GB2621181A

GB2621181A - Method, apparatus and computer program

Info

Publication number: GB2621181A
Application number: GB2211471.4A
Authority: GB
Inventors: Landais Bruno; Godin Philippe; Thomas Belling Horst; Navrátil David
Original assignee: Nokia Solutions and Networks Oy
Current assignee: Nokia Solutions and Networks Oy
Priority date: 2022-08-05
Filing date: 2022-08-05
Publication date: 2024-02-07
Also published as: GB202211471D0

Abstract

There is provided an apparatus comprising means for: receiving, at a Multicast/Broadcast Session Management Function (MB-SMF) from at least one Access and Mobility Management Function (AMF) of an AMF set, a request (504) for shared delivery establishment for a multicast Multicast/Broadcast Service (MBS) session, wherein the request comprises information identifying the AMF and information identifying the AMF set to which it belongs; storing, by the MB-SMF, the information identifying the AMF and the information identifying the AMF set (510); selecting, by the MB-SMF, an AMF of the AMF set to send a message associated with the MBS session based on the stored information; and sending, from the MB-SMF to the selected AMF of the AMF set, a message associated with the MBS session (512). The message may also be sent to any non-failed AMF of the AMF set through which a shared MBS session has been established. A determination of whether the AMF function first selected has failed may be made.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM

FIELD

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to coordinating shared delivery of a multicast Mulficast/Broadcast Session.

BACKGROUND

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email), text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

In a wireless communication system at least a part of a communication session between at least two stations occurs over a wireless link. Examples of wireless systems comprise public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). Some wireless systems can be divided into cells, and are therefore often referred to as cellular systems.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and/or receive communications on the carrier.

The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio). Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology and so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP).

SUMMARY

According to an aspect, there is provided an apparatus comprising means for: receiving, at a Multicast/Broadcast Session Management Function from at least one Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast MuIticast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying the Access and Mobility Management Function set to which it belongs; storing, by the Mulficast/Broadcast Session Management Function, the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set; selecting, by the Multicast/Broadcast Session Management Function, an Access and Mobility Management Function of the Access and Mobility Management Function set to send a message associated with the Mulficast/Broadcast Service session based on the stored information; and sending, from the Mulficast/Broadcast Session Management Function to the selected Access and Mobility Management Function of the Access and Mobility Management Function set, a message associated with the Multicast/Broadcast Service session.

The sending may comprise sending, by the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session only to one selected Access and Mobility Management Function of every Access and Mobility Management Function set through which shared delivery of the Mulficast/Broadcast Service session has been established.

The sending may comprise sending, by the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session to the selected Access and Mobility Management Function and any non-failed Access and Mobility Management Function of the Access and Mobility Management Function set through which shared delivery Mulficast/Broadcast Service session has been established.

The sending may further comprise sending an indication to the selected Access and Mobility Management Function requesting the selected Access and Mobility Management Function to distribute the message to one of: all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set; or all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through the selected Access and Mobility Management Function and/or through an at least one further Access and Mobility Management Function indicated in the message, wherein the selected Access and Mobility Management Function is part of the same Access and Mobility Management Function set as the at least one further Access and Mobility Management Function, or wherein the selected Access and Mobility Management Function is a backup Access and Mobility Management Function of the at least one further Access and Mobility Management Function.

The means may be for: determining, by the Multicast/Broadcast Session Management Function, that a first Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; wherein the selecting comprises selecting an Access and Mobility Management Function comprised in the same Access and Mobility Management Function set as the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session, and wherein the selected Access and Mobility Management Function is different to the first Access and Mobility Management Function.

Determining that the first Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable may comprise at least one of: receiving, at the Multicast/Broadcast Session Management Function from a Network Repository Function, information indicating that the first Access and Mobility Management Function has failed or is otherwise unreachable; sending, by the Multicast/Broadcast Session Management Function, one or more requests to the first Access and Mobility Management Function and receiving, by the Multicast/Broadcast Session Management Function, one or more error responses; sending, by the Multicast/Broadcast Session Management Function, one or more requests to the first Access and Mobility Management Function without receiving one or more responses; detecting an HTTP connection failure or being unable to setup a HTTP connection with the first Access and Mobility Management Function; receiving, at the Multicast/Broadcast Session Management Function from the at least one Access and Mobility Management Function of the Access and Mobility Management Function set, information indicating that the first Access and Mobility Management Function has failed or is otherwise unreachable.

The information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set may comprise information identifying the Access and Mobility Management Function and information identifying a backup Access and Mobility Management Function.

The means may be for: determining, by the Multicast/Broadcast Session Management Function, that the Access and Mobility Management Function has failed or is otherwise unreachable, wherein the selecting comprises selecting the backup Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session.

The request for shared delivery may comprise the identity of the backup Access and Mobility Management Function.

According to an aspect there is provided an apparatus comprising means for: sending, from an Access and Mobility Management Function to an Mulficast/Broadcast Session Management Function, a request for shared delivery for a multicast Mulficast/Broadcast Service session for an access node, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying an Access and Mobility Management Function set comprising the Access and Mobility Management Function; storing, by the Access and Mobility Management Function, information identifying the access node in a shared data store, wherein the shared data store is shared between the Access and Mobility Management Function and the other Access and Mobility Management Functions in the Access and Mobility Management Function set, and wherein the shared data store comprises information identifying one or more further access nodes that have requested shared delivery for the multicast Multicast/Broadcast Service session via one or more of the other Access and Mobility Management Functions in the Access and Mobility Management Function set; receiving, at the Access and Mobility Management Function from the Multicast/Broadcast Session Management Function, a message associated with the Mulficast/Broadcast Service session; determining, by the Access and Mobility Management Function, at least one access node to send the message associated with the Multicast/Broadcast Service session to, based on the information stored in the shared data store; and sending, from the Access and Mobility Management Function to the determined at least one access node, the message associated with the Multicast/Broadcast Service session.

The receiving may further comprise receiving an indication requesting the Access and Mobility Management Function to distribute the message to all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set, wherein the determining comprises determining all the access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set.

The receiving may further comprise receiving an indication requesting the Access and Mobility Management Function to distribute the message to all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through the Access and Mobility Management Function and/or through at least one further Access and Mobility Management Function indicated in the message, wherein the at least one further Access and Mobility Management Function has failed or is otherwise unreachable by the Multicast/Broadcast Session Management Function, wherein the determining comprises determining all access nodes that have established shared delivery for the multicast Multicast/Broadcast Service session through the Access and Mobility Management Function and/or the at least one further Access and Mobility Management Function.

The means may be for: determining, by the Access and Mobility Management Function, that the at least one further Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; and sending, from the Access and Mobility Management Function to the Multicast/Broadcast Session Management Function, information indicating that the at least one further Access and Mobility Management Function has failed or is otherwise unreachable.

The information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set may comprise information identifying a first Access and Mobility Management Function and information identifying a backup Access and Mobility Management Function, wherein the first Access and Mobility Management Function and the backup Access and Mobility Management Function are configured for shared delivery of the multicast Multicast/Broadcast Service session for the access node, and wherein the Access and Mobility Management Function is one of the first Access and Mobility Management Function and the backup Access and Mobility Management Function.

According to an aspect, there is provided an apparatus comprising means for: receiving, at a Multicast/Broadcast Session Management Function from a first Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function; receiving, from a second Access and Mobility Management Function of the Access and Mobility Management Function set, a request to update context information of the multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by the first Access and Mobility Management Function; updating the context information of the multicast Access and Mobility Management Function session based on the request received from the second Access and Mobility Management Function; and sending, from the Multicast/Broadcast Session Management Function to the further Access and Mobility Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function.

The further Access and Mobility Management Function may be the second Access and Mobility Management Function.

The means may be for: receiving, at the Multicast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast MBS session; wherein the sending comprises sending, to the second Access and Mobility Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.

The further Access and Mobility Management Function may be an Access and Mobility Management Function for which shared delivery of the multicast Multicast/Broadcast Service session has not previously been established.

