Network structure and service providing method for supporting multicast and broadcast service in mobile communication network

Abstract

The present disclosure relates to a communication technique and a system for integrating a 5G communication system with IoT technology to support higher data transmission rates than those of 4G systems. The present disclosure can be applied to intelligent services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail, security and safety-related services, etc.) based on 5G communication technology and IoT-related technology. According to the present disclosure, MBS services for flexible and dynamic MBS service scenarios are made possible in next-generation wireless communication systems.

Description

Technology Field

[0001] In order to transmit the same data to a large number of terminals concentrated in a specific area within a mobile communication network, data can be transmitted individually to each terminal via unicast; however, for resource efficiency, it is necessary to provide data services through multicast / broadcast. For example, a method is required to transmit data via multicast / broadcast to a large number of terminals in a specific area for TV / audio services, vehicle-to-everything communication (V2X) services, or massive Cellular IoT (CIoT) services. This concerns a network configuration plan to support MBS (Multicast / Broadcast service), which involves defining Network Functions (NFs) or NF Services for this purpose, and performing actions such as exposing, discovering, and selecting the corresponding NFs or NF services. Background Technology

[0002] Efforts are being made to develop improved 5G or pre-5G communication systems to meet the increasing demand for wireless data traffic since the commercialization of 4G communication systems. For this reason, 5G or pre-5G communication systems are referred to as systems beyond the 4G network or systems following the LTE system. To achieve high data transmission rates, the implementation of 5G communication systems in the mmWave band (e.g., the 60 GHz band) is being considered. To mitigate path loss and increase transmission distance in the mmWave band, technologies such as beamforming, massive MIMO, full Dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antennas are being discussed for 5G communication systems. In addition, to improve the network of the system, the development of technologies such as advanced small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation is being carried out in 5G communication systems.In addition, advanced coding modulation (ACM) methods such as FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), as well as advanced access technologies such as FBMC (Filter Bank Multi Carrier), NOMA (non-orthogonal multiple access), and SCMA (sparse code multiple access), are being developed in 5G systems.

[0003] Meanwhile, the Internet is evolving from a human-centered network where humans generate and consume information into an IoT (Internet of Things) network that processes information by exchanging it among distributed components, such as objects. IoE (Internet of Everything) technology, which combines IoT with Big Data processing technologies through connections with cloud servers, is also emerging. To implement IoT, technological elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required; consequently, technologies such as sensor networks, Machine-to-Machine (M2M) communication, and Machine-Type Communication (MTC) are currently being researched to facilitate the connection of objects. In an IoT environment, intelligent IT services that create new value for human life by collecting and analyzing data generated from connected objects can be provided. Through the convergence and integration of existing IT technologies with various industries, IoT can be applied to fields such as smart homes, smart buildings, smart cities, smart or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services.

[0004] Accordingly, various attempts are being made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, Machine to Machine (M2M), and Machine Type Communication (MTC) are being implemented using 5G communication techniques such as beamforming, MIMO, and array antennas. The application of cloud RAN as a big data processing technology, as previously described, can also be considered an example of the convergence of 5G and IoT technologies.

[0005] Meanwhile, the need arose to provide a service for transmitting the same data to multiple terminals in next-generation wireless communication systems. The problem to be solved

[0006] In order to transmit the same data to a large number of terminals concentrated in a specific area within a mobile communication network, it is necessary to provide data services via Multicast / Broadcast. For example, a method is required to transmit data via Multicast / Broadcast to a large number of terminals in a specific area for TV / audio services, V2X services, or massive CIoT services. This concerns a network configuration plan to support MBS (Multicast / Broadcast service), which includes defining Network Functions (NFs) or NF Services for this purpose, and exposing, discovering, and selecting the relevant NFs or NF Services.

[0007] In existing LTE networks, multicast / broadcast services were supported by introducing a BM-SC (broadcast multicast service center) and an MBMS-GW in the core network and a MCE (multi-cell / Multicast coordination Entity) in the E-UTRAN. However, in 5GS, there is a need for a configuration plan for an MBS network for 5GS to support multicast / broadcast services, increase flexibility in deployment and operation, and dynamically coordinate multicast / broadcast services. This invention introduces a method for service exposure for NF or NF services to support MBS services, and for discovering and selecting NF or NF services. means of solving the problem

[0008] A method for controlling a first entity in a wireless communication system may include: receiving information about data traffic of a session of a multicast / broadcast service (MBS); receiving internet protocol (IP) address information of a second entity; generating context information for managing the MBS session; and establishing a control session for the second entity based on the IP address information of the second entity and the context information.

[0009] Meanwhile, in a wireless communication system, the first entity may include a control unit that receives information regarding data traffic of a session of a multicast / broadcast service (MBS) and controls the transceiver to receive internet protocol (IP) address information of the second entity, generates context information for managing the MBS session, and controls the establishment of a control session for the second entity based on the IP address information of the second entity and the context information. Effects of the invention

[0010] Through the present invention, MBS services for flexible and dynamic MBS service scenarios in 5GS become possible. Brief explanation of the drawing

[0011] FIGS. 1a and FIG. 1b illustrate a 5GS structure for MBS according to an embodiment of the present invention. FIG. 2 illustrates the process of creating an MBS session according to an embodiment of the present invention. FIG. 3 illustrates the process of MBS-related entities registering a profile in the NRF according to an embodiment of the present invention. FIG. 4 illustrates the process of an AF (AS or contents provider) selecting a suitable BM-CPF to provide MBS services according to an embodiment of the present invention. FIG. 5 illustrates the process of selecting a suitable BM-UPF for BM-CPF to provide MBS services according to an embodiment of the present invention. FIG. 6 illustrates the process of selecting a suitable SMF for BM-CPF to provide MBS services according to an embodiment of the present invention. FIG. 7 illustrates the process of an SMF selecting a suitable UPF to provide MBS services according to an embodiment of the present invention. FIG. 8 illustrates the process of an SMF selecting a suitable AMF to provide MBS services according to an embodiment of the present invention. FIG. 9 illustrates the process of an SMF selecting a suitable NG-MCE to provide MBS services according to an embodiment of the present invention. FIG. 10 illustrates the structure of a first entity in a wireless communication system according to one embodiment of the present disclosure. FIG. 11 illustrates the structure of a second entity in a wireless communication system according to one embodiment of the present disclosure. Specific details for implementing the invention

[0012] The operating principle of the present invention will be described in detail below with reference to the attached drawings. In describing the present invention below, specific descriptions of related known functions or configurations will be omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the invention. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, their definitions should be based on the content throughout this specification.

[0013] For the same reason, some components in the attached drawings have been exaggerated, omitted, or schematically depicted. Additionally, the size of each component does not entirely reflect its actual dimensions. Identical or corresponding components in each drawing have been assigned the same reference number.

[0014] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. The embodiments of the present disclosure are provided merely to make the present disclosure complete and to fully inform those skilled in the art of the scope of the invention, and the present disclosure is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0015] At this point, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory can also produce a manufactured item containing means of instruction to perform the function described in the flow diagram block(s). Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that execute a computer or other programmable data processing equipment by performing a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer may also provide steps for executing the functions described in the flowchart block(s).

[0016] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specific logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For instance, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may be executed in reverse order depending on the corresponding function.

[0017] In this embodiment, the term "part" used refers to a software or hardware component such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), and the "part" performs certain roles. However, the meaning of "part" is not limited to software or hardware. The "part" may be configured to reside in an addressable storage medium or may be configured to run one or more processors. Accordingly, according to some embodiments, the "part" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, 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." In addition, the components and 'parts' may be implemented to utilize one or more CPUs within the device or secure multimedia card. Furthermore, according to some embodiments, the 'parts' may include one or more processors.

