Method and apparatus for terminal to join multicast service

Abstract

A method and apparatus for a terminal to join a multicast service are disclosed. A method performed by a session management function (SMF) can include receiving a join request message for a terminal to join a multicast service, transmitting a discovery request message including a multicast / broadcast service (MBS) session ID related to the multicast service to an NF repository function (NRF), receiving a discovery response message from the NRF in response to the discovery request message, the discovery response message including an MB-SMF ID mapped to the MBS session ID, acquiring information related to a MBS session indicated by the MBS session ID from an MB-SMF identified by the MB-SMF ID, and notifying a radio access network (RAN) to which the UE is connected of the information related to the MBS session based on the acquired information.

Description

Technical Field

[0001] This disclosure relates to the field of mobile communication systems that provide data services via multicast / broadcast, and to a method and apparatus that support multicast services for a UE. Background Technology

[0002] To meet the increased demand for wireless data services since the deployment of 4G (fourth generation) communication systems, efforts have been made to develop improved 5G (fifth generation) or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also referred to as "post-4G networks" or "post-LTE systems".

[0003] 5G communication systems are considered to be implemented in higher frequency (millimeter wave) bands, such as the 60 GHz band, to achieve higher data rates. To reduce radio wave propagation loss and increase transmission distance, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO technologies are discussed in 5G communication systems.

[0004] In addition, in 5G communication systems, development is underway to improve system networks based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), and receiver interference cancellation.

[0005] In 5G systems, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding and modulation (ACM), and filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies have been developed.

[0006] Meanwhile, when providing multicast broadcast service (MBS) to UE in a 5G network, it is necessary to discover and select appropriate network entities during the UE joining the multicast service operation. Summary of the Invention

[0007] [The problem to be solved]

[0008] In order to send the same data to multiple UEs in a mobile communication network, it is necessary to provide multicast and / or broadcast services (MBS). For example, it is necessary to send data to multiple UEs in a specific area via multicast / broadcast to provide TV / audio services, vehicle-to-everything (V2X) services, or massive consumer Internet of Things (CIoT) services.

[0009] In order to send data via multicast / broadcast, it is necessary to define a network function (NF) or NF service and to support related multicast / broadcast service (MBS) processes, such as exposing, discovering or selecting each NF or NF service.

[0010] In the case of multicast services, when a UE joins a multicast service, the network entity receiving the join request from the UE (e.g., Session Management Function (SMF) or Access and Mobility Management Function (AMF)) needs to select the appropriate MBS entity (e.g., Multicast / Broadcast Session Management Function (MB-SMF)) and obtain information for providing multicast services. Therefore, a method is needed for discovering and selecting MB-SMFs that support multicast services.

[0011] [Technical Solution]

[0012] According to an embodiment, a method for a UE to join a multicast service, performed by a Session Management Function (SMF), may include: receiving a join request message for the UE to join the multicast service; sending a discovery request message to a Network Function (NF) Storehouse Function (NRF) including a multicast / broadcast service (MBS) session ID associated with the multicast service; in response to the discovery request message, receiving from the NRF a discovery response message including a multicast / broadcast (MB)-SMF ID mapped to the MBS session ID; obtaining information related to the MBS session indicated by the MBS session ID from the MB-SMF identified by the MB-SMF ID; and, based on the obtained information, notifying the Radio Access Network (RAN) accessed by the UE of the information related to the MBS session.

[0013] According to an embodiment, a method for a UE to join a multicast service, performed by the Multicast / Broadcast Session Management Function (MB-SMF), may include: creating an MBS session with an MBS session ID for providing the multicast service; sending a request message to a Network Function (NF) Storehouse Function (NRF) requesting the storage of an MB-SMF ID that identifies the MB-SMF used for the MBS session ID; requesting a Multicast / Broadcast User Plane Function (MB-UPF) to set up a tunnel for transmitting data services of the MBS session; and sending the entry address of the MBS session received from the MB-UPF to the Application Function (AF) providing the multicast service.

[0014] According to an embodiment, the device supporting the Session Management Function (SMF) for UE joining a multicast service may include a transceiver and a controller connected to the transceiver. The controller may be configured to: receive a join request message for the UE to join the multicast service; send a discovery request message to the Network Function (NF) Store Function (NRF) including a multicast / broadcast service (MBS) session ID associated with the multicast service; in response to the discovery request message, receive from the NRF a discovery response message including a multicast / broadcast MB-SMF ID mapped to the MBS session ID; obtain information about the MBS session indicated by the MBS session ID from the MB-SMF identified by the (MB)-SMF ID; and, based on the obtained information, notify the Radio Access Network (RAN) accessed by the UE of the information related to the MBS session.

[0015] According to an embodiment, a device supporting the Multicast / Broadcast Session Management Function (MB-SMF) for UE joining multicast services may include a transceiver and a controller connected to the transceiver. The controller may be configured to: create a multicast / broadcast service (MBS) session with an MBS session ID for providing multicast services; send a request message to the Network Function (NF) repository function (NRF) requesting the storage of an MB-SMF ID that identifies the MB-SMF used for the MBS session ID; request the Multicast / Broadcast User Plane Function (MB-UPF) to set up a tunnel for transmitting data services of the MBS session; and send the ingress address of the MBS session received from the MB-UPF to the Application Function (AF) providing the multicast service.

[0016] [Beneficial Effects]

[0017] According to various embodiments, an effective method can be provided for discovering and selecting MB-SMFs that support multicast services among network entities and smoothly obtaining information for multicast services when a UE of a 5G system joins a multicast service. Attached Figure Description

[0018] Figure 1 This is a view illustrating an example of the structure of a cellular system for MBS service according to an embodiment;

[0019] Figure 2 This is a view illustrating an example of the process for a UE to join a multicast service to initiate MBS service, according to an embodiment;

[0020] Figure 3 This is a view illustrating an example of the multicast session creation process for initiating the MBS service according to an embodiment;

[0021] Figure 4This is a view illustrating an example of a process for discovering MB-SMFs that support multicast services joined by a UE, according to an embodiment;

[0022] Figure 5 This is a view illustrating an example of the process for discovering MB-SMFs that support UE joining multicast services via BSF, according to an embodiment;

[0023] Figure 6 This is a view illustrating an example of the process for discovering MB-SMFs that support UE joining multicast services via NRF, according to an embodiment;

[0024] Figure 7 This is a view illustrating an example of the process for discovering MB-SMFs that support UEs joining multicast services via NEF or MBSF, according to an embodiment;

[0025] Figure 8 This is a block diagram illustrating the structure of a network entity according to an embodiment; and

[0026] Figure 9 This is a block diagram illustrating the structure of a UE according to an embodiment. Detailed Implementation

[0027] In the following description, the working principle of embodiments of this disclosure will be described with reference to the accompanying drawings. Detailed descriptions of known functions or configurations may be omitted when it is determined that this would obscure the subject matter of the disclosure. The terminology used herein is defined in consideration of the functions in this disclosure and may be replaced by other terms depending on the intent or practice of the user or operator. Therefore, these terms should be defined on a holistic basis within the disclosure.