According to an aspect, there is provided an apparatus comprising means for: sending, to a Multicast/Broadcast Session Management Function from a second Access and Mobility Management Function of an Access and Mobility Management Function set, a request to update context information of a multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by a first Access and Mobility Management Function of the Access and Mobility Management Function set; receiving, from the Multicast/Broadcast Session Management Function, a message associated with the Mulficast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function; determining, by the second Access and Mobility Management Function, the one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session to; and sending, from the second Access and Mobility Management Function to the determined one or more access nodes, the message associated with the Mulficast/Broadcast Service session.

The means may be for: sending, to the Multicast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast Multicast/Broadcast Service session; and wherein the receiving comprises receiving, from the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function, wherein the determining comprises determining the one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.

The further Access and Mobility Management Function may be an Access and Mobility Management Function for which shared delivery of the multicast Multicast/Broadcast Service session has not previously been established The message may be associated with at least one of an activation, deactivation, and update associated with the multicast Multicast/Broadcast Service session.

According to an aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, at a Mulficast/Broadcast Session Management Function from at least one Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying the Access and Mobility Management Function set to which it belongs; store, by the Mulficast/Broadcast Session Management Function, the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set; select, by the Multicast/Broadcast Session Management Function, an Access and Mobility Management Function of the Access and Mobility Management Function set to send a message associated with the Mulficast/Broadcast Service session based on the stored information; and send, from the Multicast/Broadcast Session Management Function to the selected Access and Mobility Management Function of the Access and Mobility Management Function set, a message associated with the Multicast/Broadcast Service session.

The at least one processor may be configured to cause the apparatus to send, by the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session only to one selected Access and Mobility Management Function of every Access and Mobility Management Function set through which shared delivery of the Multicast/Broadcast Service session has been established.

The at least one processor may be configured to cause the apparatus to send, by the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session to the selected Access and Mobility Management Function and any non-failed Access and Mobility Management Function of the Access and Mobility Management Function set through which shared delivery Multicast/Broadcast Service session has been established.

The at least one processor may be configured to cause the apparatus to further send an indication to the selected Access and Mobility Management Function requesting the selected Access and Mobility Management Function to distribute the message to one of: all access nodes having established shared delivery for the mulficast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set; or all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through the selected Access and Mobility Management Function and/or through an at least one further Access and Mobility Management Function indicated in the message, wherein the selected Access and Mobility Management Function is part of the same Access and Mobility Management Function set as the at least one further Access and Mobility Management Function, or wherein the selected Access and Mobility Management Function is a backup Access and Mobility Management Function of the at least one further Access and Mobility Management Function.

The at least one processor may be configured to cause the apparatus to: determine, by the Multicast/Broadcast Session Management Function, that a first Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; wherein the at least one processor may be configured to cause the apparatus to select an Access and Mobility Management Function comprised in the same Access and Mobility Management Function set as the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session, and wherein the selected Access and Mobility Management Function is different to the first Access and Mobility Management Function.

The at least one processor may be configured to cause the apparatus to determine that the first Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable by performing at least one of: receiving, at the Multicast/Broadcast Session Management Function from a Network Repository Function, information indicating that the first Access and Mobility Management Function has failed or is otherwise unreachable; sending, by the Multicast/Broadcast Session Management Function, one or more requests to the first Access and Mobility Management Function and receiving, by the Multicast/Broadcast Session Management Function, one or more error responses; sending, by the Multicast/Broadcast Session Management Function, one or more requests to the first Access and Mobility Management Function without receiving one or more responses; detecting an HTTP connection failure or being unable to setup a HTTP connection with the first Access and Mobility Management Function; receiving, at the Multicast/Broadcast Session Management Function from the at least one Access and Mobility Management Function of the Access and Mobility Management Function set, information indicating that the first Access and Mobility Management Function has failed or is otherwise unreachable.

The at least one processor may be configured to cause the apparatus to: determine, by the Multicast/Broadcast Session Management Function, that the Access and Mobility Management Function has failed or is otherwise unreachable, wherein the at least one processor may be configured to cause the apparatus to select the backup Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session.

According to an aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: send, from an Access and Mobility Management Function to an Multicast/Broadcast Session Management Function, a request for shared delivery for a multicast Multicast/Broadcast Service session for an access node, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying an Access and Mobility Management Function set comprising the Access and Mobility Management Function; store, by the Access and Mobility Management Function, information identifying the access node in a shared data store, wherein the shared data store is shared between the Access and Mobility Management Function and the other Access and Mobility Management Functions in the Access and Mobility Management Function set, and wherein the shared data store comprises information identifying one or more further access nodes that have requested shared delivery for the multicast Multicast/Broadcast Service session via one or more of the other Access and Mobility Management Functions in the Access and Mobility Management Function set; receive, at the Access and Mobility Management Function from the Multicast/Broadcast Session Management Function, a message associated with the Mulficast/Broadcast Service session; determine, by the Access and Mobility Management Function, at least one access node to send the message associated with the Multicast/Broadcast Service session to, based on the information stored in the shared data store; and send, from the Access and Mobility Management Function to the determined at least one access node, the message associated with the Multicast/Broadcast Service session.

The at least one processor may be configured to cause the apparatus to receive an indication requesting the Access and Mobility Management Function to distribute the message to all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set, wherein the determining comprises determining all the access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set.

The at least one processor may be configured to cause the apparatus to receive an indication requesting the Access and Mobility Management Function to distribute the message to all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through the Access and Mobility Management Function and/or through at least one further Access and Mobility Management Function indicated in the message, wherein the at least one further Access and Mobility Management Function has failed or is otherwise unreachable by the Multicast/Broadcast Session Management Function, wherein the determining comprises determining all access nodes that have established shared delivery for the multicast Multicast/Broadcast Service session through the Access and Mobility Management Function and/or the at least one further Access and Mobility Management Function.

The at least one processor may be configured to cause the apparatus to: determine, by the Access and Mobility Management Function, that the at least one further Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; and send, from the Access and Mobility Management Function to the Multicast/Broadcast Session Management Function, information indicating that the at least one further Access and Mobility Management Function has failed or is otherwise unreachable.

The information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set may comprise information identifying a first Access and Mobility Management Function and information identifying a backup Access and Mobility Management Function, wherein the first Access and Mobility Management Function and the backup Access and Mobility Management Function are configured for shared delivery of the multicast Mulficast/Broadcast Service session for the access node, and wherein the Access and Mobility Management Function is one of the first Access and Mobility Management Function and the backup Access and Mobility Management Function.

According to an aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, at a Mulficast/Broadcast Session Management Function from a first Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function; receive, from a second Access and Mobility Management Function of the Access and Mobility Management Function set, a request to update context information of the multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by the first Access and Mobility Management Function; update the context information of the multicast Access and Mobility Management Function session based on the request received from the second Access and Mobility Management Function; and send, from the Mulficast/Broadcast Session Management Function to the further Access and Mobility Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function.

The at least one processor may be configured to cause the apparatus to: receive, at the Multicast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast MBS session; wherein the at least one processor may be configured to cause the apparatus to send, to the second Access and Mobility Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.

According to an aspect, there is provided an apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: send, to a Multicast/Broadcast Session Management Function from a second Access and Mobility Management Function of an Access and Mobility Management Function set, a request to update context information of a multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by a first Access and Mobility Management Function of the Access and Mobility Management Function set; receive, from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function; determine, by the second Access and Mobility Management Function, the one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session to; and send, from the second Access and Mobility Management Function to the determined one or more access nodes, the message associated with the Multicast/Broadcast Service session.

The at least one processor may be configured to cause the apparatus to: send, to the Multicast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast Multicast/Broadcast Service session; and wherein the at least one processor may be configured to cause the apparatus to receive, from the Mulficast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function, wherein the determining comprises determining the one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.

The further Access and Mobility Management Function may be an Access and Mobility Management Function for which shared delivery of the multicast Mulficast/Broadcast Service session has not previously been established.

The message may be associated with at least one of an activation, deactivation, and update associated with the multicast Multicast/Broadcast Service session.

