6 Functional model
23.2823GPPFunctional architecture and information flows to support Mission Critical Data (MCData)Release 18Stage 2TS
6.1 General
This clause defines the functional model for MCData service.
The security solution for the MCData service, including end-to-end encryption, is specified in 3GPP TS 33.180 [13].
6.2 Description of the planes
The functional model for the support of MCData is defined as a series of planes to allow for the breakdown of the architectural description.
The description of the planes and the relationship between the planes are contained in the common functional architecture to support MC services in 3GPP TS 23.280 [5].
6.3 Transmission and reception control aspects
6.3.1 General
The transmission and reception control are functions of the MCData server.
For small data transmissions there is no need for prior grant of request to transmit. The procedures in the present document describe when data is automatically sent.
For large data transmissions, i.e. large files, the data is transmitted only after request to transmit is granted. The data to be transmitted and/or received may be stored in a data repository associated with the transmission and reception control functions.
NOTE: An overview of transmission control process and possible arbitration mechanisms is provided in the Annex B.
6.4 Generic functional model
6.4.1 On-network functional model
Figure 6.4.1-1 shows the generic application plane functional model.
Figure 6.4.1-1: Generic application plane functional model
In the model shown in figure 6.4.1-1, capability functions (SDS, FD, DS, IPcon) of the MCData client and the MCData server along with their reference points (MCData-cap-1 to MCData-cap-n) are described in the respective functional models for each capability.
NOTE 1: The security aspects of new network components (MCData message store, Message store client and MCData notification server) and the associated new reference points are the responsibility of SA3 and thus outside the scope of the present document.
An MCData server controls the signaling reference points and the corresponding media allowing different paths for media and signalling.The MCData server determines if it needs to stay in the media path based on the feature(s) involved in the MCData communication, e.g., if the MCData message store is required in the MCData communication, the MCData server shall remain in the media path.
NOTE 2: If the MCData server is not in the MCData communication media path, any implications regarding MC user data logging are left to implementation.
6.4.2 Off-network functional model
6.4.3 Functional entities description
Editor’s note: Combining functional models describing each capability into one functional model is FFS.
6.4.3.1 Application plane
6.4.3.1.1 MCData client
The MCData client functional entity acts as the user agent for all MCData application transactions. The client supports SDS, file distribution, data streaming and IP connectivity MCData capabilities utilized by MCData services like conversation management, robots control, enhanced status, database enquiries and secured internet.
6.4.3.1.2 MCData server
The MCData server functional entity provides centralised support for MCData services suite. Conversation management, robots, enhanced status, database enquiries and secured internet MCData services requiring one-to-one or group data communication are realized using SDS, file distribution, data streaming and IP connectivity MCData communication capabilities.
All the MCData clients supporting users belonging to a single group are required to use the same MCData server for that group. An MCData client supporting a user involved in multiple groups can have relationships with multiple MCData servers.
For MBMS delivery, the MCData server functional entity represents a specific instantiation of the GCS AS described in 3GPP TS 23.468 [8] to control multicast and unicast operations for group communications.
If the MBMS user service architecture is utilized, the MCData server functional entity represents a specific instantiation of the content provider as described in 3GPP TS 26.346 [21] to control multicast operations for file distribution.
The MCData server functional entity is supported by the SIP AS functional entity of the signalling control plane.
The MCData server shall support the controlling role and the participating role. The MCData server may perform the controlling role for one-to-one and group data communication. The MCData server performing the controlling role for a one-to-one or group data communication may also perform a participating role for the same one-to-one or group data communication. For each one-to-one and group data communication, there shall be only one MCData server assuming the controlling role, while one or more MCData servers in participating role may be involved.
The MCData server performing the controlling role is responsible for:
– handling transmission and reception control (e.g. policy enforcement for participation in the MCData group communication) towards all the MCData users of the one-to-one and group data communication;
– interfacing with the group management server for group policy and affiliation status information of this MCData server’s served affiliated users;
– managing SDS and FD data distribution during MCData group communication; and
– managing the MCData transport service for IP connectivity.