[0028] The terms used herein to identify access nodes, network entities, messages, inter-network entity interfaces, and various identifying information are provided as examples for ease of description. Therefore, this disclosure is not limited to these terms, and these terms may be replaced by other terms that refer to objects having equivalent technical concepts.

[0029] For ease of description, this disclosure uses terms and names defined in 5G system standards. However, this disclosure is not limited to these terms and names and is equally applicable to systems conforming to other standards.

[0030] Figure 1 This is a view illustrating an example of the structure of a cellular system for MBS service according to an embodiment. Figure 1 The structure of, for example, a 5G system (5GS) is shown.

[0031] Reference Figure 1The cellular system may include a User Equipment (UE) 102 and one or more Network Function (NF) entities. One or more NFs may include at least one of the following: for example, an NG Radio Access Network (NG-RAN) 104 operating as a base station, an Access and Mobility Management Function (AMF) entity 112, a Multicast / Broadcast User Plane Function (MB-UPF) entity 106, a Multicast / Broadcast Session Management Function (MB-SMF) entity 114, a Policy Control Function (PCF) entity 126, a Session Management Function (SMF) entity 116, a Network Exposure Function (NEF) entity 128, a Multicast / Broadcast Service Function (MBSF) entity 108b, a Multicast / Broadcast Service Service Function (MBSTF) entity 108a, an Application Function (AF) entity 11030 that can act as a Content Provider (CP) or Application Server (AS), a Unified Data Management (UDM) entity 120, a User Plane Function (UPF) entity 118, an Authentication Server Function (AUSF) entity 122, or an NF Repository Function (NRF) entity 124. In some embodiments, SMF 116 and MB-SMF 114 can be deployed in the same location or separately. In some embodiments, UPF 118 and MB-UPF 106 can be configured in the same location or separately.

[0032] exist Figure 1 In the description, each 5G network function (NF) will be described as a "network function entity" or "network function" itself. However, those skilled in the art will understand that an NF and / or NF device can be implemented in one or more specific devices (e.g., a server), or two or more NFs performing the same operation can be implemented in a single server.

[0033] In some cases, one or more network elements (NFs) can be implemented as a single network slice. These network slices can be created for specific purposes. For example, user groups can be configured to provide the same type of service, such as maximum transfer rate, data usage, guaranteed minimum transfer rate, etc. Furthermore, network slices can be implemented for various other purposes. Further descriptions of network slices will be omitted here.

[0034] Figure 1The interfaces between nodes are shown. The Uu interface can be used between UE 102 and NG-RAN 104. The N2 interface can be used between NG-RAN 104 and AMF 112. The N3 interface can be used between NG-RAN 104 and UPF 118. The N3mb interface can be used between NG-RAN 104 and MB-UPF 106. The N4mb interface can be used between MB-UPF 106 and MB-SMF 114. The N19mb interface can be used between MB-UPF 106 and UPF 118. The N4 interface can be used between SMF 116 and UPF 118. The N6mb interface can be used between MB-UPF 106 and AF 110. The Nmb2 interface can be used between MBSF 108b and MBSTF 108a. The Nmb9 interface can be used between MB-UPF 106 and MBSTF 108a. The Mmb8 / xMB-U / MB2-U interface can be used between the AF110 and the MBSTF 108a21.

[0035] These interfaces can refer to the definitions in NR standard specifications (e.g., 3GPP TS 23.247).

[0036] In one embodiment, in order to support MBS services in 5G, a cellular system for MBS can be configured to have the following NFs and services.

[0037] AF 110 can be, for example, a V2X application server, a cellular Internet of Things (CIoT) application server, a task threshold push-to-talk (MCPTT) application, a content provider, a TV service provider, an audio service provider, or a streaming video service provider.

[0038] AF 110 can request and manage MBS service sessions and control services to provide MBS services via MBSF 108b. MBSF 108b can receive requests for MBS services from AF 110, manage MBS service sessions related to MBS services, and control MBS data services related to MBS services. MBSF 108a can receive media (or media data) related to MBS services from AF 110 (e.g., an application server (AS) or content provider (CP)). AF 110 provides MBS and processes data services based on the control of MBSF 108b, and MBSF 108a can act as a media anchor, for example, for MBS data services in 5G.

[0039] In one embodiment, an MBS system excluding MBSF 108b and MBSTF 108a can be configured in the 5G core network (5GC). When MBSF 108b and MBSTF 108a are not included, AF 110 can request MB-SMF 114 to provide MBS services directly or via NEF 128. MBS data can be provided to the 5G network (e.g., UPF 118 and NG-RAN 104) from the MBS-providing AF 110 (e.g., application server (AS) or content provider (CP)) via MB-UPF 106.

[0040] In one embodiment, AF 110 may be an application server (AS) for providing specific multicast / broadcast application services. In one embodiment, the AS may be understood as being the same as AF 110 or co-located with AF 130. AF 110 may send a request to MBSF 108b to provide MBS services to UE 102. In response to the request, MBSF 108b may control MBSTF 108a, which is a media anchor in 5GS that sends MBS data traffic to UE 102 so that MBS services associated with MBS services are transmitted to UE 102. MBS services may refer to multicast / broadcast service data and / or MBS data packets received from the AF (e.g., a content provider (CP)).

[0041] In one embodiment, MBSF 108b and MBSTF 108a can be configured to be integrated (or co-located) into a single entity or NF. In one embodiment, MBSF 108b can be configured to be integrated (or co-located) into NEF 128 or another NF (e.g., AF 110). In one embodiment, AF 110 can directly send an MBS service request for UE 102 to MB-SMF 114 without MBSF 108b and MBSTF 108a. MB-UPF 106 can receive media (or media data) related to the MBS service request from AF 110 (e.g., an application server (AS) or content provider (CP)) and forward data services to NG-RAN 104 via UPF 118.

[0042] In one embodiment, MBS sessions can be managed, and data services can be generated via MBSF 108b and MBSTF 108a. When data services are delivered to UE 102 via multicast / broadcast, MBS sessions (e.g., multicast MBS sessions or broadcast MBS sessions) can be allocated to manage the data services. MBSF 108b can be used as the control plane for managing MBS sessions, and MBSTF 108a can be used as the user plane for processing services.

[0043] In some embodiments, the “Multimedia Broadcast-Multicast Service Gateway-Control Plane (MBMS-GW-C) service” may include control functions or services for creating MBS contexts for MBS sessions, managing MBS sessions, and transmitting services (e.g., MBS services) of MBS sessions to NG-RAN 104, which is a base station, via IP multicast.

[0044] In one embodiment, the MBMS-GW-C service can be provided by an MB-SMF 114 or another NF (e.g., SMF 116 or a new NF) that manages unicast PDU sessions and has MBS session control functionality. The MB-SMF 114 can support the MBMS-GW-C service and can have the functionality of an existing SMF (e.g., SMF 116).

[0045] In some embodiments, the service of transferring MBS services received from MB-UPF 106 for MBS sessions based on MBS context (or MBS session context) to NG-RAN 20 performing multicast / broadcast based on MBMS-GW-C services via IP multicast is called Multimedia Broadcast-Multicast Service Gateway-User Plane (MBMS-GW-U) service.