[0018] The operating principle of the present invention will be described in detail below with reference to the attached drawings. In describing the present invention below, if it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. Hereinafter, a base station is an entity that performs resource allocation for terminals and may be at least one of a gNode B, eNode B, Node B, BS (Base Station), wireless access unit, base station controller, or a node on a network. A terminal may include a UE (User Equipment), MS (Mobile Station), cellular phone, smartphone, computer, or a multimedia system capable of performing communication functions. Of course, it is not limited to the above examples. Hereinafter, the present disclosure describes a technology for a terminal to receive broadcast information from a base station in a wireless communication system. The present disclosure relates to a communication technique and a system for integrating a 5G (5th generation) communication system with IoT (Internet of Things) technology to support higher data transmission rates than those of 4G (4th generation) systems. The present disclosure can be applied to intelligent services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail, security and safety-related services, etc.) based on 5G communication technology and IoT-related technology.

[0019] Terms used in the following description to refer to broadcast information, control information, communication coverage, state changes (e.g., events), network entities, messages, and device components are examples provided for the convenience of explanation. Accordingly, the present invention is not limited to the terms described below, and other terms having equivalent technical meanings may be used.

[0020] Furthermore, terms used in the following description to identify connection nodes, terms referring to network entities, terms referring to messages, terms referring to interfaces between network entities, terms referring to various identification information, etc., are provided as examples for the convenience of explanation. Accordingly, the present invention is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

[0021] For convenience of explanation below, the present invention uses terms and names defined in the specifications for 5G systems. However, the present invention is not limited by the above terms and names and can be applied in the same way to systems conforming to other specifications.

[0023] First, FIGS. 1a and FIG. 1b illustrate the structure of a cellular system for MBS services, for example, the structure of a 5GS, according to an embodiment of the present invention.

[0024] To support MBS services on the existing 5GS, the cellular system for MBS is configured with the following network functions and services.

[0025] When an application server, such as a V2X application server, CIoT application server, or MCPTT application, or a content provider, such as a TV or audio service provider or streaming video service provider, requests an MBS service, there is a BM-CPF (broadcast / multicast-control plane function), which is a network function that manages the MBS service session and controls the MBS service traffic, and a BM-UPF (broadcast / multicast-user plane function), which is an MBS service media anchor within the 5GS that receives media from the AS or content provider and processes the media traffic as controlled by the BM-CPF. The interface between the BM-CPF and the BM-UPF is named the Nxxx interface. The BM-CPF and the BM-UPF may be integrated into a single entity or a single NF. For example, the BM-CPF may be the first entity and the BM-UPF may be the second entity.

[0026] MBS sessions are managed and service traffic is generated through the aforementioned BM-CPF and BM-UPF. When service traffic is delivered to a terminal via multicast / broadcast, an MBS PDU session is allocated to manage the traffic. The function or service that creates an MBS context for the MBS PDU session, manages the MBS PDU session, and controls the delivery of the MBS PDU session traffic to the NG-RAN via IP multicast is collectively referred to as the MBMS-GW-C (multimedia broadcast-multicast service gateway - control plane) service. The MBMS-GW-C service may be integrated into the existing SMF that manages unicast PDU sessions to form an SMF with MBS PDU session control functions, or it may be configured as a separate NF. In this document, an NF configured separately solely for the MBMS-GW-C service is referred to as the MB-SMF (multicast / broadcast session management function).

[0027] In addition, the service that transmits traffic received from the BM-UPF via IP multicast to the NG-RAN performing multicast / broadcast according to the MBMS-GW-C service, based on the MBS context for the aforementioned MBS PDU Session, is collectively referred to as the MBMS-GW-U (multimedia broadcast-multicast service gateway - user plane) service. The aforementioned MBMS-GW-U service may be configured as a UPF integrated into the existing UPF that handles unicast PDU Sessions, thereby having the function of transmitting MBS traffic via IP multicast to the appropriate NG-RAN, or it may be configured as a separate NF. In this document, an NF configured separately solely for the aforementioned MBMS-GW-U service is referred to as the MB-UPF (multicast / broadcast User Plane function).

[0028] The above MBMS-GW-C service uses the N4-MBS interface to control the MBMS-GW-U service.

[0029] In describing the embodiments in this document, the above MBMS-GW-C and MBMS-GW-U are mainly referred to as SMF and UPF, respectively, for convenience; however, to avoid confusion, their usage is described as unicast-only, multicast / broadcast-only, or whether both are supported, as needed.

[0030] MBS session traffic is transmitted from the MBMS-GW-U (or UPF or MB-UPF) to the NG-RANs. For example, it is transmitted to the NG-RAN using IP multicast. In this case, the tunnel between the MBMS-GW-U (or UPF or MB-UPF) and the NG-RAN is called the M1 tunnel.

[0031] In order to set up the above M1 tunnel, the above MBMS-GW-C (or SMF or MB-SMF) sends a control message to NG-RAN through NG-MCE (Next Generation - Multicell Coordination Entity) or sends a control message directly to NG-RAN.

[0032] At this time, communication with the MBMS-GW-C can be established through an AMF that has an M3 connection with the NG-MCE or NG-RAN as shown in Fig. 1a. Alternatively, as shown in Fig. 1b, the MBMS-GW-C can directly transmit a control message to the appropriate NG-MCE through an M3 connection, and the NG-MCE can transmit the received control message from the MBMS-GW-C to the NG-RANs through an M2 connection. Alternatively, the MBMS-GW-C can send a control message directly to the NG-RAN through an M3 connection.

[0033] According to an embodiment of the present invention, the MBS service is provided through the following procedure. First, the terminals are notified that the MBS service is available, and terminals wishing to receive the service perform a procedure to register for the service if necessary for the MBS service and to obtain the associated parameters required to receive the service.

[0034] Meanwhile, in 5GS, a session is created to send MBS data, and a signaling procedure is performed to create and manage a tunnel for MBS data to be transmitted from the MBS service provider or Application server (AS) to the base station in the corresponding area.

[0035] When MBS data arrives at the base station through the aforementioned tunnel, the base station broadcasts information regarding when and how to transmit MBS data, so that terminals that have acquired MBS service parameters can know, and broadcasts the MBS data according to the said information.

[0036] If the above MBS service is no longer performed, the created session may be released, and the tunnel allocated for this purpose may also be removed.

[0037] FIG. 2 illustrates a process for initiating an MBS session in a 5G network according to an embodiment of the present invention.

[0038] In step S200, the Application Server (AS) or MBS contents provider transmits information regarding MBS session data traffic to the MBS function of the 5GS network in order to transmit MBS data traffic through the 5GS, and obtains IP address information of the Media Anchor within the 5GS to transmit the MBS data. For example, the MBS function may be a BM-CPF or an SMF or BMSC that includes an MBS service session management function as a first entity. Additionally, the Media Anchor may be a BM-UPF or a UPF or BMSC that includes a media source function for the MBS service session as a second entity.

[0039] The above MBS function can be performed by, for example, a BM-CPF (Broadcast Multicast-control plane function), an SMF (Session Management function) with added MBS service session management function, or a BMSC (Broadcast Multicast Service Center).

[0040] In addition, the Media Anchor within the above 5GS can be performed by a BM-UPF (Broadcast Multicast-user plane function), a UPF (User Plane function) with added media source function for an MBS service session, or a BMSC (Broadcast Multicast Service Center).

