WO2023143097A1

WO2023143097A1 - Method and apparatus for multicast/broadcast service

Info

Publication number: WO2023143097A1
Application number: PCT/CN2023/071897
Authority: WO
Inventors: Jie LING; Juying GAN; Shabnam Sultana; Paul Schliwa-Bertling
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2022-01-28
Filing date: 2023-01-12
Publication date: 2023-08-03

Abstract

Embodiments of the present disclosure provide method and apparatus for multicast/broadcast service (MBS). A method performed by an application node comprises sending a first message to a first network function in a first network or a second network function in the first network. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

Description

METHOD AND APPARATUS FOR MULTICAST/BROADCAST SERVICE

TECHNICAL FIELD

The non-limiting and exemplary embodiments of the present disclosure generally relate to the technical field of communications, and specifically to methods and apparatuses for multicast/broadcast service (MBS) .

BACKGROUND

This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

Third Generation Partnership Project (3GPP) TS 23.247 V17.4.0, the disclosure of which is incorporated by reference herein in its entirety, describes architectural enhancements for 5G (fifth generation) multicast-broadcast services. 3GPP TS 23.682 V17.2.0, the disclosure of which is incorporated by reference herein in its entirety, describes group message delivery procedures. 3GPP TS 23.246 V16.1.0, the disclosure of which is incorporated by reference herein in its entirety, describes Multimedia Broadcast/Multicast Service (MBMS) , architecture and functional description.

Multicast and Broadcast Service (MBS) is a point-to-multipoint service in which data is transmitted from a single source entity to multiple recipients, either to all users in a broadcast service area, or to users in a multicast group. The corresponding types of MBS session are broadcast session and multicast session.

The MBS architecture follows the fifth generation (5G) System architectural principles as defined in 3GPP TS 23.501 V17.5.0, the disclosure of which is incorporated by reference herein in its entirety, enabling distribution of the MBS data from the 5GS (5G system) ingress to NG-RAN (next generation radio access network) node (s) and then to the UE (user equipment) . The MBS architecture provides efficient usage of RAN (radio access network) and CN (core network) resources, with an emphasis on radio interface efficiency, and efficient transport for a variety of multicast and broadcast services.

According to clause 5.18 of 3GPP TS 23.501 V17.5.0, a network sharing architecture may allow multiple participating operators to share resources of a single shared network according to agreed allocation schemes. The shared network includes a radio access network. The shared resources include radio resources. In a 5G Multi-Operator Core Network (5G MOCN) , multiple core networks (CNs) are connected to the same NG-RAN.

When the same multicast content is to be delivered to multiple CNs, an application function (AF) will set up multiple multicast MBS sessions towards those CNs, each CN delivering the same content towards the same shared NG-RAN node. Therefore, for a multicast MBS Session, the consumed radio resource will be (N-1) times more than needed, where N is the number of CNs involved.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

As described in R3-225229, LS on the scope of resource efficiency for MBS reception in RAN sharing scenario, 3GPP TSG-RAN3 (Technical Specifications Group-Radio Access Network3) Meeting #117-e Electronic meeting, 15 -24 August 2022, RAN3 raised the issue of scope mismatch between RAN and SA2 (Service and System Aspects Working Group 2) . In SA2 SID, the scope focuses on broadcast MBS sessions only. In RAN WID, the scope covers both broadcast and multicast.

In the RAN3 discussion, it had been acknowledged that it is a valid use case in multicast about resource efficiency for MBS reception in RAN sharing scenario.

However, in SA2 SID and 3GPP TR 23.700-47 v1.0.0, the disclosure of which is incorporated by reference herein in its entirety, only the broadcast has been addressed in key issue description as well as in the relevant solutions.

There are no solutions describing how the resource optimization can be achieved for multicast MBS sessions for MOCN RAN sharing scenario.

To overcome or mitigate at least one above mentioned problems or other problems, the embodiments of the present disclosure propose an improved MBS solution.

In a first aspect of the disclosure, there is provided a method performed by an application node. The method comprises sending a first message to a first network function in a first network or a second network function in the first network. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In an embodiment, the first network function comprises at least one of Network Exposure Function (NEF) , Multicast/Broadcast Service Function (MBSF) , or a combined NEF and MBSF.

In an embodiment, the second network function comprises Multicast/Broadcast Session Management Function (MB-SMF) .

In an embodiment, the first message is an MBS session create request.

In an embodiment, two or more core networks of the two or more networks are connected to a radio access network node.

In an embodiment, the application node comprises an application function.

In an embodiment, the at least one associated session ID comprises at least one of at least one source-specific multicast Internet protocol address, or at least one temporary mobile group identity (TMGI) or an MOCN network sharing indicator.

In an embodiment, the at least one TMGI is selected from TMGIs allocated in two or more networks which are to be used as MBS session identifiers of the MBS sessions transmitting the same content and/or a same TMGI is used for the MBS session ID of each of the two or more multicast MBS sessions and the same TMGI and the MOCN network sharing indicator are used to identify the two or more multicast MBS sessions with same content across two or more networks.

In a second aspect of the disclosure, there is provided a method performed by a first network function in a first network. The method comprises receiving a first message from an application node. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The method further comprises sending (304) a second message to a second network function in the first network. The second message comprises the MBS session ID and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In an embodiment, the first message is an MBS session create request and the second message is an MBS session create request.

In an embodiment, the application node comprises an application function.

In an embodiment, the at least one associated session ID comprises at least one of at least one source-specific multicast Internet protocol address, or at least one temporary mobile group identity (TMGI) or an MOCN network sharing indicator .

In a third aspect of the disclosure, there is provided a method performed by a second network function in a first network. The method comprises receiving a first message or a second message from an application node or a first network function in the first network. The first message and/or the second message comprise a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The method further comprises sending a third message to a third network function in the first network or a fourth network function in the first network. The third message comprises the MBS session identifier and the at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In an embodiment, the first message is an MBS session create request, the second message is an MBS session create request, and the third message is an MBS session context status subscribe response or an MBS session context status update response.

In an embodiment, the at least one associated session ID is included in N2 SM information which is a Distribution Setup Response.

In an embodiment, the third network function comprises a session management function (SMF) and/or the fourth network function comprises an access and mobility management function (AMF) .

In an embodiment, the application node comprises an application function.

In a fourth aspect of the disclosure, there is provided a method performed by a third network function in a first network. The method comprises receiving a third message from a second network function in the first network. The third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The method further comprises sending a fourth message to a fourth network function in a first network. The fourth message comprises the MBS session ID and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In an embodiment, the third message is an MBS session context status subscribe response, and the fourth message is a protocol data unit (PDU) session update session management (SM) context response or an N1N2 Message Transfer request.

In an embodiment, the at least one associated session ID is included in N2 SM information which is a PDU session resource setup request or PDU session modification request.

In an embodiment, the third network function comprises a session management function (SMF) .

In an embodiment, the fourth network function comprises an access and mobility management function (AMF) .

In a fifth aspect of the disclosure, there is provided a method performed by a fourth network function. The method comprises receiving a fourth message from a third network function in the first network or another fourth network function in the first network or a third message from a second network function in the first network. The fourth message and/or the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The method further comprises sending a fifth message to a radio access network node. The fifth message comprises the MBS session ID and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In an embodiment, the fourth message is a protocol data unit (PDU) session update session management (SM) context response or an N1N2 Message Transfer request or a communication create user equipment (UE) context request and the fifth message is an N2 message.

In an embodiment, the third message is an MBS session context status update response.

In an embodiment, the N2 message may comprise at least one of a Distribution Setup Response, a PDU session resource setup request, a PDU session modification request, or a handover request.

In an embodiment, two or more core networks of the two or more networks are connected to the radio access network node.

In an embodiment, the fourth network function comprises an access and mobility management function (AMF) or a target AMF.

In an embodiment, the another fourth network function in the first network comprises a source AMF.

In a sixth aspect of the disclosure, there is provided a method performed by a radio access network node. The method comprises receiving a fifth message from a fourth network function in a first network or another radio access network node. The fifth message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The method further comprises checking whether at least one radio resource has been allocated for delivering the same content. The method further comprises, when the at least one radio resource has not been allocated, allocating the at least one radio resource. The method further comprises, when the at least one radio resource has been allocated, skipping allocating the at least one radio resource.

In an embodiment, the fifth message is an N2 message.

In an embodiment, the N2 message may comprise at least one of a PDU session resource setup request, a PDU session modification request, a distribution setup response, or a handover request.

In an embodiment, the method further comprises establishing a user plane of an associated multicast MBS session of the first network.

In an embodiment, the method further comprises, when a predefined number of user planes of the two or more multicast MBS sessions have not been established, establishing a user plane of an associated multicast MBS session of the first network.

In an embodiment, the method further comprises, when a predefined number of user planes of the two or more multicast MBS sessions have been established, skipping an establishment of a user plane of an associated multicast MBS session of the first network.

In an embodiment, the method further comprises, when the same content can be received from a user plane function of another network, skipping an establishment of a user plane of an associated multicast MBS session of the first network.

In an embodiment, the method further comprises, when no terminal device is joined in a current multicast MBS session, releasing a user plane of the current multicast MBS session.

In an embodiment, the method further comprises, when at least one terminal device is joined in the two or more multicast MBS sessions and the user plane of the current multicast MBS session is released, selecting another network to establish a user plane of an associated multicast MBS session to receive the same content.

In an embodiment, the method further comprises detecting there is a failure in a network which causes the radio access network node cannot deliver the same content.

In an embodiment, the method further comprises selecting another network to establish a user plane of an associated multicast MBS session to receive the same content.

In an embodiment, the method further comprises, when no terminal device is joined in the two or more multicast MBS sessions, releasing the at least one radio resource.

In an embodiment, the method further comprises, for paging and notification in MBS session activation, paging all terminal devices joined in the two or more multicast MBS sessions which are in CM-IDLE state or in CM-CONNECTED with RRC_INACTIVE state.

In an embodiment, the method further comprises, when MBS session update, making the MBS session update to take effect to all the associated MBS sessions transmitting the same content.

In an embodiment, when same multicast data is received from two or more networks, only a single copy of the same multicast data is transmitted and the other copies of the same multicast data are dropped.

In an embodiment, the method further comprises sending a sixth message to a target radio access network node. The sixth message comprises the MBS session ID and the at least one associated session ID.

In an embodiment, the sixth message is an Xn message.

In an embodiment, the Xn message may comprise at least one of a Retrieve UE Context Response, a RAN Multicast Group paging message, or a handover request.

In a seventh aspect of the disclosure, there is provided an application node. The application node comprises a processor and a memory coupled to the processor. Said memory contains instructions executable by said processor. Said application node is operative to send a first message to a first network function in a first network or a second network function in the first network. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In an eighth aspect of the disclosure, there is provided a first network function in a first network. The first network function comprises a processor and a memory coupled to the processor. Said memory contains instructions executable by said processor. Said first network function is operative to receive a first message from an application node. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. Said first network function is further operative to send a second message to a second network function in the first network. The second message comprises the MBS session ID and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In a ninth aspect of the disclosure, there is provided a second network function in a first network. The second network function comprises a processor and a memory coupled to the processor. Said memory contains instructions executable by said processor. Said second network function is operative to receive a first message or a second message from an application node or a first network function in the first network. The first message and/or the second message comprise a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. Said second network function is further operative to send a third message to a third network function in the first network or a fourth network function in the first network. The third message comprises the MBS session identifier and the at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In a tenth aspect of the disclosure, there is provided a third network function in a first network. The third network function comprises a processor and a memory coupled to the processor. Said memory contains instructions executable by said processor. Said third network function is operative to receive a third message from a second network function in the first network. The third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. Said third network function is further operative to send a fourth message to a fourth network function in a first network. The fourth message comprises the MBS session ID and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In an eleventh aspect of the disclosure, there is provided a fourth network function. The fourth network function comprises a processor and a memory coupled to the processor. Said memory contains instructions executable by said processor. Said fourth network function is operative to receive a fourth message from a third network function in the first network or another fourth network function in the first network or a third message from a second network function in the first network. The fourth message and/or the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. Said fourth network function is further operative to send a fifth message to a radio access network node. The fifth message comprises the MBS session ID and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In a twelfth aspect of the disclosure, there is provided a radio access network node. The radio access network node comprises a processor and a memory coupled to the processor. Said memory contains instructions executable by said processor. Said radio access network node is operative to receive a fifth message from a fourth network function in a first network or another radio access network node. The fifth message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. Said radio access network node is further operative to check whether at least one radio resource has been allocated for delivering the same content. Said radio access network node is further operative to, when the at least one radio resource has not been allocated, allocate the at least one radio resource. Said radio access network node is further operative to, when the at least one radio resource has been allocated, skip allocating the at least one radio resource.

In another aspect of the disclosure, there is provided an application node. The application node comprises a sending module configured to send a first message to a first network function in a first network or a second network function in the first network. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In another aspect of the disclosure, there is provided a first network function. The first network function comprises a receiving module configured to receive a first message from an application node. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The first network function further comprises a sending module configured to send a second message to a second network function in the first network. The second message comprises the MBS session ID and at least one associated session ID.

In another aspect of the disclosure, there is provided a second network function. The second network function comprises a receiving module configured to receive a first message or a second message from an application node or a first network function in the first network. The first message and/or the second message comprise a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The second network function further comprises a sending module configured to send a third message to a third network function in the first network or a fourth network function in the first network. The third message comprises the MBS session identifier and the at least one associated session ID.

In another aspect of the disclosure, there is provided a third network function. The third network function comprises a receiving module configured to receive a third message from a second network function in the first network. The third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The third network function further comprises a sending module configured to send a fourth message to a fourth network function in a first network. The fourth message comprises the MBS session ID and at least one associated session ID.

In another aspect of the disclosure, there is provided a fourth network function. The fourth network function comprises a receiving module configured to receive a fourth message from a third network function in the first network or another fourth network function in the first network or a third message from a second network function in the first network. The fourth message and/or the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The fourth network function further comprises a sending module configured to send a fifth message to a radio access network node. The fifth message comprises the MBS session ID and at least one associated session ID.

In another aspect of the disclosure, there is provided a radio access network node. The radio access network node comprises a first receiving module configured to a fifth message from a fourth network function in a first network or another radio access network node. The fifth message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The radio access network node further comprises a checking module configured to check whether at least one radio resource has been allocated for delivering the same content. The radio access network node further comprises an allocating receiving module configured to, when the at least one radio resource has not been allocated, allocate the at least one radio resource. The radio access network node further comprises a first skipping module configured to, when the at least one radio resource has been allocated, skip allocating the at least one radio resource.

In an embodiment, the radio access network node further comprises a first establishing module configured to establish a user plane of an associated multicast MBS session of the first network.

In an embodiment, the radio access network node further comprises a second establishing module configured to, when a predefined number of user planes of the two or more multicast MBS sessions have not been established, establish a user plane of an associated multicast MBS session of the first network.

In an embodiment, the radio access network node further comprises a second skipping module configured to, when a predefined number of user planes of the two or more multicast MBS sessions have been established, skip an establishment of a user plane of an associated multicast MBS session of the first network.

In an embodiment, the radio access network node further comprises a third skipping module configured to, when the same content can be received from a user plane function of another network, skip an establishment of a user plane of an associated multicast MBS session of the first network.

In an embodiment, the radio access network node further comprises a first releasing module configured to, when no terminal device is joined in a current multicast MBS session, release a user plane of the current multicast MBS session.

In an embodiment, the radio access network node further comprises a first selecting module configured to, when at least one terminal device is joined in the two or more multicast MBS sessions and the user plane of the current multicast MBS session is released, select another network to establish a user plane of an associated multicast MBS session to receive the same content.

In an embodiment, the radio access network node further comprises a detecting module configured to detect there is a failure in a network which causes the radio access network node cannot deliver the same content.

In an embodiment, the radio access network node further comprises a second selecting module configured to select another network to establish a user plane of an associated multicast MBS session to receive the same content.

In an embodiment, the radio access network node further comprises a second releasing module configured to, when no terminal device is joined in the two or more multicast MBS sessions, release the at least one radio resource.

In an embodiment, the radio access network node further comprises a paging module configured to, for paging and notification in MBS session activation, page all terminal devices joined in the two or more multicast MBS sessions which are in CM-IDLE state or in CM-CONNECTED with RRC_INACTIVE state.

In an embodiment, the radio access network node further comprises a making module configured to, when MBS session update, make the MBS session update to take effect to all the associated MBS sessions transmitting the same content.

In an embodiment, the radio access network node further comprises a sending module configured to send a sixth message to a target radio access network node. The sixth message comprises the MBS session ID and the at least one associated session ID.

In another aspect of the disclosure, there is provided a computer-readable storage medium storing instructions which when executed by at least one processor, cause the at least one processor to perform any of the methods according to the first, second, third, fourth, fifth and sixth aspects of the disclosure.

In another aspect of the disclosure, there is provided a computer program product, comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out any of the methods according to the first, second, third, fourth, fifth and sixth aspects of the disclosure.

Many advantages may be achieved by applying the proposed solution according to embodiments of the present disclosure. For example, some embodiments herein may enable radio resource efficiency for multicast MBS sessions from different CNs in MOCN RAN sharing deployment, which transmit the same content. Some embodiments herein may further optimize the user plane handling across those multicast MBS sessions. The embodiments herein are not limited to the features and advantages mentioned above. A person skilled in the art will recognize additional features and advantages upon reading the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent, by way of example, from the following detailed description with reference to the accompanying drawings, in which like reference numerals or letters are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and not necessarily drawn to scale, in which:

FIG. 1a shows a 5G system architecture for Multicast and Broadcast Service;

FIG. 1b shows a 5G System architecture for Multicast and Broadcast Service in reference point representation;

FIG. 1c shows a flowchart of PDU Session modification for UE joining Multicast MBS session;

FIG. 1d shows a flowchart of UE initiated Multicast MBS Session leave;

FIG. 1e shows a flowchart of MBS Session Release or Multicast session leave requested by the network;

FIG. 1f shows a flowchart of Xn based handover with MBS Session;

FIG. 1g shows a flowchart of N2 based handover with MBS Session;

FIG. 1h shows a flowchart of MBS session activation procedure;

FIG. 1i shows a flowchart of MBS session deactivation procedure;

FIG. 1j shows a flowchart of Multicast MBS Session update procedure;

FIG. 1k shows a flowchart of MBS Session Creation for MOCN RAN sharing;

FIG. 1l shows a flowchart of MBS Session Start for Broadcast for MOCN RAN sharing;

FIG. 1m shows a flowchart of MBS Session Release for Broadcast for MOCN RAN sharing;

FIG. 1n shows a flowchart of Broadcast MBS Session Transport Request;

FIG. 2 shows a flowchart of a method according to an embodiment of the present disclosure;

FIG. 3 shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 4a shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 4b shows a flowchart of establishment of shared delivery toward RAN node according to another embodiment of the present disclosure;

FIG. 5 shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 6 shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 7a shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 7b shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 7c shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 7d shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 7e shows a flowchart of a method according to another embodiment of the present disclosure;

FIG. 7f shows a flowchart of MBS Session Join for MOCN RAN sharing according to another embodiment of the present disclosure;

FIG. 7g shows a flowchart of Multicast Session Leave requested by the UE for MOCN RAN sharing according to another embodiment of the present disclosure;

FIG. 7h shows a flowchart of Multicast Session Leave requested by the network or MBS session release for MOCN RAN sharing according to another embodiment of the present disclosure;

FIG. 7i shows a flowchart of Xn based handover for MOCN RAN sharing according to another embodiment of the present disclosure;

FIG. 7j shows a flowchart of N2 based handover for MOCN RAN sharing according to another embodiment of the present disclosure;

FIG. 7k shows a flowchart of MBS session activation for MOCN RAN sharing according to another embodiment of the present disclosure;

FIG. 7l shows a flowchart of MBS session deactivation for MOCN RAN sharing according to another embodiment of the present disclosure;

FIG. 7m shows a flowchart of Multicast MBS Session update procedure for MOCN RAN sharing according to another embodiment of the present disclosure;

FIG. 7n shows a flowchart of Broadcast MBS Session Transport Request according to another embodiment of the present disclosure;

FIG. 8a is a block diagram showing an apparatus suitable for practicing some embodiments of the disclosure;

FIG. 8b is a block diagram showing an application node according to an embodiment of the disclosure’

FIG. 8c is a block diagram showing a first network function according to an embodiment of the disclosure;

FIG. 8d is a block diagram showing a second network function according to an embodiment of the disclosure;

FIG. 8e is a block diagram showing a third network function according to an embodiment of the disclosure;

FIG. 8f is a block diagram showing a fourth network function according to an embodiment of the disclosure;

FIG. 9 is a block diagram showing a radio access network node according to an embodiment of the disclosure;

FIG. 10 shows an example of a communication system according to an embodiment of the disclosure;

FIG. 11 is a block diagram of a host according to an embodiment of the disclosure; and

FIG. 12 shows a communication diagram of a host communicating via a network node with a UE over a partially wireless connection according to an embodiment of the disclosure.