[0046] In one embodiment, the MBMS-GW-U service can be provided by MB-UPF 106, or by another NF (e.g., UPF 118 or a new NF), which has the capability to process unicast PDU sessions and deliver MBS services to the appropriate NG-RAN 20 via IP multicast. MB-UPF 106 can support the MBMS-GW-U service and can have the functionality of an existing UPF (e.g., UPF 118).

[0047] The MBMS-GW-C service can use the N4mb interface as described above to control the MBMS-GW-U service.

[0048] In one embodiment, MBMS-GW-C and MBMS-GW-U may be provided by SMF 116 and UPF 118 or MB-SMF114 and MB-UPF 106, respectively, but if required, the MBS service transmission scheme may be referred to as at least one of unicast, multicast or broadcast.

[0049] In one embodiment, MBS services can be transmitted from MBMS-GW-U (e.g., by UPF118 or MB-UPF 106) to at least one NG-RAN (e.g., NG-RAN 104). For example, MBS services can be transmitted to NG-RAN20 via IP multicast. In one embodiment, a tunnel (e.g., a shared delivery tunnel or a shared N3 tunnel) between UPF 118 or MB-UPF 106 and NG-RAN 104 can be activated.

[0050] In one embodiment, to establish an M1 tunnel, the MBMS-GW-C (e.g., SMF 116 or MB-SMF 114) can send control messages to the NG-RAN 104 via the AMF 112. Figure 2 This is a view illustrating an example of the process for a UE to join a multicast service to initiate MBS service, according to an embodiment.

[0051] Reference Figure 2 In Operation 201, an AF (e.g., AF 110) may request a multicast service (e.g., MBS service) for use in a multicast service via a NEF (e.g., NEF 128) or an MBSF (e.g., MBSF 108b) (hereinafter referred to as NEF / MBSF), and may perform multicast session creation (e.g., MBS session creation) for multicast services in a cellular network (e.g., a 5G core system). In Operation 201, the NEF / MBSF may request the creation of a multicast session (e.g., an MBS session) for transmitting MBS data for the multicast service using an MB-SMF discovered and selected for the multicast service. The MB-SMF may create the multicast session (e.g., the MBS session) and assign a multicast session ID (e.g., MBS session ID) and TMGI associated with the multicast session (e.g., the MBS session).

[0052] In operation 203, the AF or NEF / MBSF performs an MBS service announcement to the UE (e.g., UE 102), thereby informing the UE of information about the multicast service (or the multicast session or MBS session associated with the multicast service), which may include at least one of, for example, MBS session ID (or multicast session ID), Temporary Mobile Group Identifier (TMGI), specific source multicast address or other information.

[0053] In operation 202, the UE can access the NG-RAN (e.g., NG-RAN 104) and perform a registration procedure, and if necessary, a PDU session establishment procedure. In operation 203, the UE can be notified of the progress of the multicast service via an MBS service advertisement. In operation 204, the UE can send an MBS session (or multicast session) join request message to the relevant network entity (e.g., via AMF to SMF) that includes multicast service related information (e.g., at least one of multicast session ID, e.g., multicast group ID, or TMGI) to join the multicast service. In one embodiment, the MBS session (or multicast session) join request message can be passed from the AMF to the SMF via a PDU session establishment request message or a PDU session modification request message or a separate SM session management non-access stratum (SM NAS) message.

[0054] If the SMF receiving the MBS session (or multicast session) join request message has information about the multicast session associated with the multicast service (e.g., identified by the multicast session ID) (e.g., MBS session context) and determines that multicast transmission to the UE is possible, then operation 208 can be performed. In operation 208, the SMF can access the UPF and request the creation of a tunnel (e.g., a multicast distribution tunnel) for transmitting multicast service traffic (e.g., data traffic or MBS traffic) of the MBS session to the NG-RAN. The NG-RAN can receive the multicast service traffic (e.g., multicast PDU) associated with the multicast service via the tunnel and forward the multicast data traffic to the UE via a point-to-point (PTP) or point-to-multipoint (PTM) bearer.

[0055] In one embodiment, if the SMF receiving the MBS session (or multicast session) join request message of operation 204 does not have information about the multicast session (e.g., MBS session context) related to the multicast service (e.g., identified by the multicast session ID), the SMF can perform operation 205 to obtain information about the multicast session. Operation 205 may include operations 206 and 207. In operation 206, the SMF may send a request to the User Data Repository (UDR) including information identifying the multicast session (e.g., at least one of TMGI, multicast session ID (e.g., MBS session ID), or multicast group ID) to discover the MB-SMF serving the multicast session and receive a response from the UDR including the MB-SMF ID identifying the MB-SMF serving the multicast session. In operation 207, the SMF may request the MB-SMF corresponding to the obtained MB-SMF ID to receive information about the multicast service and multicast session (e.g., QoS information and endpoint information for the DL tunnel). Then, SMF can proceed to operation 208.

[0056] In operation 208, the SMF can access the UPF and request the creation of a tunnel to send multicast service services (e.g., MBS services) to the NG-RAN. The NG-RAN can receive multicast service services related to the multicast service via the tunnel and forward the multicast service services to the UE via PTP or PTM bearer.

[0057] Although operation 205 describes the SMF obtaining information about the appropriate MB-SMF from the UDR, the SMF may obtain information about the appropriate MB-SMF in other ways due to security considerations in the embodiments described below.

[0058] Figure 3 This is a view illustrating an example of a process for configuring a multicast session according to an embodiment. The operations shown in the embodiment may correspond to... Figure 2 Operation 201. Operations for configuring multicast services in a cellular network to initiate MBS services are described. In various embodiments, at least some of the operations described below may be omitted, modified, or reordered.

[0059] Reference Figure 3 In operation 301, the AF (e.g., AF 110) may send a request message to the NEF or MBSF (hereinafter referred to as NEF / MBSF) for multicast services, requesting a multicast session for the multicast service. The request message may include information about the multicast service (e.g., at least one of a multicast group ID that identifies the multicast group using the multicast service, a multicast session ID (e.g., an MBS session ID), or a TMGI), and may also include a QoS request for the multicast service if necessary.

[0060] In operation 302, the NEF / MBSF receiving the request message can continue service authorization through an authorization check regarding whether to serve the multicast session, and if multicast sessions are allowed, selects the MB-SMF to manage the multicast session. In operation 303, the NEF / MBSF can send information related to the selected MB-SMF (e.g., at least one of the MB-SMF ID or multicast group ID) to the UDR for storage. In one embodiment, the information stored in the UDR may include at least one of the MB-SMF ID or MB-SMF address, corresponding to at least one of the following: a multicast group ID used to indicate the multicast group using multicast services, a multicast session ID (e.g., MBS session ID), or a TMGI.

[0061] In operation 304, the NEF / MBSF may send a session creation request message (e.g., a multicast distribution session request message or an MBS session creation request message) to the selected MB-SMF to request a transport session (e.g., a multicast session or an MBS session) associated with the multicast service. In one embodiment, the request message may include at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI.