[0041] In step S210, the MBS function creates an MBS context to manage the MBS service session in the 5GS and sets up a control session for the MBS media anchor in the 5GS.

[0042] In step S220, the MBS function determines whether to transmit MBS data traffic via broadcast, multicast, or unicast. The determination of the transmission method may be based on the density of terminals receiving MBS session services—that is, how many terminals receive service in the area to be broadcast / multicasted—or based on whether the base station where the terminals receiving MBS session services are located has an MBS function.

[0043] If, in step S230, the transmission of the MBS data traffic is determined to be broadcast / multicast, a tunnel is created between the base stations in the area where the MBS data traffic is to be broadcast and the Media Anchor. The tunnel between the Media Anchor and the base stations consists of a tunnel between the Media Anchor and the UPF for broadcast / multicast, and a tunnel between the UPF for broadcast / multicast and the base stations in the area where the broadcast is to be broadcast. The MBS function sets up a control session to manage the tunnel between the Media Anchor and the UPF for broadcast / multicast. The MBMS-GW-C (or SMF or MB-SMF) sets up a control session to manage the tunnel between the UPF for broadcast / multicast and the base stations in the area where the broadcast is to be broadcast.

[0044] Meanwhile, when the BM-UPF acting as the Media Anchor and the UPF for broadcast / multicast, namely the MB-UPF, are implemented as a single entity, the two tunnels can be configured and managed as one. Accordingly, the MBS function and the MBMS-GW-C are configured as one to set up a control session for managing the tunnel between the Media Anchor and the base stations.

[0045] On the other hand, if the transmission for the above MBS data traffic is determined to be unicast, the MBS function creates a PDU session for the DN (Data Network) for the MBS service, and creates a tunnel between the base station to which the terminal is connected and the Media Anchor, or between the base station and the UPF with added media source function, or between the base station and the UPF for MBS.

[0046] In describing an embodiment of the invention, the MBS function and service of the 5GS is designated as BM-CPF. However, the MBS function and service may be located in the SMF or together with the user plane as BM-SC. Additionally, the Media Anchor of the 5GS is designated as BM-UPF. However, the Media Anchor may be located in the UPF or together with the control plane as BM-SC.

[0047] The above BM-CPF performs the function of controlling the transmission of MBS data through the 5GS by receiving MBS data from the AS or MBS contents provider through the 5GS by making a service announcement for MBS services in the 5GS, managing MBS user service sessions, deciding whether to transmit MBS data via broadcast / multicast or unicast, and managing the BM-UPF, which is a Media Anchor.

[0048] In order to provide MBS services according to an embodiment of the present invention, a method is required to expose the MBS function and service of 5GS outside the 5GS network, and for an AS (Application server) or MBS contents provider to discover and select a suitable MBS function and service.

[0049] To this end, MBS functions and services must be registered with NRF (Network Repository function) and NEF (Network Exposure function) to support other NF (Network function) or AF (application function) in discovering and selecting the MBS functions and services.

[0050] Meanwhile, FIG. 3 illustrates the process of a network function (NF) (300) registering, updating, or canceling a profile for MBS services to an NRF (310) according to an embodiment of the present invention.

[0051] NF (300) can request registration from NRF (310) via the Nnrf_NFManagement_NFRegister_request message, including NF type, NF instance ID, name of the NF service provided, PLMN ID, information, as well as information necessary for the service provided (step S320). Then, NRF (310) can save it as the profile of the NF (300) (step S330) and notify the NF (300) that it has been registered via the Nnrf_NFManagement_NFRegister_response message (step S340).

[0052] Additionally, when NF (300) updates its profile, it may request an update to the NRF via the Nnrf_NFManagement_NFUpdate_request message, which includes the NF (300) profile information that is to be changed or the information of the service being changed along with the NF instance ID (step S320). Then, the NRF (310) updates the profile (step S330) and may notify the NF (300) of the result via the Nnrf_NFManagement_NFUpdate_response message (step S340).

[0053] Additionally, if the NF (300) is not providing its service, it may request the NRF (310) to terminate the service with the reason and the NF instance ID via the Nnrf_NFManagement_NFDeregister_request message (step S320). After the termination process, the NRF (310) updates the status of the NR (300) to the NRF (310) as unavailable (step S330), and may notify the NF (300) of the result via the Nnrf_NFManagement_NFDeregister_response (step S340).

[0054] Here, the above NF (300) is an NF for MBS services and can be BM-CPF, BM-UPF, SMF, UPF, or AMF, and each NF's profile explains what service-related information is registered / updated / unregistered in the profile.

[0055] First, when the above NF (300) is a BM-CPF, the information required for the service to be registered in the NRF (310) so that an AF (application function) or AF (Application server) or contents provider can select a suitable BM-CPF to provide MBS services is NF type = BM-CPF, NF instance ID, name of the NF service provided (e.g., Nbmcpf_MBSservice, etc.), PLMN ID, and a service ID indicating the type of MBS service that the above BM-CPF can support may be, for example, TV service, Video service, Radio service, IoT service, V2X service, public safety service. Alternatively, information including more detailed service information may be included, for example, a service ID indicating a TV service on channel x, a police network service among public safety services, a firefighter network service among public safety services, or an IoT service for subscribers of a specific company. In addition, the area of ​​the MBS service supported by the above BM-CPF, for example, the MBS Service Area, or a TAI list, or part or all of the Cell ID list may be included. Also, a broadcast group ID list, which is a list of groups of terminals capable of receiving the service, for example, the range of the corresponding TMGI or the TMGI list may be included. Additionally, information such as network slice info (e.g., S-NSSAI, NW slice instance ID) and DNN that the BM-CPF supports may be included.

[0056] A method for discovering and selecting a suitable BM-CPF using the information stored in the profile of the BM-CPF of the above NRF (310) is covered in another embodiment.

[0057] If the above NF (300) is a BM-UPF, the information required for the service to be registered with the NRF (310) so that the BM-CPF can select a suitable BM-UPF to receive MBS traffic provided by an AF (application function), an AF (Application server), or a contents provider at the 5GS and to serve as a Media Anchor at the 5GS may include NF type = BM-UPF, NF instance ID, the name of the NF service provided (e.g., Nbmupf_MBSservice, etc.), PLMN ID, and a service ID indicating the type of MBS service that the above BM-UPF can support, e.g., TV service, Video service, Radio service, IoT service, V2X service, public safety service. Alternatively, information including more detailed service information may be included, e.g., a service ID indicating a TV service on channel x, a police network service among public safety services, a firefighter network service among public safety services, or an IoT service for subscribers of a specific company. In addition, the area of ​​the MBS service supported by the above BM-UPF, for example, the MBS Service Area, or the TAI list, or part or all of the Cell ID list or DNAI, may be included. Also, a broadcast group ID list, which is a list of groups of terminals capable of receiving the service, for example, the range of the corresponding TMGI or the TMGI list, may be included. Additionally, information such as network slice info (e.g., S-NSSAI, NW slice instance ID) supported by the BM-UPF may be included.

[0058] A method for BM-CPF to discover and select a suitable BM-UPF using information stored in the profile of the BM-UPF of the above NRF (310) is covered in another embodiment.