DETAILED DESCRIPTION

The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Furthermore, the described features, advantages, and characteristics of the disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the disclosure may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

As used herein, the term “network” refers to a network following any suitable communication standards such as new radio (NR) , long term evolution (LTE) , LTE-Advanced, wideband code division multiple access (WCDMA) , high-speed packet access (HSPA) , Code Division Multiple Access (CDMA) , Time Division Multiple Address (TDMA) , Frequency Division Multiple Access (FDMA) , Orthogonal Frequency-Division Multiple Access (OFDMA) , Single carrier frequency division multiple access (SC-FDMA) and other wireless networks. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , etc. UTRA includes WCDMA and other variants of CDMA. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, Ad-hoc network, wireless sensor network, etc. In the following description, the terms “network” and “system” can be used interchangeably. Furthermore, the communications between two devices in the network may be performed according to any suitable communication protocols, including, but not limited to, the communication protocols as defined by a standard organization such as 3GPP. For example, the communication protocols may comprise the first generation (1G) , 2G, 3G, 4G, 4.5G, 5G communication protocols, and/or any other protocols either currently known or to be developed in the future.

The term “network device” or “network node” or “network function (NF) ” refers to any suitable function which can be implemented in a network element (physical or virtual) of a communication network. For example, the network function can be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g. on a cloud infrastructure. For example, the 5G system (5GS) may comprise a plurality of NFs such as AMF (Access and mobility Function) , SMF (Session Management Function) , AUSF (Authentication Service Function) , UDM (Unified Data Management) , PCF (Policy Control Function) , AF (Application Function) , NEF (Network Exposure Function) , UPF (User plane Function) and NRF (Network Repository Function) , RAN (radio access network) , SCP (service communication proxy) , NWDAF (network data analytics function) , NSSF (Network Slice Selection Function) , NSSAAF (Network Slice-Specific Authentication and Authorization Function) , etc.

The term “terminal device” refers to any end device that can access a communication network and receive services therefrom. By way of example and not limitation, the terminal device refers to a mobile terminal, user equipment (UE) , or other suitable devices. The UE may be, for example, a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a portable computer, an image capture terminal device such as a digital camera, a gaming terminal device, a music storage and a playback appliance, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet, a wearable device, a personal digital assistant (PDA) , a portable computer, a desktop computer, a wearable terminal device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop-embedded equipment (LEE) , a laptop-mounted equipment (LME) , a USB dongle, a smart device, a wireless customer-premises equipment (CPE) and the like. In the following description, the terms “terminal device” , “terminal” , “user equipment” and “UE” may be used interchangeably. As one example, a terminal device may represent a UE configured for communication in accordance with one or more communication standards promulgated by the 3GPP (3rd Generation Partnership Project) , such as 3GPP’ LTE standard or NR standard. As used herein, a “user equipment” or “UE” may not necessarily have a “user” in the sense of a human user who owns and/or operates the relevant device. In some embodiments, a terminal device may be configured to transmit and/or receive information without direct human interaction. For instance, a terminal device may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the communication network. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but that may not initially be associated with a specific human user.

As yet another example, in an Internet of Things (IoT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another terminal device and/or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

References in the specification to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed terms.

As used herein, the phrase “at least one of A and B” or “at least one of A or B” should be understood to mean “only A, only B, or both A and B. ” The phrase “A and/or B” should be understood to mean “only A, only B, or both A and B” .

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

It is noted that these terms as used in this document are used only for ease of description and differentiation among nodes, devices or networks etc. With the development of the technology, other terms with the similar/same meanings may also be used.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

Although the subject matter described herein may be implemented in any appropriate type of system using any suitable components, the embodiments disclosed herein are described in relation to a communication system complied with the exemplary system architecture illustrated in FIG. 1a and FIG. 1b. For simplicity, the system architecture of FIG. 1a and FIG. 1b only depicts some exemplary elements. In practice, a communication system may further include any additional elements suitable to support communication between terminal devices or between a wireless device and another communication device, such as a landline telephone, a service provider, or any other network node or terminal device. The communication system may provide communication and various types of services to one or more terminal devices to facilitate the terminal devices’a ccess to and/or use of the services provided by, or via, the communication system.

FIG. 1a shows a 5G system architecture for Multicast and Broadcast Service, which is same as Figure 5.1-1 of 3GPP TS 23.247 V17.4.0. FIG. 1b shows a 5G System architecture for Multicast and Broadcast Service in reference point representation, which is same as Figure 5.1-2 of 3GPP TS 23.247 V17.4.0. The 5G MBS system architecture may comprise functional entities such as PCF (Policy Control Function) , MB-SMF (Multicast/Broadcast Session Management Function) , SMF (Session Management Function) , MB-UPF (Multicast/Broadcast User plane Function) , UPF (User plane Function) , AMF (Access and mobility Function) , NG-RAN (next generation radio access network) , UE (user equipment) , AF/AS (Application Function/Application Server) , NEF (Network Exposure Function) , MBSF (Multicast/Broadcast Service Function) , MBSTF (Multicast/Broadcast Service Transport Function) , UDM (Unified Data Management) , UDR (Unified Data Repository) , NRF (Network Repository Function) , etc. These functional entities have been described in clause 5.3.2 of 3GPP TS 23.247 V17.4.0.

The MBSF is optional and may be collocated with the NEF or AF/AS, and the MBSTF is an optional network function.

The existing service-based interfaces of Nnrf, Nudm, and Nsmf are enhanced to support MBS. The existing service-based interfaces of Npcf and Nnef are enhanced to support MBS.

A MBS-enabled AF uses either Nmbsf or Nnef to interact with the MBSF.

SMF and MB-SMF may be co-located or deployed separately.

The MBS System Architecture may contain the following reference points:

N3mb: Reference point between the (R) AN and the MB-UPF.

N4mb: Reference point between the MB-SMF and the MB-UPF.

N6mb: Reference point between the MB-UPF and the AF/AS.

N7mb: Reference point between the MB-SMF and the PCF.

N11mb: Reference point between the AMF and the MB-SMF.

N16mb: Reference point between the SMF and the MB-SMF.

N19mb: Reference Point between the UPF and the MB-UPF.

N29mb: Reference point between the MB-SMF and the NEF.

Nmb1: Reference point between the MB-SMF and the MBSF.

Nmb2: Reference point between the MBSF and the MBSTF.

Nmb5: Reference point between the MBSF and the NEF.

Nmb8: Reference point between the MBSTF and the AF.

Nmb9: Reference point between the MB-UPF and the MBSTF.

Nmb10: Reference point between the MBSF and the AF.

Nmb12: Reference point between the MBSF and the PCF.

Nmb13: Reference point between the MB-SMF and the AF.

The existing reference points of N1, N2, N4, N10, N11, N30 and N33 are enhanced to support MBS.

Regarding the functionalities, Nmb13, N29mb and Nmb1 are identical, Nmb5 and Nmb10 are identical, Nmb9 and N6mb are identical.

The following content are mainly from clause 7.2.1.3 of 3GPP TS 23.247 v17.4.0.

Multicast session join and session establishment procedure

The following steps are executed before the UE requests to join the MBS session:

- The MBS Session may have been created in the 5GC (see clause 7.1.1 for details) .

- The UE registers in the PLMN or SNPN and may have established a PDU session that can be associated with multicast session (s) .

- The UE has known at least the MBS Session ID of a multicast group that the UE can join, e.g. via service announcement.

FIG. 1c shows a flowchart of PDU Session modification for UE joining Multicast MBS session, which is same as Figure 7.2.1.3-1 of 3GPP TS 23.247 v17.4.0.

1. To join a multicast group:

- if there is an existing PDU session that can be used to send the UE join request for the multicast MBS Session, the UE sends a PDU Session Modification Request over that PDU session (i.e. associated PDU Session) which additionally contains one or several MBS Session ID (s) and join request. The MBS Session ID (s) indicate the multicast MBS session (s) that UE wants to join.

- if the UE has no appropriate PDU session established with the DNN and S-NSSAI for the multicast MBS session, the UE joins the multicast MBS session by sending PDU Session Establishment Request for associated PDU session together with one or several MBS Session ID (s) and join request. In that case, before step 2, the network proceeds with establishment of the associated PDU session executing steps 4 to 10 of PDU Session Establishment procedure as specified in TS 23.502 [6] clause 4.3.2.2.

2. [Conditional] Based on the received MBS Session ID and join request, the SMF determines this is MBS Session join request.

If SMF has no information about MBS Session Context for the indicated MBS Session ID (s) , SMF discovers and selects an MB-SMF for the MBS Session via the NRF as described in clause 7.1.2. If no MB-SMF is assigned for the MBS Session ID (i.e. the NRF provides empty MB-SMF profile) , the SMF may select an MB-SMF and request it to configure the multicast MBS session or the SMF may reject the join request and respond to the UE with an appropriate cause value.

NOTE 1: Details about how the SMF selects an MB-SMF and requests it to configure the multicast MBS session are left to SMF implementation.

3. [Conditional] For each MBS session in step 1, if the SMF has not subscribed to the MBS Session Context, it invokes Nmbsmf_MBSSession_ContextStatusSubscribe request (MBS Session ID) towards the MB-SMF to subscribe to events notifications related to the multicast MBS session and to request information about the MBS Session Context. The MB-SMF responds with the information about the indicated multicast MBS session in Nmbsmf_MBSSession_ContextStatusSubscribe response (multicast QoS flow information (e.g. QoS profile (s) for the multicast MBS session) , [start time] , [session state (Active/Inactive) ] , [Any UE indication] , [multicast DL tunnel info] ) .

If it is the first time for the MB-SMF to receive Nmbsmf_MBSSession_ContextStatusSubscribe request of the indicated MBS Session from any SMF, the MB-SMF learns it is the first UE joining the multicast MBS session. For multicast transport between MB-UPF and content provider, if it is the first UE joining the multicast MBS session, and MB-UPF has not joined the multicast tree in the MBS session creation procedure, described in clause 7.1.1, the MB-SMF requests the MB-UPF to join the multicast tree towards the AF/MBSF, otherwise MB-SMF will not send the request to the MB-UPF.

NOTE 2: The MB-SMF can answer the Nmbsmf_MBSSession_ContextStatusSubscribe request either based on information received in the MBS session creation procedures in clause 7.1.1 or based on preconfigured information. The pre-configuration also includes information about the MBS session stored in the NRF. If the MB-SMF uses preconfigured information, the pre-configuration also includes MB-UPF configuration.

4. The SMF determines whether the user is authorized to join the Multicast MBS session taking into account the MBS subscription data received from the UDM and the Any UE indication if received from the MB-SMF. The SMF considers the UE as authorized to the Multicast MBS session if the UE is authorized to use multicast MBS services, and if the MBS Session ID (s) in the PDU Session Modification Request is included in the MBS subscription data or Any UE indication is received. If authorization check fails, the SMF rejects the join request with a cause value. If a UE joins prior to the start time of the multicast MBS session, the SMF may accept the join request and indicate to the UE the start time, or it may reject the join request with an appropriate error cause and optionally a back-off timer. If a UE joins while the multicast MBS session is inactive, the SMF accepts the join request.

5. If the join request is accepted, the SMF responds to the AMF through Nsmf_PDUSession_UpdateSMContext response (N2 SM information (PDU Session ID, MBS Session ID, [updated PDU Session information] , [mapping information between unicast QoS flow (s) and multicast QoS flow (s) ] ) , N1 SM container (PDU Session Modification Command) ) to:

- create an MBS Session Context for the indicated MBS session in the RAN, if it does not exist in the RAN already; and

- inform the NG-RAN about the relation between the Multicast MBS Session Context and the UE's PDU Session context by including the MBS Session ID and the mapping between the multicast QoS flow (s) and associated QoS flow (s) .

Based on operator policy, the SMF may prepare for 5GC Individual MBS traffic delivery fall-back. The SMF maps the received QoS information of the multicast QoS Flow into PDU Session's unicast QoS Flow information, and includes the information of the QoS Flows and the mapping information about the QoS Flows (termed "associated QoS flow information" ) in the SM information sent to RAN. The SMF compares the QFIs of the multicast QoS Flows received from the MB-SMF with QFIs in use for the PDU Session and assigns unused QFIs to the PDU Session's unicast QoS Flows corresponding to multicast QoS Flows.

NOTE 3: Detailed information included in N2 SM information will be aligned with by RAN WG3.

NOTE 4: The SMF uses the same QoS in the received MBS QoS Flow QoS information for the associated QoS Flow in the unicast PDU session.

If the MBS session join procedure was triggered by the UE together with PDU Session Establishment procedure for the associated PDU session, the SMF provides the N2 SM information and N1 SM container for the associated PDU session in Namf_Communication_N1N2MessageTransfer service operation towards the AMF, as described in step 11 of clause 4.3.2.2.1 in TS 23.502 [6] . The N2 SM information also includes the MBS Session ID and, if 5GC individual MBS traffic delivery fall-back is supported, the mapping information between unicast QoS flow (s) and multicast QoS flow (s) .

If the join request is rejected, the SMF responds to the AMF through Nsmf_PDUSession_UpdateSMContext response (N1 SM container (PDU Session Modification Reject) ) and the message will not contain any MBS Session Context or the N2 SM information for the associated PDU session. The PDU Session Modification Reject message is forwarded to the UE via the NG-RAN, and the following steps are skipped.

6. The N2 message, which includes the MBS Session ID (s) the UE has joined and, if applicable, associated QoS Flow, is sent to the NG-RAN.

If the MBS is supported by NG-RAN, 5GC Shared MBS traffic delivery is adopted. If the MBS is not supported by NG-RAN, 5GC Individual MBS traffic delivery is used if the PDU Session's unicast QoS Flow include QoS Flows for the multicast session.

If the NG-RAN supports MBS, the NG-RAN uses the MBS Session ID to determine that the PDU Session identified by the PDU Session ID is associated with the indicated multicast MBS session.

If the NG-RAN supports MBS, the associated unicast QoS flow information, if provided, is not used to allocate the radio resource and CN resource for corresponding QoS flows.

NOTE 6: UE join request via PDU Session signalling will fail if NG-RAN rejects the PDU Session Resource setup request (e.g. due to the number of UEs reaching a limit) .

7. [Conditional] If shared tunnel has not been established for the multicast MBS session towards the NG-RAN node, the procedures in clause 7.2.1.4 for the establishment of shared delivery toward NG-RAN node are executed. This step is executed separately for each multicast MBS session.

NOTE 7: If in step 7 the NG-RAN node is informed that the MBS session is active, it is the NG-RAN node that decides whether radio resources are allocated.

7a. If the MBS Session is active, the NG-RAN configures radio resources for MBS session.

8. If the MBS Session is active, the NG-RAN node performs AN specific signalling exchange with the UE to configure the UE with radio resources for the multicast MBS session. If the NG-RAN does not support MBS and the MBS Session is active, radio resources are reconfigured for unicast transmission of the MBS data over the associated PDU session. As part of the AN specific signalling exchange, the N1 SM container (PDU Session Modification Command) is provided to the UE.

9. The NG-RAN node sends the PDU session modification response.

If the MBS is not supported by NG-RAN, the accepted unicast QoS flow is included in the N2 SM response container. If the MBS is supported by NG-RAN, the N2 SM response container further includes the indication of supporting MBS.

10. The AMF invokes Nsmf_PDUSession_UpdateSMContext request ( [N2 SM container] ) to the SMF.

Per the indication of whether the NG-RAN supports MBS, the SMF determines whether 5GC Individual MBS traffic delivery is used for multicast data transmission.

NOTE 8: If the shared tunnel is used, no interaction with UPF is needed for the indicated multicast MBS session

[Conditional] This step is used for 5GC Individual MBS traffic delivery, if the related NG-RAN does not support MBS. If a shared tunnel between the UPF (PSA) and MB-UPF for 5GC Individual MBS traffic delivery has not yet been established by the SMF for the multicast MBS session, steps 11a to 11d are executed. Step 11e is executed irrespective of that.

11a. The SMF contacts the UPF to request the creation of a tunnel and provides the MBS Session ID. The UPF indicates to the SMF whether the tunnel for this multicast MBS session is newly allocated (as there can be multiple SMFs interacting with the same UPF for the same multicast MBS Session) .

If the UPF determines to use unicast transport over N19mb, the UPF allocates a DL N19mb Tunnel endpoint for the multicast MBS session if the SMF request is the first one to allocate DL N19mb Tunnel endpoint for the multicast MBS Session in the UPF. The UPF includes the DL Tunnel Info in the response to the SMF. The DL tunnel info includes the downlink tunnel ID and the UPF address.

If the UPF determines to use multicast transport over N19mb, the UPF joins the multicast distribution if the SMF request is the first one for the MBS Session in the UPF. Steps 11b to 11d are skipped.

11b. If the UPF indicates the DL N19mb Tunnel is newly allocated, the SMF invokes Nmbsmf_MBSSession_ContextUpdate request (MBS Session ID, [DL tunnel info] ) towards the MB-SMF for establishing the multicast MBS session transport between MB-UPF and UPF.

11c. If the DL tunnel info of the UPF is received, the MB-SMF configures the MB-UPF to transmit the multicast MBS session data towards UPF using the possibly received downlink tunnel ID.