According to an aspect, there is provided a method comprising: receiving, at a Multicast/Broadcast Session Management Function from at least one Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Mulficast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying the Access and Mobility Management Function set to which it belongs; storing, by the Multicast/Broadcast Session Management Function, the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set; selecting, by the Mulficast/Broadcast Session Management Function, an Access and Mobility Management Function of the Access and Mobility Management Function set to send a message associated with the Multicast/Broadcast Service session based on the stored information; and sending, from the Mulficast/Broadcast Session Management Function to the selected Access and Mobility Management Function of the Access and Mobility Management Function set, a message associated with the Multicast/Broadcast Service session.

The sending may comprise sending, by the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session to the selected Access and Mobility Management Function and any non-failed Access and Mobility Management Function of the Access and Mobility Management Function set through which shared delivery Multicast/Broadcast Service session has been established.

The sending may further comprise sending an indication to the selected Access and Mobility Management Function requesting the selected Access and Mobility Management Function to distribute the message to one of all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set; or all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through the selected Access and Mobility Management Function and/or through an at least one further Access and Mobility Management Function indicated in the message, wherein the selected Access and Mobility Management Function is part of the same Access and Mobility Management Function set as the at least one further Access and Mobility Management Function, or wherein the selected Access and Mobility Management Function is a backup Access and Mobility Management Function of the at least one further Access and Mobility Management Function.

The method may comprise: determining, by the Multicast/Broadcast Session Management Function, that a first Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; wherein the selecting comprises selecting an Access and Mobility Management Function comprised in the same Access and Mobility Management Function set as the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session, and wherein the selected Access and Mobility Management Function is different to the first Access and Mobility Management Function.

Determining that the first Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable may comprise at least one of: receiving, at the Multicast/Broadcast Session Management Function from a Network Repository Function, information indicating that the first Access and Mobility Management Function has failed or is otherwise unreachable; sending, by the Multicast/Broadcast Session Management Function, one or more requests to the first Access and Mobility Management Function and receiving, by the Multicast/Broadcast Session Management Function, one or more error responses; sending, by the Multicast/Broadcast Session Management Function, one or more requests to the first Access and Mobility Management Function without receiving one or more responses; detecting an HTTP connection failure or being unable to setup a HTTP connection with the first Access and Mobility Management Function; receiving, at the Mulficast/Broadcast Session Management Function from the at least one Access and Mobility Management Function of the Access and Mobility Management Function set, information indicating that the first Access and Mobility Management Function has failed or is otherwise unreachable.

The method may comprise: determining, by the Multicast/Broadcast Session Management Function, that the Access and Mobility Management Function has failed or is otherwise unreachable, wherein the selecting comprises selecting the backup Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session.

According to an aspect there is provided a method comprising: sending, from an Access and Mobility Management Function to an Multicast/Broadcast Session Management Function, a request for shared delivery for a multicast Multicast/Broadcast Service session for an access node, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying an Access and Mobility Management Function set comprising the Access and Mobility Management Function; storing, by the Access and Mobility Management Function, information identifying the access node in a shared data store, wherein the shared data store is shared between the Access and Mobility Management Function and the other Access and Mobility Management Functions in the Access and Mobility Management Function set, and wherein the shared data store comprises information identifying one or more further access nodes that have requested shared delivery for the multicast Multicast/Broadcast Service session via one or more of the other Access and Mobility Management Functions in the Access and Mobility Management Function set; receiving, at the Access and Mobility Management Function from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session; determining, by the Access and Mobility Management Function, at least one access node to send the message associated with the Multicast/Broadcast Service session to, based on the information stored in the shared data store; and sending, from the Access and Mobility Management Function to the determined at least one access node, the message associated with the Mulficast/Broadcast Service session.

The receiving may further comprise receiving an indication requesting the Access and Mobility Management Function to distribute the message to all access nodes having established shared delivery for the multicast Mulficast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set, wherein the determining comprises determining all the access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set.

The method may comprise: determining, by the Access and Mobility Management Function, that the at least one further Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; and sending, from the Access and Mobility Management Function to the Multicast/Broadcast Session Management Function, information indicating that the at least one further Access and Mobility Management Function has failed or is otherwise unreachable.

According to an aspect, there is provided a method comprising: receiving, at a Multicast/Broadcast Session Management Function from a first Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Mulficast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function; receiving, from a second Access and Mobility Management Function of the Access and Mobility Management Function set, a request to update context information of the multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by the first Access and Mobility Management Function; updating the context information of the multicast Access and Mobility Management Function session based on the request received from the second Access and Mobility Management Function; and sending, from the Multicast/Broadcast Session Management Function to the further Access and Mobility Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function.

The method may comprise: receiving, at the Mulficast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast MBS session; wherein the sending comprises sending, to the second Access and Mobility Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.

The further Access and Mobility Management Function may be an Access and Mobility Management Function for which shared delivery of the multicast Multicast/Broadcast Service session has not previously been established According to an aspect, there is provided a method comprising: sending, to a Multicast/Broadcast Session Management Function from a second Access and Mobility Management Function of an Access and Mobility Management Function set, a request to update context information of a multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by a first Access and Mobility Management Function of the Access and Mobility Management Function set; receiving, from the Multicast/Broadcast Session Management Function, a message associated with the Mulficast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function; determining, by the second Access and Mobility Management Function, the one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session to; and sending, from the second Access and Mobility Management Function to the determined one or more access nodes, the message associated with the Mulficast/Broadcast Service session.

The method may comprise: sending, to the Multicast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast Multicast/Broadcast Service session; and wherein the receiving comprises receiving, from the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function, wherein the determining comprises determining the one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the second Access and Mobility Management Function.

The message may be associated with at least one of an activation, deactivation, and update associated with the multicast Mulficast/Broadcast Service session.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, at a Mulficast/Broadcast Session Management Function from at least one Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Mulficast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying the Access and Mobility Management Function set to which it belongs; storing, by the Multicast/Broadcast Session Management Function, the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set; selecting, by the Multicast/Broadcast Session Management Function, an Access and Mobility Management Function of the Access and Mobility Management Function set to send a message associated with the Multicast/Broadcast Service session based on the stored information; and sending, from the Mulficast/Broadcast Session Management Function to the selected Access and Mobility Management Function of the Access and Mobility Management Function set, a message associated with the Multicast/Broadcast Service session.

The sending may comprise sending, by the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session only to one selected Access and Mobility Management Function of every Access and Mobility Management Function set through which shared delivery of the Multicast/Broadcast Service session has been established.

The computer readable medium may comprises instructions which, when executed by the apparatus, cause the apparatus to further perform: determining, by the Multicast/Broadcast Session Management Function, that a first Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; wherein the selecting comprises selecting an Access and Mobility Management Function comprised in the same Access and Mobility Management Function set as the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session, and wherein the selected Access and Mobility Management Function is different to the first Access and Mobility Management Function.

The computer readable medium may comprises instructions which, when executed by the apparatus, cause the apparatus to further perform: determining, by the Mulficast/Broadcast Session Management Function, that the Access and Mobility Management Function has failed or is otherwise unreachable, wherein the selecting comprises selecting the backup Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session.

The request for shared delivery may comprise the identity of the backup Access and Mobility 20 Management Function.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: sending, from an Access and Mobility Management Function to an Mulficast/Broadcast Session Management Function, a request for shared delivery for a multicast Multicast/Broadcast Service session for an access node, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying an Access and Mobility Management Function set comprising the Access and Mobility Management Function; storing, by the Access and Mobility Management Function, information identifying the access node in a shared data store, wherein the shared data store is shared between the Access and Mobility Management Function and the other Access and Mobility Management Functions in the Access and Mobility Management Function set, and wherein the shared data store comprises information identifying one or more further access nodes that have requested shared delivery for the multicast Multicast/Broadcast Service session via one or more of the other Access and Mobility Management Functions in the Access and Mobility Management Function set; receiving, at the Access and Mobility Management Function from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session; determining, by the Access and Mobility Management Function, at least one access node to send the message associated with the Multicast/Broadcast Service session to, based on the information stored in the shared data store; and sending, from the Access and Mobility Management Function to the determined at least one access node, the message associated with the Multicast/Broadcast Service session.

