Hierarchical Modulation for DVB-T · Hierarchical Modulation 3 assured communications ™ 21-Jun-04...

21-Jun-04Hierarchical Modulation 1 assured communications ™

Hierarchical Modulation for DVB-T

Implementation & ApplicationBernhard Baumgartner

Senior Product Manager


Hierarchical Modulation for DVB-T

• Hierarchical Modulation is nothing new ……it is part of the DVB-T standard 300 744 for several years.

• But– The receiver industry did not always consider it exactly. – Planners seldom check if hierarchical modulation adds

additional value to their DVB-T network application

Target of this presentation is to …explain the theory of hierarchical modulation for DVB …and to provide examples for possible implementations


What is hierarchical Modulation ?

• Hierarchical Modulation allows to transmit two digital data streams via one transmitter

– the LP Stream (Low Priority)• higher bit rate• sensitive (higher C/N needed)

– the HP Stream (High Priority)• lower bit rate• Very robust (less C/N needed)


I

Q

I

Q

I

Q

QPSK 16-QAM 64-QAM

00

0110

110000

1100 0110

1000

QPSK: 4 carrier positions

A QPSK carrier can transport 2 bits

16-QAM: 16 carrier positions

A 16-QAM carrier can transport 4 bits

64-QAM: 64 carrier positions

A 64-QAM carrier can transport 6 bits

Sub Carrier Modulationnon-hierarchical modes


I

Q

Hierarchical ModulationQPSK in 16-QAM

I

QI

Q

High priority bit stream (HP)defines actual quadrant

Low priority bit stream (LP)defines position in actual quadrant


Hierarchical ModulationQPSK in 64-QAM

High priority bit stream (HP)defines actual quadrant

Low priority bit stream (LP)defines position in actual quadrant

I

Q

I

Q

Q

I


αααα- Factor, C/NQPSK in uniform 16-QAM

1

1

1

1 33

3

3

I

Q

αααα = 1:

LP: QPSK, CR 2/3, �� Req. C/N ~ 11.1 dB�� ~ 7.5 Mbps

HP: QPSK, CR 2/3, �� Req. C/N ~8.2 dB�� ~ 7.5 Mbps

Required C/N values are for QEF reception after RS decoder !


αααα- Factor, C/NQPSK in non-uniform 16-QAM

Q6

4

6

6 64

4

4

I

αααα = 4:

LP: QPSK, CR 2/3, �� Req. C/N ~ 19.1 dB�� ~ 7.5 Mbps

HP: QPSK, CR 2/3, �� Req. C/N ~5.9dB�� ~ 7.5 Mbps

Required C/N values are for QEF reception after RS decoder !


Distance in km

Fie

ld s

tren

gth 64 QAM

Code rate 7/8~ 30 Mbit /s

16 QAM Code rate 3/4

~ 15 Mbit/s

QPSK Code rate 1/2

~ 5 Mbit/s

The area covered by a DVB-T transmitter is strongly depending on the selected parameters for the COFDM signal

Coverrage Area of DVB-T

Transmitters

noise floor

C/N

C/N

C/N


Possible applications for hierarchical modulation

• transmit services to portable and fixed receivers at the same time

• increase net bit rate of the broadcast channel

• transmit services to stationary and mobile receivers at the same time

• transmit HDTV and SDTV at the same time with different coverage areas


Stationary vs Portable receivers

Non-Hierarchical

Non-hierarchical:64 QAM, GI 1/8, FEC 2/3Bit rate: 22.12 MbpsC/N (Gaussian): 16.5 dB

HP

HP:QPSK, GI 1/8, FEC 1/2Bit rate: 5.53 MbpsC/N (Gaussian): 8.9 dB

LP

LP:16-QAM, GI 1/8, FEC 2/3Bit rate: 14.75 MbpsC/N (Gaussian): 16.9 dB


Increased useful bit rate

Non-Hierarchical



HP

LP:16-QAM, GI 1/8, FEC 3/4Bit rate: 16.59 MbpsC/N (Gaussian): 18.6 dB

LP

+2.76 Mbps


Mobile & Stationary reception

RF1Non-

Hierarchical

Non-hierarchical RF1:64 QAM, GI 1/8, FEC 2/3 = 22.12 MbpsNon-hierarchical RF2:QPSK, GI 1/8, FEC 2/3 = 7.37 Mbps

RF 2Non-

Hierarchical

HP - RF1:QPSK, GI 1/8, FEC 1/2 = 5.53 MbpsLP - RF1:16-QAM, GI 1/8, FEC 3/4 = 16.59Mbps

RF 1HP

RF1LP


Simulcast HDTV & SDTV

HP(SDTV)


LP(HDTV)

LP:16-QAM, GI 1/16, FEC 3/4Bit rate: 17.56 MbpsC/N (Gaussian): 21 dB


Non-Hierarchical

(HDTV)


Hierarchical Modulation in SFN Operation

Only Requirement:• Correct maximum network delay entered in SFN adapter

TransportStream

MultiplexerLP

TransportStream

MultiplexerLP

ModulatorAmplifier

ModulatorAmplifier

ModulatorAmplifier

Audio/VideoEncoder

Telecom Network(Microwave, Fibre optics)Audio/Video

Encoder

Audio/VideoEncoder

Audio/VideoEncoder

Telecom Network(Microwave, Fibre optics)

SFNAdapter

TransportStream

MultiplexerHP

TransportStream

MultiplexerHP


� 1U rackable frame� Input redundancy management� Automatic bit rate adaptation process� Mandatory and optional MIP management� NIT update feature� Embedded SNMP agent� Internal PRBS generators for test purpose

Time Stamp generation

for Hierarchical M

odulation

integrated as

a standard feature !

Synchrony – SFN Adapter


Hierarchical Modulation

Is available as a standard

option for all Harris DVB-T

Transmitters

Atlas - DTV660 Product Line

Air Liquid


Summary

• Hierarchical modulation allows the – Transmission of two independent ASI data streams with different

characteristic via one transmitter– Transmission to stationary and mobile receivers on

the same channel.– Broadcasting of SDTV and HDTV on the same channel

• The required technology is now available as a standard transmitter option

Hierarchical Modulation adds a lot of advantages and flexibility …

... to make Hierarchical Modulation a long term success DVB-T equipment manufacturers and broadcasters have to work together !


Herzlichen Dank für Ihre Aufmerksamkeit!

Hierarchical Modulation for DVB-T · Hierarchical Modulation 3 assured communications ™ 21-Jun-04...

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Transcript of Hierarchical Modulation for DVB-T · Hierarchical Modulation 3 assured communications ™ 21-Jun-04...