11d. The MB-SMF responds to the SMF through Nmbsmf_MBSSession_ContextUpdate response (MBS Session ID, [multicast DL tunnel info] ) . If the UPF DL tunnel info for unicast transport is not received by the MB-SMF, multicast transport between MB-UPF and UPF is to be used, and the MB-SMF includes the downlink tunnel information with the low layer transport multicast address for the multicast MBS session.

11e. The MB-SMF configures the MB-UPF to forward the received multicast MBS session data within the PDU session. (This step may be combined with step 11a) .

12. The SMF responds to the AMF with Nsmf_PDUSession_UpdateSMContext response message.

13. The MB-UPF receives multicast PDUs, either directly from the content provider or via the MBSTF that can manipulate the data.

Steps 14 to 16 are for 5GC Shared MBS traffic delivery:

14. The MB-UPF sends multicast PDUs in the N3mb tunnel associated to the multicast MBS session to the NG-RAN. There is only one tunnel per multicast MBS session per MBS service area and NG-RAN node, i.e. all the UEs which have joined the multicast MBS session via the NG-RAN node share this tunnel for reception of the multicast MBS session data.

15. Void.

16. The NG-RAN transmits the multicast MBS session data to the UE (s) via the MBS Radio Bearer using either PTP or PTM transmission.

Steps 17 to 19 are for 5GC Individual MBS traffic delivery:

17. The MB-UPF sends multicast PDUs in the N19mb tunnel associated to the multicast MBS session to the UPF. There is only one tunnel per multicast MBS session and destination UPF, i.e. all associated PDU sessions served by the destination UPF share this tunnel.

18. The UPF forwards the multicast data towards the NG-RAN via unicast (i.e. in the N3 tunnel of the associated PDU Session) .

19. The NG-RAN forwards the multicast MBS session data to the UE via unicast (i.e. over the radio bearer (s) corresponding to the associated QoS flow (s) of the associated PDU Session) .

NOTE 9: Details of the DL MBS data transmission are described in clause 6.7.

NOTE 10: When the MBSF is involved in the multicast MBS session, the tunnel between MBSTF and MB-UPF has been established in the MBS session creation procedure.

The following content are mainly from clause 7.2.2.2 of 3GPP TS 23.247 v17.4.0.

Multicast Session leave requested by the UE

When the UE determines to leave the Multicast MBS session, it shall send PDU session Modification request to inform the 5GC the leaving operation. The Figure 7.2.2.2-1 describes the procedure.

FIG. 1d shows a flowchart of UE initiated Multicast MBS Session leave, which is same as Figure 7.2.2.2-1 of 3GPP TS 23.247 v17.4.0.

1. The UE sends the PDU Session Modification Request when the UE determine to leave the multicast MBS Session. The PDU Session Modification Request carries leave indication and the MBS Session ID which the UE want to leave.

2. The AMF invokes Nsmf_PDUSession_UpdateSMContext (N1 SM container (PDU Session Modification Request) ) to the SMF.

3a. [Conditional] If 5GC individual MBS traffic delivery is applied towards the UE, the SMF sends an N4 Session Modification Request to the UPF (PSA) . The SMF reconfigures the UPF to terminate the distribution of multicast data via the PDU session.

3b. [Conditional] The UPF (PSA) sends an N4 Session Modification Response to the SMF.

If there are no PDU sessions to transmit the multicast MBS session data in the UPF, and unicast transport is used over N19mb, the UPF releases the DL N19mb tunnel endpoint and informs the SMF.

If there are no PDU sessions to transmit the multicast MBS session data in the UPF, and multicast transport is used over N19mb, the UPF leaves the multicast distribution tree of MB-UPF.

4. [Conditional] If the UPF indicates the tunnel release (i.e. unicast transport was used) , the SMF invokes Nmbsmf_MBSSession_ContextUpdate Request (Release, MBS Session ID, tunnel information) to release the tunnel between UPF and MB-UPF for this multicast MBS session. The MB-SMF determines whether the context update is for tunnel release or create based on whether the tunnel information exists in the multicast MBS Session Context stored in the MB-SMF or not.

5. [Conditional] If the MB-SMF determines the context update is for tunnel release, the MB-SMF request to MB-UPF to release the tunnel between UPF and MB-UPF for the multicast MBS session.

6. [Conditional] The MB-SMF responds to the SMF for step 4.

7. The SMF invokes the Nsmf_PDUSession_UpdateSMContext Response (PDU Session ID, N2 SM information ( [MBS Session ID] , [leave indication] ) , N1 SM container) service operation. In the N2 SM information, the MBS Session ID and the leave indication are included for informing the NG-RAN to remove the UE from this MBS session if 5GC Shared MBS traffic delivery method is used towards the UE. If 5GC Individual MBS traffic delivery method is used towards the UE, the N2 SM information does not include MBS related information.

In the N2 SM information, the SMF also informs the NG-RAN to release the associated QoS Flow (s) , which carry or intend to carry the multicast MBS session traffic for 5GC individual MBS traffic delivery.

The associated QoS Flow (s) are released as defined in TS 23.502 [6] clause 4.3.3.2.

8. The AMF send N2 message (N2 SM information, N1 SM container) to the NG-RAN

9. The NG-RAN node performs the necessary AN-specific resource modification procedure toward the UE and transports the N1 SM container received in step 7 to the UE.

10. The NG-RAN node removes the UE from this multicast MBS session and sends a N2 message to the AMF.

11. The AMF transfers the N2 message received in step 9 to the SMF via the Nsmf_PDUSession_UpdateSMContext service operation.

The SMF updates the associated PDU session context, e.g. remove the MBS Session ID from the associated PDU session context. In addition, if associated QoS flow is used for the multicast MBS session, the SMF also removes the associated QoS flow information associated with the indicated multicast MBS session from the associated PDU session context.

12. [Conditional] If the UE is the last joined one of the multicast MBS session in the SMF, The SMF also indicates that the last UE served by the SMF leaves the Multicast MBS Session, the SMF unsubscribes the notifications of the MBS Session Context status updates from the MB-SMF by invoking Nmbsmf_MBSSession_ContextStatusUnsubscribe service operation. The MB-SMF will no longer notify the SMF of the further context status updates of the multicast MBS session (e.g. activation, deactivation, update, release, etc. ) . For multicast transport between MB-UPF and content provider, if the SMF is the last remaining SMF that is subscribed for the MBS Session notification from the MB-SMF, i.e. if it is the last UE leaving the MBS session, the MB-SMF requests the MB-UPF to stop forwarding the multicast MBS session data and may request the MB-UPF to leave the multicast tree towards the AF/MBSF, if the MB-UPF joins the multicast tree when the first UE joins the MBS session.

13. [Conditional] If the UE is the last UE in this RAN node for this multicast MBS session, the NG-RAN release shared delivery between NG-RAN and MB-UPF as described in clause 7.2.2.4.

If release of the PDU Session associated with a multicast MBS session is triggered, corresponding procedures between UE, NG-RAN, AMF, and SMF are performed as described in clause 4.3.4 of TS 23.502 [6] , and SMF triggers the UE leave the multicast MBS session by performing steps 3-6 in Figure 7.2.2.2-1 for each multicast MBS session (s) associated with the PDU Session, and UE considers as left all the multicast MBS sessions associated with the PDU Session.

NOTE: If the associated PDU Session is released, the UE leaves MBS Session (s) associated with that PDU session implicitly. To resume the reception of the related MBS service (s) , the UE needs to initiate the procedures as defined in clause 7.2.1 to re-join the MBS Session (s) .

If the UE deregistration procedure is executed, corresponding procedures between UE, NG-RAN, AMF, and SMF are performed as described in clause 4.2.2.3 of TS 23.502 [6] , and SMF performs steps 3-6 in Figure 7.2.2.2-1 for all multicast MBS sessions joined by the UE. When the PDU Session Release procedure or UE deregistration procedure is executed, according to the UE context, NG-RAN performs step 12 for each multicast MBS session associated with the released PDU Session (s) .

The following content are mainly from clause 7.2.2.3 of 3GPP TS 23.247 v17.4.0.

Multicast session leave requested by the network or MBS session release

This procedure applies to the following scenarios:

1. When the MB-SMF decides to release an MBS Session:

- based on a request from the AF (directly or via the NEF/MBSF) ;

In this scenario, the MB-SMF notifies the SMF of multicast session release, and the SMF initiates procedures to remove all joined UEs from the MBS session.

2. When the SMF decides to remove a UE from an MBS session:

- based on a request from the UDM (subscription change) ; or

- due to local and location dependent MBS service is described in clause 7.2.4; or

- due to network internal reasons.

For the active MBS session, to release radio resources as early as possible, the MB-SMF may trigger Multicast Session Deactivation towards the NG-RAN as specified in steps 5-9 of clause 7.2.5.3, prior to or in parallel with triggering MBS Session Release to the SMF.

FIG. 1e shows a flowchart of MBS Session Release or Multicast session leave requested by the network, which is same as Figure 7.2.2.3-1 of 3GPP TS 23.247 v17.4.0.

1a. For MB-SMF triggered MBS session release, the SMF receives Nmbsmf_MBSSession_ContextStatusNotify (MBS Session ID, multicast session release) from the MB-SMF with MBS Session ID. The SMF checks all joined UEs and perform step 2 to step 9 for each UE.

1b. The SMF decides to remove a UE from the MBS session without MBS session release (e.g. due to UE moving out of MBS service area for local or location dependent MBS service as described in clause 7.2.4) .

2. For UEs without activated UP, the SMF may perform the same procedure as defined in step 3-7 in clause 7.2.5.2.

Alternatively, for UEs without activated UP, the SMF does not trigger message to the AMF, instead the SMF marks that the UE is to be informed of the MBS Session release. In this case, the SMF initiates PDU Session Modification to inform the UE of the MBS Session release at next UP activation of the associated PDU Session, if needed.

3. For the joined UEs with UP activated, the SMF invokes Namf_Communicate_N1N2MessageTransfer to the AMF. The N1 SM container indicates UE removed from MBS session with appropriate cause (e.g. MBS session release, out of MBS service area, etc. ) . In N2 SM information, the SMF informs the NG-RAN to remove the UE from the MBS session. If there are associated QoS Flow (s) for individual delivery, the SMF also releases those QoS Flow (s) as specified in TS 23.502 [6] clause 4.3.3.2.

4. The AMF sends N2 Request to the NG-RAN.

5. The NG-RAN transports the N1 SM container (PDU Session Modification Command (MBS Session ID, UE removed from MBS session with appropriate cause) ) to the UE.

6. The NG-RAN performs radio resource modification. If there are no joined UEs in the MBS session, the NG-RAN releases the radio resources.

7. If there are no joined UEs in the MBS session, for unicast transport of N3mb, the NG-RAN initiates the DL tunnel release towards MB-UPF via AMF and MB-SMF. For multicast transportation of N3mb, the NG-RAN performs IGMP/MLD Leave for the MBS session. See clause 7.2.2.4 for details.

8. The NG-RAN sends N2 Response to the AMF. If there are no joined UEs in the MBS session, the MBS Session Context is removed from the NG-RAN.

9. The AMF transfers the N2 message received in step 8 to the SMF via the Nsmf_PDUSession_UpdateSMContext service operation. The SMF removes the UE from the MBS Session.

The following content are mainly from clause 7.2.3.2 of 3GPP TS 23.247 v17.4.0.

Xn based handover from MBS supporting NG-RAN node

This clause describes an Xn based handover with MBS traffic delivered to the UE at the source NG-RAN node supporting MBS.

FIG. 1f shows a flowchart of Xn based handover with MBS Session, which is same as Figure 7.2.3.2-1 of 3GPP TS 23.247 v17.4.0.

The following additions apply compared to clause 4.9.1.2 of TS 23.502 V17.5.0, the disclosure of which is incorporated by reference herein in its entirety:

Before Handover:

The source NG RAN has been provided with MBS Session Resource information (including the MBS Session ID and multicast QoS flow information) and the UE Context information contains a mapping information within the PDU Session Resource associated with the MBS Session Resource, e.g. including mapped unicast QoS Flows associated with the multicast QoS flow (s) of the MBS Session Resource.

Handover Preparation Phase:

At Xn handover, the target NG-RAN is provided with MBS session information by the source NG-RAN which causes:

- an MBS non-supporting target NG-RAN node to prepare the unicast resources according to associated QoS flow (s) information.

‐ an MBS supporting target NG-RAN node to allocate to the UE shared NG-RAN resources according to the MBS session information. If the 5GC Shared MBS traffic delivery for the indicated multicast MBS Session has not been established in target NG-RAN, target NG-RAN triggers setup of the resources for the 5GC Shared MBS traffic delivery, see clause 7.2.1.4 for details.

1. Target NG-RAN to AMF: the target NG-RAN sends N2 Path Switch Request to AMF.

The target NG-RAN node, if MBS-capable, indicates it supports of MBS to SMF in N2 SM information. Per the received N2 SM information, the SMF knows whether the target NG-RAN node supports MBS and determines the delivery method, i.e. whether the 5GC Shared MBS traffic delivery or 5GC Individual MBS traffic delivery is used for MBS data transferring.

The SMF differentiates two cases:

Case A) The target NG-RAN supports MBS. Step 3 applies and step 4 is skipped.

3. SMF to UPF: The SMF invokes N4 Session Modification procedure with the UPF (PSA) only for unicast PDU Session.

Case B) The target NG-RAN does not support MBS. Step 3 is skipped, step 4 applies.

4. This steps is same as described in step 11 of clause 7.2.1.3.

The details of how to perform data forwarding refers to clause 7.2.3.5.

5. SMF to AMF: The SMF responds to AMF through Nsmf_PDUSession_UpdateSMContext response.

6. AMF to target NG-RAN: The AMF sends the path switch Ack to target NG-RAN.

The following content are mainly from clause 7.2.3.3 of 3GPP TS 23.247 v17.4.0.

N2 based handover from MBS supporting NG-RAN node

This clause describes the N2 based handover with MBS traffic delivered to the UE at the source NG-RAN node supporting MBS.

FIG. 1g shows a flowchart of N2 based handover with MBS Session, which is same as Figure 7.2.3.3-1 of 3GPP TS 23.247 v17.4.0.

The following additions apply compared to clause 4.9.1.3 of TS 23.502 V17.5.0:

1. Source NG-RAN to S-AMF: Handover Required (RAN container (MBS Session information, associated PDU session information, associated QoS flow information and corresponding multicast QoS flow information) ) .

2. S-AMF to T-AMF: The T-AMF is provided with associated PDU Session information and the MBS session related information.

4. T-AMF to Target NG-RAN: The Target NG-RAN prepares the radio resource based on the received information:

- If the Target NG-RAN does not support MBS, the MBS Session related information is not used. The Target NG-RAN uses the associated PDU Session information to allocate resource to deliver MBS data. The MBS data are transmitted via the associated QoS flows within the associated PDU Session.

- If the Target NG-RAN supports MBS, the Target NG-RAN uses the multicast MBS Session related information to allocate RAN resources to deliver the MBS data. If 5GC Shared MBS traffic delivery for the indicated multicast MBS session has not been established towards the Target NG-RAN, the Target NG-RAN initiates the shared delivery establishment towards the MB-SMF via AMF as described in clause 7.2.1.4.

5. Target NG-RAN to T-AMF: The target NG-RAN sends Handover Request Ack to T-AMF.

The target NG-RAN node, if MBS-capable, indicates it supports MBS to SMF in N2 SM information. Per the received N2 SM information, the SMF knows whether the target NG-RAN node supports MBS and determines the delivery method, i.e. whether the 5GC Shared MBS traffic delivery or 5GC Individual MBS traffic delivery is used for MBS data transferring.

12. T-AMF to SMF: The AMF invokes Nsmf_PDUSession_UpdateSMContext request towards SMF, the message includes the received N2 SM information received from the target NG-RAN.

13-14. Same as described in steps 3-4 of clause 7.2.3.2.

The details of how to perform data forwarding, refers to clause 7.2.3.5.

15. SMF to T-AMF: The SMF sends the Nsmf_PDUSession_UpdateSMContext Response to the T-AMF.

The following content are mainly from clause 7.2.5.2 of 3GPP TS 23.247 v17.4.0.

MBS session activation procedure

The following can trigger the MBS session activation procedure:

- AF requests MB-SMF to activate the MBS session;

- MB-UPF receives the multicast data and notifies MB-SMF.

FIG. 1h shows a flowchart of MBS session activation procedure, which is same as Figure 7.2.5.2-1 of 3GPP TS 23.247 v17.4.0.

In this procedure, steps 11 to 15 are executed if the MB-SMF finds out there are shared tunnel established. Steps 11 to 15, if needed, are executed in parallel with steps 2 to 10.

1. The procedure may be triggered by the following events:

- When the MB-UPF receives downlink data for a multicast MBS session, based on the instruction from the MB-SMF (as described in clause 7.2.5.3) , the MB-UPF sends N4mb Notification (N4 Session ID) to the MB-SMF for indicating the arrival of DL MBS data.

- The AF sends MBS Activation request (TMGI) to the MB-SMF directly or via NEF.

2. MB-SMF sends Nmbsmf_MBSSession_ContextStatusNotify (MBS Session ID, multicast session state = Active) to SMF (s) .

The SMF sets the related multicast MBS session state to Active and finds out the list of UEs that joined the multicast MBS session identified by the related TMGI. If the SMF determines the user plane of the associated PDU session (s) of the UE (s) with respect to the TMGI are activated already, steps 3-8a will be skipped for those UE (s) , i.e. executed from step 8b.

3. The SMF invokes Namf_MT_EnableGroupReachability Request (List of UEs, [PDU Session ID of the associated PDU Sessions] , TMGI, [UE reachability Notification Address] , [most demanding ARP, 5QI of all MBS QoS Flow within MBS session] ) ) to AMF (s) . When later UE is reachable, the UE reachability Notification Address is used by the AMF to identify and notify the related SMF.

After receiving the request, for each UE in the list, the AMF determines CM state of the UE: see steps 4 -7.

4a. If there are UEs involved in the multicast MBS Session and in CM-CONNECTED state, the AMF indicates those UEs to the SMF, using Namf_MT_EnableGroupReachability Response (UE list) . Otherwise, the response does not include UE list.

4b. For each UE in the UE list included in step 4a, if the QoS profile (s) for associated PDU Session has not yet been provided, the SMF invokes Namf_Communication_N1N2MessageTransfer (N2 SM information (PDU Session ID, MBS Session ID, [QoS profile (s) for associated QoS flow (s) ] , [mapping information between the unicast QoS flow and multicast QoS flow] ) ) to the AMF for the UE which is identified in step 4a. The associated unicast QoS Flow (s) as well as the mapping information between the unicast QoS Flow (s) and multicast QoS Flow (s) are included to support the 5GC Individual MBS traffic delivery.

The procedure continues at step 9.

5. [Conditional] If AMF determines that there are UEs in CM-IDLE state and involved in the multicast MBS Session, the AMF figures out the paging area covering all the registration areas of those UE (s) , which need to be paged. The AMF may apply paging differentiation as specified in clause 6.12. The AMF sends a Multicast Group paging request message to the NG-RAN node (s) belonging to this Multicast Paging Area with the involved UE list and TMGI as the identifier to be paged if the related NG-RAN node (s) support MBS. If the NG-RAN node (s) do not support MBS, the AMF sends Paging message (s) to the NG-RAN node (s) per UE as described in step 4b in clause 4.2.3.3 of TS 23.502 [6] .