The computer readable medium may comprises instructions which, when executed by the apparatus, cause the apparatus to further perform: determining, by the Access and Mobility Management Function, that the at least one further Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; and sending, from the Access and Mobility Management Function to the Multicast/Broadcast Session Management Function, information indicating that the at least one further Access and Mobility Management Function has failed or is otherwise unreachable.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, at a Mulficast/Broadcast Session Management Function from a first Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function; receiving, from a second Access and Mobility Management Function of the Access and Mobility Management Function set, a request to update context information of the multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by the first Access and Mobility Management Function; updating the context information of the multicast Access and Mobility Management Function session based on the request received from the second Access and Mobility Management Function; and sending, from the Multicast/Broadcast Session Management Function to the further Access and Mobility Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function.

The computer readable medium may comprises instructions which, when executed by the apparatus, cause the apparatus to further perform: receiving, at the Multicast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast M BS session; wherein the sending comprises sending, to the second Access and Mobility Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.

According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by an apparatus, cause the apparatus to perform at least the following: sending, to a Multicast/Broadcast Session Management Function from a second Access and Mobility Management Function of an Access and Mobility Management Function set, a request to update context information of a multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by a first Access and Mobility Management Function of the Access and Mobility Management Function set; receiving, from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function; determining, by the second Access and Mobility Management Function, the one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session to; and sending, from the second Access and Mobility Management Function to the determined one or more access nodes, the message associated with the Multicast/Broadcast Service session.

The computer readable medium may comprises instructions which, when executed by the apparatus, cause the apparatus to further perform: sending, to the Multicast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast Multicast/Broadcast Service session; and wherein the receiving comprises receiving, from the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function, wherein the determining comprises determining the one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.

According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the method according to any of the preceding aspects.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above

DESCRIPTION OF FIGURES

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which: Figure 1 shows a representation of a network system according to some example embodiments; Figure 2 shows a representation of a control apparatus according to some example embodiments; Figure 3 shows a representation of an apparatus according to some example embodiments; Figure 4 shows methods according to some examples; and Figures 5 to 10 show various signalling exchanges according to some examples.

DETAILED DESCRIPTION

In the following certain embodiments are explained with reference to mobile communication devices capable of communication via a wireless cellular system and mobile communication systems serving such mobile communication devices. Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system, access systems thereof, and mobile communication devices are briefly explained with reference to Figures 1, 2 and 3 to assist in understanding the technology underlying the described examples.

Figure 1 shows a schematic representation of a 5G system (5GS). The 5GS may be comprised by a terminal or user equipment (UE), a 5G radio access network (5GRAN) or next generation radio access network (NG-RAN), a 5G core network (5GC), one or more application function (AF) and one or more data networks (DN).

The 5G-RAN may comprise one or more gNodeB (GNB) or one or more gNodeB (GNB) distributed unit functions connected to one or more gNodeB (GNB) centralized unit functions. The 5GC may comprise the following entities: Network Slice Selection Function (NSSF); Network Exposure Function; Network Repository Function (NRF); Policy Control Function (PCF); Unified Data Management (UDM); Application Function (AF); Authentication Server Function (AUSF); an Access and Mobility Management Function (AMF); Session Management Function (SMF); Multicast/Broadcast Session Management Function (MB-SMF) and Multicast/Broadcast User Plane Function (MB-UPF).

Figure 2 illustrates an example of a control apparatus 200 for controlling a function of the 5GRAN or the 5GC as illustrated on Figure 1. The control apparatus may comprise at least one random access memory (RAM) 211a, at least on read only memory (ROM) 211b, at least one processor 212, 213 and an input/output interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects. The software code 215 may be stored in the ROM 211b. The control apparatus 200 may be interconnected with another control apparatus 200 controlling another function of the 5GRAN or the 5GC. In some embodiments, each function of the 5GRAN or the 5GC comprises a control apparatus 200. In alternative embodiments, two or more functions of the 5GRAN or the 5GC may share a control apparatus.

Figure 3 illustrates an example of a terminal 300, such as the terminal illustrated on Figure 1. The terminal 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a user equipment, a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, an Internet of things (loT) type communication device or any combinations of these or the like. The terminal 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.

The terminal 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 3 transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

The terminal 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302a.

The processor, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 304. The device may optionally have a user interface such as key pad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

In 3GPP, Multicast and Broadcast Service (M BS) is a point-to-multipoint service in which data is transmitted from a single source entity to multiple recipients, such as users in a broadcast service area or users in a multicast group.

An access node (e.g. 5G RAN, gNB) in the network may be configured via signalling between an access node and one or more AM Fs. Each AMF may interface with an MB-SMF to perform MBS session management and may select one or more of the access nodes for MBS traffic distribution.

Where more than one access node is configured for the same MBS service area, different access nodes of the same MBS service area may request shared delivery of MBS data (i.e. MBS traffic) for the same multicast MBS session through different AMFs. An AMF may store a list of access node IDs that have established shared delivery through that AMF, and the MB-SMF may store the identity of the AMF(s) that have established shared delivery of the same MBS session.

The different AMFs may be part of a same AMF Set. An AMF set is a set of functionally equivalent AMFs.

However some network architectures for providing MBS may result in inefficient signalling in some circumstances.

For example, a set of AMFs may comprise AMF1-4. NG-RAN node 1 may have established 20 shared delivery for a MBS session via AMF1, NG-RAN Node 2 may have established shared delivery for the MBS session via AMF2, and NG-RAN Node 3 may have established shared delivery for the MBS session via AMF3.

The MB-SMF may have stored the information that AMF1, AMF2, and AMF3 have established shared delivery for the multicast MBS session.

If the MB-SMF wishes to update or (de)activate the MBS session (for example by sending a request such as an Namf_MBSCommunication_N2MessageTransfer Request), the MB-SMF may send a request to AMF1, AMF2 and AMF3.

However if AMF 1 failed after NG-RAN node 1 established shared delivery for the MBS session via the AMF 1, or if AMF 1 is not reachable by the MB-SMF, a problem exists in how to ensure that NG-RAN node 1 receives the request once and only once in such a scenario. Indeed, per existing 3GPP specifications, the MB-SMF shall send MBS session update requests or MBS session (de)activation requests via the same AMF as the AMF through which shared delivery was established.

Thus there may be a problem when performing MBS session modification or (de)activation operations when different access nodes of the same MBS service area may request shared delivery for the same multicast MBS session through different AM Fs of a same AM F set and when one or more of these AM Fs become no longer reachable after the establishment of shared delivery.

Some examples may address some of these problems.

Reference is made to Figure 4, which shows methods according to some examples.

At 400, a method comprises receiving, at a Multicast/Broadcast Session Management Function from at least one Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying the Access and Mobility Management Function set to which it belongs.

At 402, the method comprises storing, by the Multicast/Broadcast Session Management Function, the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set.

At 404, the method comprises selecting, by the Multicast/Broadcast Session Management Function, an Access and Mobility Management Function of the Access and Mobility Management Function set to send a message associated with the Multicast/Broadcast Service session based on the stored information.

At 406, the method comprises sending, from the Multicast/Broadcast Session Management Function to the selected Access and Mobility Management Function of the Access and Mobility Management Function set, a message associated with the Multicast/Broadcast Service session.

At 408, a method comprises sending, from an Access and Mobility Management Function to an Multicast/Broadcast Session Management Function, a request for shared delivery for a multicast Multicast/Broadcast Service session for an access node, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying an Access and Mobility Management Function set comprising the Access and Mobility Management Function.

At 410, the method comprises storing, by the Access and Mobility Management Function, information identifying the access node in a shared data store, wherein the shared data store is shared between the Access and Mobility Management Function and the other Access and Mobility Management Functions in the Access and Mobility Management Function set, and wherein the shared data store comprises information identifying one or more further access nodes that have requested shared delivery for the multicast Multicast/Broadcast Service session via one or more of the other Access and Mobility Management Functions in the Access and Mobility Management Function set.

At 412, the method comprises receiving, at the Access and Mobility Management Function from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session.

