GB2607267A

GB2607267A - Storing multicast information

Info

Publication number: GB2607267A
Application number: GB2104848.3A
Authority: GB
Inventors: Thomas Belling Horst
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2021-04-06
Filing date: 2021-04-06
Publication date: 2022-12-07
Also published as: GB202104848D0

Abstract

Method and apparatus for handling users joining a multicast session in a communication system are disclosed. A received distribution request for a multicast session includes a source-specific IP multicast address of the multicast session. A temporary group identity (e.g. Temporary Mobile Group Identity, TMGI) can be assigned for the source specific IP multicast address and the assigned temporary group identity and its association to the source specific IP multicast address are stored in a database for subsequent use by at least one network entity for handling a request from a user to join the multicast session. When receiving a request to join a multicast session, the request specifying a source-specific IP multicast address the database may be queried to determine the associated TMGI and use it to discover at least one network entity controlling the multicast session. The database may comprise a unified data management (UDM) entity or unified data repository (UDR). The entity discovered may be a multicast broadcast session management function (SMF or MB-SMF) or entity providing quality of service information.

Description

Storing multicast information

Field

The present disclosure relates to methods, apparatuses and computer program products for handling multicasting in a communication system, and more particularly to storing information in association with multicast sessions.

Background

A communication system provides a facility communication between two or more devices such as user terminals, machine-like terminals, base stations and other access points, network entities, service provider entities and/or other devices. A communication system can be provided for example by means of a communication network and one or more compatible devices providing communication channels for carrying information between the communicating entities. Communication sessions may comprise, for example, communication of data for carrying communications for services such as voice, video, electronic mail (email), text message, multimedia, control data and/or content data and so on.

In a mobile or wireless communication system at least a part of a communications between at least two devices occurs over a wireless or radio 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). A user can access the wider communication system via an access system means of an appropriate communication device or terminal. Non-limiting examples of communication devices are a user equipment (UE) or user device and various machine-like terminals. The wireless access can be provided by a base station of a radio access system or network (RAN). Radio access systems provide local coverage areas and are connected to a larger communication system, known as the core network.

The core network comprises a wide variety of entities providing various functions and services. Similar functions and/or services may be provided by different entities in separate locations and/or by distributed data processing. At least some of the functions and/or services may be provided by virtual data processing instances. Providing data communications between the accessing devices and the service providing entities such as content providers can involve intermediate and otherwise associated entities, processes and functions.

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. Examples of communication systems are those based on fifth generation (5G) networks standardized by the 3rd Generation Partnership Project (3GPP).

Multicasting enables one-to-many and many-to-many real-time communication in a network. Multicasting can serve large number of receiver devices while requiring neither prior knowledge of identities nor prior knowledge of the number of the receiver devices. A user can join a multicast session using signalling related to a unicast protocol data unit (PDU) session, and vice versa.

When a user joins a multicast session a multicast broadcast session management function (MB-SMF) can be discovered by querying a network function repository function (NRF) using a multicast session ID. The MB-SMF can register its network function (NE) profile to a network function repository function (NRF). The NF profile includes various information, e.g., single network slice selection assistance information (S-NSSAI), data network name (DNN) and MB-SMF service area. A network exposure function (NEF) and/or a multicast broadcast service function (MBSF) can discover the MB-SMF, if not locally configured, by querying the NRF using this information during multicast/broadcast session configuration.

When a multicast/broadcast session is configured/established, the MB-SMF can update its network function (NF) profile with the multicast session ID to the NRF. During the join procedure, if needed, the SMF retrieves the MB-SMF ID from the NRF using the multicast session ID and selects an MB-SMF based on the MB-SMF information returned by the NRF. For local MBS services, the SMF can take MB-SMF service area into account when selecting the MB-SMF. Current NRF configurations may not be readily suited in all occasions to store source specific multicast addresses in MB-SMF profiles. Source specific addresses are allocated by external entities, typically application functions (AFs) and pre-allocation or distribution thereof in advance to MB-SMFs may not be feasible in all occasions. Also, the NRF discovery service allows for a subscription of profile changes of MB-SMF profiles. That may in certain occasions result in high load by distributing a large MB-SMF profile each time a new source specific multicast address is added to the MB-SMF profile.