NOTE 1: In addition to the paging in clause 6.12, other paging strategies is up to AMF implementation.

NOTE 2: The details of the paging are specified by the RAN WGs.

6. Receiving the paging, the UE (s) in CM-IDLE state sends Service Request message to the AMF, see clause 4.2.3 of TS 23.502 [6] .

NOTE 3: Step 6 for a UE can be parallel to step 5 for another UE (s) , which has not received any paging yet.

7a/7b. After receiving the Service Request sent by the UE (s) ,

- Either based on the received PDU Session ID in step 3, the AMF identifies the related SMF and invokes Nsmf_PDUSession_UpdateSMContext request. The procedure continues at step 9; or:

- Based on the received UE reachability Notification Address in step 3, the AMF identifies and notifies the related SMF of the UE (s) , which are reachable now and the Location Information, by using the Namf_MT_UEReachabilityInfoNotify message. In this case, it can be a separated notification or combined with step 8.

8a. For UE (s) that do not respond to paging, the AMF informs the SMF of the paging failure in Namf_MT_UEReachabilityInfoNotify.

8b. For UE (s) that is indicated as reachable via the Namf_MT_UEReachabilityInfoNotify message, or user plane of the associated PDU session is activated already but the QoS profile (s) for associated QoS flow (s) needs to be provided for the PDU session, the SMF invokes Namf_Communication_N1N2MessageTransfer (N2 SM information () ) to the AMF same as described in step 4b.

9. The AMF sends N2 request message (N2 SM information () ) to the RAN node.

NOTE 4: A joined UE is not able to receive MBS data if NG-RAN rejects the PDU Session Resource setup request (due to implementation specific reasons, e.g. activation of user plane fails due to the number of UEs reaching a limit) .

10a. If the shared tunnel has not been established before, the shared tunnel is established at this step, as defined in clause 7.2.1.4. The NG-RAN configures UE with RRC messages if needed.

10b. Steps 8 to 12 defined in clause 7.2.1.3 are performed. If 5GC Individual MBS traffic delivery is used, the SMF configures the UPF for individual delivery and if necessary, requests the MB-SMF to configure the MB-UPF to send multicast data to the UPF.

11. If the MB-SMF finds out there are shared tunnel established, step11-15 are performed. The MB-SMF invokes Namf_MBSCommunication_N2MessageTransfer Request (TMGI, N2 SM Information (Activation, TMGI) ) to the AMF for those NG-RAN nodes, which have shared tunnel with MB-UPF. This step may be performed in parallel with step 2.

NOTE 5: The messages in steps 10a, 11 and 12 are MBS-specific and it is possible that the AMF (s) in steps 10a, 11 and 12 are not associate to any UEs involved in the multicast MBS Session.

12. The AMF sends NGAP activation request message (N2 SM Information () ) to the NG-RAN nodes. For those UEs that have joined in the MBS Session and are in RRC_INACTIVE state, the RAN nodes perform RAN paging as specified in TS 38.300 [9] .

13. The NG-RAN nodes responses to AMF by NGAP activation response message. The NG-RAN nodes establish radio resources to transmit multicast MBS session data to the UE (s) . The NG-RAN shall not release the radio connection of a UE that has joined into the Multicast MBS session only because no unicast traffic is received for the UE.

14. AMF to MB-SMF: Namf_MBSCommunication_N2MessageTransfer Response () .

15. The MB-SMF sends N4mb Session Modification Request to the MB-UPF to forward the receiving packet. The MB-UPF responds to the MB-SMF with N4mb Session Modification Response acknowledging the MB-SMF request. See clause 4.4 of TS 23.502 [6] for more details.

The following content are mainly from clause 7.2.5.3 of 3GPP TS 23.247 v17.4.0.

MBS session deactivation procedure

FIG. 1i shows a flowchart of MBS session deactivation procedure, which is same as Figure 7.2.5.3-1 of 3GPP TS 23.247 v17.4.0.

In this procedure, steps 3 to 4 and steps 5 to 9 are executed in parallel.

1. The procedure may be triggered by the following events:

- When MB-UPF detects there is no data receives for the MBS Session, MB-UPF sends MB-N4 Notification (N4 Session ID) to the MB-SMF for deactivating the MBS session.

- AF sends MBS Deactivation request (TMGI) to the MB-SMF directly or via NEF.

2. The MB-SMF send N4mb Session Modification Request (TMGI, Buffered Downlink Traffic detection) to the MB-UPF. See clause 4.4 of TS 23.502 [6] for more details. The Buffered Downlink Traffic detection is requested by MB-SMF for next time MBS session activation. If the MBS session is to be activated via the AF request directly, this indication is not needed. The MB-SMF also indicates the MB-UPF to remove the shared tunnel (s) that are used for Individual MBS traffic delivery over N19mb interface.

MB-UPF to MB-SMF: N4mb Session Modification Response acknowledging the MB-SMF request.

3. The MB-SMF sends Nmbsmf_MBSSession_ContextStatusNotify request (MBS Session ID) to the SMFs.

Based on the received MBS Session ID, the SMF sets the indicated multicast MBS session state to Inactive:

‐ If the SMF finds out there are UE (s) that joined the indicated multicast MBS session and use 5GC Individual MBS traffic delivery, step 4 is performed for those UE (s) .

‐ If SMF find there are no UE (s) that joined the indicated MBS session and use 5GC Individual MBS traffic delivery, no further operation for SMF is required.

4. [Conditional] For those UE (s) that the 5GC individual delivery is used, step 3b and steps 4-8 in clause 4.3.3.2 of TS 23.502 [6] are performed to remove the associated QoS flow (s) related to the multicast MBS session.

NOTE 1: Whether the associated QoS Flow (s) are removed from UE, NG-RAN, or only resource in NG-RAN is removed is up to implementation.

5. If the MB-SMF finds out there are shared tunnel established over N3mb interface, the MB-SMF sends Namf_MBSCommunication_N2MessageTransfer Request (TMGI, N2 SM information (Deactivation, TMGI) ) to the AMFs.

6. The AMF sends NGAP deactivation request message (N2 SM information () ) to the NG-RAN nodes.

7. The NG-RAN node keeps the multicast MBS Session Context and N3mb shared tunnel for the multicast MBS session.

If the MBS Session Context indicates no UE for the multicast MBS session (e.g. due to UE becomes CM-IDLE state) , the NG-RAN triggers release of the shared delivery as described in clause 7.2.2.4.

8. NG-RAN acknowledges the NGAP deactivation Response message.

9. The AMF invokes Namf_MBSCommunication_N2MessageTransfer Response to acknowledge the service for MB-SMF.

When the MBS session is in "Inactive" state and handover procedure is triggered, it is defined in clause 7.2.3.6.

NOTE 2: There is no explicit "deactivation" indication to the UE, how the UE is changed to IDLE state is defined in TS 38.300 [9] .

The following content are mainly from clause 7.2.6 of 3GPP TS 23.247 v17.4.0.

Multicast session update procedure

Multicast MBS session update procedure is invoked by the AF to update the service requirement (result in multicast QoS parameters update and/or multicast QoS flow addition/removal) and/or MBS Service Area for an ongoing Multicast MBS session. For the interaction between AF and MB-SMF, see clause 7.1.1.6 and 7.1.1.7 of 3GPP TS 23.247 v17.4.0.

FIG. 1j shows a flowchart of Multicast MBS Session update procedure, which is same as Figure 7.2.6-1 of 3GPP TS 23.247 v17.4.0.

1. This procedure is triggered by the MB-SMF receiving the updated service requirement and/or MBS Service Area for a multicast MBS Session, see clauses 7.1.1.6 and 7.1.1.7.

2. The AF providing the updated service area may also inform UEs at application level about the new service area via a service announcement.

NOTE 1: If a UE is located in a cell which was previously outside the service area and is now inside the updated service area, the UE can join the multicast service as specified in clause 7.2.1.3.

For QoS updates steps 3 to 7 are performed.

For MBS Service Area update steps 3 to 7 may be performed to allow NG-RAN to terminate data transmission in the area which is no longer in the MBS Service Area.

3. The MB-SMF invokes Namf_MBSCommunication_N2MessageTransfer service operation (MBS Session ID, [Area Session ID] , N2 SM message container (TMGI, [QoS profile (s) for multicast MBS session] , [MBS Service Area] , [Area Session Id] ) ) to the AMF (s) .

4. The involved AMF sends N2 MBS session request (N2 SM message container) to NG-RAN nodes handling the multicast MBS session and possible Area Session ID based on the RAN node IDs stored in the AMF for the MBS session.

5. The NG-RAN node updates the QoS profile and/or MBS Service Area for the multicast MBS session based on the N2 MBS session request. If only QoS parameters are updated without multicast QoS flows added/removed, the NG-RAN may also update the QoS parameters of the associating PDU Sessions.

For MBS Service Area update, the NG-RAN updates the MBS Session Context with the updated MBS Service Area. The NG-RAN stops transmission of the related multicast data in the cell (s) which is within the old MBS Service Area but now outside the updated MBS Service Area. The NG-RAN also configures the UE not to receive the MBS data over the radio interface if the NG-RAN detects the UE (s) was in the previous MBS Service Area but is outside the updated MBS Service Area. If the NG-RAN node no longer serves any cells within the updated MBS service area, it requests to release shared delivery resource as defined in clause 7.2.2.4.

6. The NG-RAN node (s) acknowledges N2 MBS session request by sending an N2 MBS session Response message to the AMF.

7. The AMF invokes the Nmbsmf_MBSSession_ContextUpdate () to the MB-SMF.

8. The MB-SMF sends Nmbsmf_MBSSession_ContextStatusNotify request (MBS Session ID, [QoS profiles for multicast for MBS session] , [MBS Service Area] , [Area Session ID] ) to the SMFs. For MBS Service Area updates, if an Area Session ID exists, the MB-SMF provides the MBS Service Area corresponding to the Area Session ID to the SMFs involved in the multicast MBS session. For QoS updates, the MB-SMF notifies SMFs handling all service areas.

9. The SMF determines the affected UEs it serves based on the multicast MBS Session ID and Area Session ID (if provided) received in the step 8.

The subsequent steps 10 to 12 are executed for each affected UE. For QoS updates, steps 10 and 11 are skipped.

10. [Conditional] For an MBS Service Area update, if the SMF previously subscribed at the AMF to notifications about the UE moving in or out of a subscribed "Area Of Interest" , the SMF updates the subscription with the new MBS Service Area as area of interest.

11. [Optional] When the MBS Service Area is updated, if the SMF does not have the latest UE location, the SMF queries AMF which then query the NG-RAN for the current location of the UE to determine whether the UE is within the updated MBS Service Area.

12. [Conditional] For QoS Updates, if the 5GC Individual MBS traffic delivery is used, or if the associated QoS flows is to be added/removed, the SMF triggers PDU Session Modification procedure as defined in TS 23.502 [6] .

For MBS Service Area update, the SMF triggers the PDU Session Modification procedure as defined in TS 23.502 [6] with the following enhancement:

The SMF also updates the PDU session resources associated to the multicast MBS session with the new MBS service area in an N2 container. The RAN node serving the PDU session starts or terminates transmission of multicast content in cells which are added or removed in the updated service area, respectively, and if necessary, interacts with the MB-SMF to start or terminate the distribution of multicast data to the RAN node.

- Towards the UE, the SMF provides the MBS service area in N1 SM container to the UE. For a UE previously inside the MBS service area but now outside the updated MBS service area of the multicast MBS session, the SMF may alternatively, based on operator policy, inform the UE in the N1 SM container that the UE has been removed from the multicast MBS session.

- Towards the NG-RAN, the SMF provides the updated MBS service area in N2 SM information. For a NG-RAN node supporting MBS, it starts transmission of multicast content in cells which are added in the updated MBS service area if UEs within the Multicast MBS session are within those cells, and if necessary, the NG-RAN interacts with the MB-SMF to start the distribution of multicast data to the RAN node. The RAN node stops transmission of multicast content in cells which are removed from the updated MBS service area, and if necessary, the NG-RAN interacts with the MB-SMF to terminate the distribution of multicast data to the RAN node

- For Individual delivery and a local Multicast MBS session the following applies: For a UE previously inside the service area but now outside the updated MBS service area, the SMF removes associated unicast QoS flows for the multicast MBS session. For a UE previously outside the service area but now inside the updated service area, the SMF adds associated unicast QoS flows for the multicast MBS session to the PDU session resources.

The following content are mainly from clause 6.7 of 3GPP TR 23.700-47 v1.0.0.

6.7 Solution #7: MOCN RAN Sharing

6.7.1 Introduction

This solution addresses Key Issue #2.

6.7.2 Functional description

This solution utilizes the associated session identifier (e.g. SSM used by AF) to be the identifier to associate broadcast MBS sessions from different CNs which transmitting the same content.

The AF provides the associated session ID when creating broadcast MBS sessions with the same broadcast content. In all CNs, MB-SMF provides the associated session ID to the NG-RAN via the AMF. And then, the NG-RAN can utilize the associated session ID to associate those broadcast MBS sessions.

NG-RAN establishes the user planes for the first broadcast MBS session it receives. The NG-RAN delivers the packets received from the established user plane over the air. For the other broadcast MBS sessions which are associated with the broadcast MBS session, the NG-RAN creates the broadcast MBS session contexts, advertises the TMGIs, but does not establish the user planes.

In case there is a failure in the established user plane, the NG-RAN selects another associated broadcast MBS session to establish the user plane and continue to deliver the packets received from the newly established user plane over the air.

NOTE: The security mechanism for MBS traffic transmission specified in clause W. 4 of TS 33.501 [14] is not applicable, while the content protection in AF can be applied for the content encryption and decryption.

6.7.3 Procedures

6.7.3.1 General

NOTE: The message names in the procedures below are descriptive. It is assumed that the names are updated with corresponding SBI based names where applicable during the normative phase.

The following content are mainly from clause 6.7.3.2 of 3GPP TR 23.700-47 v1.0.0.

MBS Session Creation

FIG. 1k shows a flowchart of MBS Session Creation for MOCN RAN sharing, which is same as Figure 6.7.3.2-1 of 3GPP TR 23.700-47 v1.0.0.

The following additions apply compared to clause 7.1.1.2 of 3GPP TS 23.247 V17.4.0:

8. The AF provides the associated session ID (e.g. SSM used by AF) to the NEF/MBSF when invoking Nnef_MBSSession_Create Request.

11. The NEF/MBSF provides the associated session ID to the MB-SMF when invoking Nmbsmf_MBSSession_Create Request. The MB-SMF stores the associated session ID as a part of the MBS session context to be further distributed to NG-RAN in clause 6.7.3.3.

The same updates apply to clause 7.1.1.3 of 3GPP TS 23.247 V17.4.0.

The following content are mainly from clause 6.7.3.3 of 3GPP TR 23.700-47 v1.0.0.

MBS Session Start for Broadcast

FIG. 1l shows a flowchart of MBS Session Start for Broadcast for MOCN RAN sharing, which is same as Figure 6.7.3.3-1 of 3GPP TR 23.700-47 v1.0.0.

The following additions apply compared to clause 7.3.1 of 3GPP TS 23.247 V17.4.0:

2-3. The MB-SMF provides the associated session ID in the N2 SM container to the NG-RAN via AMF.

4. The NG-RAN creates the Broadcast MBS Session context including the associated session ID. If the NG-RAN determines there is already established user plane of another broadcast MBS session which is associated (identified by same associated session ID) , the NG-RAN skips the user plane establishment of this broadcast MBS session.

If multicast transport of N3mb applies, the NG-RAN skips step 5.

If unicast transport of N3mb applies, the NG-RAN does not allocate N3mb DL Tunnel Info in step 6, and not include it in the N2 message towards MB-SMF in step 6-7 or step 10-11, so that step 8 or step 12 can also be skipped.

9. If the NG-RAN determines the radio resource of another broadcast MBS Session is allocated which is associated (identified by the same associated session ID) , the NG-RAN advertises the TMGI of the broadcast MBS session and link the TMGI to the existing radio resources.

14-15. In case the user plane of the broadcast MBS session is not established, the NG-RAN will not receive the packets from the MB-UPF.

The following content are mainly from clause 6.7.3.4 of 3GPP TR 23.700-47 v1.0.0.

MBS Session Release for Broadcast

FIG. 1m shows a flowchart of MBS Session Release for Broadcast for MOCN RAN sharing, which is same as Figure 6.7.3.4-1 of 3GPP TR 23.700-47 v1.0.0.

The following additions apply compared to clause 7.3.2 of 3GPP TS 23.247 V17.4.0:

5. If the user plane of the broadcast MBS session has not been established, the NG-RAN simply stops the advertisement of the TMGI without releasing the user plane which hasn't been established. That is, step 6 is skipped for multicast transport of N3mb, and for unicast transport of N3mb DL Tunnel Info is not provided in steps 7-8.

If the user plane of the broadcast MBS session has been established, the NG-RAN checks whether there are other associated broadcast MBS sessions. If there are, the NG-RAN may trigger Broadcast MBS Session Transport Request as specified in clause 6.7.3.5.

The following content are mainly from clause 6.7.3.5 of 3GPP TR 23.700-47 v1.0.0.

Broadcast MBS Session Transport Request

When NG-RAN detects there is a failure in the user plane which causes the NG-RAN cannot deliver the contents, the NG-RAN select another CN to trigger Broadcast MBS Session Transport Request procedure to establish the user plane. The selecting of CN can be up to NG-RAN implementation.

It may apply to the scenario when the broadcast MBS session is released in that CN, whose user plane is used to content transmission, while there are some other broadcast MBS sessions not released.

FIG. 1n shows a flowchart of Broadcast MBS Session Transport Request, which is same as Figure 6.7.3.5-1 of 3GPP TR 23.700-47 v1.0.0.

1. NG-RAN selects a CN to establish user plane, utilizing the broadcast MBS session context stored in the NG-RAN.

2. If multicast transport of N3mb applies, the NG-RAN performs join the multicast group towards the LL SSM provided by the CN, and skip step 2 to step 5.

3. If unicast transport of N3mb applies, the NG-RAN allocates N3mb DL Tunnel Info, and sends N2 message (e.g. BROADCAST SESSION TRANSPORT REQUEST) to AMF, including the MBS Session ID and the N3mb DL Tunnel Info.

4. The AMF transfers the Namf_MBSBroadcast_ContextStatusNotify request to the MB-SMF, which contains the N2 message.

5. If unicast transport of N3mb applies, the MB-SMF sends an N4mb Session Modification Request to the MB-UPF to allocate the N3mb point-to-point transport tunnel for a replicated MBS stream for the MBS Session. The MB-UPF sends N4mb Session Modification Response to the MB-SMF.

