mbms support in e-utran - march 2011

© 3GPP 2009 Mobile World Congress, Barcelona, 19th February 2009© 3GPP 2011 MBMS support in E-UTRAN, March 16th 2011 1

Thomas Sälzer (Huawei Technologies, LTE MBMS rapporteur)

Version 1.0

MBMS support in E-UTRANMBMS support in E-UTRAN

3GPP-DVB Workshop RCD-11002Kansas City, USA16th March 2011


LTE-MBMS MBSFN principle

Multicast/Broadcast over a Single Frequency Network (MBSFN)• Simulcast transmission technique realised by transmission of identical

waveforms at the same time from multiple cells. • An MBSFN transmission from multiple cells within an MBSFN Area is seen as a

single transmission by a UE.• MBSFN reception is possible in connected and idle states independent of

incoming or outgoing calls.

From "LTE – The UMTS Long Term Evolution"Sesia, Toufik, BakerJohn Wiley & Sons


Overview of MBMS support in E-UTRAN

Supported from Rel-9• Shared carrier deployments (TDM on sub-frame level shared with unicast)• Semi-Static MBSFN areas with possible overlap• Downlink only transmission (no feedback channels)

Supported from Rel-10 • Counting of MBMS interested UEs in connected mode• Semi-static activation/deactivation of eMBMS session per MBSFN area

Further work on service continuity is foreseen for Rel-11• Mobility (cell selection/reselection and handover)


MBMS service area

MBMS Service Area

MBSFN Area

MBSFN Area

MBSFN Area

MBSFN Area Reserved Cell


MBMS channels Downlink channels related to MBMS

• MCCH Multicast Control Channel• MTCH Multicast Traffic Channel• MCH Multicast Channel• PMCH Physical Multicast Channel

Multiplexing of MBMS and unicast is realized in the time domain onlyMCH is transmitted over MBSFN in specific subrames on physical layerMCH is a downlink only channel (no HARQ, no RLC repetitions)• Higher Layer Forward Error Correction (see TS26.346)

A single transport block is used per subframeDifferent services (MTCHs and MCCH) can be multiplexed The MCS of each MCH is fixed in the MBSFN area and selected by the network


Frame structure for shared carriers TDM principle • MBSFN is not transmitted in subframes 0, 4, 5 and 9 (FDD)

and subframes 0, 1, 2, 5, 6 (TDD)• The subframe ratio available for MBMS ranges from 1/320 to 192/320• A 10/40ms pattern repeats over {1, 2, 4, 8, 16, 32}radio frames

Single MBSFN subframe contains single cell control part and MBSFN part

MBSFN RS + MBMS Data

One Subframe

RS

/PC

FIC

H/

PD

CC

H/P

HIC

H

Single cell transmission Multi-cell transmission

1 ms


Main characteristics of MBSFN

Transmission scheme OFDM

Channel bandwidths 1.4, 3, 5, 10, 15, 20 MHz

Carrier spacing 15 kHz

Guard interval 16.7 us

Modulation schemes QPSK, 16QAM, 64QAM

MIMO scheme single antenna port

Transport block transmission duration 1 ms

Number of coded blocks per transport block Variable

Typical transmit powerThe eNodeB (Macro cells) maximum transmit power is left to

implementation, but most coexistence analyses assume Macro Tx Powers around 40W (46dBm)


Reference signals

0l 5l 0l 5l

even-numbered slots odd-numbered slots

Antenna port 4

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

4R

extended cyclic prefix, 15kHz carrier spacing

Single antenna portClose frequency spacing to support larger delay spreads


Performance of MBSFN

Summary of MBSFN performance, dedicated carrier (TR 25.912)

Deployment Spectrum Efficiency[bps/Hz]

Inter-site Distance @ 1bps/Hz[m]

Case 1 3.13 1619

Case 2 3.02 2310

Case 3 0.99 1619

Case 4 3.18 4375

Case Band(MHz)

Site to site distance(m)

Speed(kph)

1 2000 500 3

2 2000 500 30

3 2000 1732 3

4 900 1000 3

Simulation assumptions:

R1-070674: "LTE physical layer framework for performance verification" Orange, China Mobile, KPN, NTT DoCoMo, Sprint, T-Mobile, Vodafone, Telecom Italia.