At 414, the method comprises determining, by the Access and Mobility Management Function, at least one access node to send the message associated with the Multicast/Broadcast Service session to, based on the information stored in the shared data store.

At 416, the method comprises sending, from the Access and Mobility Management Function 20 to the determined at least one access node, the message associated with the Multicast/Broadcast Service session.

At 418, a method comprises receiving, at a Multicast/Broadcast Session Management Function from a first Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function.

At 420, the method comprises receiving, from a second Access and Mobility Management Function of the Access and Mobility Management Function set, a request to update context information of the multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by the first Access and Mobility Management Function.

At 422, the method comprises updating the context information of the multicast Access and Mobility Management Function session based on the request received from the second Access and Mobility Management Function.

At 424, the method comprises sending, from the Mulficast/Broadcast Session Management Function to the further Access and Mobility Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function.

At 426, a method comprises sending, to a Multicast/Broadcast Session Management Function from a second Access and Mobility Management Function of an Access and Mobility Management Function set, a request to update context information of a multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by a first Access and Mobility Management Function of the Access and Mobility Management Function set.

At 428, the method comprises receiving, from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function.

At 430, the method comprises determining, by the second Access and Mobility Management Function, the one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function to send the message associated with the Mulficast/Broadcast Service session to.

At 432, the method comprises sending, from the second Access and Mobility Management Function to the determined one or more access nodes, the message associated with the Multicast/Broadcast Service session.

In some examples, an access node may send a request to establish shared delivery via any AMF of an AMF set When establishing shared delivery with the MB-SMF, the AMF may include, in a request sent to the MB-SMF, its AMF Set ID, and optionally a preferred AMF in the AMF set for receiving subsequent requests for the related multicast MBS session (for example in a Nmbsmf MbsSession_ContextUpdate request).

In some examples, the AMF set ID and optional preferred AMF in the AMF set may be provided either as new parameters in the request payload or using a binding indication in the request.

The MB-SMF may store the AMF Set ID associated to each multicast MBS session (instead of, or in addition to, storing the list of AMF IDs) and the preferred AMF, if included.

When access nodes establish or release shared delivery for the MBS session, the list of access node IDs associated to the multicast MBS session may be updated by each AMF in the AMF set. That is to say, in some examples the association between access nodes and an MBS session may be stored in a shared context data for the entire AMF set between all AMFs in the AMF set.

In some examples, when the SMF needs to activate, deactivate or update the multicast MBS session, the MB-SMF may send a request (such as an Namf_MBSCommunication_N2MessageTransfer Request) to one AMF of the AMF set. The AMF of the AMF set can be any AMF of the AMF set and may be a different AMF for different requests over time.

In some examples the MB-SMF may select any AMF in the AMF set that supports the MBS service (i.e. which has registered support of the MBS service in its AMF profile in NRF). Accordingly, if in some deployments MBS was not supported or configured to be used by all AMFs in the AMF set (e.g. if access nodes would be configured to use a subset of the AMFs in the AMF set for MBS services), some examples may ensure that the SMF (re)selects an AMF in the set that supports MBS service for all the access node served by the AMF set.

The receiving AMF may send an N2 container to the complete list access node IDs associated to the multicast MBS session and AMF set, as stored in the shared multicast MBS session context.

Reference is made to Figure 5, which shows an example signalling exchange for establishing shared delivery for multicast MBS session traffic.

At 500, the access node determines to establish shared delivery for a multicast MBS session, e.g. when a first UE served by the access node requests to join the multicast MBS session.

At 502, responsive to the determination at 500, the access node sends a request message to a serving AMF. The request message may indicate that the access node wants to establish shared delivery for the multicast MBS session traffic.

At 504, based on the request received at 502, the AMF sends a request message to the MBSMF to establish shared delivery for the multicast MBS session traffic. The request message sent by the AMF at 504 may comprise information identifying an AMF set that the AMF is associated with, and optionally information identifying an preferred AM F of the AMF set for the SMF to provide subsequent requests associated with the multicast MBS session.

At 506, the AMF may store information of the access node(s) that have requested shared delivery for the multicast MBS session traffic. In some examples, when different access nodes establish or release shared delivery for the MBS session via the same or different AMF of the same AMF set, each AMF of the AMF set may store a list of access node IDs associated with the multicast MBS session for the entire AMF set in shared context data between the AM Fs in the AMF set.

At 508, based on the request received at 504, the MB-SMF may configure the MB-UPF to send multicast data for the multicast MBS session towards the GIP tunnel endpoint provided by the access node, when using unicast transport between the MB-UPF and Access node.

At 510, based on the request received at 504, the MB-SMF may store information identifying the AMF and the information identifying the AM F set that the AM F is associated with. The MB-SMF may also optionally store the information identifying the preferred AMF of the AMF set for the MB-SMF to provide subsequent requests associated with the multicast MBS session.

At 512, in response to establishing shared delivery for the MBS session, the MB-SMF sends a response message to the AMF.

At 514, the AMF sends a response message to the access node indicating that the shared delivery for multicast MBS session traffic has been established.

Thus in some examples, upon receiving a request from an Access node to establish shared delivery of an multicast MBS session, the AM F may send a request to the MB-SMF for shared delivery of multicast MBS session traffic, and this request may comprise information identifying an AMF set that the AMF is associated with, and optionally information identifying a preferred AMF of the AMF set for the MB-SMF to provide subsequent requests associated with the multicast MBS session.

Reference is made to Figure 6, which shows a signalling exchange according to some

examples.

At 600a, gNB1 establishes shared delivery via AMF1 for multicast MBS session traffic; at 600b, gNB2 establishes shared delivery via AMF2 for multicast MBS session traffic; and at 600c, gNB3 establishes shared delivery via AMF3 for multicast MBS session traffic, for the same multicast MBS session. The establishing may be by any suitable means, such as but not limited to that described above with reference to Figure 5.

While three gN Bs and three AMFs are shown in Figure 6, it should be understood that in some implementations there may be two or more gNBs and a respective two or more AMFs.

Thus as part of steps 600a-c, each AMF adds its AMF set ID, and optionally a preferred AMF in the AMF set for receiving subsequent requests for the MBS session, to a request message for establishing shared delivery of MBS session traffic. The AMF sends this request message to the MB-SMF. Each AMF also stores a list of access nodes associated with the multicast MBS session for the entire AMF set, for example in shared context data between the AM Fs in the AMF set. In the example call flow, after step 600c, the shared context data between all the AMFs in the AMF set would contain the identities of Access node 1, Access node 2 and Access node 3 for the multicast MBS session.

At 602, the MB-SMF determines that a change to the MBS session is required. For example, the MB-SMF may determine that it needs to activate, deactivate, or update the MBS session.

At 604, in response to the determining at step 602 and based on the request messages received from AM Fs1-3 at step 600, the MB-SMF selects one of the AMFs in the set of AMFs for sending a message associated with the MBS session.

The AMF may be any of the AM Fs comprised in the set of AMFs. If a preferred AMF has been indicated in step 600, then the M B-SMF may select the preferred AMF.

For example, the MB-SMF may select AM F1 to deliver a message indicating a change in the MBS session to access nodes 1-3.

At 606, the MB-SMF sends the message associated with the MBS session to the AMF selected at 604.

The message may for example comprise a Namf MBSCommunication_N2MessageTransfer Request. The request may comprise a TMGI and N2 container. The request may contain an indicator requesting the AMF to distribute the request to all NG-RAN nodes having established shared delivery for this multicast MBS session through any of the AMF of the AMF set.

At 608, in response to receiving the message at 606, the selected AMF identifies the access nodes to forward the received message to based on the information stored at this point in time in the shared multicast MBS session context.

At 610, the AMF sends the received message to the identified access nodes associated to the multicast MBS session and the AMF set.

In some examples, when the selected AMF has failed or is otherwise unreachable by the MBSMF, the MB-SMF may (re)send the message at 606 to any other available/reachable AMF in the AMF set.

