Itu seminar isdb t 001108
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Transcript of Itu seminar isdb t 001108
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The ISDB-T System
NHK Science & Technical Research Laboratories(Japan Broadcasting Corporation)
Masafumi Saito
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Contents
1. Concept of ISDB
2. Requirements for ISDB-T
3. Transmission and Services
4. Experimental Results
5. Present Situation in Japan
6. Conclusions
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Concept of ISDB (Integrated Services Digital Broadcasting)
Video
Audio
Data
Coding
Coding
Coding
Multiplexing
Error correctionRS(204,188)
Error correctionRS(204,188)
Error correctionRS(204,188)+Conv. code
ModulationTC-8PSK
Modulation64QAM
ModulationSegmented OFDM
Satellite
Cable
Terrestrial
MPEG-2
Package Media, Communication Systemsor Other Media (DVB and ATSC)
MPEG-2 TS
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Requirements for ISDB-T(ISDB-Terrestrial)
ISDB-T should
- have the capability to provide various services, including
HDTV, multi-channel SDTV, data services, etc.
- have sufficient transmission quality for the portable
and mobile reception.
- ensure flexible use of transmission capacity.
- be able to achieve effective use of frequency using
SFN (Single Frequency Networks) technology.
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Modulation Scheme of ISDB-T(Band Segmented OFDM)
5.6 MHz
frequency429 kHzOFDM Segment
o Bandwidth of an OFDM segment is 6/14 MHz (≅ 429 kHz).
o All segments have a common structure.
o Number of OFDM segments is 13 for wide-band ISDB-T and 1 or 3 for narrow-band ISDB-T.
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Multiplexing and Spectrum of ISDB-T
HDTVProgram
Narrow band Receiver(Pocket-size)
Wideband Receiver(Integrated Receiver)
Multiplexing
AudioProgram
OFDM Segments
5.6 MHz 5.6 MHz 1.3 MHz
Wideband ISDB-TNarrow band ISDB-T
(ISDB-TSB)
429 kHz
SDTV forMobile
Reception
SDTV forStationary Reception
Data
Spectrum
AudioProgram
AudioProgram
AudioProgram
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Service Examples
HDTV
or3 SDTV Programs
Stationary Reception
+
+
+
MobileReception
Example 1
+
+
Integrated Receiver(all services)
Car Receiver(Audio and Data)
Mobile Receiver(SDTV, Audio and Data)
Still Picture
+
Example 2 Example 3
DataAudioandData
SDTV
Data
StationaryReception
MobileReception
SDTV
Data Data
MobileReception
Pocket-size Receiver(Audio and Data)
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Parameters of ISDB-T (6MHz Bandwidth)
QPSK , 16QAM , 64QAM , DQPSK
Convolutional code (1/2 , 2/3 , 3/4 , 5/6 , 7/8)
Parameters
Number of OFDM segmentsUseful bandwidth
Carrier spacingNumber of active carriers
ModulationNumber of symbols per frameActive symbol durationGuard interval duration
Inner code
Outer code
Useful bit rate
Mode 1 Mode 2 Mode 313
5.575 MHz 5.573 MHz 5.572 MHz3.968 kHz 1.984 kHz 0.992 kHz
1405 2809 4992
204252オs 504オs 1.008 ms
1/4 , 1/8 , 1/16 , 1/32 of active symbol duration
RS (204,188)0 ̃ 0.44 s
3.651 Mbps ̃ 23.234 Mbps
Time interleaving
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Channel Coding
Re-Multiplexer
- Single TS- Constant clock rateinserting null-TSP
Compensating for the delay differenceamong three layers caused by Byte-wise interleaving
Code rate: 1/2, 2/3, 3/4, 5/6, 7/8
Outer coderRS (204,188)
EnergyDispersal
DelayAdjustment
Byte-wiseInterleaving
Convulutionalcoder
SplitterEnergy
Dispersal
EnergyDispersal
DelayAdjustment
DelayAdjustment
Byte-wiseInterleaving
Byte-wiseInterleaving
Convulutionalcoder
ConvulutionalcoderCoded stream is divided
into up to three layers
TS
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Modulation
Length of time interleaving:0 ms, 110 ms, 220 ms, 440 ms, 880 ms
Frequency Interleaver consists ofIntra-Segment Interleaver andInter-Segment Interleaver
- TMCC (Transmission and MultiplexingConfiguration Control)
- SP (Scattered Pilot)- CP (Continual Pilot)- AC (Auxiliary Channel)Bit
Interleaving
Bit Interleaving
Bit Interleaving
Mapping
Mapping
Mapping
TimeInterleaving
FrequencyInterleaving
OFDMFrame
Pilot and Control signals
IFFT Guard IntervalInsertion
Guard Interval Ratio:1/32, 1/16, 1/8, and 1/4
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Features of the Transmission Scheme of ISDB-T
o Different parameters can be set for each layer → Wide variety of services
o Robust against fading in mobile environment → Suitable for mobile reception
o Segment structure → Partial reception is possible
o OFDM modulation → Effective use of frequency by SFN (Single Frequency Networks)
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Practical Experiments (Field Trials)
Phase 1 (November 1998 to March 1999)HDTV, Multi-channel SDTV, Mobile reception, etc.