The herein described examples aim to address one or several of the shortcomings associated with the use of the multicast source addresses.

Summary

In accordance with an aspect there is provided a method comprising receiving a distribution request for a multicast session, the distribution request including a source specific IF multicast address of the multicast session, assigning a temporary group identity for the source specific IF multicast address, and causing storing of the assigned temporary group identity and its association to the source specific IF multicast address in a database for subsequent use by at least one network entity for handling a request from a user to join the multicast session.

According to an aspect there is provided an apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to receive a distribution request for a multicast session, the distribution request including a source specific IF multicast address of the multicast session, assign a temporary group identity for the source specific IF multicast address, and cause storing of the assigned temporary group identity and its association to the source specific IF multicast address in a database for subsequent use by at least one network entity for handling a request from a user to join the multicast session.

The source specific IF multicast address and the temporary group identity may be sent in a message to the database.

According to an aspect there is provided a method comprising receiving a request for joining a multicast session, the request including a source specific IF multicast address of the multicast session, querying a database by providing the source specific IF multicast address to obtain a temporary group identity associated with the source specific IF multicast address, and using the obtained temporary group identity to discover at least one network entity controlling the multicast session.

According to an aspect there is provided an apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to receive a request for joining a multicast session, the request including a source specific IF multicast address of the multicast session, query a database by providing the source specific IF multicast address to obtain a temporary group identity associated with the source specific IF multicast address, and use the obtained temporary group identity to discover at least one network entity controlling the multicast session.

According to another aspect there is provided a method, comprising storing a temporary group identity and an associated source specific IF multicast address for subsequent use by at least one network entity for handling a request from a user to join the multicast session, receiving a request for the temporary group identity, the request including the source specific IF multicast address, and responding the request by including the temporary group identity associated with the source specific IF multicast address.

According to a yet another aspect there is provided an apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to store a temporary group identity and an associated source specific IF multicast address for subsequent use by at least one network entity for handling a request from a user to join the multicast session, receive a request for the temporary group identity, the request including the source specific IF multicast address, and respond the request by including in the response the temporary group identity associated with the source specific IF multicast address.

According to a more specific aspect the storing is performed in response to receiving a request to store the temporary group identity and the associated source specific IP multicast address.

According to a specific aspect the database comprises an entity providing unified data management and/or unified data repository.

A temporary group identity may be used by sending the temporary group identity to a network function repository function to discover at least one multicast broadcast session management function.

A temporary group identity may be used in discovering at least one network entity providing quality of service information for the multicast session. The quality of service information may comprises quality of service flows for the multicast session.

A source specific IP multicast address may comprise an internet protocol (IP) multicast address allocated by an application function. A source specific IP multicast address may comprise an IF source address and an IF destination multicast address. A temporary group identity may comprise a temporary mobile group identity.

Means for implementing the herein disclosed operations and functions can also be provided.

A computer software product embodying at least a part of the herein described functions may also be provided. In accordance with an aspect a computer program comprises instructions for performing at least one of the methods described herein.

Brief description of Drawings

Some aspects will now be described in further detail, by way of example only, with reference to the following examples and accompanying drawings, in which: Figure 1 illustrates a schematic example of a system where the herein disclosed principles can be practiced; Figure 2 shows an example of a control apparatus; Figures 3, 4 and 5 are flowcharts according to certain examples; and Figures 6 and 7 are signaling flowcharts according to certain examples.

Detailed description of examples

The following description gives an exemplifying description of some possibilities and useful background information to practise the invention. Although the specification may refer to "an", "one", or "some" examples or embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same example of embodiment(s), or that a particular feature only applies to a single example or embodiment. Single features of different examples and embodiments may also be combined to provide other embodiments.

Figure 1 shows a schematic presentation of system 1 comprising a radio access system 2 (radio access network; RAN) and a core network (CN) system shown as cloud 3. A radio access system can comprise one or a plurality of access points. A number of radio access systems can be connected to the core network. In Figure 1 the access point and the radio access system are schematically presented by a base station. An access point can comprise any node that can transmit/receive radio signals (e.g., a TRP, a base station such as gNB, eNB, a user device such as a UE and so forth). An example of wireless access architecture is 3GPP 5G radio access architecture. However, embodiments are not limited to such an architecture.

