WO2021233555A1

WO2021233555A1 - Apparatus, methods, and computer programs for multicast session management in 5g networks

Info

Publication number: WO2021233555A1
Application number: PCT/EP2020/064331
Authority: WO
Inventors: Thomas Belling; David NAVRÁTIL; Laurent Thiebaut
Original assignee: Nokia Technologies Oy
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2021-11-25
Also published as: EP4154469A1

Abstract

Some methods comprises receiving at an access node information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session. The method further comprises causing at least one message to be sent from the access node to the identified one or more control entities requesting that data associated with the multicast session be provided to the access node.

Description

APPARATUS, METHODS, AND COMPUTER PROGRAMS FOR MULTICAST SESSION MANAGEMENT IN 5G NETWORKS

Field of the disclosure The present disclosure relates to apparatus, methods, and computer programs and in particular but not exclusively to apparatus, methods and computer programs supporting and/or multicasting of data.

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, access nodes 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 communications devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and/or content data and so on. Content may be multicast or uni-cast to communications devices.

A user can access the communication system by means of an appropriate communications device or terminal. A communications device of a user is often referred to as user equipment (UE) or user device. The communications device may access a carrier provided by an access node and transmit and/or receive communications on the carrier.

The communication system and associated devices typically operate in accordance with a required 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). Another example of an architecture that is known as the long-term evolution (LTE) or the Universal Mobile Telecommunications System (UMTS) radio-access technology. Another example communication system is so called 5G radio or new radio (NR) access technology.

Summary

According to an aspect, there is provided an apparatus in an access node, said apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: receive information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and cause at least one message to be sent from the access node to the identified one or more control entities requesting that data associated with the multicast session be provided to the access node.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to: in response to receiving the information indicating that the communications device is to receive data associated with the multicast session and information identifying the one or more control entities controlling the multicast session, determine whether the access node already receives data associated with the multicast session, and when it is determined that the access node does not already receive data associated with the multicast session, cause the at least one message to be sent from the access node to the identified one or more control entities.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to: receive the information indicating that the communications device is to receive data associated with the multicast session and the information identifying the one or more control entities controlling the multicast session from one or more session managing entities managing a session of the communications device.

The information that the communications device is to receive data associated with multicast session may comprise an identity for the multicast session. The received information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session may be received in at least one of: a protocol data unit session resource management message; a message associated with a reconnection of the communications device to a network; and a handover related message.

The at least one message to be sent from the access node may comprise one or more of: information identifying the multicast session; information identifying the one or more control entities; and address information associated with the access node.

The address information may comprise one or more of: an address of the access node; tunnel information; an indication that delivery of the data associated with the multicast session if via IP multicast.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to receive a response from the one or more controlling nodes.

The response from the one or more control entities may comprise multicast address information for the multicast session.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to cause resources at the access node for the reception of data from the one or more control entities to be configured.

The response from the one or more control entities may comprise quality of service information for the multicast session.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to determine if the communications device is to receive the multicast session from the access node via a unicast or via a multicast.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to: receive a message indicating that the communications device has left the multicast session and cause a message to be sent to the one or more control entities indicating that the providing of data associated with the multicast session to the access node is to be terminated.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to: determine, in response to receiving the information indicating that the communications device has left the multicast session whether the access node provides the data associated with the multicast session to one or more other communications devices and when it is determined that the access node does not provide the data associated with the multicast session to one or more other communications devices, cause the message to be sent to the one or more control entities indicating that the providing of data associated with the multicast session to the access node is to be terminated.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to in response to the communications device being handed over from the access node to another access node, cause information to be provided to the another access node about the multicast session, said information provided to the another access node comprising information identifying the one or more control entities controlling the multicast session.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to determine, in response to the communications device being handed over to the another access node, whether the access node provides the data associated with the multicast session to one or more other communications devices and when it is determined that the access node does not provide the data associated with the multicast session to one or more other communications devices, cause a message to be sent to the one or more control entities indicating that the providing of the data associated with the multicast session to the access node is to be terminated.

The access node may comprise a radio access network node.

The one or more controlling nodes may comprise: a session management function; a set of session management functions; or a broadcast multicast service centre.

The apparatus may be an access node or provided in an access node.

According to another aspect, there is provided an apparatus provided in an access node comprising means for: receiving information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and causing at least one message to be sent from the access node to the identified one or more control entities requesting that data associated with the multicast session be provided to the access node.

The means may be for, in response to receiving the information indicating that the communications device is to receive data associated with the multicast session and information identifying the one or more control entities controlling the multicast session, determining whether the access node already receives data associated with the multicast session, and when it is determined that the access node does not already receive data associated with the multicast session, causing the at least one message to be sent from the access node to the identified one or more control entities.

The means may be for receiving the information indicating that the communications device is to receive data associated with the multicast session and the information identifying the one or more control entities controlling the multicast session from one or more session managing entities managing a session of the communications device.

The address information may comprise one or more of: an address of the access node; tunnel information; an indication that delivery of the data associated with the multicast session if via IP multicast. The means may be for receiving a response from the one or more controlling nodes.

The response from the one or more controlling entities may comprise multicast address information for the multicast session. The means may be for causing resources at the access node for the reception of data from the one or more control entities to be configured.

The response from the one or more controlling nodes may comprise quality of service information for the multicast session. The means may be for determining if the communications device is to receive the multicast session from the access node via a unicast or via a multicast.

