multimedia broadcast / multicast service from geran physical layer point of view

Multimedia Broadcast Multicast Service from GERAN Physical Layer point of view 17-01-2006 Henri Virta

Multimedia Broadcast / Multicast Service from GERAN Physical Layer

Point of View

Henri VirtaHenri VirtaSupervisor: Prof. Sven-Gustav HäggmanInstructor: M.Sc. Toni Majuri

Thesis Work Presentation17.01.2006


Contents• Background• Objectives & Methodology• Introduction to MBMS• Competing technologies• MBMS from PH Reselection point of view• Summary and conclusions


Background information• Multimedia Broadcast Multicast Service (MBMS) is a new feature

specified in 3GPP Release-6• Method of delivering the same multimedia contents to several

recipients in the service area• Main idea behind the MBMS development is to provide multimedia

contents simultaneously to several users, while preserving the network and radio resources

Node B

P-t-P

Node B

MBMS


Objectives & Methodology• Objectives

Introduce the MBMS service Compare the MBMS service to other available solutions Analyze the MBMS service from GERAN/Physical Layer and

specifically from PH reselection point of view

• Methodology Literary study based on 3GPP and ETSI specifications and

change requests MBMS related conference papers and research articles Discussions within the Nokia organization on MBMS related

issues


Introduction to MBMS (1/2)• The main idea behind broadcast/multicast services is the

possibility to save resources in the radio and core networks, by sharing the transmission path

• All MBMS services can be provided with cellular point-to-point (P-t-P) connections, but MBMS is more efficient if the same contents is delivered to several recipients in the same area

• The MBMS service is a solution for transmitting light video and audio clips, although it can also be used for real time streaming videos as well


Introduction to MBMS (2/2)• MBMS bearer service offers two modes:

• Broadcast Mode: • All users in the broadcast area can receive the broadcast service

• Multicast Mode:• Only users who have subscribed to the specific multicast service

and have joined the multicast group can receive the multicast service

• The subscribers can receive services, such as streaming video in a more economical manner.

• The Operator will control the MBMS service and content and can also control the QoS for the MBMS services

• For the Operator, MBMS will allow more efficient delivery and flexible pricing of existing point-to-point multimedia services


MBMS Procedures

Broadcast mode Multicast mode

SSeerrvviiccee aannnnoouunncceemmeenntt

MMBBMMSS MMuullttiiccaasstt mmooddee bbeeaarreerr sseett--uupp

DDaattaa ttrraannssffeerr

NNoottiiffiiccaattiioonn

MMBBMMSS MMuullttiiccaasstt mmooddee bbeeaarreerr rreelleeaassee

SSuubbssccrriippttiioonn

LLeeaavviinngg

JJ ooiinniinngg

In the service area

In the service area

SSeerrvviiccee aannnnoouunncceemmeenntt

MMBBMMSS BBrrooaaddccaasstt mmooddee bbeeaarreerr sseett--uupp

DDaattaa ttrraannssffeerr

NNoottiiffiiccaattiioonn

MMBBMMSS BBrrooaaddccaasstt mmooddee bbeeaarreerr rreelleeaassee


MBMS architecture• MBMS architecture is designed so that the existing network

elements could be re-used as efficiently as possible. • A new component: Broadcast/Multicast Service Center (BM-SC) is

needed in Core Network• BM-SC serves as an entry point to content providers and is

responsible for enabling the MBMS services to be provided to the end users via the Core and GERAN / UTRAN networks.

BM-SC UTRAN

Content Provider

GGSN TPF

RNC

BSC

HLR

Content Provider GERAN Packet Data Network (e.g. Internet)

SGSN Iu

Iu/Gb


MBMS User Services• The underlying MBMS technology is transparent to the end-user• MBMS is planned for Low-to-Medium bit rate multimedia services

in areas where several users are receiving the same service

• 3GPP specifies three different service types:• Streaming: includes time synchronization• File download: high reliability is required• Carousel: a combination of streaming and file download.

Typical carousel service uses still images and text that are updated periodically.


Other available solutions• DVB-H (Digital Video Broadcast – Handheld)

• High bit rate multimedia services• Efficient wide-area delivery• No uplink access and other arrangements are needed

• 3G Point-to-Point Connections• Low-to-high bit rate multimedia services• Efficient only when delivering content to a few individual

recipients in a geographical area• Uplink easily accessible

• CBS (Cell Broadcast Service)• Kind of a pioneer in mobile broadcast services• Low bit rate messaging (SMS service)• Uplink easily accessible


Comparison to 3G P-t-P connection• MBMS advantage over traditional P-t-P connections is clear when

there are several recipients of the same multimedia data• Resources can be spared in the Core Network as well as in the

Radio Interface• The advantage of the MBMS bearer service is greatest if several

users are receiving the same service at the same time

Core Network

SGSN

GGSN

SGSN

Core Network

SGSN

GGSN

SGSN

P-t-P Connection

MBMS 1

2

3


Comparison to DVB-H• DVB-H provides digital television to mobile handsets• DVB-H is a solution to provide DVB-T(errestrial) programs to mobile

users. The programs are sent to the mobiles in bursts by using IP data casting.