6. The MB-SMF sends Namf_MBSBroadcast_ContextStatusNotify response to the AMF, which contains the N2 information.

7. The AMF forwards the received N2 information in N2 message (e.g. BROADCAST SESSION TRANSPORT RESPONSE) to the NG-RAN

8. The MB-UPF transmits the media stream to NG-RAN via N3mb multicast transport or unicast transport.

9. The NG-RAN brings the packets received over the air, reusing the existing radio resource.

The following content are mainly from clause 6.7.4 of 3GPP TR 23.700-47 v1.0.0.

Impacts on services, entities and interfaces

Functional entities defined in clause 5.3.2 of 3GPP TS 23.247 V17.4.0 are reused exception for the following additions:

AF:

- Provide the associated session ID (e.g. SSM used by AF) to 5GC when creating MBS session.

NEF:

- Provides the associated session ID to the MB-SMF if received in MBS Session Creation.

MB-SMF:

- Provides the associated session ID to the NG-RAN if received in MBS Session Start for Broadcast.

NG-RAN:

- Support the associated session ID and understand the association among those broadcast MBS sessions which delivers the same content.

- When broadcast MBS session start, if there is already established user plane of associated broadcast MBS session, the NG-RAN skips the user plane establishment of the broadcast MBS session.

- When broadcast MBS session release, if the user plane hasn't been established, the NG-RAN skips the user plane release of the broadcast MBS session. If the user plane has been established and there are some other associated broadcast MBS sessions, the NG-RAN may trigger Broadcast MBS Session Release Require procedure for each associated broadcast MBS session or trigger Broadcast MBS Session Transport Request procedure.

- When NG-RAN detects there is a failure in the CN which causes the NG-RAN cannot deliver the contents, the NG-RAN select another CN to trigger Broadcast MBS Session Transport Request procedure to establish the user plane.

FIG. 2 shows a flowchart of a method according to an embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to an application node. As such, the apparatus may provide means for accomplishing various parts of the method 200 as well as means for accomplishing other processes in conjunction with other components.

At block 202, the application node may send a first message to a first network function in a first network or a second network function in the first network.

In an embodiment, the first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID.

In an embodiment, the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

The MBS session ID may be any suitable ID. For example, the MBS session ID may be a Source Specific IP Multicast address (SSM) or a temporary mobile group identity (TMGI) or a flag. For example, it is also possible to user one specific TMGI together with MOCN flag to indicate NG-RAN the associated multicast MBS sessions.

The associated session ID may be any suitable ID. In an embodiment, the at least one associated session ID comprises at least one of at least one source-specific multicast Internet protocol address, or at least one temporary mobile group identity (TMGI) or an MOCN network sharing indicator.

For example, AF creates 3 MBS sessions (TMGI1, TMGI2, TMGI3 are to be used as MBS session IDs) and decides to use TMGI1 to be the associated session ID. Then AF creates the first MBS session with TMGI1 as MBS session ID, TMGI1 as associated session identifier. AF creates the second MBS session with TMGI2 as MBS session ID, TMGI1 as associated session identifier. AF creates the third MBS session with TMGI3 as MBS session ID, TMGI1 as associated session identifier.

For example, when there are multiple MBS sessions which are associated in shared RAN scenario, the RAN node may establish at least one user plane of those MBS sessions. NG-RAN may determine and select one MBS session to be broadcasted over the air. And it may drop the packets of other MBS sessions. Alternatively RAN node may establish the user plane of one MBS session and inform MB-SMFs of not establishing the others. And RAN node will deliver the packets of this MBS session over the air.

For example, if the application node determines to use TMGI as associated session ID, it needs to select one from those TMGIs which are to be used to create MBS sessions transmitting the same content. The AF also uses this TMGI in the service announcement.

The application node may be any suitable node which can provide similar or same function as the AF as described in 3GPP TS 23.501 V17.5.0 or the Application Server (AS) or Services Capability Server (SCS) as described in 3GPP TS 23.682 V17.2.0. For example, the application node may be a content provider or a multicast source or a broadcast source.

In an embodiment, the application node comprises AF as described in 3GPP TS 23.501 V17.5.0.

In an embodiment, the application node comprises AS/SCS as described in 3GPP TS 23.682 V17.2.0.

In an embodiment, the application node comprises Edge Enabler Server (EES) as described in 3GPP TS 23.558 V17.4.0.

In an embodiment, the application node may determine to multicast the same content towards different PLMNs (e.g., via different MB-SMFs) . The application node may know that multiple CNs of different PLMNs are connected to the same RAN.

The first network may be any suitable network such as wireless network. In an embodiment, the first network may comprise a 3GPP network.

The first network function may be any suitable network function which can provide similar or same function as the NEF, MBSF, a combined NEF and MBSF as described in 3GPP TS 23.501 V17.5.0 or Service Capability Exposure Function (SCEF) as described in 3GPP TS 23.682 V17.2.0. In an embodiment, the first network function comprises at least one of NEF, MBSF, or a combined NEF and MBSF. In another embodiment, the first network function comprises SCEF.

The second network function may be any suitable network function which can provide similar or same function as the Multicast/Broadcast Session Management Function (MB-SMF) as described in 3GPP TS 23.501 V17.5.0 or Broadcast Multicast Service Centre (BM-SC) as described in 3GPP TS 23.682 V17.2.0. In an embodiment, the second network function comprises MB-SMF. In another embodiment, the second network function comprises BM-SC.

The first message may be any suitable message such as an existing message or a new message.

In an embodiment, the first message may be MBS session create request such as Nnef_MBSSession_Create Request as described in clause 7.1.1 of 3GPP TS 23.247 V17.4.0.

The MBS identifier may be any suitable identifier which can be used to identify a multicast MBS Session. In an embodiment, the multicast or broadcast service identifier may comprise a temporary mobile group identity (TMGI) .

The MBS identifier may be allocated by a network function (such as MB-SMF or BM-SC) in a network. For example, in 5G MOCN network sharing scenarios, the MBS identifier may be allocated by a MB-SMF of a network.

Clause 7.1.1.2 of 3GPP TS 23.247 V17.4.0 describes TMGI Allocation Procedure. For example, AF may send Nnef_TMGI_Allocate Request (TMGI number) message to NEF/MBSF to request allocation of a TMGI (s) to identify new MBS session (s) . AF may send an Nmbsmf_TMGI_Allocate Request (TMGI number) message to the MB-SMF when the AF is in the trusted domain where NEF is not mandated. Alternatively AF may request that the network allocates an identifier for the MBS session (i.e., TMGI) via a Nnef_MBSSession_Create request or Nmbsmf_MBSSession_Create Request. 3GPP TS 23.468 V16.0.0, the disclosure of which is incorporated by reference herein in its entirety, also describes TMGI Allocation Procedure and Activate MBMS Bearer Procedure.

FIG. 3 shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a first network function in a first network. As such, the apparatus may provide means for accomplishing various parts of the method 300 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 302, the first network function may receive a first message from an application node. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID.

For example, the application node may send the first message to the first network function at block 202 of FIG. 2, and then the first network function may receive the first message from the application node.

In an embodiment, the first network function may be SCEF.

In an embodiment, the first message may be MBS session create request such as Nnef_MBSSession_Create Request as described in as described in clause 7.1.1 of 3GPP TS 23.247 V17.4.0.

In an embodiment, the application node comprises an application function.

In an embodiment, the first network comprises a 3rd Generation Partnership Project (3GPP) network.

At block 304, the first network function may send a second message to a second network function in the first network. The second message comprises the MBS session ID and at least one associated session ID.

In an embodiment, the second network function comprises Multicast/Broadcast Session Management Function (MB-SMF) or BM-SC.

The second message may be any suitable message such as an existing message or a new message.

In an embodiment, the second message may be an MBS session create request such as Nmbsmf_MBSSession_Create Request as described in as described in clause 7.1.1 of 3GPP TS 23.247 V17.4.0.

FIG. 4a shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a second network function in a first network. As such, the apparatus may provide means for accomplishing various parts of the method 400 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 402, the second network function may receive a first message or a second message from an application node or a first network function in the first network. The first message and/or the second message comprise a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID.

In an embodiment, the first message may be an MBS session create request.

In an embodiment, the second message may be an MBS session create request.

In an embodiment, the at least one associated session ID may be used to make an association for two or more multicast MBS sessions with same content across two or more networks.

In an embodiment, the first network function may comprise at least one of Network Exposure Function (NEF) , Multicast/Broadcast Service Function (MBSF) , or a combined NEF and MBSF.

In an embodiment, the second network function may comprise Multicast/Broadcast Session Management Function (MB-SMF) .

At block 404, the second network function may send a third message to a third network function in the first network or a fourth network function in the first network. The third message comprises the MBS session identifier and the at least one associated session ID.

The third message may be any suitable message such as a new message or an existing message.

In an embodiment, the third message may be an MBS session context status subscribe response such as Nmbsmf_MBSSession_ContextStatusSubscribe response as described in clause 7.2.1.3 of 3GPP TS 23.247 V17.4.0.

In an embodiment, the third message may be an MBS session context status update response such as Nmbsmf_MBSSession_ContextUpdate response as described in clause 7.2.1.3 of 3GPP TS 23.247 V17.4.0.

In an embodiment, the at least one associated session ID is included in N2 SM information which is a Distribution Setup Response specified in clause 9.2.17.2 of 3GPP TS 38.413 V17.2.0.

For example, the N2 SM information (Distribution Setup Response) may be applied to MBS session context status update response.

In an embodiment, the third message (such as MBS session context status subscribe response) may be not caused by the first/second message (such as MBS session create request) . The third message may be caused by MBS session context status subscribe request, which may be caused by UE Join or other suitable reasons.

The third network function may be any suitable network function. In an embodiment, the third network function may comprise a session management function (SMF) .

In an embodiment, the application node comprises an application function.

The fourth network function may be any suitable network function. The fourth network function comprises an access and mobility management function (AMF) .

FIG. 4b shows a flowchart of establishment of shared delivery toward RAN node according to another embodiment of the present disclosure, which is similar to the procedure of establishment of shared delivery toward RAN node as described in clause 7.2.1.4 of 3GPP TS 23.247 V17.4.0.

Clause 7.2.1.4 of 3GPP TS 23.247 V17.4.0 described the steps as below.

1. A NG-RAN node decides to establish shared delivery for a multicast MBS session when it serves at least one UE within the multicast MBS session. For location dependent services, the NG-RAN node needs to establish shared delivery for the location dependent contents of a multicast MBS session if it serves at least one UE assigned to an MBS Session ID and Area Session ID.

2. The NG-RAN sends an N2 MBS Session request message (MBS Session ID, [Area Session ID] , N2 SM information ( [unicast DL tunnel Info] ) ) towards the AMF.

If the NG-RAN node is configured to use unicast transport for the shared delivery, it allocates a GTP tunnel endpoint and provides the unicast DL tunnel Info in the request, which includes the GTP tunnel endpoint and NG-RAN node address. For location dependent MBS services, the NG-RAN node also provides the Area Session ID.

3. The AMF selects the MB-SMF serving the multicast MBS session, e.g. using the NRF discovery service or locally stored information. It invokes Nmbsmf_MBSSession_ContextUpdate request (MBS Session ID, [Area Session ID] , N2 SM information) to the MB-SMF.

The AMF stores the information of the NG-RAN nodes (e.g. NG-RAN node ID) for the subsequent signaling related to the multicast MBS Session.

4. [Conditional] If the MB-SMF received unicast DL tunnel Info in step 3, it configures the MB-UPF to send multicast data for the multicast MBS session (or location dependent content of the multicast MBS session if an Area Session ID was received) towards that GTP tunnel endpoint via unicast transport.

5. The MB-SMF stores the information of the AMF (e.g. AMF ID) in the MBS Multicast MBS session context (or location dependent part of the Multicast MBS Session Context if an Area Session ID was received) to enable subsequent signalling towards that AMF.

6. The MB-SMF sends Nmbsmf_MBSSession_ContextUpdate response (MBS Session ID, [Area Session ID] , N2 SM information ( [TMGI] , multicast QoS flow information, session state (Active/Inactive) , [multicast DL tunnel Info] , [MBS service areas] ) ) to the AMF. If the MB-SMF did not receive unicast DL tunnel Info in step 3, it provides the multicast DL tunnel info that includes transport multicast address (e.g. a LL SSM) and a GTP tunnel endpoint for multicast transport of the shared delivery.

7. The AMF sends an N2 MBS Session response message (MBS Session ID, [Area Session ID] , N2 SM information) to the NG-RAN node. If the NG-RAN node receives the multicast DL tunnel Info of the shared delivery, it uses the transport multicast address included in the multicast DL tunnel info to join the multicast transport distribution.

The following additions apply compared to clause 7.2.1.4 of 3GPP TS 23.247 V17.4.0:

In step 5, MB-SMF includes the associated session ID in N2 SM info.

In step 6, MB-SMF sends the N2 message in Nmbsmf_MBSSession_ContextUpdate response to AMF.

In step 7, AMF sends N2 message to NG-RAN. The N2 message is Distribution Setup Response specified in clause 9.2.17.2 of 3GPP TS 38.413 V17.2.0.

FIG. 5 shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a third network function in a first network. As such, the apparatus may provide means for accomplishing various parts of the method 500 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 502, the third network function may receive a third message from a second network function in the first network. The third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID.

In an embodiment, the third message may be an MBS session context status subscribe response.

In an embodiment, the third message (such as MBS session context status subscribe response) may be caused by MBS session context status subscribe request sent by the third network function, which may be caused by UE Join or other suitable reasons.

In an embodiment, the third network function may comprise a session management function (SMF) .

At block 504, the third network function may send a fourth message to a fourth network function in a first network. The fourth message comprises the MBS session ID and at least one associated session ID.

The fourth message may be any suitable message such as a new message or an existing message.

In an embodiment, the fourth message may be a protocol data unit (PDU) session update session management (SM) context response such as Nsmf_PDUSession_UpdateSMContext response as described in clause 7.2.1.3 of 3GPP TS 23.247 V17.4.0 or an N1N2 Message Transfer request as described in 3GPP TS 23.502 V17.5.0.

In an embodiment, the fourth message may be caused by Nsmf_PDUSession_UpdateSMContext request sent by the fourth network function, which may be caused by UE Join or other suitable reasons.

In an embodiment, the at least one associated session ID may be included in N2 SM information which may be a PDU session resource setup request or PDU session modification request.

The fourth network function may be any suitable network function. For example, the fourth network function may be AMF as described in 3GPP TS 23.501 V17.5.0 or MBMS-GW (MBMS gateway) /GGSN (Gateway GPRS (General Packet Radio Service) Support Node) MME (Mobile Management Entity) /SGSN (Serving GPRS Support Node) as described in 3GPP TS 23.682 V17.2.0.

In an embodiment, the fourth network function may comprise an access and mobility management function (AMF) .

In an embodiment, the fourth network function may comprise MBMS-GW/GGSN/MME/SGSN.

FIG. 6 shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a fourth network function in a first network. As such, the apparatus may provide means for accomplishing various parts of the method 600 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 602, the fourth network function may receive a fourth message from a third network function in the first network or another fourth network function in the first network or a third message from a second network function in the first network. The fourth message and/or the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID.

In an embodiment, the fourth message may be a protocol data unit (PDU) session update session management (SM) context response or an N1N2 Message Transfer request or a communication create user equipment (UE) context request.

In an embodiment, the third network function may comprise a session management function (SMF) or BM-SC.

At block 604, the fourth network function may send a fifth message to a radio access network node. The fifth message comprises the MBS session ID and at least one associated session ID.

The fifth message may be any suitable message such as an existing message or a new message. In an embodiment, the fifth message may be an N2 message such as the N2 message request as described in clause 7.2.1 of 3GPP TS 23.247 V17.4.0.

In an embodiment, the N2 message may comprise at least one of a Distribution Setup Response for example as described in 3GPP TS 38.413 V17.2.0, a PDU session resource setup request for example as described in 3GPP TS 23.247 V17.4.0, a PDU session modification request for example as described in 3GPP TS 23.247 V17.4.0, or a handover request for example as described in 3GPP TS 23.247 V17.4.0.

In an embodiment, the fourth network function may comprise an access and mobility management function (AMF) or a target AMF.

For example, in N2 based handover as described in clause 7.2.3.3 of 3GPP TS 23.247 V17.4.0. Source AMF may send a Namf_Communication_CreateUEContext request to Target AMF. The T-AMF is provided with associated PDU Session information and the MBS session related information. SMF sends update SM context response to Target AMF. Target AMF sends Handover Request to NG-RAN. The Handover Request is a N2 message. And then, it may trigger NG-RAN to establish the shared delivery. At this time, NG-RAN may detect whether there is associated MBS session already available.

FIG. 7a shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a radio access network node. As such, the apparatus may provide means for accomplishing various parts of the method 700 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 702, the radio access network node may receive a fifth message from a fourth network function in a first network or another radio access network node. The fifth message may comprise a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID may be used to make an association for two or more multicast MBS sessions with same content across two or more networks.

For example, in Xn based handover as described in clause 7.2.3.2 of 3GPP TS 23.247 V17.4.0. Source NG-RAN may send Xn message to Target NG-RAN. Target NG-RAN may establish the shared delivery. At this time, NG-RAN may detect whether there is associated MBS session already available.

At block 704, the radio access network node may check whether at least one radio resource has been allocated for delivering the same content.

At block 706, when the at least one radio resource has not been allocated, the radio access network node may allocate the at least one radio resource.

At block 708, when the at least one radio resource has been allocated, the radio access network node may skip allocating the at least one radio resource.

In an embodiment, the radio access network node may link the MBS session ID and/or the at least one associated session ID to the at least one radio resource.

In an embodiment, the fifth message may be an N2 message.

In an embodiment, the N2 message comprises at least one of a PDU session resource setup request, a PDU session modification request, a distribution setup response, or a handover request.

FIG. 7b shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a radio access network node. As such, the apparatus may provide means for accomplishing various parts of the method 710 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 712, optionally, the radio access network node may establish a user plane of an associated multicast MBS session of the first network. For example, the radio access network node may use the Multicast session join and session establishment procedure as described in clause 7.2.1.3 of 3GPP TS 23.247 V17.4.0 to establish a user plane of an associated multicast MBS session of the first network.

At block 714, optionally, when a predefined number of user planes of the two or more multicast MBS sessions have not been established, the radio access network node may establish a user plane of an associated multicast MBS session of the first network.

At block 716, optionally, when a predefined number of user planes of the two or more multicast MBS sessions have been established, the radio access network node may skip an establishment of a user plane of an associated multicast MBS session of the first network.

At block 718, optionally, when the same content can be received from a user plane function of another network, the radio access network node may skip an establishment of a user plane of an associated multicast MBS session of the first network.

FIG. 7c shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a radio access network node. As such, the apparatus may provide means for accomplishing various parts of the method 720 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 722, when no terminal device is joined in a current multicast MBS session, the radio access network node may release a user plane of the current multicast MBS session.

For example, the radio access network node may use the procedure of UE initiated Multicast MBS Session leave as described in clause 7.2.2.4 of 3GPP TS 23.247 V17.4.0 to release a user plane of the current multicast MBS session. For example, the radio access network node may send an N2 MBS Session Release request to AMF and receive an N2 MBS Session Release response from the AMF.