In some examples, when the MB-SMF needs to activate, deactivate or update the multicast MBS session and the MB-SMF detects that the selected AMF of the AMFs of the set of AMFs has failed or is not reachable, the MB-SMF may reselect an alternative AMF (supporting MBS) in the AMF set. For example, if the MB-SMF selects AMF1 but then detects that AMF1 is not reachable, the SMF may reselect AMF2, 3 or 4.

Having reselected the alternative AMF, the MB-SMF may send a new request for the multicast MBS session to the alternative AMF, and the alternative AMF may forward the request on to the access nodes that had established shared delivery for this MBS session through any AMF of the AMF set (i.e. to the access nodes stored in the shared context data for this multicast MBS session). In some examples the request may comprise a N2 container. In some examples, the request may contain an indicator requesting the AMF to distribute the request to all NG-RAN nodes having established shared delivery for this multicast MBS session through any of the AMF of the AMF set.

In some examples, while performing the reselecting and sending described above, the MB-SMF may also send a request to other AMFs in the AMF set. Thus the MB-SMF may prefer to use one of these requests to request the delivery of the request to the access nodes that were handled by the failed AMF.

In some examples, the request from MB-SMF to the alternative AMF may include information identifying the AMF that failed or with which the MB-SM F cannot communicate.

The alternative AM F may retrieve the access node I Ds that were associated to this AMF from the shared context, or from the list of access node I Ds that were handled by AM Fl.

The alternative AMF may then send the request to the access nodes that had established shared delivery through AM Fl.

The alternative AM F may indicate in a response to the MB-SMF (or in a separate request such as a Nmbsmf MbsSession_ContextUpdate request) that the alternative AMF is newly handling shared delivery for this multicast MBS session Of it had not done so beforehand) and/or indicate that the failed AMF1 is no longer doing so.

The MB-SMF may store the alternative AMF as an additional AMF through which shared delivery is established for this mulficast MBS session and/or to remove the failed AMF. The alternative AMF may also update the information (AMF ID associated to access node IDs) in the shared data.

Reference is made to Figure 7, which shows a signalling exchange according to some examples Steps 700a-c correspond to steps 600a-c from Figure 6.

At 702, the SMF determines that AM F1 has failed or is otherwise unreachable by the SMF.The MB-SMF may determine this, for example, based on sending a message to the AMF1 and getting no response, or based on receiving a notification from the NRF that it ceased to receive keep alive message from AMF1, or based on HTTP connection failures, such as procedures specified in 3GPP TS 23.527.

At 704, the MB-SMF determines that a change to the MBS session is required. For example, the MB-SMF may determine that it needs to activate, deactivate, or update the MBS session.

At 706, the MB-SMF selects an alternative AMF in the AMF set for sending a message associated with the MBS session to access nodes that were handled by the failed AMF.

The message may for example comprise a Namf MBSCommunication_N2MessageTransfer Request.

For example, as shown in Figure 7, when AMF1 has failed the MB-SMF may select AMF3 to deliver the message to access node 1.

At 708, the MB-SMF sends the message associated with the MBS session to the alternative AMF selected at 706. The MB-SMF may also send the message to an AMF in the set of AMF that has not failed. In the example of Figure 7, the MB-SMF sends a message to AMF2 (to send to access node 2) and AMF3 (to send to access node 1 and 3).

At 710, in response to receiving the message at 708, the selected AMF identifies the access nodes to send the message to based on the information stored in the shared multicast MBS session context.

At 712, the AMF sends the message to the access nodes associated to the multicast MBS session and the failed AMF as well as to the access nodes associated to the multicast MBS session and the selected AMF.

Thus in the example of Figure 7, AMF3 may send the message to access node 1 and access node 3 In some examples, upon detecting failure of one of the AMFs in the AMF set (for example using similar principles to those described above in relation to the MB-SMF), the AMF set may reassign the access node IDs stored by the failed AMF to an alternative AMF in the set. If the alternative AMF is an AMF for which no shared delivery had been established yet for this multicast MBS session, the alternative AMF may send a Nmbsmf MbsSession_ContextUpdate request to the MB-SMF for updating the MB-SMF that the alternative AMF is handling shared delivery for some access nodes and that the failed AMF is no longer doing so.

Reference is made to Figure 8, which shows a signalling exchange according to some

examples.

Steps 800a-c follow similar steps 600a-c described previously in relation to Figure 6, except that in some examples the AMF Set ID may not be signalled to the MB-SMF during the shared delivery establishment. Instead, each AMF may store its own RAN IDs of RAN(s) having established shared delivery via the AMF.

At 802, at least one AMF in the AMF set determines that another AMF in the AMF set has failed or is otherwise unreachable. For example, AMF3 may determine that AMF1 has failed.

At 804, at least one AM F in the AMF set sends a request to the MB-SMF to update the MBS session context. The request may indicate the failed AMF and that a new AMF in the AMF set is handling shared delivery for access nodes that were previously handled by the failed AMF. The new AM F may not have previously had shared delivery established for the multicast M BS session.

At 806, the MB-SMF updates the MBS session context based on the request received at 804.

At 808, the MB-SMF sends a message associated with the MBS session to the new AMF indicated in step 804 (and any other AMFs in the AMF set as required) for forwarding to the access nodes which requested shared delivery of the M BS session traffic via the AM F in steps 800a-c and any access nodes that the AM F has taken over responsibility for handling shared delivery in step 804.

At 810 the AM Fs determine the access nodes to forward the message on to. In the example of Figure 8, AM F2 would determine to forward the message on to access node 2 (as access node 2 requested the shared delivery via AM F2), and AMF3 would determine access nodes 1 and 3 (as access node 3 requested shared delivery via AMF3, and AMF3 has taken over shared delivery for access node 1).

At 812, the AM Fs forward the message on to the determined access node(s).

In some examples, the AMF set can be replaced by signalling a "backup AM F", for example when two AMFs share context data. The AM F Instance ID of the backup AM F may be signalled to the MB-SMF during shared delivery establishment, and the MB-SMF may send the subsequent messages associated with the MBS session to the backup AMF when the initial AMF is no longer reachable by the MB-SMF. The initial AMF or backup AMF may send the N2 container to all access nodes that have established shared delivery via any of these two AMFs.

Reference is made to Figure 9, which shows an example signalling exchange for establishing shared delivery for multicast MBS session traffic.

Steps 900-902 follows steps 500-502 described previously in relation to Figure 5.

At 904, based on the request received at 902, the AMF sends a request message to the MB-SMF to establish shared delivery for multicast MBS session traffic. The request message sent by the AMF at 904 may comprise information identifying a backup AMF for the MB-SMF to use to send messages associated with the MBS session when the AMF has failed or is otherwise unreachable by the MB-SMF.

At 906, the AMF may store information of the access node(s) that have requested shared delivery for the multicast MBS session traffic.

At 908, based on the request received at 904, the MB-SMF may configure the MB-UPF to send multicast data for the multicast MBS session towards the GIP tunnel endpoint provided by the access node, when using unicast transport between the MB-UPF and Access node.

At 910, based on the request received at 904, the MB-SMF may store information identifying the AMF and the information identifying the backup AMF.

At 912, in response to establishing the session at 908, the MB-SMF sends a response message to the AMF.

At 914, the AMF sends a response message to the access node indicating that the shared delivery for multicast MBS session traffic has been established.

Reference is made to Figure 10, which shows a signalling exchange according to some examples At 1000, the access node establishes shared delivery for a multicast MBS session via AMF1, for example following the process described above in relation to Figure 9.

At 1002, the MB-SMF determines that AMF1 has failed or is otherwise unreachable by the MB-SMF.

At 1004, the MB-SMF determines that a change to the MBS session is required. For example, the MB-SMF may determine that it needs to activate, deactivate, or update the MBS session.

At 1006, responsive to the determinations at 1002 and 1004, the MB-SMF sends a message associated with the M BS session to the backup AMF. The message may for example comprise a Namf_MBSCommunicafion_N2MessageTransfer Request. The message may include an indicator requesting the backup AMF to distribute the request to all NG-RAN nodes having established shared delivery for this multicast MBS session through the original AMF or backup AMF.