[0062] In operation 305, the MB-SMF may, in response to a request message, send an MBS policy association request message to the PCF (e.g., PCF 126) serving the multicast group ID (or multicast session ID (e.g., MBS session ID) or TMGI). In operation 306, the PCF may register binding information with the BSF for MBS session binding. In one embodiment, the binding information may include a PCF ID and a multicast group ID (or multicast session ID (e.g., MBS session ID) or TMGI) for identifying the PCF. If necessary, in operation 307, the PCF may obtain information about at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI from the UDR via a data management (DM) query. In operation 308, the PCF may determine a policy for the multicast session identified by at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI, and transmit information about the determined policy to the MB-SMF via an MBS policy association response message.

[0063] In operations 309 and 310, the MB-SMF may request the MB-UPF to establish a tunnel via signaling (e.g., session request messages and session response messages) for transmitting MBS services for multicast sessions (e.g., MBS sessions).

[0064] In one embodiment, if the MBSF is not in use, the ingress address (e.g., IP address and port number) can be transmitted to the MB-SMF via the session response message of operation 310. In one embodiment, the MB-SMF can directly transmit information about the ingress address to the AF. In one embodiment, in operation 311, the MB-SMF can send information about the ingress address obtained through the session response message to the session creation request of operation 304 (e.g., a multicast distribution session response message or an MBS session creation response message), and in operation 312, information about the ingress address can be transmitted from the NEF / MBSF to the AF via a multicast session response message.

[0065] In one embodiment, when using MBSF, in operation 310, the tunnel endpoint can be transmitted to MB-SMF via a session response message. In operation 311, MB-SMF can transmit information about the tunnel endpoint to MBSF, and in operation 312, MBSF can transmit information about the ingress address assigned by MBSF (or MBSTF) to AF. AF can use the transmitted ingress address to send multicast service data.

[0066] Figure 4 This is a view illustrating an example of the process for discovering MB-SMFs that support UE joining a multicast service, according to an embodiment. In various embodiments, at least some of the operations described below may be omitted, modified, or reordered.

[0067] Reference Figure 4 In operation 401, the AF (e.g., AF 110) may send a request message to the NEF or MBSF (hereinafter referred to as NEF / MBSF) for a multicast session (e.g., an MBS session) requesting the multicast service. The request message may include information about the multicast service (e.g., at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI that identifies the multicast group using the multicast service), and may also include a QoS request for the multicast service if necessary.

[0068] In operation 402, the NEF / MBSF receiving the request message can continue service authorization through an authorization check regarding whether to serve the multicast session, and if multicast sessions are allowed, selects the MB-SMF to manage the multicast session. In operation 403, the NEF / MBSF can send information related to the selected MB-SMF (e.g., MB-SMF ID) and information related to the multicast session (e.g., at least one of multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI) to the UDR to be stored. In one embodiment, the information stored in the UDR may include at least one of the MB-SMF ID or MB-SMF address, corresponding to at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI used to indicate the multicast group using multicast services.

[0069] In operation 404, the NEF / MBSF may send a session creation request message (e.g., a multicast session multicast distribution session message or an MBS session creation request message) to the selected MB-SMF to request a transport session (e.g., a multicast session or an MBS session) for data transmission related to the multicast service. In one embodiment, the request message may include at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI.

[0070] In operation 405, the MB-SMF may, in response to a request message, send an MBS policy association request message to the PCF (e.g., PCF 126) serving the multicast group ID (or multicast session ID or TMGI). In operation 406, the PCF may register binding information with the BSF for MBS session binding. In one embodiment, the binding information may include a PCF ID and a multicast group ID (or multicast session ID (e.g., MBS session ID) or TMGI) for identifying the PCF. In one embodiment, the binding information may also include an MB-SMF ID (or MB-SMF address). If necessary, in operation 407, the PCF may obtain information about the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI from the UDR via a DM query.

[0071] In operation 408, the PCF may determine a policy for a multicast session identified by at least one of the obtained multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI, and transmit information about the determined policy to the MB-SMF via an MBS policy association response message.

[0072] In operations 409 and 410, the MB-SMF can request the MB-UPF to establish a tunnel via signaling (e.g., session request messages and session response messages) for transmitting MBS services for multicast sessions (e.g., MBS sessions). In one embodiment, in operation 411, the MB-SMF can send the information about the ingress address obtained through the session response message of operation 410 to the NEF / MBSF via a response message to the session creation request of operation 404 (e.g., a multicast distribution session response message or an MBS session creation response message), and in operation 412, the information about the ingress address can be transmitted from the NEF / MBSF to the AF via a multicast session response message. In one embodiment, the MB-SMF can directly transmit the information about the ingress address to the AF.

[0073] In one embodiment, an MBS session join request message from a UE (e.g., UE 102) can be as follows: Figure 2 Operation 204 is received by the SMF. In one embodiment, operation 205 for discovering an MB-SMF serving a multicast session (e.g., an MBS session) requested by an MBS session join request message (e.g., identified by the MBMS session ID included in the MBS session join request message) may include operations 413 and 414, but not operation 206.

[0074] In one embodiment, in operation 413, the SMF may send a discovery request message (e.g., an Nbsf_Management_Discovery request message) to the BSF. The discovery request message may include information about at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI associated with the requested multicast session. In operation 414, in response to the discovery request message, the BSF may send a discovery response message (e.g., an Nbsf_Management_Discovery response message) to the SMF that includes information about the MB-SMF (e.g., the MB-SMF ID), the information about the MB-SMF being mapped to at least one of the multicast group ID, MBS session ID, or TMGI registered in operation 406. In one embodiment, the SMF may perform operations 207 and 208 based on the MB-SMF ID.

[0075] Figure 5 This is a view illustrating an example of the process for discovering MB-SMFs that support UE joining multicast services via BSF, according to an embodiment. In various embodiments, at least some of the operations described below may be omitted, modified, or reordered.

[0076] Reference Figure 5 In operation 501, the AF (e.g., AF 110) may send a request message to the NEF or MBSF (hereinafter referred to as NEF / MBSF) for a multicast session (e.g., an MBS session) requesting the multicast service. The request message may include information about the multicast service (e.g., at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI that identifies the multicast group using the multicast service), and may also include a QoS request for the multicast service if necessary.

[0077] In operation 502, the NEF / MBSF receiving the request message can continue service authorization through an authorization check regarding whether to serve the multicast session, and if multicast sessions are allowed, selects the MB-SMF to manage the multicast session. In operation 503, the NEF / MBSF can send information related to the selected MB-SMF (e.g., MB-SMF ID) and information related to the multicast session (e.g., at least one of multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI) to the UDR to be stored. In one embodiment, the information stored in the UDR may include at least one of the MB-SMF ID or MB-SMF address, corresponding to at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI used to indicate the multicast group when using multicast services.

[0078] In operation 504, the NEF / MBSF may send a session creation request message (e.g., a multicast distribution session message or an MBS session creation request message) to the selected MB-SMF to request a transport session (e.g., a multicast session or an MBS session) for data transmission related to the multicast service. In one embodiment, the request message may include at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI.