The access node may comprise a radio access network node. The one or more controlling nodes may comprise: a session management function, a set of session management functions; or a broadcast multicast service centre. The means may be for receiving at the access node a message indicating that the communications device has left the multicast session and causing a message to be sent to the one or more control entities indicating that the providing of data associated with the multicast session to the access node is to be terminated.

The means may be for determining, in response to receiving the information indicating that the communications device has left the multicast session whether the access node provides the data associated with the multicast session to one or more other communications devices and when it is determined that the access node does not provide the data associated with the multicast session to one or more other communications devices, causing the message to be sent to the one or more control entities indicating that the providing of data associated with the multicast session to the access node is to be terminated.

The means may be for, in response to the communications device being handed over from the access node to another access node causing information to be provided from the access node to the another access node about the multicast session, said information provided to the another access node comprising information identifying the one or more control entities controlling the multicast session.

The means may be for determining, in response to the communications device being handed over to another access node, whether that access node provides the data associated with the multicast session to one or more other communications devices and when it is determined that the access node does not provide the data associated with the multicast session to one or more other communications devices, causing a message to be sent to the one or more control entities indicating that the providing of the data associated with the multicast session to the access node is to be terminated.

The apparatus may be provided in or be an access node.

According to another aspect, there is provided a method comprising: receiving at an access node information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and causing at least one message to be sent from the access node to the identified one or more control entities requesting that data associated with the multicast session be provided to the access node.

The method may comprise: in response to receiving the information indicating that the communications device is to receive data associated with the multicast session and information identifying the one or more control entities controlling the multicast session, determining whether the access node already receives data associated with the multicast session, and when it is determined that the access node does not already receive data associated with the multicast session, causing the at least one message to be sent from the access node to the identified one or more control entities.

The method may comprise receiving the information indicating that the communications device is to receive data associated with the multicast session and the information identifying the one or more control entities controlling the multicast session from one or more session managing entities managing a session of the communications device.

The information that the communications device is to receive data associated with multicast session may comprise an identity for the multicast session.

The received information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session may be received in at least one of: a protocol data unit session resource management message; a message associated with a reconnection of the communications device to a network; and a handover related message.

The address information may comprise one or more of: an address of the access node; tunnel information; an indication that delivery of the data associated with the multicast session if via IP multicast. The method may comprise receiving a response from the one or more controlling nodes.

The response from the one or more controlling entities may comprise multicast address information for the multicast session.

The method may comprise causing resources at the access node for the reception of data from the one or more control entities to be configured.

The response from the one or more controlling nodes may comprise quality of service information for the multicast session.

The method may comprise determining if the communications device is to receive the multicast session from the access node via a unicast or via a multicast.

The access node may comprise a radio access network node.

The one or more controlling nodes may comprise: a session management function, a set of session management functions; or a broadcast multicast service centre.

The method may comprise receiving at the access node a message indicating that the communications device has left the multicast session and causing a message to be sent to the one or more control entities indicating that the providing of data associated with the multicast session to the access node is to be terminated.

The method may comprise determining, in response to receiving the information indicating that the communications device has left the multicast session whether the access node provides the data associated with the multicast session to one or more other communications devices and when it is determined that the access node does not provide the data associated with the multicast session to one or more other communications devices, causing the message to be sent to the one or more control entities indicating that the providing of data associated with the multicast session to the access node is to be terminated. The method may comprise, in response to the communications device being handed over from the access node to another access node causing information to be provided from the access node to the another access node about the multicast session, said information provided to the another access node comprising information identifying the one or more control entities controlling the multicast session.

The method may comprise determining, in response to the communications device being handed over to another access node, whether that access node provides the data associated with the multicast session to one or more other communications devices and when it is determined that the access node does not provide the data associated with the multicast session to one or more other communications devices,, causing a message to be sent to the one or more control entities indicating that the providing of the data associated with the multicast session to the access node is to be terminated.

According to another aspect, there is provided an apparatus in an session managing entity, said apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: manage a session of a communications device; receive a request from the communications device to join a multicast session; determine one or more control nodes controlling the multicast session; and cause at least one message to be sent, to an access node or access management entity, from the session managing entity, said message comprising information indicating that the communications device is to receive data associated with the multicast session and information identifying the one or more control nodes controlling the multicast session.

The at least one memory and the computer program code may be configured, with the at least one processor, to cause the apparatus to: determine that the communications device is to stop receiving data associated with the multicast session; and cause at least one message to be sent to the access node or access management entity from the session managing entity, said message comprising information indicating that the communications device is to stop receiving data associated with the multicast session. The at least one memory and the computer program code may be configured, with the at least one processor, to cause the apparatus to determine that the communications device is to stop receiving data associated with the multicast session based on at least one of: a received request from the communications device to leave the multicast session; that the communications device did not refresh a request to join the multicast session for a configured period of time; and a received message indicating that the communication device is no longer permitted to receive data associated with the multicast session.

The at least one message may comprise one or more of: information identifying the multicast session; information identifying the one or more control entities; and address information associated with the access node.

The at least one memory and the computer program code may be configured, with the at least one processor, to cause the apparatus to obtain the information identifying the one or more control nodes from a data repository.

The apparatus may be the session managing entity or an apparatus of the session managing entity.