At 1008, the backup AMF forwards the message received at 1006 to one or more access nodes for which shared delivery of the MBS session traffic has been configured in step 1000.

More generally, the backup AMF forwards the message received at 1006 to one or more access nodes for which shared delivery of the MBS session traffic has been established through the initial AMF (AM Fl) or backup AMF. The Initial AMF and backup AMF share the information about the access nodes having established shared delivery via the initial AMF or backup AMF.

Therefore, some examples may support shared delivery of multicast MBS session traffic to a plurality of access nodes via a set of AMFs. The AMFs in the set may store information identifying the access nodes in a shared data store, so that an AMF can identify all access nodes associated with the shared delivery of the multicast MBS session when performing shared delivery. The MB-SMF can store information identifying the set of AMFs that are configured for shared delivery of the multicast MBS session, so that the MB-SMF can select any one of the AMFs or reselect a different AMF should the initially selected AMF fail or be otherwise unreachable by the MB-SMF, when updating, activating or deactivating the multicast MBS session. As such, some examples may improve the flexibility, efficiency and reliability of the network for supporting the shared delivery of the multicast MBS session.

In some examples, there is provided an apparatus comprising means for: receiving, at a Multicast/Broadcast Session Management Function from at least one Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying the Access and Mobility Management Function set to which it belongs; storing, by the Multicast/Broadcast Session Management Function, the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set; selecting, by the Mulficast/Broadcast Session Management Function, an Access and Mobility Management Function of the Access and Mobility Management Function set to send a message associated with the Multicast/Broadcast Service session based on the stored information; and sending, from the Multicast/Broadcast Session Management Function to the selected Access and Mobility Management Function of the Access and Mobility Management Function set, a message associated with the Multicast/Broadcast Service session.

In some examples, the apparatus comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, at a Multicast/Broadcast Session Management Function from at least one Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Mulficast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying the Access and Mobility Management Function set to which it belongs; store, by the Multicast/Broadcast Session Management Function, the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set; select, by the Multicast/Broadcast Session Management Function, an Access and Mobility Management Function of the Access and Mobility Management Function set to send a message associated with the Mulficast/Broadcast Service session based on the stored information; and send, from the Multicast/Broadcast Session Management Function to the selected Access and Mobility Management Function of the Access and Mobility Management Function set, a message associated with the Mulficast/Broadcast Service session In some examples, there is provided an apparatus comprising means for: sending, from an Access and Mobility Management Function to an Multicast/Broadcast Session Management Function, a request for shared delivery for a multicast Multicast/Broadcast Service session for an access node, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying an Access and Mobility Management Function set comprising the Access and Mobility Management Function; storing, by the Access and Mobility Management Function, information identifying the access node in a shared data store, wherein the shared data store is shared between the Access and Mobility Management Function and the other Access and Mobility Management Functions in the Access and Mobility Management Function set, and wherein the shared data store comprises information identifying one or more further access nodes that have requested shared delivery for the multicast Multicast/Broadcast Service session via one or more of the other Access and Mobility Management Functions in the Access and Mobility Management Function set; receiving, at the Access and Mobility Management Function from the Mulficast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session; determining, by the Access and Mobility Management Function, at least one access node to send the message associated with the Mulficast/Broadcast Service session to, based on the information stored in the shared data store; and sending, from the Access and Mobility Management Function to the determined at least one access node, the message associated with the Multicast/Broadcast Service session.

In some examples, the apparatus comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: send, from an Access and Mobility Management Function to an Mulficast/Broadcast Session Management Function, a request for shared delivery for a multicast Multicast/Broadcast Service session for an access node, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying an Access and Mobility Management Function set comprising the Access and Mobility Management Function; store, by the Access and Mobility Management Function, information identifying the access node in a shared data store, wherein the shared data store is shared between the Access and Mobility Management Function and the other Access and Mobility Management Functions in the Access and Mobility Management Function set, and wherein the shared data store comprises information identifying one or more further access nodes that have requested shared delivery for the multicast Multicast/Broadcast Service session via one or more of the other Access and Mobility Management Functions in the Access and Mobility Management Function set; receive, at the Access and Mobility Management Function from the Mulficast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session; determine, by the Access and Mobility Management Function, at least one access node to send the message associated with the Multicast/Broadcast Service session to, based on the information stored in the shared data store; and send, from the Access and Mobility Management Function to the determined at least one access node, the message associated with the Multicast/Broadcast Service session.

In some examples, there is provided an apparatus comprising means for: receiving, at a Multicast/Broadcast Session Management Function from a first Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Mulficast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function; receiving, from a second Access and Mobility Management Function of the Access and Mobility Management Function set, a request to update context information of the multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by the first Access and Mobility Management Function; updating the context information of the multicast Access and Mobility Management Function session based on the request received from the second Access and Mobility Management Function; and sending, from the Multicast/Broadcast Session Management Function to the further Access and Mobility Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function.

In some examples, the apparatus comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, at a Multicast/Broadcast Session Management Function from a first Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Mulficast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function; receive, from a second Access and Mobility Management Function of the Access and Mobility Management Function set, a request to update context information of the multicast Mulficast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by the first Access and Mobility Management Function; update the context information of the multicast Access and Mobility Management Function session based on the request received from the second Access and Mobility Management Function; and send, from the Multicast/Broadcast Session Management Function to the further Access and Mobility Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function.

In some examples, there is provided an apparatus comprising means for: sending, to a Multicast/Broadcast Session Management Function from a second Access and Mobility Management Function of an Access and Mobility Management Function set, a request to update context information of a multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by a first Access and Mobility Management Function of the Access and Mobility Management Function set; receiving, from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function; determining, by the second Access and Mobility Management Function, the one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session to; and sending, from the second Access and Mobility Management Function to the determined one or more access nodes, the message associated with the Multicast/Broadcast Service session.

In some examples, the apparatus comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: send, to a Multicast/Broadcast Session Management Function from a second Access and Mobility Management Function of an Access and Mobility Management Function set, a request to update context information of a multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by a first Access and Mobility Management Function of the Access and Mobility Management Function set; receive, from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function; determine, by the second Access and Mobility Management Function, the one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session to; and send, from the second Access and Mobility Management Function to the determined one or more access nodes, the message associated with the Multicast/Broadcast Service session.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception.

Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems.

Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

As used herein, "at least one of the following: <a list of two or more elements>" and "at least one of <a list of two or more elements>" and similar wording, where the list of two or more elements are joined by "and" or "or', mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation." This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

The embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media.

The term "non-transitory," as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

The memory 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 memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process.

Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The scope of protection sought for various embodiments of the disclosure is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this disclosure. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this disclosure will still fall within the scope of this invention as defined in the appended claims. Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