[0079] In operation 505, the MB-SMF may, in response to a request message, send an MBS policy association request message to the PCF (e.g., PCF 126) serving the multicast group ID (or multicast session ID or TMGI). In operation 506, the PCF may register binding information with the BSF for MBS session binding. In one embodiment, the binding information may include a PCF ID and a multicast group ID (or multicast session ID (e.g., MBS session ID) or TMGI) for identifying the PCF. If necessary, in operation 507, the PCF may obtain information about the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI from the UDR via a DM query. The information obtained from the UDR may include information about the MB-SMF mapped to at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI (e.g., MB-SMF ID or MB-SMF address).

[0080] In operation 508, the PCF can determine the policy of a multicast session identified by at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI obtained from the UDR, and transmit information about the determined policy to the MB-SMF via an MBS policy association response message.

[0081] In operations 509 and 510, the MB-SMF can request the MB-UPF to establish a tunnel for transmitting MBS services for a multicast session (e.g., an MBS session) via signaling (e.g., a session request message and a session response message). In operation 511, the MB-SMF can send the information about the ingress address obtained through the session response message in operation 510 to the NEF / MBSF via a response message to the session creation request in operation 504 (e.g., a multicast distribution session response message or an MBS session creation response message), and in operation 512, the information about the ingress address can be transmitted from the NEF / MBSF to the AF via a multicast session response message. In one embodiment, the MB-SMF can directly transmit the information about the ingress address to the AF.

[0082] In one embodiment, an MBS session join request message from a UE (e.g., UE 102) can be as follows: Figure 2 Operation 204 is received by the SMF. In one embodiment, operation 205 for discovering an MB-SMF serving a multicast session (e.g., an MBS session) requested by an MBS session join request message (e.g., identified by the MBMS session ID included in the MBS session join request message) may include operations 513 to 517 (and operation 507a), but not operation 206.

[0083] In one embodiment, in operation 513, the SMF may send a discovery request message (e.g., an Nbsf_Management_Discovery request message) to the BSF. The discovery request message may include information about at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI associated with the requested multicast session. In operation 514, in response to the discovery request message, the BSF may send a discovery response message (e.g., an Nbsf_Management_Discovery response message) to the SMF, which includes PCF information (e.g., a PCF ID) mapped to at least one of the multicast group ID, MBS session ID, or TMGI registered in operation 506.

[0084] In operation 515, the SMF may send a discovery request message (e.g., an Npcf_NFDiscovery request message) to the PCF identified by the PCF ID. The discovery request message may include information about at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI associated with the multicast session to be requested.

[0085] In one embodiment, if the PCF does not have information about at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI included in the discovery request message, then in operation 507a, the PCF may send a message for a DM query (e.g., Nudr_DM query) to the UDR and obtain information from the UDR about the MB-SMF serving at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI (e.g., MB-SMF ID or MB-SMF address). If the PCF has information about at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI included in the discovery request message, then operation 507a may be omitted. In operation 517, the PCF may send a discovery response message (e.g., Npcf_NFDiscovery response message) to the SMF that includes the obtained MB-SMF information (e.g., MB-SMF ID or MB-SMF address). In one embodiment, the SMF may perform operations 207 and 208 based on the MB-SMF ID.

[0086] Figure 6 This is a view illustrating an example of a process for discovering an MB-SMF that supports a multicast service joined by a UE via an NRF, according to an embodiment. In various embodiments, at least some of the operations described below may be omitted, modified, or reordered.

[0087] Reference Figure 6 In operation 601, the AF (e.g., AF 110) may send a request message to the NEF or MBSF (hereinafter referred to as NEF / MBSF) for a multicast session (e.g., an MBS session) requesting the multicast service. The request message may include information about the multicast service (e.g., at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI that identifies the multicast group using the multicast service), and may also include a QoS request for the multicast service if necessary.

[0088] In operation 602, the NEF / MBSF receiving the request message can continue service authorization through an authorization check regarding whether to serve the multicast session, and if the multicast session is allowed, selects an MB-SMF (e.g., MB-SMF 114) to manage the multicast session. In operation 603, the NEF / MBSF can send information related to the selected MB-SMF (e.g., MB-SMF ID) and information related to the multicast session (e.g., at least one of a multicast group ID, a multicast session ID (e.g., MBS session ID), or a TMGI) to the UDR to be stored. In one embodiment, the information stored in the UDR may include at least one of the MB-SMF ID or the address of the MB-SMF, corresponding to at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI used to indicate the multicast group using multicast services. In one embodiment, operation 603 may be omitted.

[0089] In operation 604, the NEF / MBSF may send a session creation request message (e.g., a multicast distribution session message or an MBS session creation request message) to the selected MB-SMF to request a transport session (e.g., a multicast session or an MBS session) for data transmission related to the multicast service. In one embodiment, the request message may include at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI.

[0090] In operation 605, the MB-SMF may, in response to a request message, send an MBS policy association request message to the PCF (e.g., PCF 126) serving the multicast service corresponding to the multicast group ID (or multicast session ID (e.g., MBS session ID) or TMGI). In operation 606, the PCF may register binding information with the BSF for MBS session binding. In one embodiment, the binding information may include a PCF ID and a multicast group ID (or multicast session ID (e.g., MBS session ID) or TMGI) for identifying the PCF. If necessary, in operation 607, the PCF may obtain information about the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI from the UDR via a DM query.

[0091] In operation 608, the PCF can determine the policy of a multicast session identified by at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI obtained from the UDR, and transmit information about the determined policy to the MB-SMF via an MBS policy association response message.

[0092] In operations 609 and 610, the MB-SMF can request the MB-UPF (e.g., MB-UPF 106) to establish a tunnel for transmitting MBS services for a multicast session (e.g., an MBS session) via signaling (e.g., N4mb session request messages and N4mb session response messages). In operation 611, the MB-SMF can send information about the ingress address obtained through the N4mb session response message to the NEF / MBSF via a response message to the session creation request of operation 604 (e.g., a multicast distribution session response message or an MBS session creation response message), and in operation 612, information about the ingress address can be transmitted from the NEF / MBSF to the AF via the MBS session creation response message. In one embodiment, the MB-SMF can directly transmit information about the ingress address to the AF.

[0093] In one embodiment, if it is determined that an MBS session needs to be served (e.g., after receiving the message of operation 608 or after completing operation 610), the MB-SMF may perform operation 613. In operation 613, the MB-SMF may register with the NRF (e.g., NRF 124) information identifying the MB-SMF (e.g., MB-SMF ID or MB-SMF address) for at least one of the following: multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI.

[0094] In one embodiment, the Nnrf_NFManagement_NFRegister message or the Nnrf_NFManagement_NFUpdate message can be used to register an MB-SMF with the NRF. In one embodiment, the Nnrf_NFManagement_NFRegister message can be used to register the MB-SMF's NF profile with the NRF for the first time. The NF profile may include information identifying the MB-SMF (e.g., MB-SMF ID or MB-SMF address) for information related to a specific multicast session (e.g., a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI). In one embodiment, the Nnrf_NFmanagement_NFUpdate message can be used to transmit an updated NF profile of the MB-SMF to the NRF.

[0095] In one embodiment, the information stored in the NRF may further include expiration times for services used for multicast group IDs, multicast session IDs (e.g., MBS session IDs), or TMGI. The NRF can continuously identify expiration times and can prevent incorrect information from being provided to the SMF by deleting the relevant information after the expiration time.