According to another aspect, there is provided an apparatus in an session managing entity, said apparatus comprising means for: managing a session of a communications device; receiving a request from the communications device to join a multicast session; determining one or more control nodes controlling the multicast session; and causing at least one message to be sent, to an access node or access management entity, from the session managing entity, said message comprising information indicating that the communications device is to receive data associated with the multicast session and information identifying the one or more control nodes controlling the multicast session. The method may comprise determining that the communications device is to stop receiving data associated with the multicast session and causing at least one message to be sent to the access node or access management entity from the session managing entity, said message comprising information indicating that the communications device is to stop receiving data associated with the multicast session

The method may comprise determining that the communications device is to stop receiving data associated with the multicast session based on at least one of: a received request from the communications device to leave the multicast session; that the communications device did not refresh a request to join the multicast session for a configured period of time; and a received message indicating that the communication device is no longer permitted to receive data associated with the multicast session.

The means may be for obtaining the information identifying the one or more control nodes from a data repository.

According to another aspect, there is provided a method comprising: managing a session of a communications device; receiving a request from the communications device to join a multicast session; determining one or more control nodes controlling the multicast session; and causing at least one message to be sent, to an access node or access management entity, from the session managing entity, said message comprising information indicating that the communications device is to receive data associated with the multicast session and information identifying the one or more control nodes controlling the multicast session. The means may be for determining that the communication device is to stop receiving data associated with the multicast session and causing at least one message to be sent to the access node or access management entity from the session managing entity, said message comprising information indicating that the communications device is to stop receiving data associated with the multicast session.

The means may be for determining that the communications device is to stop receiving data associated with the multicast session based on at least one of: a received request from the communications device to leave the multicast session; that the communications device did not refresh a request to join the multicast session for a configured period of time; and a received message indicating that the communication device is no longer permitted to receive data associated with the multicast session.

The method may comprise obtaining the information identifying the one or more control nodes from a data repository.

The method may be performed by the session managing entity or an apparatus of the session managing entity.

According to another aspect, there is provided an apparatus in a control entity, said apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: control a multicast session;receive at least one message from an access node, said message comprising information identifying the access node which is to receive data associated with the multicast session; and cause a message to be provided to an ingress entity requesting that the data associated with the multicast session is to be provided to the access node for the communications device.

The request from the access node may request starting or stopping transfer of data associated with the multicast session towards the access node.

The request from the access node may be handled as a protocol data unit session establishment and/or release

The at least one memory and the computer program code may be configured, with the at least one processor, to cause the apparatus to receive a response message from the ingress entity indicating that the multicast data will be provided to the access node.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to: send a response to the access node, the response comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session.

The at least one message may comprise one or more of: information identifying the multicast session; and address information associated with the access node.

The at least one memory and the computer program code may be configured, with the at least one processor, to cause the apparatus to cause a response to be provided to the access node.

The response may comprise multicast address information for the multicast session.

The response may comprise quality of service information for the multicast session. The apparatus may comprise the control entity or may be provided in the control entity.

According to another aspect, there is provided an apparatus in a control entity, said apparatus comprising means for: controlling a multicast session; receiving at least one message from an access node, said message comprising information identifying the access node which is to receive data associated with the multicast session; and causing a message to be provided to an ingress entity requesting that the data associated with the multicast session is to be provided to the access node for the communications device.

The means may be for receiving a response message from the ingress entity indicating that the multicast data will be provided to the access node.

The means may be for sending a response to the access node, the response comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session

The means may be for causing a response to be provided to the access node.

The response may comprise multicast address information for the multicast session. The response may comprise quality of service information for the multicast session.

The apparatus may comprise the control entity or may be provided in the control entity.

According to another aspect, there is provided a method comprising: controlling a multicast session; receiving at least one message from an access node, said message comprising information identifying the access node which is to receive data associated with the multicast session; and causing a message to be provided to an ingress entity requesting that the data associated with the multicast session is to be provided to the access node for the communications device.

The method may comprise receiving a response message from the ingress entity indicating that the multicast data will be provided to the access node.

The method may comprise sending a response to the access node, the response comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session

The method may comprise causing a response to be provided to the access node.

According to another aspect, there is provided an apparatus in a access management entity comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: receive information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and cause at least one message to be sent to an access node with the information indicating that a communications device is to receive the data associated with a multicast session and the information identifying one or more control entities controlling the multicast session. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to: receive at least one message from the access node, said message comprising information identifying the one or more control entities controlling a multicast session and a request that the access node stop receiving data associated with the multicast session; and cause at least one message to be sent to the one or more control entities with the request that the access node stop receiving data associated with the multicast session.

The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus to: in response to the message with the request that the access node request stop receiving data associated with the multicast session, receive at least one message from the one or more control entities comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session; and cause at least one message to be sent to the access node comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session.

The message from the access node may be handled as a protocol data unit session establishment. According to another aspect, there is provided an apparatus in a access management entity comprising means for: receiving information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and causing at least one message to be sent to an access node with the information indicating that a communications device is to receive the data associated with a multicast session and the information identifying one or more control entities controlling the multicast session.

The means may be for: receiving at least one message from the access node, said message comprising information identifying the one or more control entities controlling a multicast session and a request that the access node stop receiving data associated with the multicast session; and causing at least one message to be sent to the one or more control entities with the request that the access node stop receiving data associated with the multicast session.

The means may be for: in response to the message with the request that the access node stop receiving data associated with the multicast session, receive at least one message from the one or more control entities comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session; and causing at least one message to be sent to the access node comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session.

The message from the access node may be handled as a protocol data unit session establishment

According to another aspect, there is provided a method comprising: receiving at an access management entity information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and causing at least one message to be sent from the access management entity to an access node with the information indicating that a communications device is to receive the data associated with a multicast session and the information identifying one or more control entities controlling the multicast session.