[0059] When the above NF (300) is an SMF, the information required for the service to be registered with the NRF (310) so that the BM-CPF can select a suitable SMF to manage the MBS session and control the tunnel for transmitting the MBS traffic, such as creating / modifying / terminating the tunnel, is NF type = SMF, NF instance ID, the name of the NF service provided (e.g., Nsmf_PDUSession, Nsmf_Multicast&BroadcastPDUSession, etc.), PLMN ID, along with whether the above SMF supports IP multicast, whether it supports broadcast / multicast transmission method, or whether it supports unicast transmission method, and the supported IP version, and the service ID indicating the type of MBS service that the SMF supports, e.g., TV service, Video service, Radio service, IoT service, V2X service, public safety service. Alternatively, information containing more detailed service information may be included, for example, a service ID representing a TV service on channel x, a police network service among public safety services, a firefighter network service among public safety services, or an IoT service for a subscriber of a specific company. In addition, the area of ​​MBS services supported by the SMF, for example, an MBS Service Area, or a TAI list, or a Cell ID list or part or all of a DNAI, may be included. Furthermore, a broadcast group ID list, which is a list of groups of terminals capable of receiving the service, for example, a range of the corresponding TMGI or a TMGI list, may be included. Additionally, information such as network slice info supported by the SMF (e.g., S-NSSAI, NW slice instance ID) may be included.In addition, information regarding whether the SMF supports switching and steering functions between broadcast / multicast transmission methods and unicast transmission methods may be included.

[0060] A method for discovering and selecting a suitable SMF using the information stored in the profile of the SMF of the above NRF (310) is covered in another embodiment.

[0061] When the above NF (300) is a UPF, the information required for the service to register with the NRF so that the SMF can select the appropriate UPF, which is one end of the tunnel transmitting the corresponding MBS traffic according to the MBS session, may include NF type = UPF, NF instance ID, the name of the NF service provided (e.g., Nupf_PDUSession, Nupf_Multicast&BroadcastPDUSession, etc.), PLMN ID, and whether the UPF supports IP multicast, broadcast / multicast transmission method, or unicast transmission method, and the supported IP version, the area of ​​the MBS service that the UPF supports, e.g., MBS Service Area, or TAI list, or Cell ID list, or part or all of the DNAI. Additionally, information such as network slice info that the UPF supports (e.g., S-NSSAI, NW slice instance ID) may be included. Additionally, information regarding whether the UPF supports switching and steering functions between the broadcast / multicast transmission method and the unicast transmission method may be included.

[0062] A method for discovering and selecting a suitable UPF using the information stored in the profile of the UPF of the above NRF is covered in another embodiment.

[0063] If the above NF (300) is an AMF, the information required for a service to be registered in the NRF (310) so that the SMF can select a suitable AMF to relay control messages between the SMF and NG-RAN (e.g., NG-Multicell Coordination Entity (MCE) or eNB or gNB) in order to transmit QoS / Policy information regarding the tunnel configuration and MBS traffic, etc., between the SMF that controls and manages the tunnel transmitting the corresponding MBS traffic according to the MBS session and the NG-RAN which is one end of the tunnel, is NF type = AMF, NF instance ID, name of the NF service provided (e.g., Namf_Communication_N1N2MessageTransfer, Namf_Communication_M3MessageTransfer, etc.), PLMN ID, along with whether the M3 interface, which is an interface for MBS with the NG-MCE or NG-RAN, is set up on the AMF, the AMF's GUAMI information, and the range of MBS services that the AMF can support, e.g., MBS Service It may include part or all of the Area, TAI list, or Cell ID list. Additionally, it may include information such as network slice info supported by AMF (e.g., S-NSSAI, NW slice instance ID).

[0064] A method for discovering and selecting a suitable AMF using the information stored in the profile of the AMF of the above NRF (310) is covered in another embodiment.

[0065] When the above NF (300) is an NG-MCE, the information required for the service to be registered with the NRF so that the SMF can select the appropriate NG-MCE when the SMF directly sends a control message to the NG-MCE or NG-RAN to transmit the tunnel configuration and QoS / Policy information for the MBS traffic, etc., to the NG-RAN, which is one end of the tunnel, according to the MBS session, is an NF type = NG-MCE, NF instance ID, the name of the NF service provided (e.g., Nmce_Communication_M3 MessageTransfer, etc.), PLMN ID, and the NG-RAN connected to the NG-MCE through M2, which is an interface for MBS, may include a list of NG-RANs connected to the NG-MCE, an area of ​​MBS service that the NG-MCE can support, e.g., MBS Service Area, or TAI list, or part or all of a Cell ID list. In addition, information such as network slice info (e.g., S-NSSAI, NW slice instance ID) that NG-MCE can support may be included.

[0066] A method for discovering and selecting a suitable NG-MCE using the information stored in the profile of the NG-MCE of the above NRF (310) is covered in another embodiment.

[0067] Meanwhile, FIG. 4 illustrates the process of an AF (400), for example, an AS or contents provider, selecting a suitable BM-CPF (430) to provide MBS services according to an embodiment of the present invention.

[0068] The AF (400) transmits information for the MBS service to the NEF (410), which exposes the MBS service capability for the MBS service, by including it in the Nnef_MBSservice_create request message. (Step S440) The information for the MBS service includes a service ID indicating the type of MBS service, e.g., TV service, Video service, Radio service, IoT service, V2X service, public safety service, or information containing more detailed service information, e.g., TV service on channel x, police network service among public safety services, firefighter network service among public safety services, IoT service for subscribers of a specific company. Additionally, the area of ​​the MBS service where the MBS service is performed, e.g., MBS Service Area, or TAI list, or Cell ID list, or part or all of the area information of an actual map, may be included. Additionally, a broadcast group ID list, which is a list of groups of terminals capable of receiving the service, e.g., the range of the corresponding TMGI, or TMGI list, may be included. In addition, all or part of the characteristics of traffic generated by the above MBS service, such as 5QI, resource type (e.g., GBR, delay critical GBR, or non-GBR), Maximum bit rate, Guaranteed bit rate, maximum delay tolerance, maximum packet loss rate, priority level, and Maximum Data burst volume, may be included as QoS information.

[0069] Upon receiving the above message, the NEF (410) sends an Nnrf_NFDiscovery_Request request message to the NRF (420) to select a suitable BM-CPF (430). (Step S445) At this time, the Nnrf_NFDiscovery_Request request message includes target NF service = Nbmcpf_MBSservice, NF type of target NF = BM-CPF, NF type of NF service consumer = AF, and ID information of AF (400). Additionally, the Nnrf_NFDiscovery_Request request message includes some or all of the information received from the AF (400), the MBS service ID, the range of the MBS service, and a list of groups of terminals capable of receiving the service. Furthermore, the Nnrf_NFDiscovery_Request request message may include the corresponding network slice info (e.g., S-NSSAI) received from the AF (400) or identified through the information received from the AF (400).

[0070] If the AF (400) belongs to the trusted domain of the 5GS, the AF (400) can directly send the Nnrf_NFDiscovery_Request request message to the NRF (420) without going through the NEF (410) to request the discovery of the appropriate BM-CPF (430).

[0071] The NRF (420) that receives the above message can confirm that the BM-CPF discovery is an allowed NF or AF. (Step S450) Then, the NRF (420) searches for / discovers a suitable BM-CPF from the profiles of BM-CPFs registered in the NRF (420) and transmits the information of the discovered BM-CPF(s) to the NEF (410) via the Nnrf_NFDiscovery_Request response message. (Step S455) The method for searching for / discovering the suitable BM-CPF (430) finds the profile of the BM-CPF (430) that is determined to be the most similar to all or part of the information sent included in the Nnrf_NFDiscovery_Request request message. The information of BM-CPF(s) included in the above Nnrf_NFDiscovery_Request response message includes NF type=BM-CPF, NF instance ID, FQDN or IP address(es) of the NF instance and, a list of services instances. In addition, it may include NF load information of BM-CPF(s) or MBS Service ID, the area of ​​the MBS service, TAI list, PLMN ID, and some or all of S-NSSAI(s).

