An MBMS user service may also be carried by more than one MBMS bearer service. The MBMS Bearer Services are embedded in MBMS User Service procedures.
Bearer Service Phases:
| Bearer Service Phase | Multicast (M) | Broadcast (B) |
| Subscription | Per User | NA |
| Service Announcement | Per Service | Per Service |
| Joining | Per User | NA |
| Session Start | Per Service | Per Service |
| MBMS Notification | Per Service | Per Service |
| Data Transfer | Per Service | Per Service |
| Session Stop | Per Service | Per Service |
| Leaving | Per User | NA |
Note 1: Session Start is the trigger for bearer resource establishment for MBMS data transfer.
Note 2: At Session Stop, the bearer resources are released
User Service Phases:
- User Service phase - User Service Discovery / Announcement
- User Service phase - User Service Initiation / termination procedure
- User Service phase - Session Start / Stop
- User Service phase - Data transmission / Reception
- User Service phase - Associated-Delivery procedures
1.1. Mapping between MBMS Bearer and User Service phases
- Figure - Mapping between MBMS Bearer Service Phases and User Service phases
- This mapping is applicable for the MBMS Broadcast and Multicast Modes.
http://docs.google.com/View?id=ddh56dhg_123dwmx7dgj
- It is assumed that the MBMS bearer service phases
- It is assumed, that the Session Start phase
1.2. MBMS Bearer Service Phases (Service Provision) –Multicast Mode
MBMS multicast service provision phases
- An example for the phases of MBMS multicast service provision (figure below) - (MBMS Multicast Bearer Service Phases) http://docs.google.com/View?id=ddh56dhg_125cvwfcmgg
- Subscription establishes the relationship between the user and the service provider, which allows the user to receive the related MBMS multicast service
- Service announcement informs UEs about forthcoming services.
- Joining (MBMS multicast activation) is the process by which a subscriber joins (becomes a member) a multicast group, i.e. the user indicates to the network that he/she is willing to receive Multicast mode data of a specific service.
- MBMS multicast mode bearer set up establishes the network resources for MBMS data transfer in the multicast area.
- MBMS notification informs the UEs about forthcoming (and potentially about ongoing) multicast data transfer.
- Data transfer is the phase when MBMS data are transferred to the UEs.
- MBMS multicast mode bearer release releases the network resources for MBMS data transfer, e.g. when no more MBMS data have to be transferred.
- Leaving (MBMS multicast deactivation) is the process by which a subscriber leaves (stops being a member) a multicast group, i.e. the user no longer wants to receive Multicast mode data of a specific service.
- The phases subscription, joining and leaving are performed individually per user. The other phases are performed for a service, i.e. for all users interested in the related service.
- The sequence of phases may repeat, e.g. depending on the need to transfer data.
- Also subscription, joining, leaving, service announcement as well as MBMS notification may run in parallel to other phases.
(1). Subscription
- Establishes the relationship between the user and the service provider, which allows the user to receive the related MBMS multicast service.
- Service Subscription is the agreement of a user to receive service(s) offered by the operator.
- Subscription information is recorded in the BM-SC.
- Subscription information and other BM-SC functionality may be on separate entities, which is enabled by proxy capability of the Gmb interface.
(2). Service announcement
- MBMS user service announcement/discovery mechanisms shall allow users to request or be informed about the range of MBMS user services available.
- This includes operator specific MBMS user services as well as services from content providers outside of the PLMN.
- Service announcement is used to distribute to users information about the service, parameters required for service activation (e.g. IP multicast address(es)) and possibly other service related parameters (e.g. service start time).
- Operators/service providers may consider several service discovery mechanisms.
- This could include standard mechanisms such as SMS, or depending on the capability of the terminal, applications that encourage user interrogation.
- The method chosen to inform users about MBMS user services may have to account for the user's location, (e.g. current cell, in the HPLMN or VPLMN). Users who have not already subscribed to a MBMS user service should also be able to discover MBMS user services.
