Digital Satellite Broadcasting
and HDTV Services in Japan
Masafumi Saito
Science and Technical Research Laboratories
NHK (Japan Broadcasting Corporation)
Contents
Present situation of satellite broadcasting
in Japan
q ISDB-S transmission system
l features
l system configuration
l service availability
q HDTV services by ISDB-S
l assessment results of picture quality
q Conclusions
q
History of Satellite Broadcasting
in Japan
May 1984: NHK started experimental broadcasting using BS-2a.
Jun. 1989: NHK started regular service(NTSC) and experimental
HDTV broadcasting using BS-2b.
Apr. 1991: BS-3 was in use. JSB started pay TV service.
Mar. 1996: Number of households that receive satellite
broadcasting exceeded 10 million.
Aug. 1997: BS-3 was replaced by BS4-1.
Mar. 2000: Number of households that receive satellite
broadcasting reached 14 million.
Dec. 2000: Launch of digital satellite broadcasting using ISDB-S.
Outline Scenario for Digital Satellite
Broadcasting
BS3
A
N
A
L
O
G
BS4-I
NHK-1
FM - NTSC
NHK-2
FM - NTSC
JSB
FM - NTSC
MUSE
D
I
G
I
T
A
L
SDTV
x3
HDTV
BS5
MUSE - HDTV
BS4-II
HDTV
Simalcast channel
Radio&Data
Digital HDTV/SDTV
HDTV
Digital HDTV/SDTV
Digital HDTV/SDTV
Radio&Data
1991
1997
2000
2007
Year
Features of ISDB-S
q Large
l
transmission capacity
two HDTV programs in one satellite channel
q Hierarchical
l
minimum service available during heavy rain
q Operational
l
l
modulation
flexibility
mixed transmission of HDTV and SDTV
independence between broadcasters who
share one transponder
q Extensibility
l
EPG, data broadcasting, downloading, etc.
Summary of the system characteristics
Modulation scheme
Raised cosine roll-off factor
Transmission symbol rate
Video coding
Audio coding
FEC (Outer code)
FEC (Inner code)
Inner code ratio
Transport Layer
Packet size
TC8PSK/QPSK/BPSK
0.35 ( square root)
28.86 Mbaud
MPEG-2
MP@HL for 1080i
MP@ML for 480i
MP@H14 for 480p
MPEG-2 AAC
Reed-Solomon
(204,188)
Convolutional
(constraint length k=7)
1/2 for BPSK
1/2, 2/3,3/4, 5/6, 7/8
for QPSK
2/3 for TC8PSK
MPEG-2 systems
188 bytes
RF Bandwidth
34.5 MHz
Payload Bit Rate
52 Mbps (max.)
Block Diagram of Channel Coding
MPEG-TS
#1
#2
..
.
Control Data
#1
#2
..
.
Main signal
Outer
coding
Frame
structure
Energy
dispersal
Interleave
Energy
dispersal
TDM
RS(204, 188)
TMCC
TMCC
encoding
Outer
coding
RS(64, 48)
Convolutional
Burst signal
Auxiliary
Information
Additional encoding
& channel coding
Inner
coding
Energy
dispersal
Modulation
Frame Structure and
Transmission Signal
Frame structure
Input TSs
1 frame = 48 slots
204 bytes
188 bytes
MPEG Packet #A
MPEG sync
MPEG Packet #B
MPEG Packet #C
service A (high layer)
parity
service B (high layer)
parity
service B (high layer)
parity
service C (high layer)
parity
........
service A (low layer)
parity
service B (low layer)
parity
Transmission signal
frame #8
TMCC
TMCC
slot #1
slot #1
1 super
frame
= 8 frames
slot #1
slot #1
slot #1
frame #1
slot #1
slot #2
slot #1
slot #48
slot #48
Transmission and Multiplexing
Configuration Control (TMCC)
TMCC carries:
l
l
l
l
l
frame synchronization
modulation scheme and coding rate applied to
each slot
TS identification for each slot
emergency alert signal
information about site-diversity operation, etc.
TMCC is modulated with BPSK
and coded with RS(64,48)
TC8PSK
NTSC audio
collapse
98
0
0.2
0.5
99.9
99
0.1
BPSK (r=1/2)
QPSK (r=1/2)
1
2
5
Location
Location == Tokyo
Tokyo
Antenna
Antenna == 45
45 cm
cm
2
4
6
8
10
20
10
CNR (dB)
12
14
16
in worst month (hours)
(% of hours in worst month)
Service Availability
99.99
Cumulative Shut-off Hours
Service Availability of 12GHz
Satellite Broadcasting
Example of Hierarchical Transmission
SOMY
BS
HiVision
TC8PSK reception
?? ?? ?? ?? ?? ?? ?? ?? ??
QPSK/BPSK reception
Penetration of HDTV Receivers
in Japan
(x1,000)
reached
1000
900
934,000
at Aug. 1998
800
700
657,000
at Aug. 1998
Wide Screen TV with
MUSE/NTSC Converter
600
500
400
HDTV
Receiver
300
200
100
0
1
2
3
4
5
6
7
8
1995
9 10 11 12 1
2
3
4
5
6
7
8
1996
9 10 11 12 1
2
3
4
5
6
7
8
1997
9 10 11 12 1
2
3
4
5
6
7
1998
Relationship between viewing distance and
required number of scanning lines
Change of popular size
of TV monitors in Japan
12- inch
BB && WW
1 4-inch
? ? ? ? ? ? ?
?
?
?
20-inch
NN TT SSSS CC
1953?
29-inch
NN TT SS CC
1960?
NN TT SS CC
? ? ? ? ? ? ?
1980?
50-inch
HH DD T VV
1990?
? ? ?
Number of scanning lines
3 000
??Line
?? ??structure
?? ??
??invisible
?? ?? ?? ??
?
? 2 000
?
? 1 000 Line
?? ??structure
?? ?? ??
visible
?? ?? ?? ??
0
0
1
2
3
4
5
6
? ? ? ( (xﾗ picture
? ? ? height)
)
Viewing distance
2000?
BS? ? ? ? ? ? ? ?
?Popular
? = size
? ?has? become larger
?Viewing
? ? distance
= 2 mremains
? ( ? ? )
unchanged (about 2m)
HDTV is suitable for
the digital age
0
(DSCQS%)
Quality Degradation
Subjective Assessment of
HDTV Picture Quality
10
20
30
Original
22Mbps
40
50
A
B
C
D
18Mbps
16Mbps
E
F
G
H
J
Test Sequence (coded by MP@HL)
K
Conclusions
q ISDB
by satellite starts in December 2000
q The ISDB-S system
l
large transmission capacity of 52 Mbps/ch
z
l
robust transmission against heavy rain
z
l
two HDTV programs can be transmitted
multiple modulation schemes and hierarchical
transmission
high operational flexibility
z
independence between broadcasters who share one
transponder
q HDTV services in Japan
l ISDB-S is expected to play a central roll on digital HDTV