CLAIMS1. An apparatus comprising means for: receiving, at a Mulficast/Broadcast Session Management Function from at least one Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying the Access and Mobility Management Function set to which it belongs; storing, by the Multicast/Broadcast Session Management Function, the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set; selecting, by the Mulficast/Broadcast Session Management Function, an Access and Mobility Management Function of the Access and Mobility Management Function set to send a message associated with the Mulficast/Broadcast Service session based on the stored information; and sending, from the Multicast/Broadcast Session Management Function to the selected Access and Mobility Management Function of the Access and Mobility Management Function set, a message associated with the Multicast/Broadcast Service session.
2. The apparatus of claim 1, wherein the sending comprises sending, by the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session only to one selected Access and Mobility Management Function of every Access and Mobility Management Function set through which shared delivery of the Multicast/Broadcast Service session has been established.
3. The apparatus of claim 1, wherein the sending comprises sending, by the Multicast/Broadcast Session Management Function, the message associated with the Multicast/Broadcast Service session to the selected Access and Mobility Management Function and any non-failed Access and Mobility Management Function of the Access and Mobility Management Function set through which shared delivery Multicast/Broadcast Service session has been established.
4. The apparatus of any preceding claim, wherein the sending further comprises sending an indication to the selected Access and Mobility Management Function requesting the selected Access and Mobility Management Function to distribute the message to one of: all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set; or all access nodes having established shared delivery for the mulficast Multicast/Broadcast Service session through the selected Access and Mobility Management Function and/or through an at least one further Access and Mobility Management Function indicated in the message, wherein the selected Access and Mobility Management Function is part of the same Access and Mobility Management Function set as the at least one further Access and Mobility Management Function, or wherein the selected Access and Mobility Management Function is a backup Access and Mobility Management Function of the at least one further Access and Mobility Management Function.
5. The apparatus of any preceding claim, wherein the means is for: determining, by the Multicast/Broadcast Session Management Function, that a first 15 Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; wherein the selecting comprises selecting an Access and Mobility Management Function comprised in the same Access and Mobility Management Function set as the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session, and wherein the selected Access and Mobility Management Function is different to the first Access and Mobility Management Function.
6. The apparatus of claim 5, wherein determining that the first Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable comprises at least one of: receiving, at the Multicast/Broadcast Session Management Function from a Network Repository Function, information indicating that the first Access and Mobility Management Function has failed or is otherwise unreachable; sending, by the Multicast/Broadcast Session Management Function, one or more requests to the first Access and Mobility Management Function and receiving, by the Multicast/Broadcast Session Management Function, one or more error responses; sending, by the Multicast/Broadcast Session Management Function, one or more requests to the first Access and Mobility Management Function without receiving one or more responses; detecting an HTTP connection failure or being unable to setup a HTTP connection with the first Access and Mobility Management Function; receiving, at the Mulficast/Broadcast Session Management Function from the at least one Access and Mobility Management Function of the Access and Mobility Management Function set, information indicating that the first Access and Mobility Management Function has failed or is otherwise unreachable.
7. The apparatus of any of claims 1 to 4, wherein the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set comprises information identifying the Access and Mobility Management Function and information identifying a backup Access and Mobility Management Function.
8. The apparatus of claim 7, wherein the means is for: determining, by the Multicast/Broadcast Session Management Function, that the Access and Mobility Management Function has failed or is otherwise unreachable, wherein the selecting comprises selecting the backup Access and Mobility Management Function to send the message associated with the Mulficast/Broadcast Service session.
9. The apparatus of any of claims 7 or 8, wherein the request for shared delivery comprises the identity of the backup Access and Mobility Management Function.
10. An apparatus comprising means for: sending, from an Access and Mobility Management Function to an Multicast/Broadcast Session Management Function, a request for shared delivery for a mulficast Multicast/Broadcast Service session for an access node, wherein the request comprises information identifying the Access and Mobility Management Function and information identifying an Access and Mobility Management Function set comprising the Access and Mobility Management Function; storing, by the Access and Mobility Management Function, information identifying the access node in a shared data store, wherein the shared data store is shared between the Access and Mobility Management Function and the other Access and Mobility Management Functions in the Access and Mobility Management Function set, and wherein the shared data store comprises information identifying one or more further access nodes that have requested shared delivery for the multicast Multicast/Broadcast Service session via one or more of the other Access and Mobility Management Functions in the Access and Mobility Management Function set; receiving, at the Access and Mobility Management Function from the Multicast/Broadcast Session Management Function, a message associated with the Multicast/Broadcast Service session; determining, by the Access and Mobility Management Function, at least one access node to send the message associated with the Multicast/Broadcast Service session to, based on the information stored in the shared data store; and sending, from the Access and Mobility Management Function to the determined at least one access node, the message associated with the Multicast/Broadcast Service session.
11. The apparatus of claim 10, wherein the receiving further comprises receiving an indication requesting the Access and Mobility Management Function to distribute the message to all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set, wherein the determining comprises determining all the access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through any Access and Mobility Management Function of the Access and Mobility Management Function set.
12. The apparatus of claim 10, wherein the receiving further comprises receiving an indication requesting the Access and Mobility Management Function to distribute the message to all access nodes having established shared delivery for the multicast Multicast/Broadcast Service session through the Access and Mobility Management Function and/or through at least one further Access and Mobility Management Function indicated in the message, wherein the at least one further Access and Mobility Management Function has failed or is otherwise unreachable by the Multicast/Broadcast Session Management Function, wherein the determining comprises determining all access nodes that have established shared delivery for the multicast Multicast/Broadcast Service session through the Access and Mobility Management Function and/or the at least one further Access and Mobility Management Function.
13. The apparatus of claim 12, wherein the means is for: determining, by the Access and Mobility Management Function, that the at least one further Access and Mobility Management Function of the Access and Mobility Management Function set has failed or is otherwise unreachable; and sending, from the Access and Mobility Management Function to the Multicast/Broadcast Session Management Function, information indicating that the at least one further Access and Mobility Management Function has failed or is otherwise unreachable.
14. The apparatus of claim 10, wherein the information identifying the Access and Mobility Management Function and the information identifying the Access and Mobility Management Function set comprises information identifying a first Access and Mobility Management Function and information identifying a backup Access and Mobility Management Function, wherein the first Access and Mobility Management Function and the backup Access and Mobility Management Function are configured for shared delivery of the multicast Multicast/Broadcast Service session for the access node, and wherein the Access and Mobility Management Function is one of the first Access and Mobility Management Function and the backup Access and Mobility Management Function.
15. An apparatus comprising means for: receiving, at a Multicast/Broadcast Session Management Function from a first Access and Mobility Management Function of an Access and Mobility Management Function set, a request for shared delivery establishment for a multicast Multicast/Broadcast Service session, wherein the request comprises information identifying the Access and Mobility Management Function; receiving, from a second Access and Mobility Management Function of the Access and Mobility Management Function set, a request to update context information of the multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by the first Access and Mobility Management Function; updating the context information of the multicast Access and Mobility Management Function session based on the request received from the second Access and Mobility Management Function; and sending, from the Multicast/Broadcast Session Management Function to the further Access and Mobility Management Function, a message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function
16. The apparatus of claim 15, wherein the further Access and Mobility Management Function is the second Access and Mobility Management Function.
17. The apparatus of claim 16, wherein the means is for: receiving, at the Multicast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast M BS session; wherein the sending comprises sending, to the second Access and Mobility Management Function, the message associated with the Multicast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.
18. The apparatus of claim 15, wherein the further Access and Mobility Management Function is an Access and Mobility Management Function for which shared delivery of the multicast Mulficast/Broadcast Service session has not previously been established.
19. An apparatus comprising means for: sending, to a Mulficast/Broadcast Session Management Function from a second Access and Mobility Management Function of an Access and Mobility Management Function set, a request to update context information of a multicast Multicast/Broadcast Service session, wherein the request comprises an indication that a further Access and Mobility Management Function is handling shared delivery for access nodes that were previously handled by a first Access and Mobility Management Function of the Access and Mobility Management Function set; receiving, from the Multicast/Broadcast Session Management Function, a message associated with the Mulficast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Mulficast/Broadcast Service session via the first Access and Mobility Management Function; determining, by the second Access and Mobility Management Function, the one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function to send the message associated with the Multicast/Broadcast Service session to; and sending, from the second Access and Mobility Management Function to the determined one or more access nodes, the message associated with the Mulficast/Broadcast Service session.
20. The apparatus of claim 19, wherein the further Access and Mobility Management Function is the second Access and Mobility Management Function.
21. The apparatus of claim 20, wherein the means is for: sending, to the Mulficast/Broadcast Session Management Function from the second Access and Mobility Management Function of the Access and Mobility Management Function set, a request for shared delivery establishment for the multicast Multicast/Broadcast Service session; and wherein the receiving comprises receiving, from the Multicast/Broadcast Session Management Function, the message associated with the Mulficast/Broadcast Service session for forwarding to one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function, wherein the determining comprises determining the one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the first Access and Mobility Management Function and one or more access nodes which requested shared delivery of the multicast Multicast/Broadcast Service session via the second Access and Mobility Management Function.
22. The apparatus of claim 19, wherein the further Access and Mobility Management Function is an Access and Mobility Management Function for which shared delivery of the multicast Mulficast/Broadcast Service session has not previously been established.
23. The apparatus of any preceding claim, wherein the message is associated with at least one of an activation, deactivation, and update associated with the multicast Multicast/Broadcast Service session.