The method may comprise: receiving at least one message from the access node, said message comprising information identifying the one or more control entities controlling a multicast session and a request that the access node stop receiving data associated with the multicast session; and causing at least one message to be sent to the one or more control entities with the request that the access node stop receiving data associated with the multicast session.

The method may comprise: in response to the message with the request that the access node stop receiving data associated with the multicast session, receive at least one message from the one or more control entities comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session; and causing at least one message to be sent to the access node comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session.

The message from the access node may be handled as a protocol data unit session establishment.

According to an aspect, there is provided a computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

According to an aspect, there is provided a non-volatile tangible memory medium comprising program instructions stored thereon for performing at least one of the above methods. In the above, many different aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above.

Various other aspects are also described in the following detailed description and in the attached claims.

Brief Description of the Figures

Some embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 shows a schematic representation of a 5G system;

Figure 2 shows a schematic representation of a control apparatus;

Figure 3 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the steps of the methods of some embodiments;

Figure 4 shows a schematic representation of signalling diagram of some embodiments;

Figure 5 shows a first method of some embodiments;

Figure 6 shows a second method of some embodiments;

Figure 7 shows a third method of some embodiments; and Figure 8 shows a fourth method of some embodiments.

Detailed Description of the Figures

In the following certain embodiments are explained with reference to mobile communications devices capable of communication via a wireless cellular system and mobile communication systems serving such mobile communications devices. Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system, access systems thereof, and mobile communications 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) 100. The 5GS may comprises a terminal 102, one or more access nodes 104, a 5G core network (5GCN) 106, one or more application functions (AF) 108 and one or more data networks (DN) 110. The access node may be any suitable node such as NG RAN (next generation radio access network) node or a W-AGF (wireline access gateway function) node for wireline access or any other suitable access node. The NG RAN may comprise one or more gNodeB (GNB) distributed unit functions connected to one or more gNodeB (GNB) centralized unit functions. The RAN may comprise one or more access nodes.

The 5GCN 106 may comprise one or more access management functions (AMF), one or more session management functions (SMF), an authentication server function (AUSF) 116, a unified data management (UDM) 118, one or more user plane functions (UPF) 120, a unified data repository (UDR) 122 and/or a network exposure function (NEF) 124.

Figure 2 illustrates an example of an apparatus 200. This apparatus may be provided in an access node, an AMF, a SMF or a UPF. The 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 211 b. 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 211 b.

One or more aspects of this disclosure relate a public land mobile network (PLMN), such as a 5GS PLMN. It will be understood that although one or more aspects of this disclosure relate to a 5GS they may be applicable to other cellular systems.

Some embodiments relate to multicast-broadcast services. This may for example be 5G multicast-broadcast services (5MBS). Some embodiments may relate to a situation where a UE requests to establish a multicast session context associated with a PDU (protocol data unit) session, but the multicast session context is managed by a different SMF to the current SMF. The SMF is responsible for interacting with the data plane. The SMF creates, updates and removes PDU (protocol data unit) session and a multicast session for a multicast group. The SMF manages session context with the UPF.

A UE may be served by a SMF or a set of two or more SMFs.

Some embodiments relate to a user plane configuration for a multicast content distribution when the SMF (or SMF set) serving a UE that joins a multicast group is different from the SMF (or SMF set) controlling the ingress point and user plane configuration for this multicast group.

Some embodiments may be provided in a 5G system. However, it should be appreciated that some embodiments may be provided in other systems. Whilst the terminology used to explain some embodiments is that of the 5G system, it should be appreciated that embodiments can be applied to different systems with entities providing similar or the same functions as the example entities in the following examples.

The ingress point may be a UPF. The ingress point may be the entry point for the data to be multicast.

This situation may occur where an AF may use a specific ingress point (i.e. ingress UPF) for a multicast group before announcing a multicast session to UEs. The multicast group may be controlled by a specific SMF (or SMF set). This may be different to the one or more SMFs currently serving one or more UEs which are to join the multicast session.

This situation may alternatively or additionally occur where different UEs are assigned different SMFs (or SMF set) when a PDU session is established, i.e. before UEs join the multicast group. An ingress point may be selected when a first UE joins the multicast group and a user plane is established to the serving RAN node of the UE. When another UE served by another SMF (or SMF set) joins the same multicast group under the same or different RAN node, a problem is that the another SMF (of SMF set) is not in the control of the ingress point and the user plane configuration for the multicast group.

This situation may alternatively or additionally occur where for unicast transport of a multicast session, RAN nodes need to allocate an ingress IP address and GTP-U (GPRS (general packet radio service) tunnelling protocol -user plane) ID (identity) in order to receive the multicast content.

In some embodiments an access node entity is informed by the SMF via UE-specific signalling that the UE joins a multicast session. The access node entity may be provided with information (e.g. multicast context identity and a controlling core entity identity) to reach a core entity controlling the ingress point. The core entity may be a SMF, SMF set or a BM-SC (broadcast multicast service centre). A SMF ID, a SMF set ID, or BM-SC identity information may be provided to allow the core entity controlling the ingress point to be reached. The access node may be provided with user plane configuration for the multicast session.

The access node may be any suitable access node. The access node may be any suitable 5G access node.

The access node may check if it already receives the multicast distribution content for the multicast session. If the access node does not currently receive the multicast distribution content, the access node contacts the core entity and requests the configuration of the ingress point and the user plane for the reception of multicast content for the group. The access node may indicate the requested multicast group (e.g. using the multicast context identity) to the core entity.