[0096] In one embodiment, an MBS session join request message from a UE (e.g., UE 102) can be received by an SMF (e.g., SMF 116), such as... Figure 2 Operation 204 is shown. In one embodiment, operation 205 for discovering an MB-SMF serving a multicast session (e.g., an MBS session) requested by an MBS session join request message (e.g., identified by an MBS session ID included in the MBS session join request message) may include operations 614 and 615, but not operation 206.

[0097] In one embodiment, in operation 614, the SMF may send a discovery request message (e.g., an Nnrf_NFDiscovery request message) to the NRF. The discovery request message may include information about at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI associated with the requested multicast session. In operation 615, in response to the discovery request message, the NRF may send a discovery response message (e.g., an Nnrf_NFDiscovery response message) to the SMF that includes information about the MB-SMF (e.g., the SMF ID), the information about the MB-SMF being mapped to at least one of the multicast group ID, MBS session ID, or TMGI registered in operation 613. In one embodiment, the SMF may perform operations 207 and 208 based on the obtained MB-SMF ID.

[0098] In one embodiment, the BSF or another NF may operate in place of the NRF in operations 613, 614 and 615.

[0099] Figure 7 This is a view illustrating an example of a process for discovering an MB-SMF that supports a multicast service joined by a UE via NEF or MBSF, according to an embodiment. In various embodiments, at least some of the operations described below may be omitted, modified, or reordered.

[0100] Reference Figure 7 In operation 701, the AF (e.g., AF 110) may send a request message to the NEF or MBSF (hereinafter referred to as NEF / MBSF) for a multicast session (e.g., an MBS session) requesting the multicast service. The request message may include information about the multicast service (e.g., at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI that identifies the multicast group using the multicast service), and may also include a QoS request for the multicast service if necessary.

[0101] In operation 702, the NEF / MBSF receiving the request message can continue service authorization through an authorization check regarding whether to serve the multicast session, and if multicast sessions are allowed, selects the MB-SMF to manage the multicast session. In operation 703, the NEF / MBSF can send information related to the selected MB-SMF (e.g., MB-SMF ID) and information related to the multicast session (e.g., at least one of multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI) to the UDR to be stored. In one embodiment, the information stored in the UDR may include at least one of the MB-SMF ID or MB-SMF address, corresponding to at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI used to indicate the multicast group when using multicast service.

[0102] In operation 704, the NEF / MBSF may send a session creation request message (e.g., a multicast distribution session message or an MBS session creation request message) to the selected MB-SMF to request a transport session (e.g., a multicast session or an MBS session) for data transmission related to the multicast service. In one embodiment, the multicast distribution session request message may include at least one of a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI.

[0103] In operation 705, the MB-SMF may send an MBS policy association request message to the PCF (e.g., PCF 126) serving the multicast group ID (or multicast session ID or TMGI) in response to a multicast distribution session request message. In operation 706, the PCF may register binding information with the BSF for MBS session binding. In one embodiment, the binding information may include a PCF ID and a multicast group ID (or multicast session ID (e.g., MBS session ID) or TMGI) for identifying the PCF. If necessary, in operation 707, the PCF may obtain information about the multicast group ID, multicast session (e.g., MBS session ID), or TMGI from the UDR via a DM query.

[0104] In operation 708, the PCF can determine the policy of a multicast session identified by at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI obtained from the UDR, and transmit information about the determined policy to the MB-SMF via an MBS policy association response message.

[0105] In operations 709 and 710, the MB-SMF can request the MB-UPF to establish a tunnel via signaling (e.g., session request messages and session response messages) for transmitting MBS services for multicast sessions (e.g., MBS sessions). In operation 711, the MB-SMF can send the information about the ingress address obtained through the session response message in operation 710 to the NEF / MBSF via a response message to the session creation request in operation 704 (e.g., a multicast distribution session response message or an MBS session creation response message), and in operation 712, the information about the ingress address can be transmitted from the NEF / MBSF to the AF via a multicast session response message.

[0106] In one embodiment, an MBS session join request message from a UE (e.g., UE 102) can be as follows: Figure 2 Operation 204 is received by the SMF. In one embodiment, operation 205 for discovering an MB-SMF serving a multicast session (e.g., an MBS session) requested by an MBS session join request message (e.g., identified by the MBMS session ID included in the MBS session join request message) may include operation 713 of operation 716, but not operation 206.

[0107] In one embodiment, in operation 713, the SMF may send a discovery request message (e.g., an Nnef_NFDiscovery request message) to the NEF. The discovery request message may include information about at least one of the following: a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI associated with the requested multicast session. In operation 715, the NEF receiving the discovery request message may obtain, for example, information about the MB-SMF mapped to the information stored in operation 702 (e.g., an MB-SMF ID), such as at least one of the following: a multicast group ID, a multicast session ID (e.g., an MBS session ID), or a TMGI.

[0108] In one embodiment, if the NEF does not have an MB-SMF ID corresponding to a multicast session, operation 714 can be performed. In operation 714, the NEF may send a DM query message (e.g., Nudr_DM query) to the UDR to obtain information (e.g., MB-SMF ID or MB-SMF address) about the MB-SMF serving the multicast session corresponding to at least one of the multicast group ID, multicast session ID (e.g., MBS session ID), or TMGI.

[0109] In operation 716, the NEF may include the acquired MB-SMF information (e.g., MB-SMF ID or MB-SMF address) in a discovery response message (e.g., an Nnrf_NFDiscovery response message) and send it to the SMF. The discovery response message may include at least one of a multicast group ID, a multicast session ID (e.g., MBS session ID), or a TMGI received via the discovery request message and the MB-SMF information (e.g., MB-SMF ID or MB-SMF address). In one embodiment, the SMF may perform operations 207 and 208 based on the acquired MB-SMF ID.

[0110] In one embodiment, MBSF or another NF may replace NEF operation in operations 702, 713, 714, 715 and 716.

[0111] Figure 8 This is a block diagram illustrating the structure of a network entity according to an embodiment. In one embodiment, reference is made to... Figures 2 to 7 At least one of the described SMF 116, MB-SMF 114, NRF 124, or other NF can be implemented as Figure 8 The network entity.

[0112] Reference Figure 8 The network entity (e.g., SMF 116, MB-SMF 114, or NRF 124) may include a transceiver 810, a memory 820, and a controller 830. The transceiver 810, controller 830, and memory 820 can operate according to at least one of the communication processes described above. However, the components of the network entity are not limited thereto. For example, the network entity may include more or fewer components than those described above. Furthermore, at least one of the transceiver 810, controller 830, and memory 820 may be implemented as a single chip. For example, the controller 830 may include one or more processors.

[0113] Transceiver 810 collectively refers to a receiver and transmitter of a network entity, and can send / receive signals to / from a UE or another network entity. In one embodiment, transceiver 810 may include an RF transmitter for up-converting and amplifying transmitted signals, and an RF receiver for low-noise amplification of received signals and down-converting the frequency of received signals. In one embodiment, transceiver 810 may include software and / or hardware components supporting the aforementioned interface (e.g., N4 interface). However, this is merely an example of transceiver 810, and the components of transceiver 810 are not limited to those described in this disclosure. Transceiver 810 can output signals, messages, and / or data received from a UE and / or other network entities to controller 830, and can forward signals, messages, and / or data output from controller 830 to UE and / or other network entities.

