T-111.550 Multimedia Seminar

Carlos Herrero 55828H

Osmo Tolvanen 46958L

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 22.146

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 22.146 ”Requirements for MBMS”

• TSG 23: TS 23.246 “Architecture and functional description”

• TSG 25: TS 25.446 “UTRAN Interface Aspects”

• TSG 26: TS 26.346 “Codecs and Protocols”

• TSG 29: TS 29.846 “Procedure Description”

UE SGSN

UE GERAN

UTRAN

CBC

CSEHLR

GGSN BG

BM-SC

MulticastBroadcast

Source

MulticastBroadcast

Source

ContentProvider

Uu Iu

Iu/Gb

Um

Gr

Gn/Gp Gi

Gi

Gi

Gi

PDN(e.g. Internet)

ContentProvider

OSASCS

Gmb

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

UE SGSN

UE GERAN

UTRAN

CBC

CSEHLR

GGSN BG

BM-SC

MulticastBroadcast

Source

MulticastBroadcast

Source

ContentProvider

Uu Iu

Iu/Gb

Um

Gr

Gn/Gp Gi

Gi

Gi

Gi

PDN(e.g. Internet)

ContentProvider

OSASCS

Gmb

User Equipmen

t

UE SGSN

UE GERAN

UTRAN

CBC

CSEHLR

GGSN BG

BM-SC

MulticastBroadcast

Source

MulticastBroadcast

Source

ContentProvider

Uu Iu

Iu/Gb

Um

Gr

Gn/Gp Gi

Gi

Gi

Gi

PDN(e.g. Internet)

ContentProvider

OSASCS

Gmb

Radio Access

Network

UE SGSN

UE GERAN

UTRAN

CBC

CSEHLR

GGSN BG

BM-SC

MulticastBroadcast

Source

MulticastBroadcast

Source

ContentProvider

Uu Iu

Iu/Gb

Um

Gr

Gn/Gp Gi

Gi

Gi

Gi

PDN(e.g. Internet)

ContentProvider

OSASCS

Gmb

Serving GPRS

Support Node

UE SGSN

UE GERAN

UTRAN

CBC

CSEHLR

GGSN BG

BM-SC

MulticastBroadcast

Source

MulticastBroadcast

Source

ContentProvider

Uu Iu

Iu/Gb

Um

Gr

Gn/Gp Gi

Gi

Gi

Gi

PDN(e.g. Internet)

ContentProvider

OSASCS

Gmb

Gateway GPRS

Support Node

UE SGSN

UE GERAN

UTRAN

CBC

CSEHLR

GGSN BG

BM-SC

MulticastBroadcast

Source

MulticastBroadcast

Source

ContentProvider

Uu Iu

Iu/Gb

Um

Gr

Gn/Gp Gi

Gi

Gi

Gi

PDN(e.g. Internet)

ContentProvider

OSASCS

Gmb

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

Service announcement

Data transfer

MBMS notification

Session Start

Session Stop

Subscription

Joining

Service announcement

Data transfer

Leaving

MBMS notification

Session start

Session Stop

The multicast mode

Service announcement

Data transfer

MBMS notification

Session Start

Session Stop

• 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

Service announcement

Data transfer

MBMS notification

Session Start

Session Stop

• 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)

Service announcement

Data transfer

MBMS notification

Session Start

Session Stop

• Informs users about on-going or fothcoming services

• available for all users with activated MBMS services

MBMS notification

Service announcement

Data transfer

MBMS notification

Session Start

Session Stop

• 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

Service announcement

Data transfer

MBMS notification

Session Start

Session Stop

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

Session stop

UE1

time

UE local service activation

Broadcast service Announcement

Stop announcement

Data transfer

Service 1 Session 2

Broadcast of Data, received by any UE which is present

Service 1 session1

UE2

Local service de-activation

Start Broadcast Service announcement

Broadcast session start

Data transfer

Session stop

Idle period of seconds

Data transfer

Subscription

Joining

Service announcement

Data transfer

Leaving

MBMS notification

Session start

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

Subscription

Joining

Service announcement

Data transfer

Leaving

MBMS notification

Session start

Session Stop

• Same as in broadcast mode

Service announcement

Subscription

Joining

Service announcement

Data transfer

Leaving

MBMS notification

Session start

Session Stop

• 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

Subscription

Joining

Service announcement

Data transfer

Leaving

MBMS notification

Session start

Session Stop

• 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

Subscription

Joining

Service announcement

Data transfer

Leaving

MBMS notification

Session start

Session Stop

• 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

Subscription

Joining

Service announcement

Data transfer

Leaving

MBMS notification

Session start

Session Stop

• 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

subscription to service1

User service join

service leave

subscription to service1

UE1 events

Transfer of data

Subscription can be at any time

Start Service 1 announcement

1st Session start

Data transfer

1st session stop Service 1 Session 2

Service 1 events

Service 1 session1

UE2 events

Announcement

time

Stop Service 1 announcement

Idle period of seconds

Data transfer

Data transfer

Service join by the user can be at any time

Data sent to UE1

Data sent to UE1 and UE2

Data sent to UE1 and UE2

Data sent to UE2

• 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