The MCData server performing the participating role is responsible for:
– handling transmission control (e.g. authorization for participation in the MCData group communication) to MCData users of the one-to-one and group data communication;
– group affiliation support for MCData user, including enforcement of maximum Nc2 number of simultaneous group affiliations by a user;
– interfacing with the group management server for group policy and affiliation status information of this MCData server’s served affiliated users;
– relaying the MCData communication messages between the MCData client and the MCData server performing the controlling role; and
– handling reception control (e.g. temporarily storing the data to present to the MCData user as required) to its MCData users of the one-to-one and group data communication.
NOTE: The MCData server in the controlling role and the MCData server in the participating role can belong to the same MCData system.
6.4.3.1.3 MCData user database
This functional entity contains information of the MCData user profile associated with an MCData ID that is held by the MCData service provider at the application plane. The MCData user profile is determined by the mission critical organization, the MCData service provider, and potentially the MCData user.
6.4.3.1.4 Interworking function to LMR system
The functional entity is specified in 3GPP TS 23.283 [18].
6.4.3.1.5 MC gateway server
The MC gateway server provides support for MCData interconnection services with a partner MCData system in a different trust domain whilst providing topology hiding. It acts as a proxy for one or more MCData servers in the partner MCData system without needing to expose the MCData servers in the primary MCData system outside the trusted domain of the primary MCData system. It may be a role of the MCData server described in subclause 6.4.3.1.2 of the present document.
The MC gateway server is responsible for relaying call control and transmission control signalling messages, and media between MCData servers within the MCData system and the interconnected MCData system.
6.4.3.2 Signalling control plane
The description of the signalling control plane is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6.4.3.3 MCData message store
The MCData message store is a network base persistent store that allows Mission Critical Organization to configure their MCData users to permanently store their MCData communications. Once configured a MCData user will be allocated a secured storage area (i.e. size) in the MCData message store that is only accessible by that configured MCData user and any authorized users. The MCData user can manage how and what will be stored in his personal message store with the support of management operations such as creating, deleting and merging folders, moving stored messages and files around and synchronization all used devices to provide the same contxt view etc.
NOTE: The security aspects of access and management (such as read/write/update/sync etc.) of personal message store are the responsibility of SA3 and thus outside the scope of the present document.
6.4.3.4 Message store client
The Message store client is used to support MCData client to manage the MCData communication history stored in MCData message store for a particular MCData user, It supports the secure access to a MCData user’s configured MCData message store area and operations relevant to the stored communication history such as folders management and synchronization to the device local message store.
6.4.3.5 MCData notification server
The MCData notification server provides the centralized notification function in the network. The MCData notification server allows an application (e.g. resident in the UE) to create a communication channel to receive real-time notifications from the network in either Pull or Push mode. Depending on the channel type created, the MCData notification server provides the application a callback endpoint (i.e. URL) and may also provide a channel endpoint (i.e. URL). The application communicates the callback endpoint information to the application server (i.e. network enabler) for it to use in sending to the MCData notification server the events for delivery to the application. Depending on the type of channel created by the application the delivery of the notifications from the MCData notification server to the application may be via a Pull or Push method. If Pull method is used, then the application shall use the provided channel endpoint to pull the notifications from the MCData notification server. However, if a Push notification delivery is used, then the MCData notification server asynchronously delivers the events received from the application server to the application through a PUSH Enabler server. The MCData notification server provides a consistent way to deliver notifications by all services to reduce the complexity of service logic on the application server.
It depends on deployment, if multiple MCData notification servers aredeployed.
6.4.3.6 Message notification client
The Message notification client is used to request the notification service from the MCData notification server. Once the notification service request is authorized by the MCData notification server, the Message notification client will communicate the callback endpoint, received from the MCData notification server, to the MCData message store to be used for notification message delivery.
When multiple MCData notification servers are deployed, the Message notification client shall select one for notification service at any given time. How the Message notification client selects the appropriate MCData notification server from multiple available MCData notification servers for service is implementation specific.
6.4.4 Reference points
6.4.4.1 Application plane
6.4.4.1.1 General
The reference points for the application plane of MCData service are described in the following subclauses.