At block 724, when at least one terminal device is joined in the two or more multicast MBS sessions and the user plane of the current multicast MBS session is released (which cause no multicast content can be received by the radio access network node or the predefined number of user planes of the two or more multicast MBS sessions have not been established) , the radio access network node may select another network to establish a user plane of an associated multicast MBS session to receive the same content.

FIG. 7d shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a radio access network node. As such, the apparatus may provide means for accomplishing various parts of the method 730 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 732, the radio access network node may detect there is a failure in a network which causes the radio access network node cannot deliver the same content.

At block 734, the radio access network node may select another network to establish a user plane of an associated multicast MBS session to receive the same content.

FIG. 7e shows a flowchart of a method according to another embodiment of the present disclosure, which may be performed by an apparatus implemented in/as or communicatively coupled to a radio access network node. As such, the apparatus may provide means for accomplishing various parts of the method 740 as well as means for accomplishing other processes in conjunction with other components. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

At block 742, optionally, when no terminal device is joined in the two or more multicast MBS sessions, the radio access network node may release the at least one radio resource.

At block 744, optionally, for paging and notification in MBS session activation, the radio access network node may page all terminal devices joined in the two or more multicast MBS sessions which are in CM-IDLE state or in CM-CONNECTED with RRC_INACTIVE state.

At block 746, optionally, when MBS session update, the radio access network node may make the MBS session update to take effect to all the associated MBS sessions transmitting the same content.

At block 748, optionally, the radio access network node may send a sixth message to a target radio access network node. The sixth message comprises the MBS session ID and the at least one associated session ID. For example, the sixth message may be an Xn message in Xn based handover with MBS Session.

In an embodiment, the sixth message is an Xn message.

In an embodiment, the Xn message may comprise at least one of a Retrieve UE Context Response for example as described in 3GPP TS 38.423 V17.2.0, a RAN Multicast Group paging message for example as described in 3GPP TS 38.423 V17.2.0, or a handover request for example as described in 3GPP TS 38.423 V17.2.0.

In an embodiment, this solution is based on the solution#7 in 3GPP TR 23.700-47 v1.0.0.

It proposed to enable MB-SMF and SMF to pass associated session identifier to NG-RAN, which was received from the AF. The MOCN shared NG-RAN can identify the multicast MBS sessions from different CNs, which transmit the same content from the AF.

For those associated multicast MBS sessions, the NG-RAN only allocates the radio resource for one session and configures the UEs from different PLMNs based on such radio resource.

User plane handling:

In an embodiment, for those associated multicast MBS sessions, the optimized solution is to enable NG-RAN to establish only one user plane. That is, if NG-RAN determines there is already established user plane of another multicast MBS session which is associated (identified by same associated session ID) , the NG-RAN skips the establishment of shared delivery.

In an embodiment, if there is a failure of the on-going user plane, or the on-going user plane is released, the NG-RAN initiate the user plane establishment towards another CN, and delivery the packets from the user plane over the existing radio resource.

In an embodiment, if NG-RAN determines no UEs joined in the MBS session while the user plane of the MBS session is established, the NG-RAN may release the user plane of this MBS session and establish the user plane towards another CN where there are UE joined in the MBS session there.

In an embodiment, due to there is only one user plane established, the NG-RAN will receive only one MBS session activation request when MBS session is activated, the NG-RAN may page all the joined UEs for those multiple MBS sessions.

In an embodiment, it is also possible that NG-RAN does not optimize the user plane handling. That is, the NG-RAN may establish all user planes for those multicast MBS sessions.

In an embodiment, if there is a failure of the on-going user plane, or the on-going user plane is released, the NG-RAN may simply deliver the packets from another user plane locally.

In an embodiment, if NG-RAN determines no UEs joined in the MBS session, the NG-RAN may release the user plane of this MBS session as legacy.

In an embodiment, Due to all the user planes established, the NG-RAN may page the UEs per PLMN based on the multicast MBS session request it receives as legacy.

In an embodiment, a compromised solution could be that NG-RAN may establish multiple user planes (but not all) across multiple MBS sessions. NG-RAN may keep a counter across multiple MBS sessions with the same associated session ID. When the number exceeds the preconfigured value, the NG-RAN skip the user plane establishment. When one or more user planes have been released, the NG-RAN may actively initiate the user plane establishment towards CNs where the user plane hasn’ t been established yet.

In an embodiment, if there is a failure of the on-going user plane, or the on-going user plane is released, the NG-RAN may deliver the packets from another user plane locally. In the meantime, the NG-RAN may establish the user plane towards another CN to keep the number of user planes.

In an embodiment, if NG-RAN determines no UEs joined in the MBS session while the user plane of the MBS session is established, the NG-RAN may release the user plane of this MBS session and establish the user plane towards another CN where there are UE joined in the MBS session there, to keep the number of active user planes, if there are such CNs exist.

In an embodiment, due to not all the user planes established, the NG-RAN will receive limited number of MBS session activation requests when MBS session is activated, the NG-RAN may page all the joined UEs for those multiple MBS sessions, based on the first request it receives.

In an embodiment, regardless how many user planes have been established, the NG-RAN may only deliver the packets from one user plane over the air and drop the packets from other user planes.

In an embodiment, it is also possible to user one specific TMGI together with MOCN flag to indicate NG-RAN the associated multicast MBS sessions.

In an embodiment, use associated session ID from AF to indicate NG-RAN about the multicast MBS sessions transmitting the same content. AF may pass the associated session ID towards MB-SMF (optionally via NEF) . MB-SMF may pass it to NG-RAN via AMF, or SMF may get from MB-SMF and pass it to NG-RAN via AMF.

In an embodiment, NG-RAN may identify those multicast MBS sessions which transmit the same content based on the associated session ID. NG-RAN allocates radio resource for only one multicast MBS session and configures all the joined UEs based on it.

In an embodiment, NG-RAN may establish one user plane towards one CNs across multiple multicast MBS sessions based on the associated session ID. NG-RAN may establish all user planes or multiple user planes.

In an embodiment, clause 6.7.2 of 3GPP TR 23.700-47 v1.0.0 may be amended as following.

6.7.2. Functional description

This solution utilizes the associated session identifier (e.g. SSM used by AF) to be the identifier to associate MBS sessions from different CNs which transmitting the same content.

The AF provides the associated session ID when creating broadcast MBS sessions with the same content. In all CNs, MB-SMF and SMF provide the associated session ID to the NG-RAN via the AMF. And then, the NG-RAN can utilize the associated session ID to associate those broadcast MBS sessions.

NG-RAN establishes the user planes for the first broadcast MBS session it receives, or the first multicast MBS session joined by UEs. The NG-RAN delivers the packets received from the established user plane over the air. For the other broadcast MBS sessions which are associated with the broadcast MBS session, the NG-RAN creates the broadcast MBS session contexts and advertises the TMGIs, but does not establish the user planes. For the other multicast MBS sessions which are associated with the multicast MBS session, the NG-RAN creates the multicast MBS session contexts, configure the UEs, but does not establish the user plane.

In case there is a failure in the established user plane, the NG-RAN selects another associated MBS session to establish the user plane and continue to deliver the packets received from the newly established user plane over the air.

In an embodiment, a new clause 6.7.3. X may be added into 3GPP TR 23.700-47 v1.0.0. “X” denotes any suitable number.

6.7.3. X Multicast Sessions for MOCN Network Sharing

In the clause, the proposal is based on the two assumptions in the solution:

Associated session ID is used to identify the multiple MBS sessions cross CNs.

One user plane is established across multiple MBS sessions.

It is possible to use the same TMGI with additional MOCN flag, instead of the associated session ID to identify the multiple MBS sessions cross CNs, as specified in solution #29 of 3GPP TR 23.700-47 v1.0.0.

It is also possible to establish all user planes across multiple MBS sessions, as specified solution #2 and #24 of 3GPP TR 23.700-47 v1.0.0.

A compromised solution could be that NG-RAN establish multiple user planes (but not all) across multiple MBS sessions. NG-RAN may keep a counter of the number of user planes based on the associated session ID. When the number exceeds the preconfigured value, the NG-RAN skips the further user plane establishment. When one or more user planes have been released, the NG-RAN may actively initiate the user plane establishment towards CNs where the user plane hasn’ t been established yet, to keep the number of user planes.

To support MOCN Network Sharing for multicast MBS sessions, associated session identifier needs to be provided by the AF as described in clause 6.7.3.2 of 3GPP TR 23.700-47 v1.0.0.

The MB-SMF provides associated session identifier to the SMF in ContextStatusSubscribe response. The SMF and the MB-SMF need to include associated session identifier in N2 SM information to the NG-RANs.

When the NG-RAN needs to establish shared delivery, the NG-RAN checks whether there is already established user plane of another multicast MBS session which is associated (identified by same associated session ID) . If there is, the NG-RAN skips the establishment of shared delivery.

The NG-RAN should only release shared delivery, only when no UEs joined in the current multicast MBS session (identified by MBS session ID) . After the release of shared delivery, if there are UEs joined other relevant multicast MBS sessions (identified by same associated session ID) , the NG-RAN selects another CN to establish the user plane as described in 6.7.3.5 of 3GPP TR 23.700-47 v1.0.0.

When the NG-RAN is going to allocate radio resource, the NG-RAN checks whether the radio resource of another multicast MBS Session is allocated which is associated (identified by the same associated session ID) . If already allocated, the NG-RAN uses the existing radio resource.

The NG-RAN should only release the radio resource when there are no UEs joined the all the relevant multicast MBS sessions (identified by same associated session ID) .

For RAN paging in MBS session activation, the NG-RAN needs to page all the UEs joined those multiple multicast MBS sessions (identified by same associated session ID) which are in CM-CONNECTED with RRC_INACTIVE state, as only one shared delivery established among those multicast MBS sessions.

In an embodiment, a new clause 6.7.3. X. 1 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 1 MBS Session Creation

The additions for broadcast MBS sessions described in clause 6.7.3.2 apply to multicast MBS sessions.

In an embodiment, a new clause 6.7.3. X. 2 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 2 MBS Session Join

FIG. 7f shows a flowchart of MBS Session Join for MOCN RAN sharing according to another embodiment of the present disclosure.

The following additions apply compared to clause 7.2.1.3 of 3GPP TS 23.247 V17.4.0:

3. The associated session ID is included in ContextStatusSubscribe response sent from the MB-SMF to the SMF.

5. The SMF includes the associated session ID in N2 SM information to NG-RAN.

7. If NG-RAN determines there is already established user plane of another multicast MBS session which is associated (identified by same associated session ID) , the NG-RAN skips the establishment of shared delivery.

7a. If the NG-RAN determines the radio resource of another multicast MBS Session is allocated which is associated (identified by the same associated session ID) , the NG-RAN configures the UE with the existing radio resource.

In an embodiment, a new clause 6.7.3. X. 3 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 3 Multicast Session Leave requested by the UE

FIG. 7g shows a flowchart of Multicast Session Leave requested by the UE for MOCN RAN sharing according to another embodiment of the present disclosure.

The following additions apply compared to clause 7.2.2.2 of 3GPP TS 23.247 V17.4.0:

9. The NG-RAN should only release the MRB when there are no UEs joined the relevant multicast MBS sessions (identified by same associated session ID) .

13. The NG-RAN should release the shared delivery, only if the shared delivery has been established and no UEs joined in the multicast MBS session (identified by MBS session ID) . After the release of shared delivery, the NG-RAN checks whether there are UEs joined other relevant multicast MBS sessions (identified by same associated session ID) . If there are, NG-RAN selects another CN to establish the user plane as described in clause 6.7.3.5 below.

If the shared delivery hasn’ t been established and the UE is the last UE for the multicast MBS session (identified by MBS session ID) , the NG-RAN should skip the release of shared delivery.

In an embodiment, a new clause 6.7.3. X. 4 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 4 Multicast Session leave requested by the network or MBS session release

FIG. 7h shows a flowchart of Multicast Session Leave requested by the network or MBS session release for MOCN RAN sharing according to another embodiment of the present disclosure.

Similar as clause 6.7.3. X. 3, the following additions apply compared to clause 7.2.2.3 of 3GPP TS 23.247 V17.4.0:

6. The NG-RAN should only release the MRB when there are no UEs joined the relevant multicast MBS sessions (identified by same associated session ID) .

7. The NG-RAN should release the shared delivery, only if the shared delivery has been established and no UEs joined in the multicast MBS session (identified by MBS session ID) . After the release of shared delivery, the NG-RAN determines whether there are UEs joined other relevant multicast MBS sessions (identified by same associated session ID) . If there are, NG-RAN selects another CN to establish the user plane as described in clause 6.7.3.5 below.

If the shared delivery hasn’ t been established and no UEs joined in the multicast MBS session (identified by MBS session ID) , the NG-RAN should skip the release of shared delivery.

In an embodiment, a new clause 6.7.3. X. 5 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 5 Xn based handover

FIG. 7i shows a flowchart of Xn based handover for MOCN RAN sharing according to another embodiment of the present disclosure.

The following additions apply compared to clause 7.2.3.2 of 3GPP TS 23.247 V17.4.0:

0b. If the NG-RAN determines there is already established user plane of another multicast MBS session which is associated (identified by same associated session ID) , the NG-RAN skips the establishment of shared delivery.

In an embodiment, a new clause 6.7.3. X. 6 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 6 N2 based handover

FIG. 7j shows a flowchart of N2 based handover for MOCN RAN sharing according to another embodiment of the present disclosure.

The following additions apply compared to clause 7.2.3.3 of 3GPP TS 23.247 V17.4.0:

4b. If the NG-RAN determines there is already established user plane of another multicast MBS session which is associated (identified by same associated session ID) , the NG-RAN skips the establishment of shared delivery.

In an embodiment, a new clause 6.7.3. X. 7 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 7 MBS session activation

FIG. 7k shows a flowchart of MBS session activation for MOCN RAN sharing according to another embodiment of the present disclosure.

The following additions apply compared to clause 7.2.5.2 of 3GPP TS 23.247 V17.4.0:

4b. The SMF includes the associated session ID in N2 SM information to NG-RAN.

7b. The SMF includes the associated session ID in N2 SM information to NG-RAN.

8b. The SMF includes the associated session ID in N2 SM information to NG-RAN..

10a. If NG-RAN determines there is already established user plane of another multicast MBS session which is associated (identified by same associated session ID) , the NG-RAN skips the establishment of shared delivery.

11. The MB-SMF includes the associated session ID in N2 SM information to NG-RAN.

12. For RAN paging, the NG-RAN needs to page all the UEs joined those multiple multicast MBS sessions (identified by same associated session ID) which are in CM-CONNECTED with RRC_INACTIVE state.

For step 11 to 15, as only one user plane established, the NG-RAN should only receive one MBS session activation request from one MB-SMF, across multiple multicast MBS sessions.

In an embodiment, a new clause 6.7.3. X. 8 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 8 MBS session deactivation

FIG. 7l shows a flowchart of MBS session deactivation for MOCN RAN sharing according to another embodiment of the present disclosure.

The following additions apply compared to clause 7.2.5.3 of 3GPP TS 23.247 V17.4.0:

4. The SMF includes the associated session ID in N2 SM information to NG-RAN.

5. The MB-SMF includes the associated session ID in N2 SM information to NG-RAN.

7. The NG-RAN should set the states of relevant multicast MBS sessions (identified by the associated session ID) to inactive.

For step 5 to 9, as only one user plane established, the NG-RAN should only receive one MBS session activation request from one MB-SMF, across multiple multicast MBS sessions.

In an embodiment, a new clause 6.7.3. X. 9 may be added into 3GPP TR 23.700-47 v1.0.0.

6.7.3. X. 9 Multicast session update

FIG. 7m shows a flowchart of Multicast MBS Session update procedure for MOCN RAN sharing according to another embodiment of the present disclosure.

The following additions apply compared to clause 7.2.6 of 3GPP TS 23.247 V17.4.0:

3. The MB-SMF includes the associated session ID in N2 SM information to NG-RAN.

5. The NG-RAN updates QoS profile for multiple multicast MBS sessions (identified by associated session ID) .

If the NG-RAN determines to release shared delivery (i.e., the NG-RAN no longer serves cells for the MBS session which is identified by the MBS session ID) , it checks whether the shared delivery has been established. If not, it skips the release of shared delivery.

After the shared delivery is released, the NG-RAN further checks whether there are UEs joined other relevant multicast MBS sessions (identified by same associated session ID) . If there are, NG-RAN selects another CN to establish the user plane as described in clause 6.7.3.5 below.

For step 3 to 7, as only one user plane established, the NG-RAN should only receive one Multicast session update request from one MB-SMF, across multiple multicast MBS sessions.

In an embodiment, clause 6.7.3.5 of 3GPP TR 23.700-47 v1.0.0 may be amended as following.

6.7.3.5 MBS Session Transport Request

When NG-RAN detects there is a failure in the user plane which causes the NG-RAN cannot deliver the contents, the NG-RAN select another CN to trigger MBS Session Transport Request procedure to establish the user plane. The selecting of CN can be up to NG-RAN implementation.

It may apply to the scenario when the MBS session is released in that CN, whose user plane is used to content transmission, while there are some other MBS sessions not released.

FIG. 7n shows a flowchart of Broadcast MBS Session Transport Request according to another embodiment of the present disclosure, which is an amendment of Figure 6.7.3.5-1 of 3GPP TR 23.700-47 v1.0.0.

1. NG-RAN selects a CN to establish user plane, utilizing the MBS session context stored in the NG-RAN.

3. If unicast transport of N3mb applies, the NG-RAN allocates N3mb DL Tunnel Info, and sends N2 message (e.g. MBS SESSION TRANSPORT REQUEST) to AMF, including the MBS Session ID and the N3mb DL Tunnel Info.

4. The AMF transfers the Namf_MBSBroadcast_ContextStatusNotify request to the MB-SMF for broadcast, or Nmbsmf_MBSSession_ContextStatusNotify request for multicast, which contains the N2 message.

5. The MB-SMF sends an N4mb Session Modification Request to the MB-UPF to allocate the N3mb point-to-point transport tunnel for a replicated MBS stream for the MBS Session. The MB-UPF sends N4mb Session Modification Response to the MB-SMF.

6. The MB-SMF sends Namf_MBSBroadcast_ContextStatusNotify response to the AMF for broadcast, or Nmbsmf_MBSSession_ContextStatusNotify response for multicast, which contains the N2 response message (e.g. MBS SESSION TRANSPORT RESPONSE) .

7. The AMF forwards the N2 message to the NG-RAN

In an embodiment, clause 6.7.4 of 3GPP TR 23.700-47 v1.0.0 may be amended as following.

6.7.4 Impacts on services, entities and interfaces

AF:

NEF:

MB-SMF:

- Provides the associated session ID to the NG-RAN if received.

SMF:

- Provides the associated session ID to the NG-RAN if received.

NG-RAN:

- Support the associated session ID and understand the association among those MBS sessions which delivers the same content.

- When broadcast MBS session starts or when a UE joined a multicast MBS session, if there is already established user plane of associated MBS session, the NG-RAN skips the user plane establishment of the broadcast MBS session.