- The following could be considered useful for MBMS user service announcement mechanisms (not exhaustive):
- SMS Cell Broadcast to advertise MBMS Multicast and Broadcast user services;
- MBMS Broadcast mode to advertise MBMS Multicast and Broadcast user Services;
- MBMS Multicast mode to advertise MBMS Multicast user Services;
- PUSH mechanism (WAP, SMS-PP, MMS);
- URL (HTTP, FTP).
(3). Joining
- Joining (i.e. MBMS multicast activation by the user) is the process by which a subscriber joins (becomes a member of) a multicast group, i.e. the user indicates to the network that he/she wants to receive Multicast mode data of a specific MBMS bearer service.
- An MBMS user service may also be carried by more than one MBMS bearer service.
- In that case the MBMS user service part in the UE initiates the relevant MBMS bearer services to receive the service
(4). Session Start
- Session Start is the point at which the BM-SC is ready to send data.
- This can be identified with the start of a
- Session Start occurs independently of activation of the service by the user – i.e. a given user may activate the service before or after Session Start.
- Session Start is the trigger for bearer resource establishment for MBMS data transfer.
- If an MBMS user service is carried by more than one MBMS bearer service, a Session Start message is sent for each MBMS bearer service.
- In that case the UE may need to initiate the reception of multiple relevant MBMS bearer services to receive the MBMS user service
(5). MBMS notification
- Informs the UEs about forthcoming (and potentially about ongoing) MBMS multicast data transfer.
(6). Data transfer
- It is the phase when MBMS data are transferred to the UEs
(7). Session Stop
- It is the point at which the BM-SC determines that there will be no more data to send for some period of time – this period being long enough to justify removal of bearer resources associated with the session.
- At Session Stop, the bearer resources are released
(8). Leaving
- Leaving (i.e. MBMS multicast deactivation by the user) is the process by which a subscriber leaves (stops being a member of) a multicast group, i.e. the user no longer wants to receive Multicast mode data of a specific MBMS bearer service
1.3. MBMS Service Provision and Timeline – Multicast Mode
MBMS Multicast Mode – Phases of MBMS Multicast service provision
Figure: This is illustrated with the following example of timeline:
http://docs.google.com/View?id=ddh56dhg_127dzv7hwp9
MBMS Multicast Mode – Timeline
(1). Period between Service Announcement and Session Start
- - - The service announcement may contain a schedule of Session Start times and may be sent some time before the service is due to start. So, this time period could be hours, days or even weeks.
(2). Period between Service Announcement and Service Subscription
- Service Subscription can be done anytime before or after Service announcement.
(3). Period between Service Announcement and Joining
- - - The Joining time is chosen by the user and/or UE possibly in response to a Service Announcement. Users will typically join at the time of their choosing so that the period between announcement and joining may be very long or very short. In order to avoid overload situations being caused by many users attempting to join in a short period of time, the UE shall be able to use parameters sent by the BM-SC in the service announcement to randomise the joining time.
(4). Period between Joining and Session Start
- Some MBMS bearer services may be 'always on'. In this case, Joining can take place immediately after Service Announcement and possibly many hours before, or after, Session Start.
- In other cases, if a Session Start time is known, Joining may take place immediately before Session Start or after Session Start. For these services, the announcement may contain some indication of a time period which users and UEs should use to choose a time to Join the MBMS bearer service.
(5). Period between Session Start and First Data Arrival
- Session Start indicates that the transmission is about to start. The time delay between a Session Start indication and actual data should be long enough for the network actions required at Session Start to take place e.g. provision of service information to the UTRAN, establishment of the bearer plane.
- Session Start may be triggered by an explicit notification from the BM-SC. In the case of bearer plane resources which are set-up after the start of session data transmission, the network is not required to buffer the session data and loss of data can be assumed.
(6). Period between Session Start and Session Stop
-- ---- When the BM-SC knows that there is no more data to be sent for a
- The duration of this
- If the BM-SC wants to use session repetition identification on the MBMS bearer service level, the BM-SC must stop the MBMS session before starting the next MBMS user service session for that TMGI.