[0114] Memory 820 can store programs and data required for the operation of network entities. Memory 820 can store control information or data included in signals received by network entities. Memory 820 can be a storage medium (e.g., read-only memory (ROM), random access memory (RAM), hard disk, optical disc read-only memory (CD-ROM), or digital video disc (DVD)) or a combination of storage media. Memory 820 can be embedded in processor 830, rather than being provided separately.

[0115] Controller 830 may include software and / or hardware components for controlling a series of operations, enabling the network entity to operate according to at least one of the above embodiments. For example, controller 830 may receive signals, messages, and / or data from the UE or other network entity via transceiver 810, and process the received signals, messages, and / or data. For example, controller 830 may transmit processed signals, messages, and / or data to the UE or other network entity via transceiver 910. Multiple controllers 830 may be provided. Controller 830 may control components of the network entity by executing a program stored in memory 820.

[0116] Figure 9 This is a block diagram illustrating the structure of a UE according to an embodiment.

[0117] Reference Figure 9The UE (e.g., UE 102) may include a transceiver 910, a memory 920, and a controller 930. The transceiver 910, controller 930, and memory 920 of the UE can operate according to at least one of the communication processes described above. However, the components of the UE are not limited thereto. For example, the UE may include more or fewer components than those described above. Furthermore, at least one of the transceiver 910, controller 930, and memory 920 may be implemented as a single chip. The controller 930 may include one or more processors.

[0118] Transceiver 910 collectively refers to both the receiver and transmitter of a UE, and can transmit / receive signals to / from at least one network entity (e.g., NG-RAN 104). For this purpose, transceiver 910 may include an RF transmitter for up-converting and amplifying the transmitted signals, and an RF receiver for low-noise amplification of the received signals and down-converting the frequency of the received signals. However, this is merely an example of transceiver 910, and the components of transceiver 910 are not limited to those described in this disclosure.

[0119] Memory 920 can store programs and data required for the operation of the UE. Memory 920 can store control information or data included in signals received by the UE. Memory 1020 may include storage media (e.g., ROM, RAM, hard disk, CD-ROM, or DVD) or a combination of storage media. Memory 920 may be embedded in processor 930, rather than being provided separately.

[0120] Controller 930 may include software and / or hardware components for controlling a series of operations, enabling the UE to operate according to the embodiments described above. For example, controller 930 may receive signals, messages, and / or data via transceiver 910 and process the received signals, messages, and / or data. For example, controller 930 may transmit processed signals, messages, and / or data to a network entity via transceiver 910. Multiple controllers 930 may be provided. Controller 930 may control components of the UE by executing a program stored in memory 920.

[0121] According to an embodiment, the method for UE 102 to join a multicast service performed by Session Management Function (SMF) 116 may include: receiving (204) an join request message for UE to join a multicast service, sending (614) a discovery request message including a multicast / broadcast service (MBS) session ID associated with the multicast service to a Network Function (NF) Storehouse Function (NRF), receiving (615) a discovery response message including a multicast / broadcast (MB)-SMF ID mapped to the MBS session ID from the NRF in response to the discovery request message, obtaining (207) information about the MBS session indicated by the MBS session ID from the MB-SMF identified by the MB-SMF ID, and notifying (208) information related to the MBS session to the Radio Access Network (RAN) accessed by the UE based on the obtained information.

[0122] In one embodiment, the join request message may be received by the SMF from the Access and Mobility Management Function (AMF) that manages the UE via a Protocol Data Unit (PDU) Session Establishment Request Message, a PDU Session Modification Request Message, or a Session Management Non-Access Stratum (SM NAS) Message.

[0123] In one embodiment, the method may further include: in response to receiving a join request message, identifying whether an MBS session context associated with the multicast service exists in the SMF; and when the MBS session context is identified as not existing, determining to send a discovery request message.

[0124] In one embodiment, data services for an MBS session can be transmitted from the RAN to the UE via a point-to-point (PTP) or point-to-multipoint (PTM) bearer.

[0125] In one embodiment, the notification may include access to a UE-related User Plane Function (UPF) to request the creation of a tunnel for sending data services for MBS sessions to the RAN.

[0126] According to various embodiments, the method for UE 102 to join a multicast service, performed by the multicast / broadcast session management function (MB-SMF) 114, may include: creating (201) an MBS session with an MBS session ID for providing the multicast service; sending (613) a request message to the network function (NF) storehouse function (NRF) requesting the storehouse to identify the MB-SMF ID for the MBS session ID; requesting (309 and 310) the multicast / broadcast user plane function (MB-UPF) to set up a tunnel for transmitting data services of the MBS session; and sending (311 and 312) the ingress address of the MBS session received from the MB-UPF to the application function (AF) providing the multicast service.

[0127] In one embodiment, the method may further include: receiving (304) a request message from a Network Exposure Function (NEF) or Multicast / Broadcast Service Function (MBSF) requesting the creation of an MBS session, and sending (311) a response message including an ingress address to the NEF / MBSF.

[0128] In one embodiment, the request message may include an MBS session ID.

[0129] In one embodiment, the method may further include: sending (305) a policy association request message including an MBS session ID to a policy control function (PCF), and receiving (308) a policy association response message including information about policies related to the MBS session from the PCF.

[0130] In one embodiment, the request message may be sent to the NRF after receiving a policy-associated response message from the PCF or after receiving a session response message from the MB-UPF.

[0131] According to a preferred embodiment, the device supporting the Session Management Function (SMF) for UE joining a multicast service may include a transceiver 910 and a controller 930 connected to the transceiver. The controller may be configured to receive a join request message for UE joining a multicast service, send a discovery request message to the Network Function (NF) Storehouse Function (NRF) including a multicast / broadcast service (MBS) session ID associated with the multicast service, receive a discovery response message from the NRF in response to the discovery request message including a multicast / broadcast (MB)-SMF ID mapped to the MBS session ID, obtain information about the MBS session indicated by the MBS session ID from the MB-SMF identified by the MB-SMF ID, and notify the Radio Access Network (RAN) accessed by the UE of information related to the MBS session based on the obtained information.

[0132] In one embodiment, the join request message may be received by the SMF from the Access and Mobility Management Function (AMF) that manages the UE via a Protocol Data Unit (PDU) Session Establishment Request Message, a PDU Session Modification Request Message, or a Session Management Non-Access Stratum (SM NAS) Message.

[0133] In one embodiment, the controller may be configured to, in response to the receipt of a join request message, identify whether an MBS session context associated with the multicast service exists in the SMF, and determine to send a discovery request message when the MBS session context is identified as not existing.

[0134] According to various embodiments, the device supporting the Multicast / Broadcast Session Management Function (MB-SMF) for UE joining multicast services may include a transceiver 910 and a controller 930 connected to the transceiver. The controller may be configured to create a multicast / broadcast service (MBS) session with an MBS session ID for providing the multicast service, send a request message to the Network Function (NF) store function (NRF) requesting the store of an MB-SMF ID identifying the MB-SMF for the MBS session ID, request the Multicast / Broadcast User Plane Function (MB-UPF) to set up a tunnel for transmitting data services of the MBS session, and send the ingress address of the MBS session received from the MB-UPF to the Application Function (AF) providing the multicast service.