- When broadcast or multicast MBS session release or when the last UE leaves the multicast MBS session in the NG-RAN, if the user plane hasn't been established, the NG-RAN skips the user plane release of the broadcast MBS session. If the user plane has been established, the NG-RAN releases the user plane, and if there are some other associated MBS sessions, the NG-RAN may trigger MBS Session Transport Request procedure.

- When NG-RAN detects there is a failure in the CN which causes the NG-RAN cannot deliver the contents, the NG-RAN select another CN to trigger MBS Session Transport Request procedure to establish the user plane.

FIG. 8a is a block diagram showing an apparatus suitable for practicing some embodiments of the disclosure. For example, the application node, the first network function, the second network function, the third network function, the radio access network node, or the fourth network function described above may be implemented as or through the apparatus 800.

The apparatus 800 comprises at least one processor 821, such as a digital processor (DP) , and at least one memory (MEM) 822 coupled to the processor 821. The apparatus 800 may further comprise a transmitter TX and receiver RX 823 coupled to the processor 821. The MEM 822 stores a program (PROG) 824. The PROG 824 may include instructions that, when executed on the associated processor 821, enable the apparatus 800 to operate in accordance with the embodiments of the present disclosure. A combination of the at least one processor 821 and the at least one MEM 822 may form processing means 825 adapted to implement various embodiments of the present disclosure.

Various embodiments of the present disclosure may be implemented by computer program executable by one or more of the processor 821, software, firmware, hardware or in a combination thereof.

The MEM 822 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memories and removable memories, as non-limiting examples.

The processor 821 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples.

In an embodiment where the apparatus is implemented as or at the application node, the memory 822 contains instructions executable by the processor 821, whereby the application node operates according to any of the methods related to the application node as described above.

In an embodiment where the apparatus is implemented as or at the first network function, the memory 822 contains instructions executable by the processor 821, whereby the first network function operates according to any of the methods related to the first network function as described above.

In an embodiment where the apparatus is implemented as or at the second network function, the memory 822 contains instructions executable by the processor 821, whereby the second network function operates according to any of the methods related to the second network function as described above.

In an embodiment where the apparatus is implemented as or at the third network function, the memory 822 contains instructions executable by the processor 821, whereby the third network function operates according to any of the methods related to the third network function as described above.

In an embodiment where the apparatus is implemented as or at the radio access network node, the memory 822 contains instructions executable by the processor 821, whereby the radio access network node operates according to any of the methods related to the radio access network node as described above.

In an embodiment where the apparatus is implemented as or at the fourth network function, the memory 822 contains instructions executable by the processor 821, whereby the fourth network function operates according to any of the methods related to the fourth network function as described above.

FIG. 8b is a block diagram showing an application node according to an embodiment of the disclosure. As shown, the application node 830 comprises a sending module 831 configured to send a first message to a first network function in a first network or a second network function in the first network. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.

FIG. 8c is a block diagram showing a first network function according to an embodiment of the disclosure. As shown, the first network function 850 comprises a receiving module 851 configured to receive a first message from an application node. The first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The first network function 850 further comprises a sending module 852 configured to send a second message to a second network function in the first network. The second message comprises the MBS session ID and at least one associated session ID.

FIG. 8d is a block diagram showing a second network function according to an embodiment of the disclosure. As shown, the second network function 870 comprises a receiving module 871 configured to receive a first message or a second message from an application node or a first network function in the first network. The first message and/or the second message comprise a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The second network function 870 further comprises a sending module 872 configured to send a third message to a third network function in the first network or a fourth network function in the first network. The third message comprises the MBS session identifier and the at least one associated session ID.

FIG. 8e is a block diagram showing a third network function according to an embodiment of the disclosure. As shown, the third network function 880 comprises a receiving module 881 configured to receive a third message from a second network function in the first network. The third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The third network function 880 further comprises a sending module 882 configured to send a fourth message to a fourth network function in a first network. The fourth message comprises the MBS session ID and at least one associated session ID.

FIG. 8f is a block diagram showing a fourth network function according to an embodiment of the disclosure. As shown, the fourth network function 890 comprises a receiving module 891 configured to receive a fourth message from a third network function in the first network or another fourth network function in the first network or a third message from a second network function in the first network. The fourth message and/or the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The fourth network function 890 further comprises a sending module 892 configured to send a fifth message to a radio access network node. The fifth message comprises the MBS session ID and at least one associated session ID.

FIG. 9 is a block diagram showing a radio access network node according to an embodiment of the disclosure. As shown, the radio access network node 900 comprises a first receiving module 901 configured to a fifth message from a fourth network function in a first network or another radio access network node. The fifth message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID. The at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks. The radio access network node 900 further comprises a checking module 902 configured to check whether at least one radio resource has been allocated for delivering the same content. The radio access network node 900 further comprises an allocating receiving module 903 configured to, when the at least one radio resource has not been allocated, allocate the at least one radio resource. The radio access network node 900 further comprises a first skipping module 904 configured to, when the at least one radio resource has been allocated, skip allocating the at least one radio resource.

In an embodiment, the radio access network node 900 further comprises a first establishing module 905 configured to establish a user plane of an associated multicast MBS session of the first network.

In an embodiment, the radio access network node 900 further comprises a second establishing module 906 configured to, when a predefined number of user planes of the two or more multicast MBS sessions have not been established, establish a user plane of an associated multicast MBS session of the first network.

In an embodiment, the radio access network node 900 further comprises a second skipping module 907 configured to, when a predefined number of user planes of the two or more multicast MBS sessions have been established, skip an establishment of a user plane of an associated multicast MBS session of the first network.

In an embodiment, the radio access network node 900 further comprises a third skipping module 908 configured to, when the same content can be received from a user plane function of another network, skip an establishment of a user plane of an associated multicast MBS session of the first network.

In an embodiment, the radio access network node 900 further comprises a first releasing module 909 configured to, when no terminal device is joined in a current multicast MBS session, release a user plane of the current multicast MBS session.

In an embodiment, the radio access network node 900 further comprises a first selecting module 910 configured to, when at least one terminal device is joined in the two or more multicast MBS sessions and the user plane of the current multicast MBS session is released, select another network to establish a user plane of an associated multicast MBS session to receive the same content.

In an embodiment, the radio access network node 900 further comprises a detecting module 911 configured to detect there is a failure in a network which causes the radio access network node cannot deliver the same content.

In an embodiment, the radio access network node 900 further comprises a second selecting module 912 configured to select another network to establish a user plane of an associated multicast MBS session to receive the same content.

In an embodiment, the radio access network node 900 further comprises a second releasing module 913 configured to, when no terminal device is joined in the two or more multicast MBS sessions, release the at least one radio resource.

In an embodiment, the radio access network node 900 further comprises a paging module 914 configured to, for paging and notification in MBS session activation, page all terminal devices joined in the two or more multicast MBS sessions which are in CM-IDLE state or in CM-CONNECTED with RRC_INACTIVE state.

In an embodiment, the radio access network node 900 further comprises a making module 915 configured to, when MBS session update, make the MBS session update to take effect to all the associated MBS sessions transmitting the same content.

In an embodiment, the radio access network node 900 further comprises a sending module 916 configured to send a sixth message to a target radio access network node. The sixth message comprises the MBS session ID and the at least one associated session ID.

The term unit or module may have conventional meaning in the field of electronics, electrical devices and/or electronic devices and may include, for example, electrical and/or electronic circuitry, devices, modules, processors, memories, logic solid state and/or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and/or displaying functions, and so on, as such as those that are described herein.

With function units, the application node, the first network function, the second network function, the third network function, the radio access network node, or the fourth network function may not need a fixed processor or memory, any computing resource and storage resource may be arranged from the application node, the first network function, the second network function, the third network function, the radio access network node, or the fourth network function in the communication system. The introduction of virtualization technology and network computing technology may improve the usage efficiency of the network resources and the flexibility of the network.

According to an aspect of the disclosure it is provided a computer program product being tangibly stored on a computer readable storage medium and including instructions which, when executed on at least one processor, cause the at least one processor to carry out any of the methods as described above.

According to an aspect of the disclosure it is provided a computer-readable storage medium storing instructions which when executed by at least one processor, cause the at least one processor to carry out any of the methods as described above.

Further, the exemplary overall commutation system including the terminal device and the network node will be introduced as below.

FIG. 10 shows an example of a communication system QQ100 in accordance with some embodiments.

In the example, the communication system QQ100 includes a telecommunication network QQ102 that includes an access network QQ104, such as a radio access network (RAN) , and a core network QQ106, which includes one or more core network nodes QQ108. The access network QQ104 includes one or more access network nodes, such as network nodes QQ110a and QQ110b (one or more of which may be generally referred to as network nodes QQ110) , or any other similar 3rd Generation Partnership Project (3GPP) access node or non-3GPP access point. The network nodes QQ110 facilitate direct or indirect connection of user equipment (UE) , such as by connecting UEs QQ112a, QQ112b, QQ112c, and QQ112d (one or more of which may be generally referred to as UEs QQ112) to the core network QQ106 over one or more wireless connections.

Example wireless communications over a wireless connection include transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system QQ100 may include any number of wired or wireless networks, network nodes, UEs, and/or any other components or systems that may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections. The communication system QQ100 may include and/or interface with any type of communication, telecommunication, data, cellular, radio network, and/or other similar type of system.

The UEs QQ112 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and/or operable to communicate wirelessly with the network nodes QQ110 and other communication devices. Similarly, the network nodes QQ110 are arranged, capable, configured, and/or operable to communicate directly or indirectly with the UEs QQ112 and/or with other network nodes or equipment in the telecommunication network QQ102 to enable and/or provide network access, such as wireless network access, and/or to perform other functions, such as administration in the telecommunication network QQ102.

In the depicted example, the core network QQ106 connects the network nodes QQ110 to one or more hosts, such as host QQ116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network QQ106 includes one more core network nodes (e.g., core network node QQ108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and/or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node QQ108. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC) , Mobility Management Entity (MME) , Home Subscriber Server (HSS) , Access and Mobility Management Function (AMF) , Session Management Function (SMF) , Authentication Server Function (AUSF) , Subscription Identifier De-concealing function (SIDF) , Unified Data Management (UDM) , Security Edge Protection Proxy (SEPP) , Network Exposure Function (NEF) , and/or a User Plane Function (UPF) .

The host QQ116 may be under the ownership or control of a service provider other than an operator or provider of the access network QQ104 and/or the telecommunication network QQ102, and may be operated by the service provider or on behalf of the service provider. The host QQ116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio/video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

As a whole, the communication system QQ100 of FIG. 10 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM) ; Universal Mobile Telecommunications System (UMTS) ; Long Term Evolution (LTE) , and/or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G) ; wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi) ; and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax) , Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and/or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

In some examples, the telecommunication network QQ102 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network QQ102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network QQ102. For example, the telecommunications network QQ102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and/or Massive Machine Type Communication (mMTC) /Massive IoT services to yet further UEs.

In some examples, the UEs QQ112 are configured to transmit and/or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network QQ104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network QQ104. Additionally, a UE may be configured for operating in single-or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC) , such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio –Dual Connectivity (EN-DC) .

In the example, the hub QQ114 communicates with the access network QQ104 to facilitate indirect communication between one or more UEs (e.g., UE QQ112c and/or QQ112d) and network nodes (e.g., network node QQ110b) . In some examples, the hub QQ114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub QQ114 may be a broadband router enabling access to the core network QQ106 for the UEs. As another example, the hub QQ114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes QQ110, or by executable code, script, process, or other instructions in the hub QQ114. As another example, the hub QQ114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub QQ114 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub QQ114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub QQ114 then provides to the UE either directly, after performing local processing, and/or after adding additional local content. In still another example, the hub QQ114 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy IoT devices.

The hub QQ114 may have a constant/persistent or intermittent connection to the network node QQ110b. The hub QQ114 may also allow for a different communication scheme and/or schedule between the hub QQ114 and UEs (e.g., UE QQ112c and/or QQ112d) , and between the hub QQ114 and the core network QQ106. In other examples, the hub QQ114 is connected to the core network QQ106 and/or one or more UEs via a wired connection. Moreover, the hub QQ114 may be configured to connect to an M2M service provider over the access network QQ104 and/or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes QQ110 while still connected via the hub QQ114 via a wired or wireless connection. In some embodiments, the hub QQ114 may be a dedicated hub –that is, a hub whose primary function is to route communications to/from the UEs from/to the network node QQ110b. In other embodiments, the hub QQ114 may be a non-dedicated hub –that is, a device which is capable of operating to route communications between the UEs and network node QQ110b, but which is additionally capable of operating as a communication start and/or end point for certain data channels.

FIG. 11 is a block diagram of a host QQ400, which may be an embodiment of the host QQ116 of FIG. 10, in accordance with various aspects described herein. As used herein, the host QQ400 may be or comprise various combinations hardware and/or software, including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host QQ400 may provide one or more services to one or more UEs.

The host QQ400 includes processing circuitry QQ402 that is operatively coupled via a bus QQ404 to an input/output interface QQ406, a network interface QQ408, a power source QQ410, and a memory QQ412. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures QQ2 and QQ3, such that the descriptions thereof are generally applicable to the corresponding components of host QQ400.

The memory QQ412 may include one or more computer programs including one or more host application programs QQ414 and data QQ416, which may include user data, e.g., data generated by a UE for the host QQ400 or data generated by the host QQ400 for a UE. Embodiments of the host QQ400 may utilize only a subset or all of the components shown. The host application programs QQ414 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC) , High Efficiency Video Coding (HEVC) , Advanced Video Coding (AVC) , MPEG, VP9) and audio codecs (e.g., FLAC, Advanced Audio Coding (AAC) , MPEG, G. 711) , including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, heads-up display systems) . The host application programs QQ414 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host QQ400 may select and/or indicate a different host for over-the-top services for a UE. The host application programs QQ414 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP) , Real-Time Streaming Protocol (RTSP) , Dynamic Adaptive Streaming over HTTP (MPEG-DASH) , etc.

FIG. 12 shows a communication diagram of a host QQ602 communicating via a network node QQ604 with a UE QQ606 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as a UE QQ112a of FIG. 10 and/or UE QQ200 of Figure QQ2) , network node (such as network node QQ110a of FIG. 10 and/or network node QQ300 of Figure QQ3) , and host (such as host QQ116 of FIG. 10 and/or host QQ400 of FIG. 11) discussed in the preceding paragraphs will now be described with reference to FIG. 12.

Like host QQ400, embodiments of host QQ602 include hardware, such as a communication interface, processing circuitry, and memory. The host QQ602 also includes software, which is stored in or accessible by the host QQ602 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE QQ606 connecting via an over-the-top (OTT) connection QQ650 extending between the UE QQ606 and host QQ602. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection QQ650.

The network node QQ604 includes hardware enabling it to communicate with the host QQ602 and UE QQ606. The connection QQ660 may be direct or pass through a core network (like core network QQ106 of FIG. 10) and/or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

The UE QQ606 includes hardware and software, which is stored in or accessible by UE QQ606 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE QQ606 with the support of the host QQ602. In the host QQ602, an executing host application may communicate with the executing client application via the OTT connection QQ650 terminating at the UE QQ606 and host QQ602. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection QQ650 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection QQ650.

The OTT connection QQ650 may extend via a connection QQ660 between the host QQ602 and the network node QQ604 and via a wireless connection QQ670 between the network node QQ604 and the UE QQ606 to provide the connection between the host QQ602 and the UE QQ606. The connection QQ660 and wireless connection QQ670, over which the OTT connection QQ650 may be provided, have been drawn abstractly to illustrate the communication between the host QQ602 and the UE QQ606 via the network node QQ604, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

As an example of transmitting data via the OTT connection QQ650, in step QQ608, the host QQ602 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE QQ606. In other embodiments, the user data is associated with a UE QQ606 that shares data with the host QQ602 without explicit human interaction. In step QQ610, the host QQ602 initiates a transmission carrying the user data towards the UE QQ606. The host QQ602 may initiate the transmission responsive to a request transmitted by the UE QQ606. The request may be caused by human interaction with the UE QQ606 or by operation of the client application executing on the UE QQ606. The transmission may pass via the network node QQ604, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step QQ612, the network node QQ604 transmits to the UE QQ606 the user data that was carried in the transmission that the host QQ602 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step QQ614, the UE QQ606 receives the user data carried in the transmission, which may be performed by a client application executed on the UE QQ606 associated with the host application executed by the host QQ602.

In some examples, the UE QQ606 executes a client application which provides user data to the host QQ602. The user data may be provided in reaction or response to the data received from the host QQ602. Accordingly, in step QQ616, the UE QQ606 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input/output interface of the UE QQ606. Regardless of the specific manner in which the user data was provided, the UE QQ606 initiates, in step QQ618, transmission of the user data towards the host QQ602 via the network node QQ604. In step QQ620, in accordance with the teachings of the embodiments described throughout this disclosure, the network node QQ604 receives user data from the UE QQ606 and initiates transmission of the received user data towards the host QQ602. In step QQ622, the host QQ602 receives the user data carried in the transmission initiated by the UE QQ606.

One or more of the various embodiments improve the performance of OTT services provided to the UE QQ606 using the OTT connection QQ650, in which the wireless connection QQ670 forms the last segment. More precisely, the teachings of these embodiments may enable radio resource efficiency for multicast MBS sessions from different CNs in MOCN RAN sharing deployment, which transmit the same content. The teachings of these embodiments may further optimize the user plane handling across those multicast MBS sessions.

In an example scenario, factory status information may be collected and analyzed by the host QQ602. As another example, the host QQ602 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host QQ602 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights) . As another example, the host QQ602 may store surveillance video uploaded by a UE. As another example, the host QQ602 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, the host QQ602 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices) , or any other function of collecting, retrieving, storing, analyzing and/or transmitting data.

In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection QQ650 between the host QQ602 and UE QQ606, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of the host QQ602 and/or UE QQ606. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection QQ650 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection QQ650 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node QQ604. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency and the like, by the host QQ602. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection QQ650 while monitoring propagation times, errors, etc.

Embodiment 1. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising:

processing circuitry configured to provide user data; and

a network interface configured to initiate transmission of the user data to a network node in a cellular network for transmission to a user equipment (UE) , the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform the operations related to the wireless device as described above to transmit the user data from the host to the UE:

Embodiment 2. The host of the previous embodiment, wherein:

the processing circuitry of the host is configured to execute a host application that provides the user data; and

the UE comprises processing circuitry configured to execute a client application associated with the host application to receive the transmission of user data from the host.

Embodiment 3. A method implemented in a host configured to operate in a communication system that further includes a network node and a user equipment (UE) , the method comprising:

providing user data for the UE; and

initiating a transmission carrying the user data to the UE via a cellular network comprising the network node, wherein the network node performs the operations related to the wireless device as described above to transmit the user data from the host to the UE:

Embodiment 4. The method of the previous embodiment, further comprising, at the network node, transmitting the user data provided by the host for the UE.

Embodiment 5. The method of any of the previous 2 embodiments, wherein the user data is provided at the host by executing a host application that interacts with a client application executing on the UE, the client application being associated with the host application.