[0072] The NEF (420) can transmit the MBS service request requested by the AF (400) to a selected BM-CFP(s) among the discovered BM-CPF(s) via the Nbmcpf_MBSservice_create request message (step S460). In response, the NEF (420) can receive the Nbmcpf_MBSservice_create response message (step S465). The Nbmcpf_MBSservice_create response message includes information on the FQDN or IP address of an NF, for example, a BM-UPF, that the BM-CPF (430) uses as a media anchor within 5GS. It may also include the transmission method for the MBS service selected by the BM-CPF (430).

[0073] In the process of transmitting information for the MBS service to the NEF (410) that exposes the MBS service capability for the MBS service, if the corresponding MBS service was not previously running, the AF (400) can transmit the information for the MBS service by including it in the Nnef_MBSservice_create request message as described above, so that the BM-CPF (430) can create the MBS service anew. However, if the corresponding MBS service already exists, the AF (400) can transmit information for the MBS service through the Nnef_MBSservice_update request message in step S440 so that the BM-CPF (430) can request an update to the existing MBS service, or the BM-CPF (430) can request the release of the existing MBS service through the Nnef_MBSservice_delete request message, and the update request or release request is performed through steps S460, S465, and S470 in accordance with the request.

[0074] As shown in FIG. 4, in the process of selecting a suitable BM-CPF (430) for an AF (AS or contents provider) (400) to provide MBS services, if the AF (400) belongs to a 5GS and trusted domain, the AF (400) may send the message transmitted at step S445 directly to the NRF (420) without passing through the NEF (410), instead of sending the message transmitted at step S440. In response to this, the NRF (420) may also send the message transmitted at step S455 directly to the AF (400), allowing the AF (400) to directly select a suitable BM-CPF (430) based on the response from the NRF (420). In this case, the AF (400) may skip steps S440 and S470 and discover / select the BM-CPF (430) through steps S445, S450, and S455. And the above AF (400) can directly request MBS services through BM-CPF (430) via steps S460 and S465.

[0075] In addition, when using a Service Communication Proxy (SCP) in 5GS, instead of the AF (400), NEF (410), or BM-CPF (430) sending messages directly to each other, messaging between NFs may be performed by sending the messages to the SCP, and the SCP searching for / discovering a recipient based on information held by the NRF (420) or itself, and delivering the message to the appropriate NF for processing.

[0076] Meanwhile, FIG. 5 illustrates the process of selecting a suitable BM-UPF (520) to provide MBS services, according to an embodiment of the present invention, in which a BM-CPF (500) selects a suitable BM-UPF (520).

[0077] In order to select a suitable BM-UPF (520), the above BM-CPF (500) sends an Nnrf_NFDiscovery_Request request message to the NRF (510) in step S530. At this time, the Nnrf_NFDiscovery_Request request message may include target NF service = Nbmupf_MBSservice, NF type of target NF = BM-UPF, PLMN ID, MBS service ID indicating the type of MBS service that the BM-CPF wants to perform, and also the MBS service area to be serviced, e.g., MBS Service Area, or TAI list, or part or all of the Cell ID list or DNAI, and a broadcast group ID list, e.g., a range of the corresponding TMGI, or a TMGI list, which is a list of groups of receiving terminals targeting the service. Alternatively, it may include part or all of the information such as network slice info to which the BM-CPF (500) belongs (e.g., S-NSSAI, NW slice instance ID).

[0078] The NRF (510) that receives the above message can confirm that the BM-UPF discovery is an allowed NF. (Step S540) Then, the NRF (510) can search for / discover a suitable BM-UPF (520) from the profiles of BM-UPF (520) registered in the NRF (510) and transmit the information of the discovered BM-UPF(s) to the BM-CPF (500) through the Nnrf_NFDiscovery_Request response message. (Step S550) As a method for searching for / discovering the suitable BM-UPF (520), there may be a method of finding the profile of the BM-CPF that is judged to be the most similar to all or part of the information sent included in the Nnrf_NFDiscovery_Request request message. The information of BM-UPF(s) included in the above Nnrf_NFDiscovery_Request response message includes NF type=BM-UPF, NF instance ID, FQDN or IP address(es) of the NF instance and, a list of services instances. In addition, NF load information of BM-UPF(s) or MBS Service ID, MBS service area, TAI list, PLMN ID, S-NSSAI(s), and some or all of the DNAI may be included.

[0079] The above BM-CPF (500) can be transmitted to a selected BM-UFP(s) among the discovered BM-UPF(s) via an Nbm_Session_Establishment request message. (Step S560) While creating a control session to control MBS service session traffic between the BM-CPF (500) and the BM-UPF (520), the BM-UPF (520) can transmit an Nbm_Session_Establishment response message to the BM-CPF (500) in response to the request. (Step S570) The Nbm_Session_Establishment response message may include information on the NF used as a media anchor within 5GS, for example, the FQDN or IP address of the BM-UPF.

[0080] As described above, if a control session is not established between BM-CPF (500) and BM-UPF (520), a new session may be established by exchanging Nbm_Session_Establishment request / response messages as in steps S560 and S570. However, if BM-CPF (500) already has a control session with BM-UPF (520), the existing MBS service may be updated via the Nbm_Session_modification request message in step S560, or the BM-CPF may request the release of the existing control session via the Nbm_Session_release request message. Then, the update request or release request may be performed via step S570 in accordance with the above request.

[0081] In the case where a Service Communication Proxy (SCP) is used in 5GS, instead of the BM-CPF (500) sending messages directly to each other, the BM-UPF (520) sends the messages to the SCP, and the SCP searches for / discovers a recipient based on information held by the NRF or itself, and delivers the message to the appropriate NF for processing.

[0082] Meanwhile, FIG. 6 illustrates the process of a BM-CPF (600) selecting a suitable SMF to provide MBS services according to an embodiment of the present invention.

[0083] The above BM-CPF (600) can send MBS service traffic that has arrived at the media anchor, i.e., BM-UPF, to the appropriate GW or UPF to deliver it to the terminal via multicast or broadcast. Alternatively, the above BM-CPF (600) can send an Nnrf_NFDiscovery_Request request message to the NRF (610) to select an SMF, which is an NF for controlling the session and GW, so that it can deliver it to the terminal via unicast. (Step S630) At this time, the Nnrf_NFDiscovery_Request request message may include target NF service = Nsmf_PDUSession or Nsmf_Multicast&BroadcastPDUSession, NF type of target NF = SMF, PLMN ID, an indicator indicating whether MBS session traffic should be sent only via broadcast / multicast or whether it should also support sending via unicast in addition to broadcast / multicast, an IP version, an MBS service ID indicating the type of MBS service that BM-CPF wants to provide, an MBS service area to provide (e.g., MBS Service Area), a TAI list, a Cell ID list, or part or all of the DNAI, a broadcast group ID list which is a list of groups of receiving terminals targeting the service (e.g., range of the corresponding TMGI), or a TMGI list. Alternatively, it may include part or all of the information to which the SMF belongs (e.g., S-NSSAI, NW slice instance ID).