A communications device 10 can be located in the service area of the radio access system 2 and can thus communicate wirelessly with the access point provided by the system 2. The communications device 10 is an example of a user which can request for one or more services provided by entities of the core network 3. The device can be associated with a unique user identity. The user identity may be assigned to the device, to a user of the device or a subscription by a user of the device. The device 10 may be any suitable communications device adapted for wireless communications. Non-limiting examples comprise a mobile station (MS) (e.g., a 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), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, machine-type communications (MTC) devices, Internet of Things (loT) type communications devices or any combinations of these or the like. The device may be provided as part of another device. The device may receive signals over an air or radio interface via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. The communications can occur via multiple paths. Multiple input multiple output (MIMO) type communications may be provided with multiantenna elements.

The wider communication system (core network) 3 can comprise a 50 core network (500) and entities providing one or more interconnected network functions (NF). The system can comprise one or more data networks (DN). In Figure 1 blocks 11 to 20 denote various possible network entities. The non-liming and non-exhaustive list of these include an access and mobility management function (AMF) 11, a session management function (SMF) 12, a multicast broadcast user plane function (MB-UPF) 13, network function repository function (NRF) 14, unified data management (UDM) 15, multicast broadcast service function (MBSF) 16, unified data repository (UDR) 17, multicast broadcast session management function (MB-SMF) 18, and network exposure function (NEF) 19. A plurality of content providers 20 can also be provided. Other management, control and application functions are also possible. It shall be appreciated that at least some of the entities denoted by blocks 11 to 20 can be provided as virtual data processing instances in virtualized environment.

Functions of devices such as the access point 2 or the accessing device 10, or equipment of the service developers and/or providers and any of the network entities 11 to 20 can be provided by data processing apparatus. The data processing can be provided by apparatus comprising at least one processor and at least one memory. Figure 2 shows an example of a data processing apparatus 50 comprising processor(s) 52, 53 and memory or memories 51.

Figure 2 further shows connections between the elements of the apparatus and an interface for connecting the data processing apparatus to other components of the device. The at least one memory may comprise at least one ROM and/or at least one RAM. The communications device may comprise other possible components for use in software and hardware aided execution of tasks it is designed to perform and implementing the herein described features. The at least one processor can be coupled to the at least one memory. The at least one processor may be configured to execute an appropriate software code to implement one or more of the following aspects. The software code may be stored in the at least one memory, for example in the at least one ROM.

The processing may be distributed between several processors. The processing may be provided by virtual data processing instances such as virtual machines or separated cores (containers) operated on a shared operating system resource. In this specification the term entity covers such virtual data processing instances.

The following describes in more detail certain illustrative examples and non-limiting aspects of operations, configurations and signaling for source specific multicast using 3GPP 5G radio access network (RAN) and core network (5GC) terminology. In source-specific multicast (SSM) multicast packets are delivered such that the only packets that are delivered to a receiver are those originating from a specific source address requested by the receiver. Limiting the source this way enables reduction in demand for the network and can be used to improve security. It is noted that in accordance with IP (Internet Protocol) multicast addresses are indicated as destination addresses, not as source addresses. However, in source specific IF multicast addresses are more predominant. This means IP packets related to the multicast session have a specific source address and a specific multicast address as destination. Such source specific IF multicast addresses are used in 3GPP standards.

A device, for example the user equipment (UE) 10 can register itself with relevant core network function or functions to be able to access and use the desired service available in the system 1. For example, the device may need to register with the Access and Mobility Management Function (AMF) 11. The user equipment (UE) can join a multicast session using signalling related to a unicast protocol data unit (PDU) session.

As explained above, the current NEW configurations may not be readily suited in all occasions to store source multicast addresses, for example because source specific addresses are allocated by external entities such as application functions (AFs). Also, the NRF discovery service allows for profile changes which may in certain occasions result in high load because very large profiles may be distribute as result of new source specific multicast addresses.