Embodiment 6. A communication system configured to provide an over-the-top service, the communication system comprising:

a host comprising:

processing circuitry configured to provide user data for a user equipment (UE) , the user data being associated with the over-the-top service; and

a network interface configured to initiate transmission of the user data toward a cellular network node for transmission to the UE, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform the operations related to the wireless device as described above to transmit the user data from the host to the UE:

Embodiment 7. The communication system of the previous embodiment, further comprising:

the network node; and/or

the user equipment.

Embodiment 8. The communication system of the previous 2 embodiments, wherein:

the processing circuitry of the host is configured to execute a host application, thereby providing the user data; and

the host application is configured to interact with a client application executing on the UE, the client application being associated with the host application.

Embodiment 9. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising:

processing circuitry configured to initiate receipt of user data; and

a network interface configured to receive the user data from a network node in a cellular network, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform the operations related to the wireless device as described above to receive the user data from the UE for the host:

Embodiment 10. The host of the previous 2 embodiments, wherein:

Embodiment 11. The host of the any of the previous 2 embodiments, wherein the initiating receipt of the user data comprises requesting the user data.

Embodiment 12. A method implemented by a host configured to operate in a communication system that further includes a network node and a user equipment (UE) , the method comprising:

at the host, initiating receipt of user data from the UE, the user data originating from a transmission which the network node has received from the UE, wherein the network node performs the operations related to the wireless device as described above to receive the user data from the UE for the host:

Embodiment 13. The method of the previous embodiment, further comprising at the network node, transmitting the received user data to the host.

Embodiment 14. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising:

processing circuitry configured to provide user data; and

a network interface configured to initiate transmission of the user data to a cellular network for transmission to a user equipment (UE) , wherein the UE comprises a communication interface and processing circuitry, the communication interface and processing circuitry of the UE being configured to perform the operations related to the wireless device as described above to receive the user data from the host:

Embodiment 15. The host of the previous embodiment, wherein the cellular network further includes a network node configured to communicate with the UE to transmit the user data to the UE from the host.

Embodiment 16. The host of the previous 2 embodiments, wherein:

Embodiment 17. A method implemented by a host operating in a communication system that further includes a network node and a user equipment (UE) , the method comprising:

providing user data for the UE; and

initiating a transmission carrying the user data to the UE via a cellular network comprising the network node, wherein the UE performs the operations related to the wireless device as described above to receive the user data from the host:

Embodiment 18. The method of the previous embodiment, further comprising:

at the host, executing a host application associated with a client application executing on the UE to receive the user data from the UE.

Embodiment 19. The method of the previous embodiment, further comprising:

at the host, transmitting input data to the client application executing on the UE, the input data being provided by executing the host application,

wherein the user data is provided by the client application in response to the input data from the host application.

Embodiment 20. A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising:

processing circuitry configured to utilize user data; and

a network interface configured to receipt of transmission of the user data to a cellular network for transmission to a user equipment (UE) ,

wherein the UE comprises a communication interface and processing circuitry, the communication interface and processing circuitry of the UE being configured to perform the operations related to the wireless device as described above to transmit the user data to the host:

Embodiment 21. The host of the previous embodiment, wherein the cellular network further includes a network node configured to communicate with the UE to transmit the user data from the UE to the host.

Embodiment 22. The host of the previous 2 embodiments, wherein:

Embodiment 23. A method implemented by a host configured to operate in a communication system that further includes a network node and a user equipment (UE) , the method comprising:

at the host, receiving user data transmitted to the host via the network node by the UE, wherein the UE performs the operations related to the wireless device as described above to transmit the user data to the host:

Embodiment 24. The method of the previous embodiment, further comprising:

Embodiment 25. The method of the previous embodiments, further comprising:

In addition, the present disclosure may also provide a carrier containing the computer program as mentioned above, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium. The computer readable storage medium can be, for example, an optical compact disk or an electronic memory device like a RAM (random access memory) , a ROM (read only memory) , Flash memory, magnetic tape, CD-ROM, DVD, Blue-ray disc and the like.

The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with an embodiment comprises not only prior art means, but also means for implementing the one or more functions of the corresponding apparatus described with the embodiment and it may comprise separate means for each separate function, or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more apparatuses) , firmware (one or more apparatuses) , software (one or more modules) , or combinations thereof. For a firmware or software, implementation may be made through modules (e.g., procedures, functions, and so on) that perform the functions described herein.

Exemplary embodiments herein have been described above with reference to block diagrams and flowchart illustrations of methods and apparatuses. It will be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, can be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the subject matter described herein, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any implementation or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular implementations. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The above described embodiments are given for describing rather than limiting the disclosure, and it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the disclosure as those skilled in the art readily understand. Such modifications and variations are considered to be within the scope of the disclosure and the appended claims. The protection scope of the disclosure is defined by the accompanying claims.

Claims

A method (200) performed by an application node, comprising:

sending (202) a first message to a first network function in a first network or a second network function in the first network,

wherein the first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The method according to claim 1, wherein the first network function comprises at least one of:

Network Exposure Function (NEF) ,

Multicast/Broadcast Service Function (MBSF) , or

a combined NEF and MBSF.
The method according to claim 1 or 2, wherein the second network function comprises Multicast/Broadcast Session Management Function (MB-SMF) .
The method according to any of claims 1-3, wherein the first message is an MBS session create request.
The method according to any of claims 1-4, wherein two or more core networks of the two or more networks are connected to a radio access network node.
The method according to any of claims 1-5, wherein the application node comprises an application function.
The method according to any of claims 1-6, wherein the at least one associated session ID comprises at least one of:

at least one source-specific multicast Internet protocol address, or

at least one temporary mobile group identity (TMGI) , or

an Multi-Operator Core Network (MOCN) network sharing indicator.
The method according to claim 7, wherein the at least one TMGI is selected from TMGIs allocated in two or more networks which are to be used as MBS session identifiers of the MBS sessions transmitting the same content and/or a same TMGI is used for the MBS session ID of each of the two or more multicast MBS sessions and the same TMGI and the MOCN network sharing indicator are used to identify the two or more multicast MBS sessions with same content across two or more networks.
A method (300) performed by a first network function in a first network, comprising:

receiving (302) a first message from an application node, wherein the first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID; and

sending (304) a second message to a second network function in the first network, wherein the second message comprises the MBS session ID and at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The method according to claim 9, wherein the first network function comprises at least one of:

Network Exposure Function (NEF) ,

Multicast/Broadcast Service Function (MBSF) , or

a combined NEF and MBSF.
The method according to claim 9 or 10, wherein the second network function comprises Multicast/Broadcast Session Management Function (MB-SMF) .
The method according to any of claims 9-11, wherein the first message is an MBS session create request and the second message is an MBS session create request.
The method according to any of claims 9-12, wherein two or more core networks of the two or more networks are connected to a radio access network node.
The method according to any of claims 9-13, wherein the application node comprises an application function.
The method according to any of claims 9-14, wherein the at least one associated session ID comprises at least one of:

at least one source-specific multicast Internet protocol address, or

at least one temporary mobile group identity (TMGI) , or

an MOCN network sharing indicator.
The method according to claim 15, wherein the at least one TMGI is selected from TMGIs allocated in two or more networks which are to be used as MBS session identifiers of the MBS sessions transmitting the same content and/or a same TMGI is used for the MBS session ID of each of the two or more multicast MBS sessions and the same TMGI and the MOCN network sharing indicator are used to identify the two or more multicast MBS sessions with same content across two or more networks.
A method (400) performed by a second network function in a first network, comprising:

receiving (402) a first message or a second message from an application node or a first network function in the first network, wherein the first message and/or the second message comprise a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID; and

sending (404) a third message to a third network function in the first network or a fourth network function in the first network, wherein the third message comprises the MBS session identifier and the at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The method according to claim 17, wherein the first network function comprises at least one of:

Network Exposure Function (NEF) ,

Multicast/Broadcast Service Function (MBSF) , or

a combined NEF and MBSF.
The method according to claim 17 or 18, wherein the second network function comprises Multicast/Broadcast Session Management Function (MB-SMF) .
The method according to any of claims 17-19, wherein the first message is an MBS session create request, the second message is an MBS session create request, and the third message is an MBS session context status subscribe response or an MBS session context status update response.
The method according to claim 20, wherein the at least one associated session ID is included in N2 SM information which is a Distribution Setup Response.
The method according to any of claims 17-21, wherein the third network function comprises a session management function (SMF) and/or the fourth network function comprises an access and mobility management function (AMF) .
The method according to any of claims 17-22, wherein two or more core networks of the two or more networks are connected to a radio access network node.
The method according to any of claims 17-23, wherein the application node comprises an application function.
The method according to any of claims 17-24, wherein the at least one associated session ID comprises at least one of:

at least one source-specific multicast Internet protocol address, or

at least one temporary mobile group identity (TMGI) , or

an MOCN network sharing indicator.
The method according to claim 25, wherein the at least one TMGI is selected from TMGIs allocated in two or more networks which are to be used as MBS session identifiers of the MBS sessions transmitting the same content and/or a same TMGI is used for the MBS session ID of each of the two or more multicast MBS sessions and the same TMGI and the MOCN network sharing indicator are used to identify the two or more multicast MBS sessions with same content across two or more networks.
A method (500) performed by a third network function in a first network, comprising:

receiving (502) a third message from a second network function in the first network, wherein the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID; and

sending (504) a fourth message to a fourth network function in a first network, wherein the fourth message comprises the MBS session ID and at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The method according to claim 27, wherein the second network function comprises Multicast/Broadcast Session Management Function (MB-SMF) .
The method according to any of claims 27-28, wherein the third message is an MBS session context status subscribe response, and the fourth message is a protocol data unit (PDU) session update session management (SM) context response or an N1N2 Message Transfer request.
The method according to claim 29, wherein the at least one associated session ID is included in N2 SM information which is a PDU session resource setup request or PDU session modification request.
The method according to any of claims 27-30, wherein the third network function comprises a session management function (SMF) .
The method according to any of claims 27-31, wherein two or more core networks of the two or more networks are connected to a radio access network node.
The method according to any of claims 27-32, wherein the fourth network function comprises an access and mobility management function (AMF) .
The method according to any of claims 27-33, wherein the at least one associated session ID comprises at least one of:

at least one source-specific multicast Internet protocol address, or

at least one temporary mobile group identity (TMGI) , or

an MOCN network sharing indicator.
The method according to claim 34, wherein the at least one TMGI is selected from TMGIs allocated in two or more networks which are to be used as MBS session identifiers of the MBS sessions transmitting the same content and/or a same TMGI is used for the MBS session ID of each of the two or more multicast MBS sessions and the same TMGI and the MOCN network sharing indicator are used to identify the two or more multicast MBS sessions with same content across two or more networks.
A method (600) performed by a fourth network function in a first network, comprising:

receiving (602) a fourth message from a third network function in the first network or another fourth network function in the first network or a third message from a second network function in the first network, wherein the fourth message and/or the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID; and

sending (604) a fifth message to a radio access network node, wherein the fifth message comprises the MBS session ID and at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The method according to claim 36, wherein the fourth message is a protocol data unit (PDU) session update session management (SM) context response or an N1N2 Message Transfer request or a communication create user equipment (UE) context request, and/or the third message is an MBS session context status update response, and/or the fifth message is an N2 message.
The method according to claim 37, wherein the N2 message comprises at least one of:

a Distribution Setup Response,

a PDU session resource setup request,

a PDU session modification request, or

a handover request.
The method according to any of claims 36-38, wherein the third network function comprises a session management function (SMF) and/or the second network function comprises Multicast/Broadcast Session Management Function (MB-SMF) .
The method according to any of claims 36-39, wherein two or more core networks of the two or more networks are connected to the radio access network node.
The method according to any of claims 36-40, wherein the fourth network function of the first network comprises an access and mobility management function (AMF) or a target AMF and said another fourth network function in the first network comprises a source AMF.
The method according to any of claims 36-41, wherein the at least one associated session ID comprises at least one of:

at least one source-specific multicast Internet protocol address, or

at least one temporary mobile group identity (TMGI) , or

an MOCN network sharing indicator.
The method according to claim 42, wherein the at least one TMGI is selected from TMGIs allocated in two or more networks which are to be used as MBS session identifiers of the MBS sessions transmitting the same content and/or a same TMGI is used for the MBS session ID of each of the two or more multicast MBS sessions and the same TMGI and the MOCN network sharing indicator are used to identify the two or more multicast MBS sessions with same content across two or more networks.
A method (700) performed by a radio access network node, comprising:

receiving (702) a fifth message from a fourth network function in a first network or another radio access network node, wherein the fifth message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID, wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks;

checking (704) whether at least one radio resource has been allocated for delivering the same content;

when the at least one radio resource has not been allocated, allocating (706) the at least one radio resource; and

when the at least one radio resource has been allocated, skipping (708) allocating the at least one radio resource.
The method according to claim 44, wherein the fifth message is an N2 message.
The method according to claim 45, wherein the N2 message comprises at least one of:

a PDU session resource setup request,

a PDU session modification request,

a distribution setup response, or

a handover request.
The method according to any of claims 44-46, wherein the fourth network function comprises an access and mobility management function (AMF) .
The method according to any of claims 44-47, wherein the at least one associated session ID comprises at least one of:

at least one source-specific multicast Internet protocol address, or

at least one temporary mobile group identity (TMGI) , or

an MOCN network sharing indicator.
The method according to claim 48, wherein the at least one TMGI is selected from TMGIs allocated in two or more networks which are to be used as MBS session identifiers of the MBS sessions transmitting the same content and/or a same TMGI is used for the MBS session ID of each of the two or more multicast MBS sessions and the same TMGI and the MOCN network sharing indicator are used to identify the two or more multicast MBS sessions with same content across two or more networks.
The method according to any of claims 44-49, further comprising:

establishing (712) a user plane of an associated multicast MBS session of the first network; or

when a predefined number of user planes of the two or more multicast MBS sessions have not been established, establishing (714) a user plane of an associated multicast MBS session of the first network; or

when a predefined number of user planes of the two or more multicast MBS sessions have been established, skipping (716) an establishment of a user plane of an associated multicast MBS session of the first network; or

when the same content can be received from a user plane function of another network, skipping (718) an establishment of a user plane of an associated multicast MBS session of the first network.
The method according to any of claims 44-50, further comprising:

when no terminal device is joined in a current multicast MBS session, releasing (722) a user plane of the current multicast MBS session; and

when at least one terminal device is joined in the two or more multicast MBS sessions and the user plane of the current multicast MBS session is released, selecting (724) another network to establish a user plane of an associated multicast MBS session to receive the same content.
The method according to any of claims 44-51, further comprising:

detecting (732) there is a failure in a network which causes the radio access network node cannot deliver the same content; and

selecting (734) another network to establish a user plane of an associated multicast MBS session to receive the same content.
The method according to any of claims 44-52, further comprising:

when no terminal device is joined in the two or more multicast MBS sessions, releasing (742) the at least one radio resource.
The method according to any of claims 44-53, further comprising:

for paging and notification in MBS session activation, paging (744) all terminal devices joined in the two or more multicast MBS sessions which are in CM-IDLE state or in CM-CONNECTED with RRC_INACTIVE state.
The method according to any of claims 44-54, further comprising:

when MBS session update, making (746) the MBS session update to take effect to all the associated MBS sessions transmitting the same content.
The method according to any of claims 44-55, further comprising:

sending (748) a sixth message to a target radio access network node, wherein the sixth message comprises the MBS session ID and the at least one associated session ID.
The method according to claim 56, wherein the sixth message is an Xn message.
The method according to claim 57, wherein the Xn message comprises at least one of:

a Retrieve UE Context Response,

a RAN Multicast Group paging message, or

a handover request.
The method according to any of claims 44-58, wherein when same multicast data is received from two or more networks, only a single copy of the same multicast data is transmitted and the other copies of the same multicast data are dropped.
An application node (800) , comprising:

a processor (821) ; and

a memory (822) coupled to the processor (821) , said memory (822) containing instructions executable by said processor (821) , whereby said application node (800) is operative to:

send a first message to a first network function in a first network or a second network function in the first network,

wherein the first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The application node according to claim 60, wherein the application node is further operative to perform the method of any one of claims 2 to 8.
A first network function (800) in a first network, comprising:

a processor (821) ; and

a memory (822) coupled to the processor (821) , said memory (822) containing instructions executable by said processor (821) , whereby said first network function (800) is operative to:

receive a first message from an application node, wherein the first message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID; and

send a second message to a second network function in the first network, wherein the second message comprises the MBS session ID and at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The first network function according to claim 62, wherein the first network function is further operative to perform the method of any one of claims 10 to 16.
A second network function (800) in a first network, comprising:

a processor (821) ; and

a memory (822) coupled to the processor (821) , said memory (822) containing instructions executable by said processor (821) , whereby said second network function (800) is operative to:

receive a first message or a second message from an application node or a first network function in the first network, wherein the first message and/or the second message comprise a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID; and

send a third message to a third network function in the first network or a fourth network function in the first network, wherein the third message comprises the MBS session identifier and the at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The second network function according to claim 64, wherein the second network function is further operative to perform the method of any one of claims 18 to 26.
A third network function (800) in a first network, comprising:

a processor (821) ; and

a memory (822) coupled to the processor (821) , said memory (822) containing instructions executable by said processor (821) , whereby said third network function (800) is operative to:

receive a third message from a second network function in the first network, wherein the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID; and

send a fourth message to a fourth network function in a first network, wherein the fourth message comprises the MBS session ID and at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The third network function according to claim 66, wherein the third network function is further operative to perform the method of any one of claims 28 to 35.
A fourth network function (800) in a first network, comprising:

a processor (821) ; and

a memory (822) coupled to the processor (821) , said memory (822) containing instructions executable by said processor (821) , whereby said fourth network function (800) is operative to:

receive a fourth message from a third network function in the first network or another fourth network function in the first network or a third message from a second network function in the first network, wherein the fourth message and/or the third message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID; and

send a fifth message to a radio access network node, wherein the fifth message comprises the MBS session ID and at least one associated session ID,

wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks.
The fourth network function according to claim 68, wherein the fourth network function is further operative to perform the method of any one of claims 37 to 43.
A radio access network node (800) , comprising:

a processor (821) ; and

a memory (822) coupled to the processor (821) , said memory (822) containing instructions executable by said processor (821) , whereby said radio access network node (800) is operative to:

receive a fifth message from a fourth network function in a first network or another radio access network node, wherein the fifth message comprises a multicast or broadcast service (MBS) session identifier (ID) and at least one associated session ID, wherein the at least one associated session ID is used to make an association for two or more multicast MBS sessions with same content across two or more networks;

check whether at least one radio resource has been allocated for delivering the same content;

when the at least one radio resource has not been allocated, allocate the at least one radio resource; and

when the at least one radio resource has been allocated, skip allocating the at least one radio resource.
The radio access network node according to claim 70, wherein the radio access network node is further operative to perform the method of any one of claims 45 to 59.
A computer-readable storage medium storing instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any one of claims 1 to 59.
A computer program product comprising instructions which when executed by at least one processor, cause the at least one processor to perform the method according to any of claims 1 to 59.