6.4.4.1.2 Reference point MCData-2 (between the MCData server and the MCData user database)
The MCData-2 reference point, which exists between the MCData server and the MCData user database, is used by the MCData server to obtain information about a specific user. The MCData-2 reference point utilises a diameter management application protocol as defined in 3GPP TS 29.283 [12] and shall be intra-network.
6.4.4.1.3 Reference point MCData-3 (between the MCData server and the MCData server)
The MCData-3 reference point, which exists between the MCData server and the MCData server for MCData application signalling for establishing MCData sessions, shall use the SIP-2 reference point for transport and routing of signalling. If each MCData server is served by a different SIP core then the MCData-3 reference point shall also use the SIP-3 reference point for transport and routing of signalling. Media is also transferred using the MCData-3 reference point.
6.4.4.1.3A Reference point MCData-5 (between the MCData server and the EPS)
The MCData-5 reference point, which exists between the MCData server and the EPS, is used, subject to the conditions below, by the MCData server to obtain unicast bearers with appropriate QoS from the EPS. It utilises the Rx interface of the EPS according to 3GPP TS 23.203 [14].
MCData-5 is not used when the MCData service provider and the PLMN operator do not have an operational agreement for QoS control to be provided directly from the MCData service provider domain.
MCData-5 may be used when the MCData service provider and the PLMN operator have an operational agreement where QoS control is provided directly from the MCData service provider domain.
NOTE: Any coordination between the P-CSCF use of Rx and the MCData server use of Rx (via MCData-5) from the MCData service provider domain is not specified in this release of this specification.
6.4.4.1.4 Reference point MCData-6 (between the MCData server and the EPS)
The MCData-6 reference point, which exists between the MCData server and the EPS, is used to request the allocation and activation of multicast transport resources for MCData application usage. The MCData-6 reference point uses the MB2-C interface as defined in 3GPP TS 29.468 [16]. The MCData-6 reference point also uses the xMB-C interface as defined in 3GPP TS 29.116 [20] for file distribution.
6.4.4.1.5 Reference point IWF-2 (between the interworking function to LMR system and the MCData server)
The IWF‑2 reference point is specified in 3GPP TS 23.283 [18].
6.4.4.1.6 Reference point MCData-7 (between the Message store client and MCData message store)
The MCData-7 reference point, which exists between the Message store client and the MCData message store, is used by the Message store client to manage the information stored in the MCData message store, to subscribe to changes in the MCData message store and to synchronize between the MCData client and the MCData message store.
6.4.4.1.7 Reference point MCData-8 (between the MCData message store and McData server)
The MCData-8 reference point, which exists between the MCData server and the MCData message store, is used by the MCData server to access and manage the MCData message store such as creating MCData user folders and depositing the communications history.
6.4.4.1.8 Reference point MCData-9 (between the MC gateway server and the MC gateway server in a different MCData system)
The MCData-9 reference point, which exists between the MC gateway server and the MC gateway server in an interconnected MCData system for MCData application signalling for establishing MCData sessions, shall use the SIP‑3 reference point for transport and routing of signalling. The MCData-9 reference point also carries application data where the data size is too great to be transferred on the signalling plane.
6.4.4.1.9 Reference point MCData-10 (between the Message notification client and MCData notification server)
The MCData-10 reference point, which exists between the Message notification client and the MCData notification server, is used by the Message notification client to create an appropriate notification channel(s) at the MCData notification server in order to direct events from MCData message store to the MCData notification server for subsequent delivery to the Message notification client on the UE.
6.4.4.1.10 Reference point MCData-11 (between the MCData message store and the MCData notification server)
The MCData-11 reference point, which exists between the MCData message store and the MCData notification server, is used by the MCData message store to send notification message to the subscribed Message notification client.
6.5 Functional model for short data service
6.5.1 On-network functional model
Figure 6.5.1-1 shows the application plane functional model for SDS.
Figure 6.5.1-1: Application plane functional model for SDS
In the model shown in figure 6.5.1-1, the following apply:
– MCData-SDS-1 reference point is primarily used for MCData application signalling during session establishment in support of SDS data transfer. Secondarily, MCData-SDS-1 reference point is used for uplink and downlink unicast SDS data transaction over signalling control plane by the SDS distribution function of the MCData server and SDS function of the MCData client.