[0084] The NRF (610) that receives the above message confirms that the SMF discovery is an allowed NF, searches for / discovers a suitable SMF (620) from the profiles of SMFs registered in the NRF (610) (step S640), and can transmit information of the discovered SMF(s) to the BM-CPF (600) through the Nnrf_NFDiscovery_Request response message (step S650). A method for searching for / discovering the suitable SMF (620) may be to find the profile of an SMF that is judged to be the most similar to all or part of the information sent included in the Nnrf_NFDiscovery_Request request message. The information of the SMF(s) included in the above Nnrf_NFDiscovery_Request response message may include NF type=SMF, NF instance ID, FQDN or IP address(es) of the NF instance and, a list of services instances, whether it supports only broadcast / multicast, whether it supports sending via unicast in addition to broadcast / multicast, whether the SMF supports switching between unicast and broadcast / multicast, and whether the SMF supports steering between unicast and broadcast / multicast. In addition, the NF load information of the SMF(s) or MBS Service ID, the range of the MBS service, TAI list, PLMN ID, S-NSSAI(s), and some or all of the DNAI may be included.

[0085] The BM-CPF (600) delivers an Nsmf_MBSsession_CreateSMcontext request message to a selected SMF(s) among the discovered SMF(s). (Step S660) The request message includes the FQDN or IP address and Tunnel ID value of the BM-UPF delivering the corresponding MBS service session, and may also include an MBS Session ID for managing the MBS session. In addition, it may include an indicator indicating that the MBS session traffic is delivered via broadcast / multicast. It may also include an indicator indicating whether the SMF (620) is allowed to switch or steer the MBS session traffic between unicast and broadcast / multicast. Upon receiving the request message, the SMF (620) creates an MBS PDU Session and an SM context to control the MBS session. The above MBS PDU session ID is assigned by BM-CPF and included in the request message, or the SMF that receives the request message directly assigns the MBS PDU Session ID. In addition, the SMF selects a suitable UPF to create a tunnel between the BM-UPF and the selected UPF, and includes tunnel information such as the FQDN or IP address and tunnel ID for the corresponding UPF in the Nsmf_MBSsession_CreateSMcontext response message and transmits it to the BM-CPF (600).(Step S670) Additionally, if the BM-CPF (600) allows switching or steering of MBS session traffic between unicast and broadcast / multicast, the response message may include information regarding the transmission method, such as whether the session traffic is transmitted via unicast or broadcast / multicast, and may transmit the changed information to the BM-CPF (600) whenever the transmission method changes.

[0086] If the existing SMF (620) already has an SM context for the corresponding MBS session, in steps S660 and S670, the MBS PDU Session SMcontext may be modified through the Nsmf_MBSsession_modifySMcontext request message and Nsmf_MBSsession_modifySMcontext response message as the Nsmf_MBSsession_modifySMcontext service instead of Nsmf_MBSsession_CreateSMcontext, or the MBS PDU Session SMcontext may be released through the Nsmf_MBSsession_releaseSMcontext request message and Nsmf_MBSsession_releaseSMcontext response message as the Nsmf_MBSsession_releaseSMcontext service instead of Nsmf_MBSsession_CreateSMcontext.

[0087] In the case where a Service Communication Proxy (SCP) is used in 5GS, instead of the BM-CPF sending messages directly to each other among SMFs, messaging between NFs may be performed in a manner where the BM-CPF sends the messages to the SCP, and the SCP searches for / discovers a recipient based on information held by the NRF or itself, and delivers the message to the appropriate NF for processing.

[0088] FIG. 7 illustrates the process of an SMF (700) selecting a suitable UPF to transmit MBS service traffic according to an embodiment of the present invention.

[0089] The above SMF (700) sends an Nnrf_NFDiscovery_Request request message to the NRF (710) to control the session so that the MBS service traffic that arrived at the media anchor, i.e., BM-UPF, is sent to the appropriate UPF (720) to be delivered to the terminal via multicast or broadcast, or delivered to the terminal via unicast. (Step S730) At this time, the Nnrf_NFDiscovery_Request request message may include target NF service = Nupf_PDUSession or Nupf_Multicast&BroadcastPDUSession, NF type of target NF = UPF, PLMN ID, an indicator indicating whether MBS session traffic should be sent only via broadcast / multicast, or whether it should be supported to send via unicast in addition to broadcast / multicast, or only via unicast, an IP version, an MBS service ID indicating the type of MBS service that the SMF wants to perform, and also the MBS service area to be serviced, e.g., MBS Service Area, or TAI list, or part or all of the Cell ID list or DNAI, and a broadcast group ID list, e.g., the range or TMGI of the corresponding TMGI, which is a list of groups of receiving terminals targeting the service. Or, it may include part or all of the information to which the UPF (720) belongs, such as network slice info (e.g., S-NSSAI, NW slice instance ID).

[0090] In the above target NF service, if the SMF (700) transmits the MBS session traffic via unicast, the target NF service may be set to Nupf_PDUSession. On the other hand, if the SMF (700) transmits the MBS session traffic via broadcast / multicast, the target NF service may be set to Nupf_Multicast&BroadcastPDUSession. Additionally, when transmitting via unicast, an indicator indicating that the MBS session traffic is to be sent only via unicast or an indicator indicating that both unicast and broadcast / multicast transmission are supported may be used. On the other hand, when transmitting the MBS session traffic via multicast, an indicator indicating that the MBS session traffic is to be sent only via broadcast / multicast or an indicator indicating that both unicast and broadcast / multicast transmission are supported may be used. Upon receiving the above message, the NRF (710) confirms that the UPF discovery is an allowed NF, searches for / discovers a suitable UPF from the profiles of UPFs registered in the NRF (710) (step S740), and transmits the information of the discovered UPF(s) to the SMF (700) via the Nnrf_NFDiscovery_Request response message (step S750). The method for searching for / discovering the suitable UPF (720) finds the profile of the UPF that is determined to be the most similar to all or part of the information sent included in the Nnrf_NFDiscovery_Request request message.The information of the UPF(s) included in the above Nnrf_NFDiscovery_Request response message includes NF type=UPF, NF instance ID, FQDN or IP address(es) of the NF instance and, a list of services instances, whether it supports only broadcast / multicast, whether it supports sending via unicast in addition to broadcast / multicast, whether it supports sending via unicast only, whether the UPF (720) supports switching between unicast and broadcast / multicast, and whether the UPF (720) supports steering between unicast and broadcast / multicast. In addition, it may include some or all of the NF load information of the UPF(s), MBS Service ID, MBS service area, TAI list, PLMN ID, S-NSSAI(s), and DNAI.

[0091] The SMF (700) delivers an N4-MBS Session Establishment request message to a selected UPF(s) among the discovered UPF(s). (Step S760) The request message includes the FQDN or IP address and Tunnel ID value of the BM-UPF that delivers the corresponding MBS service session, and also includes an MBS Session ID for managing the MBS session. In addition, the request message includes an indicator indicating whether to deliver the MBS session traffic via broadcast / multicast, unicast, or both broadcast / multicast and unicast simultaneously. Furthermore, the request message includes information on whether to support switching or steering of the MBS session traffic between unicast and broadcast / multicast, and if so, how to do it. For example, information may be included to switch to unicast when the terminal recognizes that it has moved out of the broadcast / multicast service area, or to deliver traffic simultaneously using both unicast and broadcast / multicast methods when there is a need for particularly high availability.