Alternative MBSFN numerology

0l 2l 0l 2leven-numbered

slots

Antenna port 4

4R

4R

4R

4R

4R

4R

4R

4R

4R

odd-numberedslots

4R

4R

4R

4R

4R

4R

4R

4R

4R

extended cyclic prefix, 7.5kHz

Physical layer specifications contain an alternative numerology for dedicated carriers

Alternative numerology• 7.5 kHz carrier spacing• Longer guard interval of 33.3us• Reference signals as shown

This option is currently not fully supported• No related signalling• No related performance requirements


MBMS overall architecture

BMSC (broadcast multicast service center): provides functions for MBMS user service initiation and deliveryMBMS-GW (MBMS gateway): broadcasts MBMS packets to each eNB transmitting the service on M1 interfaceMCE (Multi-cell Coordination Entity)• Allocates or not the radio resources used by eNBs in the same MBSFN area• Configures MBSFN subframes for MBMS control and data broadcast• Ensures that the L2/L3 layers in eNBs are well configured for MBSFN operation• Determines the MCS for PMCH

UE eNB

MME

BMSCMBMS GW

MCE Content Provider

M2

M1

Sm

SGi-mb

SGmb

M3


MBMS RAN interfaces

Control plane interfaces• M3, M2 interface are control plane interfaces• M3 between MME and MCE carries MBMS session management

signaling• A MCE is connected to all eNBs within the same MBSFN area

through M2 interface mainly for MBMS session management signaling and radio configuration signaling

User plane interface• M1 interface is a user plane interface (no uplink data and no

control plane)• A MBMS GW is connected to multiple eNBs through M1 interface

for data distribution• IP multicast is used to deliver the downlink packets and SYNC

protocol is used over the M1 interface to keep the content synchronization


MBMS services and higher layer protocol stack

RTP PayloadFormatsMIKEY

KeyDistribution

(MTK)

MBMS SecurityMBMS Security

KeyDistribution

(MSK)

FLUTE

IP (Multicast) or IP (Unicast)

UDP

StreamingCodecs (Audio,

Video, Speech, etc.)

Download3GPP file format, Binary data, Still

images, Text, etc.

MBMS or ptp Bearer(s)

Service Announcement & Metadata (USD,

etc.)

Application(s)

FECHTTP

TCP

IP (unicast)

ptp Bearer

ptp FileRepair

Reception Reporting

MIKEY

Associated-DeliveryProcedures

Registration

RTP/RTCP

UDP

Service Announcement

& Metadata (USD, etc.)

Associated-Delivery

Procedures

ptm FileRepair

HTTP-digestSRTP

FEC

Different MBMS user services can be provided on multi-cast or uni-cast bearers• HTTP• File download• Audio/Video streaming

The figure shows the related higher layer protocol stacks (TS26.346).


Main referencesFeasibility study for evolved Universal Terrestrial Radio Access (UTRA) and Universal Terrestrial Radio Access Network (UTRAN)http://www.3gpp.org/ftp/Specs/html-info/25912.htmEvolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2http://www.3gpp.org/ftp/Specs/html-info/36300.htmEvolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation http://www.3gpp.org/ftp/Specs/html-info/36211.htmEvolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specificationhttp://www.3gpp.org/ftp/Specs/html-info/36331.htmEvolved Universal Terrestrial Radio Access Network (E-UTRAN); General aspects and principles for interfaces supporting Multimedia Broadcast Multicast Service (MBMS) within E-UTRANhttp://www.3gpp.org/ftp/Specs/html-info/36440.htmMultimedia Broadcast/Multicast Service (MBMS); Protocols and codecshttp://www.3gpp.org/ftp/Specs/html-info/26346.htm


Thank you !

mbms support in e-utran - march 2011

Technology