Consider a first scenario where a UE joins a group.

A first SMF handling a PDU Session, receives a join request from a UE for a multicast group. The first SMF will checks at the UDR whether a core entity controlling the ingress point and user plane for this multicast group exists. The UDR may store the SMF ID, SMF set ID, BM-SC ID or the like of the core entity controlling the ingress point and user plane for this multicast group.

The core entity controlling the ingress point and user plane for this multicast group is called “core control entity”. In some of the embodiments which are discussed by way of example only, this core control entity is a SMF. This may be a second SMF in some cases.

If there is no core control entity information for this multicast group stored in the UDR then the first SMF uses its identity in UE-specific signalling and may assume the role of control entity for this multicast group.

If the UDR contains the core control entity information for this multicast, then the UE- specific signalling includes the identity of the control node which is retrieved from the UDR.

The access node is informed by the first SMF via the AMF and using UE-specific signalling that the UE joins a multicast group. This signalling may indicate the multicast context identity and/or the control entity controlling the ingress point and the user plane for the multicast group.

This signalling may be implemented using NGAP (next generation application protocol) PDU session resource related signalling.

This signalling may include the corresponding S-NSSAI (single-network slice selection assistance information). S-NSSAI may be provided in NGAP PDU session resource related signalling,

The access node checks if it has the user plane configured and already receives multicast content for this multicast group (multicast context). If the access node currently does not receive the multicast distribution content, the access node selects an AMF that supports 5MBS. This may be based on configured information and/or the information received from the first SMF. This may for example use the S-NSSAI received from SMF.

The selected AMF is to be used to contact the core control entity. This selected AMF may be the AMF of the PDU Session if it supports 5MBS.

The access node may establish a dedicated NGAP association with the AMF providing the multicast context identity and the identity of the core control entity. The access node contacts via the AMF the core control entity for user plane configuration to allow the reception of multicast content for the multicast group. The access node may provide an indication of the multicast context identity.

For unicast transport in the 5G core, the access node will provide in the request downlink tunnel information (e.g. IP address and GTP-U tunnel identifier) indicating where the access node wishes to receive the multicast distribution.

For multicast transport in the 5G core, the access node does not include downlink tunnel information. The downlink tunnel information is to be provided by the core control entity in the form of a multicast tunnel (e.g. multicast address (any source multicast or source specific multicast)) and GTP-U tunnel identifier.

Upon reception of that signalling, the core control entity will for unicast transport in the 5G core configure the ingress point (for example the UPF) with the downlink tunnel information (for example indicated IP address and GTP-U tunnel identifier) and/or packet forwarding/replication rules for this tunnel to send multicast content to the access node.

Upon reception of that signalling, the core control entity will for multicast transport in the 5G core provide N3 multicast addressing information (any source multicast or source specific multicast). The access node will use the received downlink N3 multicast addressing information from the control node to join the multicast distribution tree. Upon reception of that signalling, the core control entity may also provide QoS information for the multicast group (multicast context) in the reply to the access node.

When the UE leaves the multicast group, the access node receives UE-specific signalling from the first SMF indicating that the UE left the multicast session. The access node checks if it serves other UEs that joined the multicast group identified by multicast session/context identity. If there are no other UEs, the RAN node requests the core control entity to terminate transmission of multicast content to the access node. This signalling goes from the access node to the core control entity via the AMF.

The AMF forwards the access node signalling on an association with the core control entity and then this association is released.

The core control entity may configure the UPF accordingly (e.g. removing the access node as a destination address of the multicast flow, removing downlink tunnel, and/or packet forwarding/replication rules for this tunnel).

When the UE is handed over to another access node, the information about the multicast group the UE joined and the related core control entity is transferred from the old access node to the new access node.

The old access node checks if it serves other UEs that joined the multicast group. If there are no other UEs, the access node requests the core control entity to terminate transmission of multicast content to the access node and release user plane resources. The same mechanisms may then apply as described above for the case where the UE leaves the multicast group

The new access node may check if it has a user plane configured and already receives multicast content for this multicast group (multicast context). If not, the new access node contacts the core control entity via an AMF. This is to request the core control entity to configure the user plane to allow the reception of multicast content for the multicast group by the access node. The same procedure which is described for the case where the UE joins a multicast group while served by the new access node can be applied here. A determination that a UE is to stop receiving data of a multicast session based on one or more of: a received request from the UE to leave the multicast session; that the UE did not refresh a request to join the multicast session for a configured period of time; and a received message indicating that the UE is no longer permitted to receive data associated with the multicast session.

There may be an IPM (IP multicast) domain “handled” by the UE. This may correspond to the IPM address that the UE joins. This IPM address may be part of the identifier of the “multicast session” that the UE joins.

There may be an IPM domain at the N3 interface between UPF2 and the access node. This may be used when the access node can receive over the N3 multicast the multicast content to send to the UE. There may be two variants for delivery (over N3) of the IPM content to the access node. There may be point to point delivery or by IP Multicast. In this latter option, this may use another IPM domain/another set of IPM addresses over N3 other than the set of IPM addresses that the UE can “handle”.

The access node may inform the second SMF of its access node address for point to point delivery over N3, and/or that the access node can receive the multicast content over the N3 interface.

On point to point/ point to multicast delivery, this may be preconfigured in the second SMF. The configuration could be the same on a PLMN basis if all RAN nodes are the same.