In accordance with the herein disclosed principles a database for storing information about multicast sessions is provided in the core network such that mapping between source specific addresses of multicast sessions and temporary group identifier is enabled.

Figure 3 shows a flowchart for an example method where a distribution request for a multicast session is received at 100. The distribution request includes information of a source specific IF multicast address of the multicast session. For example, in accordance with 3GPP specifications such address can include an IF source address and an IP destination multicast address. A temporary group identity is then assigned at 102 for the source specific IF multicast address. The assigned temporary group identity and its association to the source specific IF multicast address can be stored at 104 in a database for subsequent use by at least one network entity configured to control users joining the multicast session based on the source specific IF multicast address. According to a more detailed aspect the storing of the source specific IF multicast address and the temporary group identity is caused by sending thereof in a message by a management function to the database. The management 30 function can comprise a session management function (SMF). The management function may control at least one particular user wanting to join the multicast session but not the entire multicast session. The multicast session can be controlled by multicast broadcast session management function (MB-SMF).The request may have been received by the management function from an application function (AF), for example a content provider, via a gateway or interface function such as a network exposure function (NEF).

Figure 4 shows a flowchart for an example operation in the database. The database receives a request to store the temporary group identity and its association with the source specific IF multicast address. The temporary group identity and its association with the source specific IF multicast address is stored at 110 for subsequent use by at least one network entity handling at least one join request of a user for the multicast sessionbased on source specific IF multicast addresses of the multicast sessions. The stored temporary group identity is associated with the source specific IF multicast address of a multicast session, thus enabling mapping of the two. A request for a temporary group identifier is received at 112, the request including the source specific IF multicast address. The request can be responded at 114 by including the temporary group identity based on the stored information about the association between the source specific IF multicast address and the temporary group identifier.

Figure 5 shows a flowchart for an example of use of the information stored in the database. In the method a request for joining a multicast session is received at 120. The request includes a source specific IF multicast address of the multicast session. The database storing a temporary group identity associated with the source specific IF multicast address can be queried at 122 to obtain the temporary group identity. The obtained temporary group identity can be used at 124 to discover at least one network entity controlling the multicast session.

The database may comprise an entity providing unified data management function. The database may also comprise an entity providing unified data repository function.

The temporary group identity can be communicated to a network function repository function to discover at least one multicast broadcast session management function. The temporary group identity may be used in a process of discovering at least one network entity providing quality of service information for the multicast session. The quality of service information can comprise information such as quality of service flows for the multicast session.

Figure 6 shows a more detailed example for procedure where an application function (AF) registers at stage 1 a multicast session with a source specific IP multicast address. The registration can involve communications with a network exposure function (NEF). In the example the temporary group identifier is provided by a temporary mobile group identity (TMGI). A source specific IP multicast address can be associated with a temporary mobile group identity (TMGI). TMGIs can be used as MBS Session IDs in Non-Access Stratum (NAS) messages exchange between a UE and a core network (CN). The TMGI is sent to the UE and used in other signalling messages between RAN, ON and UE. TMGI can be used when the UE requests to join/leave a multicast session. A TMGI can also be allocated for MBS multicast sessions that the UE joined with a source specific IF multicast address. TMGIs are allocated by the MB-SMF and thus fixed address ranges can be assigned to MB-SMFs. The ranges can be stored in the MB-SMF profile.

The NEF can authorize and select a SMF for the AF at stage 2. A NEF is an entity that provides a means to securely expose the services and capabilities provided by core network functions and facilitates secure, robust, developer-friendly access to the exposed network services and capabilities. NEF can be used to hide specific network technology from applications and user devices that can move between e.g. 4G and 5G based systems. The NEF consolidates APIs and presenting unified access to the API framework for application developers. The NEF then sends a multicast distribution session request 3 to the selected MB-SMF. The request can include a source specific IP multicast address.

Upon receipt of the request the MB-SMF assigns a TMGI for the source specific IF multicast address at stage 4. The MB-SMF stores the information that the TMGI is assigned for the source specific IF multicast address in a database. This is illustrated by message 5 in Figure 6. The database can comprise, e.g. a UDM or UDR.