[0092] When UPF (720) receives the request message, it creates a tunnel to transmit the MBS session traffic under the control of SMF (700). To create a tunnel between BM-UPF and UPF (720), it uses the FQDN or IP address of BM-UPF received from SMF (700). Additionally, to set the tunnel endpoint in UPF (720), it includes the FQDN or IP address and tunnel ID information of UPF (720) in the N4-MBS Session Establishment response message and transmits it to SMF (700). (Step S760) Furthermore, to create a tunnel for IP multicast between UPF (720) and NG-RANs, it assigns an IP address for IP multicast and a tunnel ID, includes them in the N4-MBS Session Establishment response message, and transmits them to SMF (700). (Step S770) The IP address and tunnel ID values ​​for the IP multicast can be directly assigned by the SMF (700) and transmitted to the UPF (720) via an N4-MBS Session Establishment request message.

[0093] The above UPF (720) can transmit MBS session traffic to the NG-RAN in both ways, either through an IP multicast tunnel or through a unicast tunnel, depending on the control of the above SMF (700).

[0094] If the SMF (700) already has a control session for the corresponding UPF (720), in steps S760 and S770, the context of the MBS session of the UPF may be modified through an N4-MBS Session modification request message and an N4-MBS Session modification response message as an N4-MBS Session modification service instead of an N4-MBS Session Establishment, or the context of the MBS session of the UPF (720) may be released through an N4-MBS Session release request message and an N4-MBS Session release response message as an N4-MBS Session release service instead of an N4-MBS Session Establishment.

[0095] In the case where a Service Communication Proxy (SCP) is used in 5GS, instead of the SMFs sending messages directly to each other, messaging between NFs may be performed in a manner where the SMFs send the messages to the SCP, and the SCP searches for / discovers a recipient based on information held by the NRF or itself, and delivers the message to the appropriate NF for processing.

[0096] FIG. 8 illustrates the process of an SMF (800) selecting a suitable AMF (820) for transmitting MBS service traffic according to an embodiment of the present invention.

[0097] The above SMF (800) selects a suitable AMF (820) to transmit control information, such as IP multicast information for receiving said service traffic, to the NG-RAN located at the position where the UPF intends to transmit said MBS service traffic via multicast. To do this, the above SMF (800) sends an Nnrf_NFDiscovery_Request request message to the NRF (810). (Step S830) At this time, the Nnrf_NFDiscovery_Request request message includes target NF service = Namf_Communication_N1N2MessageTransfer or Namf_Communication_M3 MessageTransfer, NF type of target NF = AMF, PLMN ID, and an indicator indicating that the M3 interface, which is an interface for MBS with NG-MCE / NG-RAN, is set up. Additionally, the Nnrf_NFDiscovery_Request request message may include the MBS service area to be serviced, e.g., MBS Service Area, or TAI list, or Cell ID list, or part or all of the target AMF set, Regional ID, or DNAI, or a broadcast group ID list, which is a list of groups of receiving terminals targeting the service, e.g., the range of the corresponding TMGI, or TMGI list. Alternatively, the Nnrf_NFDiscovery_Request request message may include part or all of the network slice info that the AMF must support (e.g., S-NSSAI, NW slice instance ID).

[0098] Upon receiving the above message, the NRF (810) confirms that the NF is allowed for AMF discovery, searches for / discovers suitable AMFs from the profiles of AMFs registered in the NRF (step S840), and transmits the information of the discovered AMF(s) to the SMF (800) via the Nnrf_NFDiscovery_Request response message (step S850). A method for searching for / discovering the suitable AMF(s) may be used to find the profile of an AMF that is judged to be the most identical to all or part of the information sent included in the Nnrf_NFDiscovery_Request request message. For example, the NRF (810) discovers AMFs and notifies the SMF (800) so that the NG-RANs connected to the AMFs via the M3 interface can sufficiently cover the target MBS service area.

[0099] That is, the information of the AMF(s) included in the above Nnrf_NFDiscovery_Request response message includes NF type=AMF, NF instance ID, FQDN or IP address(es) or GUAMI of the NF instance and, a list of services instances, and information on whether the M3 interface, which is the interface for MBS with NG-MCE / NG-RAN, is set up on the AMF. In addition, the information of the AMF(s) included in the above Nnrf_NFDiscovery_Request response message may include some or all of the NF load information of the AMF(s), the range of MBS services that can be covered through the NG-MCE to which the AMF is connected, a TAI list, a Cell ID list, a DNAI, or the information of the S-NSSAI supported by the AMF.

[0100] The above SMF (800) may select an AMF(s) (820) corresponding to the area to be serviced from among the discovered AMF(s) and transmit a Namf_Communication_N1N2MessageTransfer request message or a Namf_Communication_M3 MessageTransfer request message. (Step S860) The AMFs that receive the message forward the control message included in the request message, for example, IP multicast tunnel information for base stations to receive IP multicast for the MBS service traffic, to the connected NG-MCEs. Then, information including a message requesting to join the IP multicast from the base station that received the control message is transmitted to the SMF (800) via the Namf_Communication_N1N2MessageTransfer response through the AMF (820). (Step S870)

[0101] Meanwhile, FIG. 9 illustrates the process of an SMF selecting a suitable NG-MCE to transmit MBS service traffic in a network structure in which, according to an embodiment of the present invention, the SMF sends control messages for MBS directly to the NG-MCE / NG-RAN without passing through the AMF as in FIG. 1b.

[0102] The above SMF (900) selects an appropriate NG-MCE (920) to transmit control information, such as IP multicast information for receiving said service traffic, to the NG-RAN located at the position where the UPF intends to transmit said MBS service traffic via multicast. To do this, the above SMF (900) sends an Nnrf_NFDiscovery_Request request message to the NRF (910). (Step S930) At this time, the Nnrf_NFDiscovery_Request request message includes target NF service = Nmce_Communication_M3 MessageTransfer, NF type of target NF = NG-MCE, and PLMN ID. Additionally, the Nnrf_NFDiscovery_Request request message may include the MBS service area to be serviced, e.g., MBS Service Area, or TAI list, or Cell ID list, or part or all of the DNAI, or a broadcast group ID list, which is a list of groups of receiving terminals targeting the service, e.g., the range of the corresponding TMGI, or TMGI list. Alternatively, the Nnrf_NFDiscovery_Request request message contains some or all of the network slice info (e.g., S-NSSAI, NW slice instance ID) that NG-MCE must support.

[0103] Upon receiving the above message, the NRF (910) confirms that the NG-MCE discovery is allowed NF, searches for / discovers suitable NG-MCEs from the profiles of NG-MCEs registered in the NRF (step S940), and transmits the information of the discovered NG-MCE(s) to the SMF (900) via the Nnrf_NFDiscovery_Request response message (step S950). A method for searching for / discovering the suitable NG-MCE(s) may be a method of finding the profile of an NG-MCE that is judged to be the most identical to all or part of the information sent included in the Nnrf_NFDiscovery_Request request message. For example, NG-MCEs are found and notified to the SMF (900) so that NG-RANs connected to the NG-MCEs via the M2 interface can sufficiently cover the target MBS service area.

[0104] That is, the information of the NG-MCE(s) included in the above Nnrf_NFDiscovery_Request response message includes NF type=NG-MCE, NF instance ID, FQDN or IP address(es) of the NF instance and, a list of services instances, information about the NG-RAN including whether the M2 interface, which is an interface for MBS, is set up on the NG-MCE. In addition, the information of the NG-MCE(s) included in the above Nnrf_NFDiscovery_Request response message may include some or all of the NF load information of the NG-MCE(s), the range of MBS services that the NG-MEC can cover, a TAI list, a Cell ID list, or the information of the S-NSSAI supported by DNAI or AMF.

