REVIEW OF DIGITAL TERRESTRIAL TELEVISION

TECHNOLOGIESExamination of Recommendations ITU-R BT.1306-4

(09/2009) and ITU-R BT.1877 (05/2010)

on error-correction, data framing, modulation and emission methods for digital terrestrial television

broadcasting systems and 2nd generation digital terrestrial television systems in the case of ITU-R BT.1877

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27 October 2010

Overview

• Foreword to the ITU recommendations

• Outline of recommendation ITU-R BT. 1306-4

• Analysis of ISDB-T and DVB-T performance as defined in ITU-R BT.1306-4

• Conclusions on performance of 1st

generation DTT systems

• Outline of recommendation ITU-R BR. 1877

• Performance assessment of 2nd generation standards

• Conclusions

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Foreword to Recommendations

• The role of the Radiocommunication Sector (in the ITU) is to ensure rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and to carry out studies without limit of frequency range on the basis of which Recommendations are adopted.

• The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups.

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Outline of ITU-R BT.1306-4

• Defines error-correction, data framing, modulation and emission methods for digital terrestrial television broadcasting systems

• Details with bibliographies– Single Carrier Systems (ATSC),

– Multi-carrier systems (DVB-T) and

– Multi-carrier systems with radio-frequency band segmentation (ISDB-T)

• Provides respective performance parameters and configuration options

• Provides a “System Selection Guide”4

Source: http://www.itu.int/rec/R-REC-BT.1306-4-200909-I/en

Analysis of ISDB-T and DVB-T performance based on ITU-R BT.1306-4

• Analysis presented in this document

– Reviewed references and bibliographies

– Exacted the performance values and parameters directly off the respective tables in ITU-R BT.1306-4

– Considered ISDB-T and DVB-T defined for 8 MHz channel bandwidth

– Calculated the respective performance edge

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ParameterISDB-T (8MHz)

(ITU-R BT.1306-4)DVB-T (8MHz)

(ITU-R BT.1306-4)

Net data rate (Min payload - Lowest C/N required) 4.87 4.98

Analysis of ISDB-T and DVB-T performance based on ITU-R BT.1306-4

• Observations on bibliography lists

– ITU-R BT.1306-4 lists 6, 7 and 8 MHz configuration options for ISDB-T • The referenced transmission and receiver standards for ISDB-T

exclusively define 6 MHz networks and receivers.

• There is no reference to any transmission or receiver specification for ISDB-T in 7 or 8 MHz.

– The specifications listed in ITU-R BT.1306-4 for DVB-T specify 6, 7 and 8 MHz channel bandwidths for DVB-T.

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Analysis of ISDB-T and DVB-T performance based on ITU-R BT.1306-4

• Observations on Guard Interval Duration – The longer the guard interval the larger the max distance between transmitters

in a Single Frequency Network without the risk of self-interference – DVB-T defines a longer guard interval duration than ISDB-T– This allows the deployment of more Single Frequency Networks over larger

coverage areas in DVB-T than is the case in ISDB-T (i.e. increased spectrum efficiency)

• Observations on Number of Carriers– DVB-T defines a larger number of carriers than ISDB-T for all modes– This allows for a higher data through-put at a longer guard interval duration

(i.e. larger network) in DVB-T than is possible in ISDB-T

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Analysis of ISDB-T and DVB-T performance based on ITU-R BT.1306-4 (Net data rate – Min)

• In the most robust configuration available for both standards (delivering the lowest data-rate) , DVB-T requires lower transmitter power (1.9 dB) to deliver 2% more data than ISDB-T and can be deployed over a 19% larger network area without the risk of self-interference

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ParameterISDB-T (8MHz)

(ITU-R BT.1306-4)DVB-T (8MHz)

(ITU-R BT.1306-4)

Performance Edge by DVB-T

Net data rate - Min (Mbit/s)(Min payload, most robust, lowest C/N required, longest GI, lowest order mode)

4.87 4.98 2%

C/N - min in AWGN channel (dB)(C/N required at Net data rate – Min)

5 3.1 1.9

Guard Interval duration at Net data rate - Min(µs)

47.25 56 19%

Analysis of ISDB-T and DVB-T performance based on ITU-R BT.1306-4 (Net data rate – Max)

• In the least robust configuration available for both standards (delivering the highest data rate), DVB-T requires lower transmitter power (2.9 dB) to deliver 2% more data than ISDB-T and can be deployed over a 19% larger network area without the risk of self-interference

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ParameterISDB-T (8MHz)

(ITU-R BT.1306-4)DVB-T (8MHz)

(ITU-R BT.1306-4)

Performance Edge by DVB-T

Net data rate - Max (Mbit/s)(Max payload, least robust, highest C/N required, shortest GI, highest order mode)

31 31.67 2%

C/N - Max in AWGN channel (dB) (C/N required at Net data rate – Max)

23 20.1 2.9

Guard Interval duration at Net data rate - Max (µs)

23.625 28 19%

Analysis of ISDB-T and DVB-T performance based on ITU-R BT.1306-4 (Summary)