In some embodiments, the second SMF sends multicast tunnel information to the access node. The access node either accept that information or sends in the response unicast downlink tunnel information. This could depend on the RAN node's support of multicast or if the RAN’s node has information whether the transport to the ingress UPF supports multicast routing.

Reference is made to the signal flow of Figure 4. In step 1 , a content provider announces a multicast session to the UE. This announcement may provide multicast session information and/or group information. This may for example comprise a multicast group identified by a multicast IP address

For example, a UE may receive a session description. This session description may be in an SDP (session description protocol) format. The session description may comprise media transport information for one or more or each media steam. The media transport information may comprise the IP multicast group address and/or the transport port for media.

In step 2, the UE registers and establishes a PDU session towards a first SMF, SMF1 . The first SMF, SMF1 assigns a first UPF, UPF1 to transmit data related to the PDU session.

In one alternative shown in steps 3a and 3b, the first SMF, SMF1 , obtains a request from the UE to join a multicast group indicated in the multicast session information in step 1 This request may comprise an IP multicast group address. In this alternative, the UE sends in step 3a a user plane request to join the multicast group to the first UPF, UPF1. This may take the form of the UE sending IGMP (Internet Group Management Protocol) or MLD (Multicast Listener Discovery Protocol as defined by IETF) signalling

In step 3b, the first UPF, UPF 1 provides a user plane event notify message to the first SMF, SMF 1.

As an alternative to steps 3a and 3b, the steps of 4a and 4b are performed. As with steps 3a and 3b, the first SMF, SMF1 , obtains a request from the UE to join a multicast group indicated in the multicast session information in step 1 This request may comprise an IP multicast group address. In this alternative, the UE sends in step 4a a PDU session modification request via the control plane to the AMF. In step 4b, the AMF sends a PDU session update SM (session management) context to the first SMF, SMF via the control plane. In step 5, the first SMF, SMF1 inquires at the UDR if a core control entity (that is an entity controlling an ingress point and user plane for the multicast group) already exists in the network. The UDR indicates that a second SMF, SMF2, is the core control entity. This indication provided by the UDR may be the SMF ID and/or SMF Set ID of the second SMF, SMF2. The UDR may provide the associated multicast session and/or context ID used internally in 5GS for this multicast group. This step may be regarded as a multicast distribution session check.

In steps 6 and 7, the first SMF, SMF1 signals via the AMF (step 6) to the RAN (step 7) that UE shall be added to the multicast group and/or context. This signalling may indicate the multicast group and/or context ID and/or session ID corresponding to the multicast group identity (e.g. the IP multicast group address as targeted by the UE). This signalling may additionally comprise the SMF ID and/or SMF Set ID of the second SMF, SMF2 as reference to the core control entity.

In step 8, the RAN node configures the resources to transmit the multicast session to UE. The RAN node may check whether the user plane for the multicast group and/or context is already established towards the RAN node.

In step 9, if no user plane is established, the RAN nodes may select based on the S- NSSAI of the PDU Session the AMF to reach SMF2 (the core control entity). The RAN node may send a request for the user plane establishment towards the core control entity via that AMF. The RAN node establishes a dedicated NGAP association with the AMF providing one or more of: multicast context/group ID/session ID; the identity of the core control entity as target of this request. This may be the SMF2 ID and/or SMF2 Set ID; and a NGAP SM message: If the RAN node is configured to use a unicast transport for multicast distribution sessions, it allocates a downlink tunnel (an IP address for the RAN node and a GTP-U ID) for the reception of the multicast distribution session and indicates the downlink tunnel information in the request sent to the core control entity. The RAN may indicate its capability to receive the multicast content (for the UE) via a multicast distribution over the interface between the RAN and the 5G Core. In step 10 the AMF forwards the request towards the second SMF, SMF2 indicated in step 9. The AMF creates an association dedicated to the multicast context identity with the core control entity. On this association the AMF relays the signalling between the RAN and the core control entity (the second SMF, SMF2). The core control entity (SMF2) may determine a QoS (quality of service) for the multicast session. The RAN node address and the GTP-U ID may be provided by the AMF to the second SMF. This may take the form of the AMF forwarding content from the NGAP message to the core control entity

In step 11 , for unicast transport of the multicast distribution session, the second SMF, SMF2 configures the second UPF, UPF2 to transmit the multicast distribution session towards the received IP address and a GTP-U ID (provided by the RAN). The second SMF, SMF 2, may provide the RAN node address and the GTP-U ID to the second UPF, UPF2.

In step 12, the second SMF, SMF2, sends a multicast distribution session response via the association to the AMF. It may indicate a QoS for the multicast session. For multicast transport of the multicast distribution session, the response may indicate in the downlink multicast address information for the multicast session.

In step 13, the AMF forwards multicast distribution session response to the RAN node. If this indicates that the multicast content (for the UE) is delivered via a multicast distribution over the interface between the RAN and the 5G Core, then the RAN releases resources associated with the tunnel information sent to the one controlling entity.

In step 14, the content provider sends multicast data to the second UPF, UPF2.

In step 15, the second UPF, UPF2 forwards the multicast data to the RAN node.

In step 16, the RAN performs a bearer selection to determine if the data is to be transported to the UE via a unicast or multicast bearer. In step 17, the multicast data is transported from the RAN to the UE via the selected unicast or multicast bearer.

It should be appreciated that one or more of the steps shown in Figure 4 may be omitted. One or more steps may be performed in a different order. One or more additional steps may be added.