– MCData-SDS-2 reference point carries uplink and downlink unicast SDS data over media plane between the SDS distribution function of the MCData server and the SDS function of the MCData client.
– MCData-SDS-3 reference point carries downlink multicast SDS data over media plane from the SDS distribution function of the MCData server to the SDS function of the MCData client.
Examples of SDS data (in the form of text, binary, application data, URL or combinations of these) are:
– information pertaining to applications e.g. health parameters of MCData user for situational awareness application;
– information pertaining to enhanced status service;
– text or URL data between MCData users;
– application data (e.g. health parameters) to the MCData user;
– location information (independent or along with user or application provided data);
– command instructions to invoke certain operations on the MCData UE e.g. invoking UE specific applications; and
– application plane identities for the MCData user and MCData application.
6.5.2 Off-network functional model
Figure 6.5.2-1 shows the off-network application plane functional model for SDS.
Figure 6.5.2-1: Application plane functional model for SDS
6.5.3 Functional entities description
6.5.3.1 Application plane
6.5.3.1.1 SDS function
SDS function of the MCData client is responsible to handle SDS capability related requests and responses.
6.5.3.1.2 SDS distribution function
The SDS distribution function of the MCData server is responsible for the SDS data transaction to MCData communication participants. The SDS distribution function of the MCData server provides the following functionality:
– reception of uplink SDS data transaction by means of the MCData-SDS-1 and MCData-SDS-2 reference points;
– replicate the SDS data as needed for distribution to those MCData communication participants using unicast transport;
– distribute downlink data by IP unicast transmission to those MCData communication participants utilizing unicast transport by means of the MCData-SDS-1 and MCData-SDS-2 reference points; and
– distribute downlink SDS data using multicast downlink transport by means of the MCData-SDS-3 reference point.
6.5.3.1.3 Transmission/Reception control
This functional entity is responsible for transmission and reception control of MCData SDS data transaction between the sending MCData UE, the MCData server, and the receiving MCData UE. For SDS capability, due to small data size, the SDS messages can be automatically sent.
6.5.3.2 Signalling control plane
The description of the signalling control plane is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6.5.4 Reference points
6.5.4.1 Application plane
6.5.4.1.1 Reference point MCData-SDS-1 (between the SDS distribution function and the SDS function)
MCData-SDS-1 reference point is used for uplink and downlink unicast SDS data transaction over signalling control plane by the SDS distribution function of the MCData server and SDS function of the MCData client. This reference point is also used for MCData application signalling during session establishment in support of SDS data transfer.
The MCData-SDS-1 reference point shall use the SIP-1 and SIP-2 reference points for transport and routing of SIP signalling. MCData-SDS-1 reference point can be used when the SDS payload data size does not exceed the configured maximum payload data size for SDS over signalling control plane, otherwise MCData-SDS-2 and MCData-SDS-3 may be used appropriately.
Reference point MCData-SDS-1 also provides support to delivered and read requests and notifications as appropriate.
6.5.4.1.2 Reference point MCData-SDS-2 (unicast between the SDS distribution function and the SDS function)
The MCData-SDS-2 reference point, which exists between the SDS distribution function and the SDS function of the MCData client, is used unicast SDS data transaction (when the SDS payload data size exceeds the configured maximum payload data size for SDS over signalling control plane) between the MCData server and the MCData client. The MCData-SDS-2 reference point uses the SGi reference point defined in 3GPP TS 23.002 [10].
Reference point MCData-SDS-2 also provides support to message thread indication using conversation identifier, delivered and read notifications as appropriate.
6.5.4.1.3 Reference point MCData-SDS-3 (multicast between the SDS distribution function and the SDS function)
The MCData-SDS-3 reference point, which exists between the SDS distribution function of the MCData server and the SDS function of the MCData client, is used by the SDS distribution function of the MCData server to send downlink multicast SDS data to the SDS function of the MCData client. The MCData-SDS-3 reference point uses the MB2-U interface defined in 3GPP TS 23.468 [8].
