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