Time slicing technique is used to achieve better battery saving percentage

MPE-FEC error correction mechanism for additional robustness and mobility

• More efficient for delivering high bit rate multimedia services to wide areas, however uplink access not available

• MBMS has a possibility to limit transmissions only to areas populated by recipients

• DVB-H pilot programs already in use


MBMS Service Positioning• Bearers competing with

MBMS:• 3G Point-to-Point bearers• DVB-H multicasting

• MBMS vs. 3G Point-to-Point competition in sharing-type services

• MBMS vs. DVB-H competition in publishing-type services

• What is the overall feasibility of the MBMS service?

• What are the boundaries between competing bearers?

Sharing(one-to-some)

Service Coverage area

User density

3G MBMS

DVB-HMulticast

Publishing(one-to-many)

3GP-t-P

Boundary Area


MBMS from Reselection point of view (1/2)

• MBMS NEIGHBOURING CELL INFORMATION• During MBMS the network may send MNCI messages,

containing information about the neighbouring cells that are providing the same MBMS session.

• Delayed Reselection During MBMS• If the mobile has not received the correct MNCI, the reselection

is delayed for 1 second or until the correct MNCI is received• Neighbour cell measurements

• If feedback is in use the mobile needs to report 6 strongest neighbour cells to the network in MBMS Ack/Nack message


MBMS from Reselection point of view (2/2)

• Reselection without the neighbour cell information• The MS must first camp to the new cells control channels• The MBMS service can be requested again from the new cell

• Fast reception resumption• The MS moves directly to the new cells traffic channel (PDTCH) and

continues to receive the MBMS session there. • While receiving the MBMS session, the camping procedure is

completed in the new cell by receiving the required (P)SI messages.• SI2n

• A new system information message introduced in 3GPP Rel-6 • Contains the necessary reselection parameters for the neighbour cells• MBMS data transfer does not need to be interrupted for neighbour cell

(P)SI reception


MBMS delayed reselection scheme • A simplified flow chart of the delayed reselection scheme

Yes

MS request the MBMS service from

the new cell

SERVING CELL

MS is camped on a suitable cell receiving an

MBMS session

PDTCH

Reselection is triggered

Yes

No

NEW CELL

MBMS reception

continues in the new cells traffic

channel

PDTCH

No

NEW CELL

Campping to the control channel

(P)CCCH / (P)BCCH

MBMS NEIGHBOURING

CELL INFORMATION

received

Suitable neighbour cell

found

MBMS NEIGHBOURING

CELL INFORMATION

received

MBMS Reselection delay

timer timeout

MBMS Reselection delay

timer started


Summary and Conclusions• MBMS is a new bearer service that provides an efficient way of

transmitting multimedia information to several users simultaneously

• MBMS is most efficient when several users are receiving the same service at the same time in a localized area

• MBMS will be competing with 3G P-t-P and DVB-H connections• From reselection point of view, a big challenge will be the Fast

reception resumption feature, since it changes the reselection and camping procedure

• Future Work:• Further studies and analysis of the MBMS features, before

starting any design or implementation for MBMS


Thank you!


Additional information• 3GPP Specifications on MBMS:

• TS 22.146 Multimedia Broadcast/Multicast Service (MBMS)• TS 22.246 Multimedia Broadcast/Multicast Service (MBMS) user services • TS 23.246 MBMS Architecture and functional description• TS 26.346 MBMS Protocols and codecs• TS 43.246 Multimedia Broadcast Multicast Service (MBMS) in the GERAN

• Other useful 3GPP Specification• 3GPP TS 45.008, Radio Access Network; Radio subsystem link control

(Release 6) • 3GPP TS 44.060 General Packet Radio Service (GPRS); Mobile Station

(MS) – Base Station System (BSS) interface, Radio Link Control/Medium Access Control (RLC/MAC) protocol (Release 6)

• This material is available from the 3GPP homepage: www.3gpp.org

http://www.3gpp.org/


Backup information• The MBMS service is analyzed from the Physical Layer (PH) point

of view presented on the right hand side of the figure below

Data Plane Control Plane

PH

LLC

RLC

SNDCP

PDP_IF

PH

MAC

RLC

LLC

SNDCP

Applications

X.25 IP

ETSI protocol stack

MAC

GMM

SM

DSP

RR

MM

RM

Physical layer

multimedia broadcast / multicast service from geran physical layer point of view

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