6.5.4.2 Signalling control plane
The description of the signalling control plane reference points is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6.6 Functional model for file distribution
6.6.1 On-network functional model
Figure 6.6.1-1 shows the application plane functional model for file distribution.
Figure 6.6.1-1: Application plane functional model for file distribution
In the model shown in figure 6.6.1-1, the following apply:
– MCData-FD-1 reference point is primarily used for MCData application signalling for establishing a session in support of MCData file distribution. Secondarily, MCData-FD-1 reference point is also used for both uplink and downlink unicast data (e.g., URL associated to file, file download completed report).
– MCData-FD-2 reference point carries uplink and downlink unicast file data between the FD functions of the MCData server and the MCData UE.
– MCData-FD-3 reference point carries downlink multicast file data from the FD function of the MCData server to the FD function of the MCData UE.
– MCData-FD-4 reference point carries uplink and downlink unicast file data between the media storage function of the MCData Content server and the media storage client of the MCData UE.
– MCData-FD-5 reference point supports the MCData server to access the stored files in the MCData content server for certain file distribution functions, such as retrieval a file to be distributed through multicast etc. This reference points also supports any necessary operational requirements.
– MCData-FD-7 reference point supports the upload and download of file data between MCData content server and MCData message store.
NOTE: The security aspects of MCData-FD-5 and MCData-FD-7 reference points are the responsibility of SA3 and thus outside the scope of the present document.
6.6.1a On-network functional model for interconnection
Figure 6.6.1a-1 shows the application plane functional model for file distribution with interconnection.
Figure 6.6.1a-1: Application plane functional model for file distribution
In the model shown in figure 6.6.1a-1, the following apply:
– MCData-FD-1, MCData-FD-2, MCData-FD-3, MCData-FD-4, MCData-FD-5 reference points are described in subclause 6.6.1.
– MCData-7 and MCData-8 reference points are described in subclause 6.4.4.1.
– The MC gateway server is described in subclause 6.4.3.1.5.
– MCData-3 and MCData-9 allow the MCData server in the primary MCData system to share URLs related to files for upload and download with the MCData server in the partner MCData system.
– MCData-FD-6 allows file contents and metadata to be shared between the MCData content server in the primary MCData system and the MCData content server in the partner MCData system. MCData‑FD‑6 is based on HTTP.
– The HTTP proxies are contained in the signalling plane. They provide topology and IP address hiding between MCData systems.
6.6.2 Off-network functional model
Figure 6.6.2-1 shows the off-network application plane functional model for FD.
Figure 6.6.2-1: Application plane functional model for FD
6.6.3 Functional entities description
6.6.3.1 Application plane
6.6.3.1.1 FD function
FD function of the MCData client and the MCData server is responsible to handle file distribution capability related requests and responses.
The FD function of the MCData server is responsible for the distribution of file to the MCData communication participants. The FD function of the MCData server provides the following functionality:
– reception of uplink file data by means of the MCData-FD-2 reference point;
– replicate the file data as needed for distribution to those MCData communication participants using unicast transport;
– distribute downlink file data by IP unicast transmission to those MCData communication participants utilizing unicast transport by means of the MCData-FD-2 reference point; and
– distribute downlink file data using multicast downlink transport by means of the MCData-FD-3 reference point.
6.6.3.1.2 Media storage client
The media storage client is used to support FD function of the MCData client for file distribution capability. FD function of the MCData client interacts with media storage client for uploading and downloading file to or from the media storage function of the MCData content server.
6.6.3.1.3 Transmission/Reception control
This functional entity is responsible for transmission and reception control of MCData file data between the sending MCData UE, the MCData server, and the receiving MCData UE. Transmission and reception control function is used to provide arbitration between multiple data requests and apply the necessary policy to ensure that appropriate data is transmitted between the MCData UE. However, when the file distribution requests are exceeding a certain size, it may be necessary to control the data that is transmitted or received by the MCData UEs. The control is subject to criteria like application level priorities (e.g. user priority, group priority), service type, emergency nature of the communication, etc.