[0135] In one embodiment, the controller may be configured to receive request messages to request the creation of an MBS session from a Network Exposure Function (NEF) or Multicast / Broadcast Service Function (MBSF), and send a response message including the ingress address to the NEF / MBSF.

[0136] The methods described in the embodiments of this disclosure or in the claims can be implemented in hardware, software, or a combination of hardware and software.

[0137] When implemented in software, a computer-readable storage medium may be provided to store one or more programs (software modules). The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions that enable the electronic device to perform methods according to embodiments described in this disclosure or the claims.

[0138] The program (software module or software) can be stored in random access memory, non-volatile memory (including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), disk storage devices, optical disc ROM, digital versatile disc (DVD), or other types of optical storage devices, or magnetic tape cassettes. Alternatively, the program can be stored in memory consisting of a combination of all or part of the program. Each of the components of the memory may include multiple memories.

[0139] The program can be stored in an attachable storage device accessible via a communication network, such as the Internet, intranet, local area network (LAN), wide area network (WAN), or storage area network (SAN), or a combination thereof. The storage device can be connected to a device executing embodiments of this disclosure via an external port. A separate storage device on the communication network can be connected to a device executing embodiments of this disclosure.

[0140] In the embodiments described above, components included in this disclosure are represented in either a singular or plural form according to the proposed embodiments. However, the singular or plural form is chosen as sufficient for the context presented for ease of description, and this disclosure is not limited to singular or plural components. As used herein, the singular forms “a,” “an,” and “described” are intended to also include the plural forms, unless the context clearly indicates otherwise. Furthermore, it should be noted that in some alternative embodiments, the functions mentioned in a block may occur in a different order. For example, two blocks shown consecutively may be executed substantially simultaneously or in reverse order, depending on their respective functions.

[0141] Although specific embodiments of the present disclosure have been described above, various modifications can be made thereto without departing from the scope of the disclosure. Therefore, the scope of the invention should not be limited to the above embodiments, but should be defined by the appended claims and their equivalents.

Claims

1. A method for a UE to join a multicast service, performed by a Session Management Function (SMF), the method comprising: Receive a join request message for the UE to join the multicast service, wherein the join request message includes a multicast / broadcast service MBS session ID associated with the multicast service; If the SMF does not have context information related to the MBS session ID, a discovery request message including the MBS session ID is sent to the Network Function NF Storehouse Function (NRF). In response to the discovery request message, a discovery response message including a multicast / broadcast MB-SMF ID mapped to the MBS session ID is received from the NRF; Retrieve information about the MBS session indicated by the MBS session ID from the MB-SMF identified by the MB-SMF ID; and Based on the acquired information, information related to the MBS session is sent to notify the radio access network (RAN) accessed by the UE.

2. The method according to claim 1, wherein, The join request message is received by the SMF from the Access and Mobility Management Function (AMF) that manages the UE via a Protocol Data Unit (PDU) Session Establishment Request Message, a PDU Session Modification Request Message, or a Session Management Non-Access Stratum (SM NAS) Message.

3. The method according to claim 1, further comprising: In response to receiving the join request message, identify whether the MBS session context related to the multicast service exists in the SMF; as well as When the MBS session context is identified as non-existent, it is determined that the discovery request message should be sent.

4. The method according to claim 1, wherein, The data services of the MBS session are transmitted from the RAN to the UE via point-to-point PTP or point-to-multipoint PTM bearers.

5. The method according to claim 1, wherein, The notification includes access to the User Plane Function (UPF) associated with the UE to request the creation of a tunnel for sending data services of the MBS session to the RAN.

6. A method for a UE to join a multicast service, performed by a multicast / broadcast session management function (MB-SMF), the method comprising: Create an MBS session with an MBS session ID for providing multicast services; Send a request message to the Network Function NF Storage Function NRF, the request message requesting the storage to identify the MB-SMF ID of the MB-SMF used for the MBS session ID; Request the Multicast / Broadcast User Plane Function (MB-UPF) to set up a tunnel for transmitting data services of the MBS session; as well as Send the entry address of the MBS session received from the MB-UPF to the application function AF that provides the multicast service.

7. The method according to claim 6, further comprising: Receive a request message from the Network Exposure Function (NEF) or Multicast / Broadcast Service Function (MBSF) to create the MBS session; as well as Send a response message including the entry address to the NEF / MBSF.

8. The method according to claim 7, wherein, The request message includes the MBS session ID.

9. The method according to claim 6, further comprising: Send a policy association request message including the MBS session ID to the policy control function (PCF); as well as Receive a policy association response message from the PCF, which includes information about policies related to the MBS session.

10. The method according to claim 9, wherein, The request message is sent to the NRF after the policy association response message is received from the PCF or after the session response message is received from the MB-UPF.

11. A device that supports a Session Management Function (SMF) for UEs joining multicast services, the device comprising: transceiver; as well as A controller, connected to the transceiver, wherein the controller is configured to: Receive a join request message for the UE to join the multicast service, wherein the join request message includes a multicast / broadcast service MBS session ID associated with the multicast service; If the SMF does not have context information related to the MBS session ID, a discovery request message including the MBS session ID is sent to the Network Function NF Storehouse Function (NRF). In response to the discovery request message, a discovery response message including a multicast / broadcast MB-SMF ID mapped to the MBS session ID is received from the NRF; Retrieve information about the MBS session indicated by the MBS session ID from the MB-SMF identified by the MB-SMF ID; and Based on the acquired information, information related to the MBS session is sent to notify the radio access network (RAN) accessed by the UE.

12. The device according to claim 11, wherein, The join request message is received by the SMF from the Access and Mobility Management Function (AMF) that manages the UE via a Protocol Data Unit (PDU) Session Establishment Request Message, a PDU Session Modification Request Message, or a Session Management Non-Access Stratum (SM NAS) Message.

13. The device according to claim 11, wherein, The controller is configured to: In response to receiving the join request message, identify whether the MBS session context related to the multicast service exists in the SMF; as well as When the MBS session context is identified as non-existent, it is determined that the discovery request message should be sent.

14. A device supporting a multicast / broadcast session management function (MB-SMF) for UEs to join multicast services, the device comprising: transceiver; as well as A controller, connected to the transceiver, wherein the controller is configured to: Create a multicast / broadcast service MBS session with an MBS session ID for providing multicast services; Send a request message to the Network Function NF Storage Function NRF, the request message requesting the storage to identify the MB-SMF ID of the MB-SMF used for the MBS session ID; Request the Multicast / Broadcast User Plane Function (MB-UPF) to set up a tunnel for transmitting data services of the MBS session; and Send the entry address of the MBS session received from the MB-UPF to the application function AF that provides the multicast service.

15. The device according to claim 14, wherein, The controller is configured to: Receive a request message from the Network Exposure Function (NEF) or Multicast / Broadcast Service Function (MBSF) to create the MBS session; and Send a response message including the entry address to the NEF / MBSF.

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