(7). Session Update
- - - Session Update is used to update specific parameters of an ongoing MBMS Multicast session. The SGSN can use the procedure to update the list of RAs where MBMS multicast users are located for an ongoing MBMS Multicast service session
1.4. MBMS Bearer Service Phases (Service Provision) – Broadcast Mode
MBMS broadcast service provision phases
- Figure: Phases of MBMS broadcast service provision (MBMS Broadcast Bearer Service Phases)
http://docs.google.com/View?id=ddh56dhg_129dhrntkfb
- Service announcement informs UEs about forthcoming services.
- MBMS broadcast mode bearer set up establishes the network resources for MBMS data transfer in the broadcast area.
- MBMS notification informs the UEs about forthcoming (and potentially about ongoing) broadcast data transfer.
- Data transfer is the phase when MBMS data are transferred to the UEs.
- MBMS broadcast mode bearer release releases the network resources for MBMS data transfer, e.g. when no more MBMS data have to be transferred.
- The sequence of phases may repeat, e.g. depending on the need to transfer data. It is also possible that the service announcement and MBMS notification phase may run in parallel with other phases, in order to inform UEs which have not yet received the related service.
(1). Service announcement
- Informs UEs about forthcoming MBMS user services. Also see on Multicast mode.
(1-1). UE local service activation
- The MBMS user service part in the UE initiates reception of the MBMS bearer service to receive an MBMS user service.
- In case one MBMS user service is carried by more than one MBMS bearer service, the UE may need to initiate the reception of multiple relevant MBMS bearer services to receive the MBMS user service.
(2). Session Start
- Session Start is the point at which the BM-SC is ready to send data.
- Session Start occurs independently of Service Activation by the user – i.e. a given user may activate the service before or after the start of the session.
- Session Start is the trigger for bearer resource establishment for MBMS data transfer.
- If an MBMS user service is carried by more than one MBMS bearer service, a Session Start message is sent for each MBMS bearer service. In that case the UE may need to initiate the reception of multiple relevant MBMS bearer services to receive the MBMS user service.
(3). MBMS notification
- Informs the UEs about forthcoming (and potentially about ongoing) MBMS broadcast data transfer.
(4). Data transfer
- It is the phase when MBMS data are transferred to the UEs.
(5). Session Stop
- It is the point at which the MBMS user service determines that there will be no more data to send for some period of time – this period being long enough to justify removal of bearer resources associated with the service.
- At Session Stop, the bearer resources are released.
(6). Session Update
- Session Update is used to update specific parameters of an ongoing MBMS Broadcast session. Parameters which can be updated are MBMS Service Area, and/or the List of SGSNs (only from BM-SC to GGSN).
- A Session Update received in one node, results in a Session Update being sent to downstream nodes, to inform of the changed MBMS Service Area.
- When a Session Update is received in the GGSN including the List of SGSN parameter, it results in a Session Start being sent to new downstream nodes, and in a Session Stop being sent to downstream nodes that have been removed from the list
1.5. MBMS Service Provision and Timeline – Broadcast Mode
Figure – MBMS Timeline Overview:
http://docs.google.com/View?id=ddh56dhg_121c5x2p6d4
(1). Period between Service Announcement and Session Start
- Same as for Multicast mode.
(2). Period between Session Start and First Data Arrival
- Same as for Multicast mode.
(3). Period between Session Start and Session Stop
- Same as for Multicast mode
1.6. User Service phase - User Service Discovery / Announcement
- The
- User Service Discovery / Announcement mechanism can provide information on available MBMS User services in pull mode, via the Web or WAP Portals, or in push mode, via SMS or MBMS Download based User Service.
- The User Service Discovery / Announcement phase provides all necessary information for the
- The necessary session parameters to configure the service activation are provided according to Session Description Protocol (SDP) specification, which are complemented by additional information containing additional service parameters.
- Additionally, Service Discovery includes DRM/security descriptions.
- In the case of a size-limited delivery method (e.g. SMS, MMS) being used during the Service Announcement / Discovery phase, it should be recognized that Service Announcement messages are not of fixed length.
- Methods of limiting the size of the message may be adopted. It is suggested that should a size-limited delivery method be selected, parameters such as URI lengths and the number of Connection data and Media announcement fields should be chosen appropriately.
