MBMS in LTE

• MBMS in WCDMA offers 6 Mobile TV Channels @ 128kbps in 5Mhz

• Difficult to implement broadcast in FDMA , TDMA and CDMA system

• All classical broadcast techniques (eg. DVB ,DAB) use OFDM

• LTE is best suited technology

• The Two major drawback in MBMS system is poor coverage to cell edge and second power consumption.

• eMBMS (evolved MBMS) tackles this aspect much better as it defines up to physical channel.

Background

MBMS In 3GMBMS is first implemented in 3GPP Release 6

The goal was to provide broadcast over cellular network

An important aspect was to keep impact on the existing network architecture asminimum as possible

Therefore only one network element introduced a new task has been assigned toexisting network nodes

Node B BMSCRNC SGSN GGSN

Protocol (SW) changes

MBMS control &traffic channels

Bearer Management, Service Area definition , counting

Bearer Management New Interface to

BMSC, join & leave indications

Bearer Management, Updated RNC

SignalingAuthentication, Charging service

scheduling

MBMS Channels

MCCH MTCH MSCH

S-CCPCH MICH Type1, Type2

FACH1/2

Active MBMS service, their configuration, MICH

info neighboring cell information

Dedicated MBMS Paging Channel

MCCH is multiplexed to FACH,BCCH contains relevant information

FACH is multiplexed on S-CCPCH

Data time multiplexing for different MBMS services is possible

Information about time multiplexed services

MTCH, MSCH will be multiplexed on different FACHs, MCCH contains the relevant

information for devices(UE)

eMBMS Architecture

MCE

BMSC

OSS/BSS

MME

MBMS GW

CP

M3 (M3-AP)

Sm (GTP-C)

M2 (M2-AP)

S1-MME

M1 (GTP-U)

SGmb (D)

SGImb (IP) IP

Open

MCE: Media Coordination EntityMBMS GW: MBMS Gateway (SGW)BMSC: Broadcast Multicast Service Centre

CP: Content Provider

MBSFN Area

MBSFN AREA 0 MBSFN AREA 255

MBSFN AREA 1

MBSFN Reserved CellA cell within MBSFN area may not support eMBMS

transmission

A cell can belong to more than one MBSFN area. Max 8

An eNodeB can transmit the identical data to multiple UE simultaneously

In some case, multiple eNodeB can transmit the identical data simultaneouslyso that UE can receive the same data from multiple eNodeB.

The resulting signal will appear to UE as just one transmission over a timedispersive radio channel.

This is referred to as MBSFN Area

Channels For eMBMS

CommonControl Infoat no RRC

ConnectionDedicated

ControlDedicated

TrafficSystem Info. Paging

PCH DL-SCH

PDSCHPDCCHPBCH PMCH

MCH

BCCH PCCH CCCH DCCH DTCH MCCH MTCH

BCH

MAC Layer

PHY Layer

MCE

The Media coordination entity server is a scheduler that provides centralizedwireless resource management function of Physical Multicast Channel (PMCH),Multicast Channel (MCH), Multicast Control Channel (MCCH) and MulticastTransport Channel (MTCH) for multiple eNodeBs

Major Functions are

Managing M2 Interface of eNodeBs using same MBSFN

Determine Radio configurations such as Modulation and Coding Scheme

Allocate wireless resources to be used by all eNodeBs

Supports 256 MBSFN Areas

Supports 15 PMCH, 15 MCH and 15 MTCH