Figure 7 illustrates an example for operation when a UE joins the multicast session. Possible underlying operations in relation to joining multicast sessions are also illustrated in Figure 7. A multicast group configuration can be formed in stage 1 in the core network. This can take place in any appropriate manner and involve entities such as an NRF, MB-SMF, MB-UPF, MBSF and the content provider of the multicast group. In stage 2 the UE can perform registration and PDU session establishment to initiate a PDU session with the communication system. The UE can access the core network via a radio access network (RAN) and register via the AMF with entities such as SMF and PCF.

At stage 3 a multicast announcement is given. The UE decides to join the multicast group and sends a message 4 'PDU session modification request' to 10 the AMF. The AMF then sends message 5 to the SMF to update the PDU session SMcontext. UE authorisation check can follow at stage 6.

In the next stage in Figure 7, if it is determined that the SMF has no cached knowledge about the multicast session, the SMF can exchange in messages 7, 7a, 7c, 8 and 9 information with entities such as the NRF and the MB-SMF to obtain information necessary to handle the joining UE. When the SMF receives a join request in message 5 including a source specific IP multicast address, and after the possible authorization check at 6, the SMF can query by message 7 including the source address the database for the TMGI corresponding to the received source specific IP multicast address. A response message 7a includes the TMGI, and this can now be used for discovery of the multicast/broadcast session management function. The SMF can query in message exchange 7c the NRF to discover an appropriate MB-SMF based on the TMGI. The TGMI can also be used in correspondence with the MB-SMF to identify the multicast session.

The information can be about quality of service (QoS) requirements.

Information of QoS flows is provided by the MB-SMF in message 9 for the given multicast session. The multicast session joining procedure can then continue by the SMF sending message 1 to the AMF and so forth, as illustrated by messages 13 -25 in Figure 7. In accordance with a possibility shown in the flowchart of Figure 7, the session management function (SMF) sends Namf Communication N1N2Message transfer notification in message 10 to the AMF.

The QoS flow information may be needed since in 5G the quality of service (QoS) is flow based. Packets are classified and marked using QoS Flow Identifier (OH). The QoS flows are mapped in the access network to Data Radio Bearers (DRBs). The 5G QoS model supports both QoS Flows that require guaranteed flow bit rate and QoS Flows that do not require guaranteed flow bit rate. The 50 QoS model also supports Reflective QoS. The QoS Flow is the finest granularity of QoS differentiation in the PDU Session. User Plane traffic with the same OH within a PDU Session receives the same traffic forwarding treatment. OH shall be used for all PDU Session Types. The QFI shall be unique within a PDU Session. At the time when the UE joins a multicast session, quality of service (QoS) flows associated to the multicast session can be added by a session management function (SMF) to the unicast PDU session. The QoS flows are marked as being associated with the multicast session in preparation to a fallback to individual delivery of multicast content via the PDU session during a handover to a 5th Generation Radio Access Network (NO-RAN) node that may not be configured to support Multicast-broadcast services in 50 (5MBS) or for an immediate start of individual delivery to such a RAN node.

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. Different features from different embodiments may be combined.

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. At least a part of the functions can be provided in virtualised environment, and at least some of the entities can be provided as virtual computing instances. Further in this regard it should be noted that any of the above procedures 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 15 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 procedures previously described. That circuitry may be provided in the network entity and/or in the communications device and/or a server and/or a 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 5 cause the communications device and/or device and/or server and/or network entity 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.

It is noted that whilst embodiments have been described in relation to certain architectures, similar principles can be applied to other systems. Therefore, although certain embodiments were described above by way of example with reference to certain exemplifying architectures for wireless networks, technologies standards, and protocols, the herein described features may be applied to any other suitable forms of systems, architectures and devices than those illustrated and described in detail in the above examples. It is also noted that different combinations of different embodiments are possible. It is also noted herein that while the above describes exemplifying embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the spirit and scope of the present invention.

