eMBMS Architecture

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UE

LTE existing ElementMME Mobility Management UnitPGW PDN GatewaySGW Serving GatewayeNB E-UTRAN Node BUE User Equipment

New LTE Elements for eMBMSBM-SC Broadcast Multicast Service CenterMBMS-GW eMBMS GatewayDistribute IP multicast content to eNodeB over M1 interface (GTP_u). MBMS Session Control Signaling to MME.

MCE Multi-cell Coordination EntityCoordinates transmissions from multiple cells. Allocates time and frequency radio resources and radio configuration on all eNodeB in the MBSFN area. The MCE can be a separate entity or part of eNodeB.

UnicastMulticast

X2

S1-MME

S1-U

M1

M3

Sm

SGmb

SGi

SGi-mb

S11

S5

M2

SGW

MME

PGWMCE

SGi

eMBMS new entitieseMBMS User Plane (Data traffic)eMBMS Control Plane (Signaling)eMBMS Service layer & Security SignalingLTE unicast control points & interfacesSYNC Protocol

MBMS-GW BM-SC

LTE BROADCAST

BM-SC & eMBMS Gateway Functional Elements

MBSFN AREA & SERVICE AREA

MBSFN Synchronization AreaAn area of the network where all eNodeBs can be syn-chronized and perform MBSFN transmissions. MBSFN Synchronization Areas are capable of supporting one or more MBSFN Areas. On a given frequency layer, an eNodeB can only belong to one MBSFN Synchroniza-tion Area.MBSFN Synchronization Areas are independent from the definition of MBMS Service Areas.

MBMS Service AreaThe area within which data of a specific MBMS session (or service) are sent. Each MBMS Session of an MBMS Service may be sent to a different MBMS Service Area.

MBSFN AreaConsists of a group of cells within an MBSFN Synchro-nization Area of a network, which are co-ordinated to achieve a MBSFN Transmission. A cell within an MBSFN Synchronization Area may form part of multi-ple MBSFN Areas, each characterized by different transmitted content and participating set of cells.

MBSFN Area Reserved CellA cell within a MBSFN Area which does not contribute to the MBSFN Transmission. The cell may be allowed to transmit for other services but at restricted power on the resource allocated for the MBSFN transmission.

2

2

2

1

2

2

2

1

3

3

1 1

1

2+32+3

1+21+2

1+2

1+2

Service Area (SA) – A

Synchronization Area (SY)

SA - B SA - CArea 3

Area 1 Area 2

SY

Area 4

SY SA - ESA - D SY

Area 5 Area 6 Area 7

A+B A+C A A A+D A+D A+E

Service AreaSynchronization AreaArea

SYNC MODULE, ENABLING SFNFOR LTE BROADCAST

Several eNodeBs are required to pave an MBSFN AreaEach eNodeB must send the same content at the same time & frequency.

eNodeBs location spread generates multipath receptionUE receives signal from several eNodeBs, each signal being delayed with reduced amplitude.

Managing Inter-Symbol Interference (ISI)This spread creates ISI. A guard interval is added to the signal: As long as the signals spread is shorter than the guard interval, an ISI-free signal can be reconstructed from these paths.

Must synchronize all eNodeBs within a MBSFN AreaThe synchronization of all eNodeBs guarantees that each MBMS bearer will be ISI free and optimally decoded.

SYNC protocolEach MBMS bearer carries SYNC informa-tion to synchronize all eNodeBs within a MBSFN Area to ensure the UE receives constructive signal from these eNodeBs (ensures that each eNodeB transmits the same content at the same time/frequency).

www.enensys.com/LTE-Broadcast

MME

SGi

Sm SGmb

HTTP (FR/RR) HTTP (FR/RR)

eNodeB M1 SGi-mb

GATEWAY

Encoder

CDN

BM-SC

GTP_uencapsulation SYNC

FLUTEFEC

RTPFEC RTP

HTTP

DASH

Security & Membership

Service Announcement

Session & transmission

Reception Reporting

File Repair

(Forward SessionManagement

to MME)

Control Plane

eNodeB MBMS GW

User Plane

MBMS GW BM-SC

Protocol stack Uplane Data Uplane Data

SYNC SYNC

UDP UDP

IP IP

Protocol stack

SYNC SYNC

GTP-U GTP-U

UDP UDP

IP IP

Uplane Data Uplane Data

MME MBMS GW

Protocol stack

GTPv2-C GTPv2-C

UDP UDP

IP IP

Protocol stack

Diameter Diameter

TCP/SCTP TCP/SCTP

IP IP

MBMS GW BM-SC

t Delayed signals seen as echoes

Delay spread shorter than GI

Guard Interval (GI) FFT window ISI free signal

Cyclic Prefix

eNB

eNB

eNB

DATA NETWORK

Encoder

CDN

SessionControl

Signalling

PGW