Some embodiments may be used where a UE is reconnecting to a multicast session or where the UE is being handed over to another access node. The multicast session information and the identity of the one or more entities controlling the multicast session may be received at the access node in a PDU session resource management message, a message associated with a reconnection of the communications device to the network; and a handover related message.

Some embodiments may allow a simple determination whether a multicast distribution towards a RAN node is required in the RAN node. This may avoid complexity of logic in the core to see if a multicast distribution towards a RAN node is required for any UE served by any SMF receiving the multicast session.

Some embodiments may avoid additional signalling in the core to determine a UE^'s location to determine the RAN node which needs to receive the multicast distribution session.

A first method of some embodiments will now be described with reference to Figure 5. The method of Figure 5 may be performed by an apparatus. The apparatus may be for example as shown in Figure 2. The apparatus may be provided in an access node or may be an access node.

In step A1 , the method comprises receiving at an access node information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session. This may be when the communications device is to join a multicast session or when a communications device is handed over from one access node to another.

The data may be content data.

In step A2, the method comprises cause at least one message to be sent from the access node to the identified one or more control entities requesting that data associated with the multicast session be provided to the access node. A second method of some embodiments will now be described with reference to Figure

6. The method of Figure 6 may be performed by an apparatus. The apparatus may be for example as shown in Figure 2. The apparatus may be provided in a session managing entity or may be a session managing entity. In step B1 , the method comprisescausing at least one message to be sent, to an access node. The session managing entity may be managing a session of a communications device with said access node. The message may comprise information indicating that the communications device is to receive data associated with a multicast session and information identifying one or more control nodes controlling the multicast session.

A third method of some embodiments will now be described with reference to Figure

7. The method of Figure 7 may be performed by an apparatus. The apparatus may be for example as shown in Figure 2. The apparatus may be provided in a control entity. In step C1 , the method comprises receiving at least one message from an access node at a control entity controlling a multicast session. The message comprises information identifying the access node associated with a communications device which is to receive data associated with the multicast session. In step C2, the method comprises causing a message to be provided to an ingress entity requesting that the data associated with the multicast session is to be provided to the access node for the communications device. A fourth method of some embodiments will now be described with reference to Figure 8. The method of Figure 8 may be performed by an apparatus. The apparatus may be for example as shown in Figure 2. The apparatus may be provided in an access management entity.

In step D1 , the method comprises receiving information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session. In step D2, the method comprises causing at least one message to be sent from the access management entity to an access node with the information indicating that a communications device is to receive the data associated with a multicast session and the information identifying one or more control entities controlling the multicast session. Figure 3 shows a schematic representation of non-volatile memory media 800a (e.g. computer disc (CD) or digital versatile disc (DVD)) and 800b (e.g. universal serial bus (USB) memory stick) storing instructions and/or parameters 802 which when executed by a processor allow the processor to perform one or more of the steps of the methods of Figures 5 to 8.

It is noted 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. It will be understood that although the above concepts have been discussed in the context of a 5GS, one or more of these concepts may be applied to other cellular systems.

The embodiments may thus vary within the scope of the attached claims. In general, some embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects 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 embodiments are not limited thereto. While various embodiments 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.

The embodiments may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any procedures, e.g., as in Figures 5 to 8, 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 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 include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi-core processor architecture, as non-limiting examples.

Alternatively or additionally some embodiments may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and/or method steps previously described. That circuitry may be provided in the base station and/or in the communications device. 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 analogue and/or digital circuitry);

(b) combinations of hardware circuits and software, such as:

(i) a combination of analogue 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 the communications device or base station to perform the various functions previously described; 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 integrated device.

The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of some embodiments 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 will still fall within the scope as defined in the appended claims.

Claims

1 . An apparatus in an access node, said apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: receive information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and cause at least one message to be sent from the access node to the identified one or more control entities requesting that data associated with the multicast session be provided to the access node.

2. The apparatus as claimed in claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: in response to receiving the information indicating that the communications device is to receive data associated with the multicast session and information identifying the one or more control entities controlling the multicast session, determine whether the access node already receives data associated with the multicast session; and when it is determined that the access node does not already receive data associated with the multicast session, cause the at least one message to be sent from the access node to the identified one or more control entities.

3. The apparatus as claimed in any preceding claim, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to receive the information indicating that the communications device is to receive data associated with the multicast session and the information identifying the one or more control entities controlling the multicast session from one or more session managing entities managing a session of the communications device.

4. The apparatus as claimed in any preceding claim, wherein said information that the communications device is to receive data associated with multicast session comprises an identity for the multicast session.

5. The apparatus as claimed in any preceding claim, wherein the received information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session are received in at least one of: a protocol data unit session resource management message ; a message associated with a reconnection of the communications device to a network; and a handover related message.

6. The apparatus as claimed in any preceding claim, wherein the at least one message to be sent from the access node comprises one or more of: information identifying the multicast session; information identifying the one or more control entities; and address information associated with the access node.

7. The apparatus as claimed in claim 6, wherein the address information comprises one or more of: an address of the access node; tunnel information; an indication that delivery of the data associated with the multicast session if via IP multicast.

8. The apparatus as claimed in any preceding claim, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to receive a response from the one or more controlling nodes.

9. The apparatus as claimed in claim 8, wherein the response from the one or more control entities comprises multicast address information for the multicast session.

10. The apparatus as claimed in claim 7, wherein the response from the one or more control entities comprises quality of service information for the multicast session.