Phase 2 (April 1999 to March 2000)Data broadcasting, Multimedia services, EPG, etc.
Phase 3 (April 2000 to March 2002)Gap-fillers, Multimedia services, etc.
Tokyo Pilot Experiments
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Tx Antenna (261 m)
TOKYO TOWER
UHF 15 ch (485.15 MHz)
Tx power: 100 W
ERP: 395W
Transmitting Station of Tokyo Pilot Experiments
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Field Trials (Fixed Reception)
0 50 km
>70dBµV/m
>60dBµV/m
>50dBµV/m
BER?2e-4BER> 2e-4
BER (measured)
Field Strength (calculated)
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60
65
70
75
80
85
90
95
100
35 40 45 50 55 60 65 70 75 80 85
Measured Field Strength (dB オ V/m)
Cor
rect
Rec
epti
on L
ocat
ion
Rat
es (%
)
Mode 3, 64QAM, 5/6, 13 Seg.Mode 2, DQPSK, 1/2, 1 Seg.Mode 2, 64QAM, 7/8 12 Seg.
Correct Reception Rate(Fixed Reception)
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Field Trials (Mobile Reception)
Total measured distance- about 3000 km
0 50 km
>70dBµV/m
>60dBµV/m
>50dBµV/m
BER?2e-4BER> 2e-4
BER (measured)
Field Strength (calculated)
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Effect of Time Interleaving(Mobile Reception)
70
75
80
85
90
95
100
35 40 45 50 55 60 65Measured Field Strength (dBオ V/m)
Cor
rect
Rec
epti
on T
ime
Rat
es (%
)
With Time Interleaving Without Time Interleaving
Mode 2, DQPSK, 1/2 , 13 seg.
99%
Depth of time interleaving: 500ms
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Pilot Experiments in 11 Areasin Japan
Sapporo
Sendai
Nagano
Kanazawa
Nagoya
Osaka
Hiroshima
Fukuoka
Naha Takamatsu
Started in April 1999
Tokyo
Purposes:キ Development of new servicessuitable for each region
キ Confirmation of receiving areaキ Training engineers, etc.
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Study on Single Frequency Networks(Development of coupling cancelers)
q Distribution methods of ISDB-T signals from main transmitters to relay transmittersn Micro Wave
l Frequency for this purpose is necessaryn Optical Fiber
l Construction and running cost is highn Relay Networks
l Low costl Interference by coupling waves is the problem
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Coupling Waves at Relay Stations
SFN Relay Station
f 1Mountains, Buildings, etc.
NHK
Receiving Antenna
Transmitting Antenna
f 1
f 1Wave from the main transmitter
f 1
Coupling Waves
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Principle of Coupling Cancelers
Coupling Canceler
Condition for canceling: W (? ) = G (? ) C (? )
+
_
_W (? )
Amplifier:G (? )
Coupling: C (? )Receiving Antenna
Wave from Main Station
Transmitting Antenna
TransversalFilter
Output Signal
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Result of Field Trials(Effect of Coupling Cancelers)
20 25 30 3510-5
10-4
10-3
10-2
10-1
C/N [dB]
BER=7ラ 10-3
D/U=-6dB
D/U=0dB
D/U=8
64QAM-OFDM,Without FEC
BE
R
Mode 3Guard Interval 1/8
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Frequency Allocation in JapanN
umbe
r of T
rans
mis
sion
Sta
tions
for A
nalo
gue
TV
0
100
200
300
400
500
600
700
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
VHF Channels
UHF lower channels(Initial Allocation)
Adjustment of analoguechannels except formajor stations
Adjustment ofanalogue channels
13 14 15 16 17 18 19 … … … 25 26 27 28 29 30 31 32
ISDB-T channels (An example)
…
UHF
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Schedule of Channel Planning in Japan
January 1999:Start of a consortium on channel plan
April 2000: Draft channel assignment for main stationsall over Japan
By the end of 2001Draft channel assignment for major relaystations
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Schedule of Implementation of ISDB-T in Japan
1999
?Final Standard
?May
Pilot Experimentson a practical scale
Service Start in Tokyo, Osaka and Nagoya (2003)
Service
FrequencyPlanning
FieldExperiments
?Apr.
Channel Plan for Main Stations
?
2000 2001 2002 2003 2004 2005 2006 2007
Service Start in other areas (2006)
?
Channel Plan for Major Relay Stations
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Conclusions
n ISDB-T system based on Band Segmented OFDM was developed in Japan.
n The ISDB-T system was standardized as thedigital terrestrial television broadcasting systemin Japan in May 1999.
n Pilot experiments of ISDB-T are carried out in 11 major cities in Japan.
n ISDB-T services are planned to start before theyear 2003.