6.5 Lte Embms From Terminal Perspective

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2013 Sequans Communications | Proprietary and Confidential 2012 Sequans Communications | Proprietary and Confidential

LTE eMBMS from terminal perspective2013-05-16Guillaume Vivier

2013 Sequans Communications | Proprietary and Confidential

Outline

Some use cases for eMBMS eMBMS in a user equipment The modem part of eMBMS Conclusion


Some use cases Venue casting: offloading unicast for

popular content Stadium

More than 12 stadium worldwide withcapacity > 100 000 seats.

Demonstration, meetings Digital signage Software upgrade Information feed

Stock, weather, traffic, news


Mobile data trend Mobile data consumption by type (Exabyte per month) By 2016, video will account for ~66% of total traffic

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Even on traditional broadcast system, service evolved to IP based VOD Bi-directionnal interactive

services eMBMS offers the flexibility

to mix broadcast, multicast and unicast services


Device architecture to support eMBMS

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Applications

Media player

DASH

clientDRM

HW support (HW accelerators, display, speakers, antenna, power supply, etc.)

eMBMS

Middleware

DASH

ServerFLUTE FEC

Modem

eMBMS

support

Security

supportIP stack / Kernel

File

Repair


General Aspects of eMBMS(Enhanced Multimedia Broadcast Multicast Service) eMBMS is an integral part of LTE, but not all device support it nowadays!

eMBMS transmissions may be performed as single-cell transmission or as multi-cell transmission In case of multi-cell transmission the cells and content are synchronized to enable for the

terminal to soft-combine the energy from multiple transmissions. The superimposed signal looks like multipath to the terminal. This concept is also known as

Single Frequency Network (SFN).

The network can configure which cells are part of an SFN for eMBMStransmission Very flexible manner to adapt the split between multivcast / unicast traffic and the area of the

service

Specific PHY has been developed for eMBMS Extended CP Specific pilots Specific logical channel (MBMS Traffic channel, MTCH) and physical channel (Physical

Multicast Channel, PMCH)

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General Aspects: MBSFN and SF split

Data is transmitted simultaneously over the air from multiple tightly time-synchronized cells

MBSFN transmission appear to a UE as a transmission from a single large cell (multipath components within the CP)

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MBSFN Synchronization area

In MBSFN area eNodeBsmust be synchronized with an accuracy of a few s to achieve symbol level alignment within the CP Same scrambling code for

MBMS transmissions from multiple cells

NID(MBSFN) is the MBSFN Area Identity

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MBSFN Subframe overview

Control Region Max # of OFDM symbols used for PDCCH is 2 PDCCH is used only for uplink resource grant Common reference symbol pattern is the same as in the non-

MBSFN subframes If the non-MBSFN subframes use the Normal CP, then normal CP

is also used in the control region of each MBSFN subframe (eNbwill send undefined signal on spare time samples)

UE making measurements on neighboring cell does not need to know in advance the allocation of MBSFN and non-MBSFN subframes

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MBSFN PMCH Data transmission is mapped

to Physical Multicast Channel (PMCH): Extended CP is used to

reduce ISI Modified RS pattern is used to

improve the accuracy of channel estimate for longer delay spreads (antenna port 4)

In addition, another OFDM parametrization can be used leading to very large CP (2*Ext CP) with 7.5 kHz subcarrier spacing

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MBSFN PMCH

Layer mapping and precoding shall be done assuming a single antenna port (port 4)

The PMCH can only be transmitted in the MBSFN region of an MBSFN subframe

No transmit diversity scheme is specified

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Some performance requirement

The standard has defined requirement related to eMBMS PHY layer reception

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Test number Bandwidth

Reference Channel

OCNG Pattern

Propagationcondition

Correlation Matrix and

antenna

Reference value MBMS UE

Category

BLER (%) SNR(dB)

1 10 MHz R.37 TDD OP.4 TDD

MBSFN channel model (Table B.2.6-

1)1x2 low 1

3.4 1-8

2 10 MHz R.38 TDD OP.4 TDD 11.1 1-8

3a 10 MHz R.39 TDD OP.4 TDD 20.1 2-8

3b 5MHz R.39-1 TDD OP.4 TDD 20.5 1

4 1.4 MHz R.40 TDD OP.4 TDD 5.8 1-8


Future improvements (LTE Rel. 10, 11, etc) Counting

To check what UE is watching what flow To adapt accordingly broadcasted flows

Allocation and retention priority To allow preemption of current flows (network side)

Better FEC Finally decision was to keep the current one

Service continuity in case of mobility

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Conclusion MBMS in mobile cellular system was unsuccessful in 3G

Market context maybe not mature enough No ecosystem

Market demand seems to appear nowadays Operator traction Mobile video becoming a must and additional services

LTE intimately integrated eMBMS support Need specific support at PHY and middleware levels Need adaptation at core network

Ecosystem is growing At least Sequans supports eMBMS!

Check M44G project outcomes SEQUANS, EXPWAY, ARCHOS, Telecom Paris Tech

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6.5 Lte Embms From Terminal Perspective