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ParameterISDB-T (8MHz)

(ITU-R BT.1306-4)DVB-T (8MHz)

(ITU-R BT.1306-4)

Performance Edge by DVB-T

Net data rate - Min (Mbit/s)(Min payload, most robust, lowest C/N required, longest GI, lowestorder mode)

4.87 4.98 2%

Net data rate - Max (Mbit/s)(Max payload, least robust, highest C/N required, shortest GI, highest order mode)

31 31.67 2%

C/N - min in AWGN channel (dB)(C/N required at Net data rate – Min)

5 3.1 1.9

C/N - Max in AWGN channel (dB) (C/N required at Net data rate – Max)

23 20.1 2.9

Guard Interval duration at Net data rate - Min (µs) 47.25 56 19%

Guard Interval duration at Net data rate – Max (µs) 23.625 28 19%

Longest Guard Interval duration at highest order mode (µs)

189 224 19%

Conclusions on Performance of 1st

Generation DTT systems (in 8 MHz) • DVB-T requires lower transmitter power

to deliver a greater data payload than ISDB-T– DVB-T is 2% more spectrum efficient than

ISDB-T in the an 8 MHz channel bandwidth

– DVB-T requires between 1.9 and 2.9 dB less C/N to deliver services in a AWGN channel than does ISDB-T

• DVB-T allows for larger and more efficient Single Frequency Networks than ISDB-T – Tx distance = Speed of light / Guard interval

– DVB-T allows for the roll out of networks at 19% greater power or 19% greater transmitter distance in a SFN as would be the case for ISDB-T.

– DVB-T delivers substantially better coverage at lower network cost over the same coverage area as would be the case with ISDB-T 11

ISDB-T DVB-T

Outline of ITU-R BT.1788

• Defines error-correction, data framing, modulation and emission methods for 2nd generation digital terrestrial television broadcasting systems– Developed to be compatible with the

provisions of GE-06 Agreement and to provide• High flexibility in system configuration

• Increased broadcasting interactivity

• Wide-ranging trade-off of minimum C/N levels and transmission capacity

• Provides respective performance parameters and configuration options (DVB-T2)

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Source: http://www.itu.int/rec/R-REC-BT.1877-0-201005-I/en

Analysis of DVB-T and DVB-T2 performance based on ITU-R BT.1306-4 and ITU-R BT. 1877

• Comparison of 1st generation standard with 2nd generation standard not easily done

• 2nd generation standard significantly more complex and structured differently

• Multiple additional parameters to consider

• Analysis focussed on performance comparison at highest order mode and maximum data rate possible (i.e. upper edge)

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Analysis of DVB-T and DVB-T2 performance based on ITU-R BT.1306-4 and ITU-R BT. 1877

• In the least robust configuration available for both standards (delivering the highest data rate), DVB-T2 requires 1.7 dB more C/N (i.e. slightly higher transmitter power) to deliver 59% more data than DVB-T for the same network structure

• DVB-T2 allows for significantly longer guard interval and thus larger SFN structures14

ParameterDVB-T (8MHz) (ITU-

R BT.1306-4)DVB-T2 (8MHz) (ITU-R BT.1788)

Performance Edge by DVB-T2 over DVB-T

Net data rate - Max (Mbit/s)DVB-T: 8k, 64QAM, FEC=7/8, GI=1/32DVB-T2: 32ke, 256QAM, FEC=5/6, GI=1/128

31.67 50.4 59%

C/N - Max in AWGN channel (dB) DVB-T: 8k, 64QAM, FEC=7/8, GI=1/32DVB-T2: 32ke, 256QAM, FEC=5/6, GI=1/128

20.1 21.8 -1.70

Guard Interval duration (µs)At Net data rate – Max

28 28 0%

Longest Guard Interval duration (µs)At highest order modeDVB-T: 8k, GI=1/4DVB-T2: 32ke, GI=1/4

224 532 138%

Conclusions

• The analysis of ITU-R BT. 1306-4 confirms that DVB-T outperforms ISDB-T by some margin– DVB-T requires between 1.9 and 2.9 dB lower C/N (lower transmitter power) to deliver a 2%

higher net data rate than does ISDB-T

– DVB-T can be deployed over larger SFN areas than ISDB-T

– DVB-T is superior to ISDB-T

• The analysis of ITU-R BT.1877 confirms that DVB-T2 outperforms ISDB-T and DVB-T by a significant margin– DVB-T2 delivers much greater net data rates than ISDB-T or DVB-T can in the same 8 MHz

channel bandwidth

– DVB-T2 requires virtually the same transmitter power than DVB-T (or ISDB-T) to deliver a net data rate 50% greater than what can be delivered via DVB-T and ISDB-T in the same 8 MHz channel bandwidth (1.7 dB greater C/N required to deliver 59% more net data rate)

– DVB-T2 can be deployed in much larger SFN networks providing for even greater spectrum efficiency

– DVB-T2 is far more superior than ISDB-T and DVB-T

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