T Multimedia Seminar Carlos Herrero55828H Osmo Tolvanen46958L

 What is MBMS and why Multicast/Broadcast is introduced to UMTS  MBMS Standarisation in 3GPP  Reference architecture model  Functional entities to support MBMS  MBMS service provisioning: broadcast vs. multicast  MBMS Main open issues  Conclusions and possible service solutions

Multimedia Broadcast/Multimedia Service Aims to offer an efficient way to transmit data from single source to multiple destinations over radio network  Network resources are saved MBMS is realised by addition of existing and new functional entities of the 3GPP architecture

For some applications multiple users can receive the same data in the same time: It would benefical for the network to transmit the data only once over a particular link. Cell Broacast Services (CBS) can be used to transmit low bitrate data to particular cells (service areas). IP multicast as such can not provide means for multiple subscribers to share radio or core network resources in UMTS system.

“With incresing use of high bandwidth applications in UMTS, especially with large number of users receiving the same high data rate services, efficient informantion distribution is essential. Thus broadcast and multicast are techniques to decrease the amount of data within the network and use the resources more efficiently.” 3GPP TS

What is 3GPP? 3rd Generation Partnership Project Established in 1998 A collaboration agreement between numerous telecommunication standardisation bodies Aims to maintain and develop GSM and 3rd Generation Mobile Systems by providing Technical Specifications (TSGs)

Technical specifications (TSGs) for MBMS TSG 22: TS ”Requirements for MBMS” TSG 23: TS “Architecture and functional description” TSG 25: TS “UTRAN Interface Aspects” TSG 26: TS “Codecs and Protocols” TSG 29: TS “Procedure Description”

 Minimum number of changes to existing infrastructure  User Equipment: UE  Radio Access Network: UTRAN/GERAN  Serving GPRS Support Node (SGSN )  Gateway GPRS Support Node (GGSN)  Broadcast-Multicast Service Centre: BM-SC

User Equipment

Radio Access Network

Serving GPRS Support Node

Gateway GPRS Support Node

Broadcast/ Multicast Service Centre

MBMS functions in two modes: The Broadcast Mode * available without subscription for all UEs in a cell The Multicast Mode * requires subscription

The connection procedure The broadcast mode The multicast mode

Operator may use different mechanisms to inform users about available MBMS services (service discovery) Announcements are available also for those who are not subscribed Location information may be used Service announcement

Establishes the needed network resources for the MBMS data transfer Resources are reserved from both core network and radio access network Session start (network set up)

Informs users about on-going or fothcoming services available for all users with activated MBMS services MBMS notification

The data is transferred to the user equipments (UEs) The UE is in connected mode No ciphering No retransmitting, so there may be some data loss Data transfer

The reserved network resources are released when there’s no more data to be transferred Session stop

First the user starts a relationship with the operator by subscribing to a spesific MBMS service After subscription the user may receive related MBMS service and operator may charge for it Subscription can be made for example in the internet Subscription

Same as in broadcast mode Service announcement

In the joining phase the user indicates to the network that he/she wants to specific multicast data stream Joining can be made at any time Used for charging so authentication is needed Joining

Same as in broadcast mode with one exception: The network decides whether a common channel for all UEs in a cell is used, or separate channel for each UE Session start

Same as in the broadcast mode MBMS notification Data transfer Data is encrypted Otherwise same as in the broadcast mode Session stop Same as in the broadcast mode

When user no longer wants to belong to a multicast group and receive data transfer Doesn’t unsubscribe the user from the service, just from the current data transfer Can be made any time Leaving

Security: Network level or application level ciphering MBMS Service Area. System requirements at User Equipment. Codecs and protocols. Mobility of user equipment

IP multicast traffic can be received by mobile subcscribers already: However, IP multicast is transparent to UMTS system and ptp connection between each UE and GGSN is used. MBMS is transparent to end users (they have same experience as with ptp connections) but saves resources on the mobile operator side: optimization of the radio access For example in a sports event, playbacks can be broadcasted to all audience UEs automatically Operators can use MBMS to inform about new services