP multimedia subsystem) related event from an AF (application function); If the above subscription request relates to an IMS event related to a specific user, a step of transmitting a subscription request message for the IMS-related event to a network entity related to user data management; and A method comprising the steps of determining at least one IMS AS (application server) to perform the subscription request, if the subscription request relates to an IMS event not related to a specific user, and transmitting a message for subscribing to an IMS-related event related to the subscription request message to the determined IMS AS.

7. In paragraph 6, The above AF corresponds to a DC AS (data channel application server).

8. In paragraph 6, A method wherein at least one of the above IMS ASs is classified as a dedicated application server (DAS) or a telephony application server (TAS).

9. In a network entity related to user data management in a wireless communication system, Transmitter and receiver; and Includes a control unit, The above control unit, Receive subscription request messages for IMS (IP multimedia subsystem) related events from NEF (network exposure function), Determine at least one IMS AS (application server) to perform the subscription request based on the subscription request message; A network entity configured to transmit a message for subscription to an IMS service related event related to the subscription request message to at least one IMS AS determined above.

10. In paragraph 9, A network entity in which the above IMS service related event is related to at least one user.

11. In paragraph 9, The above subscription request message is a network entity that includes a notification target address.

12. In paragraph 9, The above control unit, A network entity further configured to receive reporting messages regarding the occurrence of an event from at least one IMS AS.

13. In paragraph 9, The above at least one IMS AS is a network entity classified as a dedicated application server (DAS) or a telephony application server (TAS).

14. In the network exposure function (NEF) of a wireless communication system, Transmitter and receiver; and Includes a control unit, The above control unit, Receive subscription requests for IMS (IP multimedia subsystem) related events from AF (application function), If the above subscription request relates to an IMS event related to a specific user, a subscription request message for the IMS-related event is sent to the network entity related to user data management. An NEF configured to determine at least one IMS AS (application server) to perform the subscription request when the subscription request relates to an IMS event not related to a specific user, and to transmit a message for subscription to an IMS-related event related to the subscription request message to the determined IMS AS.

15. In paragraph 14, The above at least one IMS AS is classified as a dedicated application server (DAS) or a telephony application server (TAS).

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