1.7. User Service phase - User Service Initiation / termination procedure
- For MBMS User service activation, the UE needs to perform a security function and the MBMS Bearer Service activation procedures.
- In the case of MBMS Multicast Mode, an IGMP or MLD message is sent via a
- A MBMS Bearer Service (BS) context is only created once when the very first MBMS UE context is created in a node.
- In the case of MBMS Broadcast Mode, network-side elements establish the MBMS BS context without requiring user initiated messaging. The basic idea behind these procedures is that several UEs share one single bearer. The IP Multicast address and information for the MBMS User Service receiving application is given via the MBMS Service Discovery mechanism.
- In case the service requires user authentication, security procedures are performed before the MBMS bearer Service Activation procedure. The
- The
- In the case of MBMS Multicast Mode, this phase may authorize the service activation request from the UE. This function is present when security procedures like authentication and traffic encryption are required.
1.8. User Service phase - Session Start / Stop
- According to the 3GPP TS 23.246, the BM-SC controls the activation and the release of the MBMS User plane (switching of the MBMS BS context between
- The Service Provider might trigger this process on the availability of new content.
- The release of the user plane resources depends on the transmission duration of the content.
- The transmission duration depends in case of the MBMS Download User Service on the content size, on the (optional) Forward-Error-Correction (FEC) overhead for error protection and the bitrate of the MBMS bearer.
1.9. User Service phase - Data Transmission / Reception
- The
- Optionally, the content is protected by a Forward Error Correction (FEC) code.
- The traffic is sent using either IP unicast addressing or IP Multicast addressing via the BM-SC onto the MBMS Bearer Service.
- In case of IP Unicast, the BM-SC is directly addressed by the MBMS User Service Transmitter and relays the traffic to IP Multicast.
- In case of IP Multicast, the traffic is forwarded by the BM-SC and the MBMS User Service Transmitter forwards the data to an IP Multicast group. Additionally the MC-Relay in the BM-SC may perform additional source authentication procedures to avoid unauthorized traffic entering the Core Network.
- The
- Optional
- A typical associated-delivery procedure is a point-to-point file repair mechanism for delivering missing data to clients of an MBMS Download session, which perceived packet losses that are unrecoverable during the broadcast/multicast transmission.
- The load of the point-to-point repair mechanism may be spread randomly in time and also across network elements.
- The MBMS Bearer Service may be configured to provide a constant or variable bit rate as requested by the MBMS User Service.
- The MBMS Bearer Service is expected to be service independent and can be configured by a Network Provider for MBMS Download and MBMS Streaming User Services.
1.10. User Service phase - Associated-Delivery procedures
- Associated-delivery procedures may also include the usage of MBMS bearers.
File Repair service
- It should be possible for UEs to repair erroneous files, delivery by the download delivery method, by means of repair request and response operations.
Content reception reporting
- It should be however possible for the operator to collect statistical data such as lost frames, assigned resources, bit-rates achieved, etc.
1.11. System Overview of MBMS User Service
System Overview:
- Figure below gives an overview of functions (system overview) for MBMS user services based on the MBMS download and the MBMS streaming delivery methods.
- The figure also contains client and network functions, Interactions, which are only applicable for the MBMS Multicast Mode, are marked accordingly.
- The figure includes the MBMS User service provision phases (arrow on the right side of the figure).
http://docs.google.com/View?id=ddh56dhg_131ff88bhcb
- The Phase
- The break in the sequence indicates that the service activation phases are independent from the session start/stop and the data transfer phases.
- The service provider initiates the establishment of the MBMS User Plane (Session Start/Stop and the Data Transfer Phases) when there is content to be transmitted.
- The MBMS Bearer Services are embedded in MBMS User Service procedures.
- The major part of the data is transferred via the MBMS Bearer Service.
- MBMS User Services include Associated-Delivery procedures (e.g. file repair) to augment the original MBMS Bearer sessions.
- One dedicated user authentication procedure is depicted in conjunction with the MBMS Bearer Service Activation procedure within the Session Establishment phase.
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