6.6.3.1.4 Media storage function
The media storage function is responsible for the storing of media uploaded by the media storage client of the MCData UE in case of MCData file distribution. It also supports download of stored media by the MCData UE in case of file distribution via media storage client.
The media storage function supports partial download requests of stored media by the MCData UE via media storage client.
6.6.3.1.5 MCData content server
The MCData content server functional entity provides a repository area in the MCData trust domain allowing authorized MCData users to temporarily store files that are intended to share to other MCData users. It provides common pool of storage area (i.e. size) to all authorized MCData users to use, no personal space is allocated. An authorized MCData user can use the supported operations on the defined reference point to upload shared files and download the files that are shared to him. The MCData server will use the defined reference point to access the files stored in the MCData content server and support the necessary operational functionalities. As part of the file life cycle management the temporarily stored files will be removed periodically based on the Mission Critical service provider policy. An MCData content server may share files with another MCData content server in another MCData system to support interconnection.
If the MBMS user service architecture described in 3GPP TS 26.346 [21] is utilized for file distribution, the MCData content server provides the stored file associated to the established MBMS session.
NOTE: The security aspects of the MCData content server and its operational supports are the responsibility of SA3 and thus outside the scope of the present document.
6.6.3.2 Signalling control plane
The description of the signalling control plane is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6.6.4 Reference points
6.6.4.1 Application plane
6.6.4.1.1 Reference point MCData-FD-1 (between the FD functions of the MCData client and the MCData server)
MCData-FD-1 reference point is used for MCData application signalling for establishing a session in support of MCData file distribution. The bearer is also used for both uplink and downlink unicast data (e.g., URL associated to file, file download completed report). The MCData-FD-1 reference point shall use the SIP-1 and SIP-2 reference points for transport and routing of SIP signalling. MCData-FD-1 reference point can be used as long as the file size does not exceed the capabilities (e.g. payload or transmission limits) provided by MCData-FD-1.
Messages supported on this interface include the uplink and the downlink unicast file transaction between the MCData clients in MCData communication via the MCData server for:
– metadata (file size, type etc.) of the file being distributed;
– URL of the file being distributed;
– sending download completed report;
– small size file;
– conversation identifier for message thread indication; and
– application plane identities for the MCData user and MCData application.
Messages supported on this interface may also include the MCData client providing the MCData server with
– MCData application signalling for establishing a file distribution session in support of MCData communication.
6.6.4.1.2 Reference point MCData-FD-2 (unicast between the FD functions of the MCData client and the MCData server)
The MCData-FD-2 reference point, which exists between the FD functions of the MCData client and the MCData server, is used for unicast file transaction between MCData server and MCData client. The MCData-FD-2 reference point uses the SGi reference point defined in 3GPP TS 23.002 [10].
Reference point MCData-FD-2 supports the following functions:
– file being distributed from and to the MCData client;
– conversation identifier for message thread indication; and
– application plane identities for the MCData user and MCData application.
6.6.4.1.3 Reference point MCData-FD-3 (multicast between the FD functions of the MCData client and the MCData server)
The MCData-FD-3 reference point, which exists between the FD functions of the MCData client and the MCData server, is used by the FD function of the MCData server to send downlink multicast file data to the FD function of the MCData client. The MCData-FD-3 reference point uses the MB2-U interface defined in 3GPP TS 23.468 [8] or the xMB-U interface as defined in 3GPP TS 26.348 [19].
6.6.4.1.4 Reference point MCData-FD-4 (media storage function and media storage client)
The MCData-FD-4 reference point, which exists between the media storage function and the media storage client, is used by the media storage client of MCData UE to upload and download file to the media storage function of the MCData content server. The MCData-FD-4 reference point uses the HTTP reference point.
6.6.4.1.5 Reference point MCData-FD-5 (FD function and media storage function)
The MCData-FD-5 reference point, which exists between FD function and the media storage function, is used by the FD function of MCData server to fetch the file in the MCData content server that was uploaded by the media storage client of a MCData UE for multicast delivery using MBMS. It also supports necessary operational functions such as size check for transmission control etc. The MCData-FD-5 reference point uses the HTTP reference point.
