t-111.550 multimedia seminar carlos herrero55828h osmo tolvanen46958l
TRANSCRIPT
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