11 . The apparatus as claimed in any of claims claim 1 to 10, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to cause resources at the access node for the reception of data from the one or more control entities to be configured.

12. The apparatus as claimed in any preceding claim, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to determine if the communications device is to receive the multicast session from the access node via a unicast or via a multicast.

13. The apparatus as claimed in any preceding claim, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to receive a message indicating that the communications device has left the multicast session and cause a message to be sent to the one or more control entities indicating that the providing of data associated with the multicast session to the access node is to be terminated.

14. The apparatus as claimed in claim 13, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to determine, in response to receiving the information indicating that the communications device has left the multicast session, whether the access node provides the data associated with the multicast session to one or more other communications devices and when it is determined that the access node does not provide the data associated with the multicast session to one or more other communications devices, cause the message to be sent to the one or more control entities indicating that the providing of data associated with the multicast session to the access node is to be terminated.

15. The apparatus as claimed in any preceding claim, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to, in response to the communications device being handed over from the access node to another access node, cause information to be provided to the another access node about the multicast session, said information provided to the another access node comprising information identifying the one or more control entities controlling the multicast session.

16. The apparatus as claimed in claim 15, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to, determine, in response to the communications device being handed over to the another access node, whether the access node provides the data associated with the multicast session to one or more other communications devices and when it is determined that the access node does not provide the data associated with the multicast session to one or more other communications devices, cause a message to be sent to the one or more control entities indicating that the providing of the data associated with the multicast session to the access node is to be terminated.

17. An apparatus in a session managing entity, said apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: manage a session of a communications device; receive a request from the communications device to join a multicast session; determine one or more control nodes controlling the multicast session; and cause at least one message to be sent to an access node or access management entity from the session managing entity, said message comprising information indicating that the communications device is to receive data associated with the multicast session and information identifying the one or more control nodes controlling the multicast session.

18. The apparatus as claimed in claim 17, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to obtain the information identifying the one or more control nodes from a data repository.

19. The apparatus as claimed in any of claims 17 or 18, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to: determine that the communication device is to stop receiving data associated with the multicast session; and cause at least one message to be sent to the access node or access management entity from the session managing entity, said message comprising information indicating that the communications device is to stop receiving data associated with the multicast session.

20. The apparatus as claimed in claim 19, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to determine that the communications device is to stop receiving data associated with the multicast session based on at least one of: a received request from the communications device to leave the multicast session; that the communications device did not refresh a request to join the multicast session for a configured period of time; and a received message indicating that the communication device is no longer permitted to receive data associated with the multicast session.

21 . An apparatus in a control entity, said apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: control a multicast session; receive at least one message from an access node, said message comprising information identifying the access node which is to receive data associated with the multicast session; and cause a message to be provided to an ingress entity requesting that the data associated with the multicast session is to be provided to the access node for the communications device.

22. The apparatus as claimed in claim 21 , wherein the said request from the access node requests starting or stopping transfer of data associated with the multicast session towards the access node

23. The apparatus as claimed in claim 21 or 22, wherein the said request from the access node is handled as a protocol data unit session establishment and/or release

24. The apparatus as claimed in any of claims claim 21 to 23, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to receive a response message from the ingress entity indicating that the multicast data will be provided to the access node.

25. The apparatus as claimed in any claims of 21 to 24, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: send a response to the access node, the response comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session.

26. An apparatus in an access management entity, said apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: receive information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and cause at least one message to be sent to an access node with the information indicating that a communications device is to receive the data associated with a multicast session and the information identifying one or more control entities controlling the multicast session.

27. The apparatus as claimed in claim 26, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: receive at least one message from the access node, said message comprising information identifying the one or more control entities controlling a multicast session and a request that the access node stop receiving data associated with the multicast session; and cause at least one message to be sent to the one or more control entities with the request that the access node stop receiving data associated with the multicast session.

28. The apparatus as claimed in claim 27, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: in response to the message with the request that the access node request stop receiving data associated with the multicast session, receive at least one message from the one or more control entities comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session; and cause at least one message to be sent to the access node comprising at least one of multicast address information of the multicast session, and/or quality of service information of the multicast session.

29. The apparatus as claimed in 27 or 28, wherein the message from the access node is handled as a protocol data unit session establishment.

30. A method comprising: receiving at an access node information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and causing at least one message to be sent from the access node to the identified one or more control entities requesting that data associated with the multicast session be provided to the access node.

31. A method comprising: managing a session of a communications device; receiving a request from the communications device to join a multicast session; determining one or more control nodes controlling the multicast session; and causing at least one message to be sent, to an access node, from a session managing entity managing a session of a communications device with said access node, said message comprising information indicating that the communications device is to receive data associated with a multicast session and information identifying one or more control nodes controlling the multicast session.

32. A method comprising: controlling a multicast session; receiving at least one message from an access node, said message comprising information identifying the access node which is to receive data associated with the multicast session; and causing a message to be provided to an ingress entity requesting that the data associated with the multicast session is to be provided to the access node for the communications device.

33. A method comprising: receiving at an access management entity information indicating that a communications device is to receive data associated with a multicast session and information identifying one or more control entities controlling the multicast session; and causing at least one message to be sent from the access management entity to an access node with the information indicating that a communications device is to receive the data associated with a multicast session and the information identifying one or more control entities controlling the multicast session.

34. A computer program comprising computer code which when executed on at least one processor causes the method of any one of claims 30 to 33 to be performed.