6.6.4.1.6 Reference point MCData-FD-7 (media storage function and MCData message store)
The MCData-FD-7 reference point, which exists between media storage function and the MCData message store, is used by the media storage function to fetch the file residing in the MCData message store and store in its repository for distribution. It is also used by the MCData message store to download the file contents from the media storage function.
6.6.4.2 Signalling control plane
The description of the signalling control plane reference points is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6.7 Functional model for data streaming
6.7.1 On-network functional model
NOTE: As no detailed procedures are specified in the current specification the DS functional model is for information only.
Figure 6.7.1-1 shows the application plane functional model for data streaming.
Figure 6.7.1-1: Application plane functional model for data streaming
In the model shown in figure 6.7.1-1, the following apply:
– MCData-DS-1 reference point is used for MCData application signalling for establishing a session in support of MCData data streaming. The bearer is also used for both uplink and downlink unicast stream download reports (e.g. stream start and stop records).
– MCData-DS-2 reference point carries unicast data stream between the data streaming and distribution function of the MCData server and the DS function of the MCData UE. The bearer is used for both uplink and downlink unicast data streaming.
– MCData-DS-3 reference point carries multicast data stream from the data streaming and distribution function of the MCData server to the DS function of the MCData UE. The bearer is used for downlink multicast data streaming.
6.7.2 Off-network functional model
6.7.3 Functional entities description
6.7.3.1 Application plane
6.7.3.1.1 DS function
DS function of the MCData client is responsible to handle DS capability related requests and responses for data streaming. FD function may interact with storage entity for retrieving the locally stored data for data streaming.
6.7.3.1.2 Data streaming and distribution function
The data streaming and distribution function is responsible for the distribution of data stream to MCData communication participants. The data streaming and distribution function provides the following functionality:
– reception of uplink data stream transmission by means of the MCData-DS-2 reference point;
– replicate the data stream as needed for distribution to those MCData communication participants using unicast transport;
– distribute downlink data stream by IP unicast transmission to those MCData communication participants utilizing unicast transport by means of MCData-DS-2 reference point; and
– distribute downlink data stream using multicast downlink transport by means of the MCData-DS-3 reference point.
6.7.3.1.3 Transmission/Reception control
This functional entity is responsible for transmission and reception control of data stream between the sending MCData UE, the MCData server, and the receiving MCData UE. Transmission and reception control function is used to provide arbitration between multiple data requests and apply the necessary policy to ensure that appropriate data is transmitted between the MCData UEs.
6.7.3.2 Signalling control plane
The description of the signalling control plane is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6.7.4 Reference points
6.7.4.1 Application plane
6.7.4.1.1 Reference point MCData-DS-1 (between the data streaming and distribution function and the DS function)
MCData-DS-1 reference point is used for MCData application signalling for establishing a session in support of MCData data streaming. The bearer is also used for both uplink and downlink unicast stream download reports (e.g., stream start and stop records). The MCData-DS-1 reference point shall use the SIP-1 and SIP-2 reference points for transport and routing of SIP signalling.
Messages supported on this interface includes the uplink and the downlink unicast data stream between the MCData clients MCData communication via the MCData server for
– metadata of the data being streamed;
– URL of the data being streamed;
– sending stream download report;
– conversation identifier for message thread indication; and
– application plane identities for the MCData user and MCData application.
Messages supported on this interface may also include the MCData client providing the MCData server with
– MCData application signalling for establishing a UE data streaming session in support of MCData communication.
6.7.4.1.2 Reference point MCData-DS-2 (unicast between the data streaming and distribution function and the DS function)
The MCData-DS-2 reference point, which exists between the data streaming and distribution function and the DS function, is used to unicast data stream between the data streaming and distribution function of the MCData server and the DS function of the MCData client. The MCData-DS-2 reference point uses the SGi reference point defined in 3GPP TS 23.002 [10].
MCData-DS-2 supports the following functions:
– stream data from MCData UE;
– stream data from network;
– data stream controls from the authorized MCData UE;
– stream data stream controls from the MCData UE over uplink;
– start and stop data stream from MCData UE over downlink;
– conversation identifier for message thread indication; and
– application plane identities for the MCData user and MCData application.