Claims

Claims 1. A method, comprising: receiving a distribution request for a multicast session, the distribution request including a source specific IF multicast address of the multicast session, assigning a temporary group identity for the source specific IF multicast address, and causing storing of the assigned temporary group identity and its association to the source specific IF multicast address in a database for subsequent use by at least one network entity for handling a request from a user to join the multicast session.
2. A method according to claim 1, comprising sending the source specific IF multicast address and the temporary group identity in a message to the database. 15
3. A method, comprising: receiving a request for joining a multicast session, the request including a source specific IF multicast address of the multicast session, querying a database by providing the source specific IF multicast address to obtain a temporary group identity associated with the source specific IF multicast address, and using the obtained temporary group identity to discover at least one network entity controlling the multicast session.
4. A method, comprising: storing a temporary group identity and an associated source specific IF multicast address for subsequent use by at least one network entity for handling a request from a user to join the multicast session, receiving a request for the temporary group identity, the request including the source specific IF multicast address, and responding the request by including the temporary group identity associated with the source specific IF multicast address.
5. A method according to claim 4, wherein the storing is performed in response to receiving a request to store the temporary group identity and the associated source specific IF multicast address.
6. A method according to claims 4 or 5, comprising performing the steps at a database entity.
7. A method according to any preceding claim, wherein the database comprises an entity providing at least one of unified data management or unified data repository.
8. A method according to any preceding claim, wherein the use of the temporary group identity comprises sending the temporary group identity to a network function repository function to discover at least one multicast broadcast session management function.
9. A method according to any preceding claim, wherein the use of the temporary group identity comprises use thereof in discovering at least one network entity providing quality of service information for the multicast session.
10. A method according to claim 9, wherein the quality of service information comprises quality of service flows for the multicast session.
11. A method according to any preceding claim, wherein the source specific IF multicast address comprises an internet protocol multicast address allocated by an application function.
12. A method according to any preceding claim, wherein the source specific IF multicast address comprises an IF source address and an IF destination multicast address.
13. A method according to any preceding claim, wherein the temporary group identity comprises a temporary mobile group identity.
14. An apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to: receive a distribution request for a multicast session, the distribution request including a source specific IF multicast address of the multicast session, assign a temporary group identity for the source specific IF multicast 10 address, and cause storing of the assigned temporary group identity and its association to the source specific IF multicast address in a database for subsequent use by at least one network entity for handling a request from a user to join the multicast session.
15. An apparatus according to claim 14, configured to send the source specific IF multicast address and the temporary group identity in a message to the database.
16. An apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to: receive a request for joining a multicast session, the request including a source specific IF multicast address of the multicast session, query a database by providing the source specific IF multicast address to obtain a temporary group identity associated with the source specific IF multicast address, and use the obtained temporary group identity to discover at least one network entity controlling the multicast session.
17. An apparatus according to claim 16, configured to send the temporary group identity to a network function repository function to discover at least one multicast broadcast session management function.
18. An apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to: store a temporary group identity and an associated source specific IP multicast address for subsequent use by at least one network entity for handling a request from a user to join the multicast session, receive a request for the temporary group identity, the request including the source specific IF multicast address, and respond the request by including in the response the temporary group identity associated with the source specific IF multicast address.
19. An apparatus according to claim 17, configured to store the temporary group identity and the associated source specific IF multicast address in response to receiving a request to store the temporary group identity and the associated source specific IF multicast address.
20. An apparatus according to any of claims 14 to 18, wherein the database comprises an entity providing at least one of unified data management or unified data repository.
21. An apparatus according to any of claims 14 to 20, wherein the temporary group identity is for use in discovering at least one network entity providing quality of service information for the multicast session.
22. An apparatus according to claim 21, wherein the quality of service information comprises quality of service flows for the multicast session.
23. An apparatus according to any of claims 14 to 22, wherein the source specific IP multicast address comprises an internet protocol multicast address allocated by an application function.
24. An apparatus according to any of claims 14 to 23, wherein the source specific IF multicast address comprises an IF source address and an IF destination multicast address.
25. An apparatus according to any of claims 14 to 24, wherein the temporary group identity comprises a temporary mobile group identity.
26. A computer readable media comprising program code for causing a processor to perform instructions for a method as claimed in any of claims 1 to 13.