[0105] The above SMF (900) can select an NG-MCE(s) corresponding to the area to be serviced among the discovered NG-MCE(s) and transmit an Nmce_Communication_M3MessageTransfer request message. (Step S960) At least one NG-MCE (920) that receives the message forwards the control message included in the request message, for example, IP multicast tunnel information for base stations to receive IP multicast for the MBS service traffic, to the connected NG-RANs. Then, the NG-RAN that received the control message transmits information including a message requesting to join the IP multicast to the SMF through the NG-MCE via an Nmce_Communication_M3MessageTransfer response.

[0106] Meanwhile, FIG. 10 is a diagram illustrating the structure of a first entity in a wireless communication system according to one embodiment of the present disclosure. The first entity may be a BM-CPF as an MBS function.

[0107] Referring to FIG. 10, the first entity may include a transceiver (1010), a memory (1020), and a processor (1030). The transceiver (1010) and the processor (1030) of the first entity may operate according to the control method of the first entity described above. However, the components of the first entity are not limited to the examples described above. For example, the first entity may include more components or fewer components than the components described above. Furthermore, the transceiver (1010), the memory (1020), and the processor (1030) may be implemented in the form of a single chip.

[0108] The transmitting and receiving unit (1010) can transmit and receive signals with other entities. Here, the signals may include control information and data. To this end, the transmitting and receiving unit (1010) may be composed of an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies a received signal and down-converts the frequency. However, this is merely one embodiment of the transmitting and receiving unit (1010), and the components of the transmitting and receiving unit (1010) are not limited to an RF transmitter and an RF receiver.

[0109] The memory (1020) can store programs and data necessary for the operation of the first entity. Additionally, the memory (1020) can store control information or data included in signals transmitted and received by the first entity. The memory (1020) may be composed of a storage medium or a combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. Additionally, there may be multiple memory (1020).

[0110] Additionally, the processor (1030) can control a series of processes to enable the first entity to operate according to the above-described embodiment. There may be multiple processors (1030), and the processor (1030) can perform component control operations of the first entity by executing a program stored in memory (1020).

[0111] FIG. 11 is a diagram illustrating the structure of a second entity in a wireless communication system according to one embodiment of the present disclosure. The second entity may be a Media Anchor and be a BM-UPF.

[0112] Referring to FIG. 11, the second entity may include a transceiver (1110), a memory (1120), and a processor (1130). The transceiver (1110) and the processor (1130) of the second entity may operate according to the control method of the second entity described above. However, the components of the second entity are not limited to the examples described above. For example, the second entity may include more components or fewer components than the components described above. In addition, the transceiver (1110), the memory (1120), and the processor (1130) may be implemented in the form of a single chip.

[0113] The transmitting and receiving unit (1110) can transmit and receive signals with other entities. Here, the signals may include control information and data. To this end, the transmitting and receiving unit (1110) may be composed of an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies a received signal and down-converts the frequency. However, this is merely one embodiment of the transmitting and receiving unit (1110), and the components of the transmitting and receiving unit (1110) are not limited to an RF transmitter and an RF receiver.

[0114] The memory (1120) can store programs and data necessary for the operation of the second entity. Additionally, the memory (1120) can store control information or data included in signals transmitted and received by the second entity. The memory (1120) may be composed of a storage medium or a combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. Additionally, there may be multiple memory (1120).

[0115] The processor (1130) can control a series of processes to enable the second entity to operate according to the embodiments of the present disclosure described above. There may be multiple processors (1130), and the processor (1130) can perform component control operations of the second entity by executing a program stored in memory (1120).

[0116] 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.

[0117] When implemented in software, a computer-readable storage medium may be provided for storing one or more programs (software modules). One or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. One or more programs include instructions that cause the electronic device to execute methods according to the embodiments described in the claims or specification of this disclosure.

[0118] Such programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, ROM (Read Only Memory), Electrically Erasable Programmable Read Only Memory (EEPROM), magnetic disc storage devices, Compact Disc-ROM (CD-ROM), Digital Versatile Discs (DVDs), or other forms of optical storage devices, magnetic cassettes. Alternatively, they may be stored in memory composed of some or all of these. Additionally, each constituent memory may include multiple units.

[0119] Additionally, the program may be stored on an attachable storage device accessible via a communication network such as the Internet, Intranet, Local Area Network (LAN), Wide LAN (WLAN), or Storage Area Network (SAN), or a combination thereof. Such a storage device may be connected to the device performing the embodiment of the present disclosure through an external port. Additionally, a separate storage device on the communication network may be connected to the device performing the embodiment of the present disclosure.

[0120] In the specific embodiments of the present invention described above, the components included in the invention are expressed in a singular or plural form according to the specific embodiments presented. However, the singular or plural expression is selected to suit the situation presented for convenience of explanation, and the present invention is not limited to singular or plural components; even if a component is expressed in the plural form, it may be composed in the singular form, or even if a component is expressed in the singular form, it may be composed in the plural form.

[0121] Meanwhile, although specific embodiments have been described in the detailed description of the present invention, it is understood that various modifications are possible within the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof. Explanation of the symbols

[0122] 300: NF 310, 420: NRF 400: AF 410: NEF

Claims

Claim 1 A method performed by a session management function (SMF) entity, comprising: transmitting a first request message to a network repository function (NRF) entity to discover a plurality of access and mobility management function (AMF) entities based on a multicast / broadcast service (MBS) service area; receiving a response message from the NRF entity containing information about at least one discovered AMF entity; and selecting at least one AMF entity from among the plurality of discovered AMF entities that support the MBS based on the response message; and transmitting a second request message containing the control information to the selected at least one AMF entity to transmit control information to at least one next-generation (NG)-radio access network (RAN) that supports the MBS based on the MBS service area. Claim 2 A method according to claim 1, characterized in that the first request message includes a list of tracking area identifiers (TAIs). Claim 3 A method according to claim 1, wherein the at least one AMF entity is selected to correspond to a serviced area among the discovered plurality of AMF entities supporting the MBS. Claim 4 delete Claim 5 delete Claim 6 A method according to claim 1, further comprising the step of receiving a setup response message through the selected at least one AMF entity from one of the at least one NG-RANs. Claim 7 delete Claim 8 A control unit for a session management function (SMF) entity, comprising: a transceiver; and a network repository function (NRF) entity, wherein the control unit transmits a first request message through the transceiver to discover a plurality of access and mobility management function (AMF) entities based on a multicast / broadcast service (MBS) service area, receives a response message through the transceiver containing information about at least one discovered AMF entity from the NRF entity, controls the selection of at least one AMF entity among the plurality of discovered AMF entities supporting the MBS based on the response message, and controls the transmission of a second request message containing control information through the transceiver to transmit control information to at least one next-generation (NG)-radio access network (RAN) supporting the MBS based on the MBS service area to the selected at least one AMF entity. SMF entity including Claim 9 An SMF entity according to claim 8, characterized in that the first request message includes a list of tracking area identifiers (TAIs). Claim 10 In claim 8, the SMF entity is characterized in that the at least one AMF entity is selected to correspond to a serviced area among the discovered plurality of AMF entities supporting the MBS. Claim 11 delete Claim 12 delete Claim 13 In claim 8, the control unit controls the transceiver to receive a setup response message from one of the at least one NG-RANs through the selected at least one AMF entity, characterized in that the SMF entity. Claim 14 delete

Images