- A cell broadcast service (CBS) allowing for low bit-rate data to be transmitted to all subscribers in a set of given cells over a shared broadcast channel. This service offers a message-based service.
- The broadcast mode should not be confused with the existing Cell Broadcast service (CBS) which is currently used for low bit rate services (messaging) whilst the broadcast mode enables the broadcast of multimedia services (Audio, Video etc).
- The Cell Broadcast Centre (CBC) may be used to announce MBMS services to the users. The functions a CBC could provide for MBMS service announcement are FFS.
MBMS services (multicast or broadcast mode) shall be available via GERAN, UTRAN, E-UTRAN. Within the broadcast or multicast service area, it shall be possible to inform users of up-coming MBMS sessions which they may receive. This may be useful e.g. to initiate UE processes for the reception of MBMS data.
1.2. IP Unicast and Multicast in PS
| Criteria | Unicast solution | Multicast Solution |
| Data distribution | § GGSN must fork data to all SGSNs containing active subscribers to the MBMS group. Each data stream must travel the whole network between the GGSN and the SGSN in parallel. § No impact on addressing at Gn level. § Home and visited networks must both support MBMS | § GGSN sends data once to all SGSNs. Intermediate routers fork the data as required. It is possible to design the network topology so that the forking will take place near the endpoint. § Use of multicast addresses at Gn must be coordinated between network operators. § Home and visited networks must both support MBMS |
| Efficient implementation in GGSN | § Either “Control Plane procedures modified to be per service” or “change in GTP-C to GTP-U relationship” | § Change in GTP-C to GTP-U relationship, plus: IP multicast must be supported on Gn. § Multicast tunnels keyed on multicast address, not TEID. |
| Efficient implementation in SGSN | § Either “Control Plane procedures modified to be per service” or “change in GTP-C to GTP-U relationship” | § Change in GTP-C to GTP-U relationship, plus: IP multicast must be supported on Gn and Iu. § Multicast tunnels identified by multicast address, not TEID. |
| Efficient implementation in RNC | § Either “Control Plane procedures modified to be per service” or “change in GTP-C to GTP-U relationship” | § Change in GTP-C to GTP-U relationship, plus: IP multicast must be supported on Iu. § Multicast tunnels identified by multicast address, not TEID. |
| Efficient use of GGSN user plane capacity | § GGSN capacity will be consumed for each SGSN added to the multicast group.1 | § GGSN capacity will vary little with the number of SGSNs added to the multicast group. |
| Efficient use of SGSN user plane capacity | § SGSN capacity will be consumed for each RNC added to the multicast group.1 | § SGSN capacity will vary little with the number of RNC added to the multicast group. |
| Scalability | § Scalability limited by SGSN/GGSN capacity1 | § Highly scalable |
Note 1: In practice this may not be a major limitation.
Note 2: Gn is used for 1. SGSN --- SGSN 2. SGSN --- GGSN; and Iu is used for RNS --- Core Network
MBMS also enables an IMS application located on an application server to send multimedia to a set of IMS users in the service area by means of MBMS bearer service. The usage of IMS protocols can initiate and control PSS and MBMS Streaming User Services based applications. It applies to IMS enabled UEs that also implement PSS and/or MBMS clients
3GPP Packet Switch Streaming (PSS)
§ provides a framework for Internet Protocol (IP) based streaming applications in by specifying protocols and codecs within the 3GPP system.
§ Protocols for control signalling, capability exchange, media transport, rate adaptation and protection are specified.
§ Codecs for speech, natural and synthetic audio, video, still images, bitmap graphics, vector graphics, timed text and text are also specified.
3GPP Multimedia Broadcast and Multicast Service (MBMS)
§ provides a framework for broadcast and Multicast streaming and download applications in 3GPP networks supporting the MBMS bearer service.
§ The MBMS user services are enabled by a set of specified media codecs, formats and transport/application protocols.
§ MBMS user services are built on top of the MBMS bearer service.
§ MBMS delivery method: mechanism used by a MBMS user service to deliver content. An MBMS delivery method uses MBMS bearers in delivering content and may make use of associated procedures. There are two delivery methods for the MBMS user services: download and streaming.
§ MBMS download delivery method: delivery of discrete objects (e.g. files) by means of a MBMS download session
§ MBMS streaming delivery method: delivery of continuous media (e.g. real-time video) by means of a MBMS streaming session
3GPP IP Multimedia Subsystem (IMS)
§ enables the deployment of IP multimedia applications.
§ PSS and MBMS User Services are IP multimedia services but they were specified before IMS.
§ IMS brings enablers and features to operators and subscribers that can enhance the experience of PSS and MBMS User Services.
The use of the IMS is to initiate and control PSS and MBMS User Service. This should enable deployment of PSS and MBMS user services as IMS services.
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