6.7.4.1.3 Reference point MCData-DS-3 (multicast between the data streaming and distribution function and the DS function)
The MCData-DS-3 reference point, which exists between the data streaming and distribution function and the DS function, is used by the data streaming and distribution function of the MCData server to send multicast data stream to the DS function of the MCData client. The MCData-DS-3 reference point uses the MB2-U interface defined in 3GPP TS 23.468 [8].
6.7.4.2 Signalling control plane
The description of the signalling control plane reference points is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6.8 Functional model for IP connectivity
6.8.1 On-network functional model
Figure 6.8.1-1 shows the application plane functional model for User-IP connectivity.
Figure 6.8.1-1: Application plane functional model for IP connectivity
In the model shown in figure 6.8.1-1, the following apply:
– MCData-IPcon-1 reference point is used for MCData application signalling for establishing a session in support of MCData IP connectivity.
– MCData-IPcon-2 reference point carries bidirectional IP Data for point-to-point MCData IP connectivity over the media plane between the U-IPcon distribution function of the MCData server and the IPcon function of the MCData client(s).
– MCData-IPcon-3 reference point is used by the IP-con distribution function of the MCData server to send unidirectional downlink IP Data to the IP-con function of the MCData clients.
– IPcon-host reference point is used for a data host, e.g. server, to use IP connectivity service capabilities. This reference point is outside the scope of the present document.
6.8.2 Off-network functional model
6.8.3 Functional entities description
6.8.3.1 Application plane
6.8.3.1.1 IP connectivity function
IP connectivity function of the MCData client is responsible to handle IPcon capability related requests and responses.
6.8.3.1.2 IPcon distribution function
The IPcon distribution function of the MCData server is responsible for the distribution of IP Data to MCData communication participants. The IPcon distribution function of the MCData server provides the following functionality:
– reception of uplink IP Data transmission by means of the MCData-IPcon-2 reference points;
– replicate the IP Data as needed for distribution to those MCData communication participants using unicast transport;
– distribute downlink data by IP unicast transmission to those MCData communication participants utilizing unicast transport by means of the MCData-IPcon-2 reference points; and
– distribute downlink IP Data using multicast downlink transport by means of the MCData-IPcon-3 reference point.
6.8.3.1.3 Transmission/Reception control
This functional entity is responsible for transmission and reception control of IP Data transaction between the sending MCData client, the MCData server, and the receiving MCData client. Transmission and reception control function is used to provide arbitration between multiple data requests and apply the necessary policy to ensure that appropriate IP Data are transmitted between the MCData clients.
6.8.3.2 Signalling control plane
The description of the signalling control plane is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6.8.4 Reference points
6.8.4.1 Application plane
6.8.4.1.1 Reference point MCData-IPcon-1 (between the IPcon distribution function and the U-IPcon function)
MCData-IPcon-1 reference point is used for MCData application signalling for establishing a session in support of MCData IP connectivity.
6.8.4.1.2 Reference point MCData-IPcon-2 (unicast between the U-IPcon distribution function and the U-IPcon function)
MCData-IPcon-2 reference point carries bidirectional IP Data for point-to-point MCData IP connectivity over the media plane between the IPcon distribution function of the MCData server and the IPcon function of the MCData client(s).
6.8.4.1.3 Reference point MCData-IPcon-3 (multicast between the IPcon distribution function and the IPcon function)
MCData-IPcon-3 reference point carries downlink unidirectional IP Data over the media plane between the IPcon distribution function of the MCData server and the IPcon function of the MCData client(s).
6.8.4.2 Signalling control plane
The description of the signalling control plane reference points is contained in the common functional architecture to support MC services as specified in 3GPP TS 23.280 [5].
6A Identities
The MCData service specific identities (e.g. MCData ID, MCData group ID) are described in clause 8 of 3GPP TS 23.280 [5].
6B Application of functional model to deployments
The application of the functional model to deployments, and description of various deployment scenarios for the MCData service, can be found in clause 9 of 3GPP TS 23.280 [5].