Note: Descriptions are shown in the official language in which they were submitted.
WO 2005/115001 PCT/KR2005/001465
Description
DIGITAL BROADCASTING TRANSMISSION/RECEPTION
DEVICES CAPABLE OF IMPROVING A RECEIVING
PERFORMANCE AND SIGNAL PROCESSING METHOD
THEREOF
Technical Field
Ill The present invention relates to a digital broadcasting transmitter and
receiver, and
more specifically, to a digital broadcasting transmitter for replacing and
transmitting
stuff bytes inserted in data stream with predefined known data in a dual
stream to
enhance reception performance and a signal processing method thereof, and a
cor-
responding digital broadcasting receiver and a signal processing method
thereof.
Background Art
[21 The Advanced Television Systems Committee Vestigial Sideband (ATSC VSB),
U.S-oriented terrestrial waves digital broadcasting system, is a single
carrier scheme
and uses field synchronizing signal by 312 segment unit. Accordingly,
reception
performance is not good in poor channels, especially in a doppler fading
channel.
[31 Fig. 1 is a block diagram showing a conventional transmitter of the ATSC
VSB.
The digital broadcasting transmitter of Fig. 1, which is an Enhanced Vestigial
Sideband (EVSB) system proposed by Philips, forms and transmits a dual stream
by
adding a robust data to a normal data of the existing ATSC VSB system.
[41 As shown in Fig. 1, the digital broadcasting transmitter has a randomizer
(11) for
randomizing data, a first RS encoder (12) for performing RS encoding of the
randomized data, a packet formatter (13) for interleaving the robust data of
the
encoded data, restructuring a packet at 1/2 rate, inserting a packet
identifier (PID) and
multiplexing the data with the normal data, an interleaver (14) for
interleaving the data,
a Trellis encoder (15) for performing enhanced coding and then the general 2/3
rate
Trellis encoding of the robust data of the interleaved data, a controller (16)
for
outputting a signal to control the normal data and robust data, a second RS
encoder
(17) for performing RS re-encoding of the enhanced-coded robust data to be
compatible with the existing receiver and replacing parity, a multiplexer (18)
for
inserting field sync and segment sync in the Trellis-coded data, and a
modulator (19)
for adding a pilot to the multiplexed signal and carrying out Vestigial
Sideband (VSB)
modulation and RF upconverting.
[51 Referring to Fig. 1, the normal data and robust data are multiplexed (not
shown)
according to the dual stream scheme which transmits the normal data and robust
data
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in one channel and the multiplexed data are input to the randomizer (11). The
input
data are randomized by the randomizer (11), input to the first RS encoder
(12), RS
encoded to correct channel-generated errors, and input to the packet formatter
(13).
Then the robust processing is performed such that the robust data of the
encoded data
are interleaved, restructured with packet at 1/2 rate and inserted with the
PID. The data
after the robust processing are then multiplexed with the normal data and
output.
[61 Fig. 2 shows a data format output from the packet formatter (13) of Fig.
1.
[71 Referring to Fig. 2, the normal data and robust data are arranged at
certain intervals
so that the normal signal and robust signal after Trellis encoding are
distributed at
regular intervals.
[81 The resultant output data are interleaved through the interleaver (14)
which
disperses the data, the robust data are enhanced-coded, and the data are
Trellis-encoded
through the Trellis encoder (15) which performs the general 2/3 rate Trellis
encoding.
The enhanced-coded robust data are RS re-encoded to be compatible with the
existing
receiver and the parity is sent to the Trellis encoder (15) through the second
RS
encoder (17) which replaces the parity. The signal passes through the
multiplexer (18)
which inserts the field sync and segment sync in the Trellis-encoded data, and
is sent to
the modulator (19) which adds pilot and performs VSB modulation and RF up-
converting with respect to the signal, and then transmitted. Here, the normal
data and
robust data are controlled by the controller (16) which outputs a signal to
control the
normal data and robust data.
[91 The U.S-oriented terrestrial waves digital television system of Fig. 1 is
constructed
to form a dual stream by adding the robust data in the normal data of the
existing
ATSC VSB system and transmit the dual stream, so that the existing normal data
and
the robust data are transmitted altogether.
[101 However, the U.S-oriented terrestrial waves digital television system of
Fig. 1 has a
problem that in spite of transmitting the dual stream with the robust data
added, poor
transmission performance at multipath channels due to transmission of the
existing
normal stream is almost not improved. In other words, the improved normal
stream
rarely improves reception performance and the robust stream has no remarkable
effect
on reception performance in the multipath environment.
Disclosure of Invention
Technical Problem
[11] An aspect of the present invention is to provide a digital broadcasting
transmitter
which replaces stuff bytes inserted in dual stream with known data and
transmits the
data to enhance transmission performance, and a signal processing method
thereof, and
a corresponding digital broadcasting receiver and a signal processing method
thereof.
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According to one aspect of the present invention, there is provided a
digital broadcasting transmitter, comprising: a first Reed-Solomon (RS)
encoder for
performing RS encoding of a transport stream (TS), the TS comprising a robust
data
packet, a known data and a normal data packet; an interleaver for interleaving
the RS
encoded stream; a Trellis encoder for Trellis-encoding the data output from
the
interleaver; a second RS encoder for RS-encoding the robust packet of the
Trellis-
encoded data to alter parity and inputting it to the Trellis encoder; and a
modulator for
modulating the data output from the Trellis encoder and performing RF
upconverting,
wherein the Trellis encoder has a memory for Trellis encoding, and initializes
a value
of the memory at a beginning location of the known data in the TS.
According to another aspect of the present invention, there is provided
a method for signal processing for a digital broadcasting transmitter,
comprising: a
first Reed-Solomon (RS) encoding step of performing RS encoding of a transport
stream (TS), the TS comprising a robust data packet, a known data and a normal
data packet; an interleaving step of interleaving the RS encoded stream; a
Trellis
encoding step of Trellis-encoding the interleaved stream; a second RS encoding
step
of performing RS encoding of the robust packet of the Trellis-encoded data to
alter
parity and inputting it to the Trellis encoding step; and a modulating step of
modulating the data output from the Trellis encoding step and performing RF
upconverting, wherein the Trellis encoding step performs initialization of
memory for
Trellis encoding at a beginning location of the known data in the TS.
According to still another aspect of the present invention, there is
provided a digital broadcasting receiver comprising: a known data detector for
detecting location of known data from a data stream comprising the known data
and
an additional data stream, if the data stream is received; and a processor for
processing the data stream using the detected location of known data, wherein
the
data stream is received from a digital broadcasting transmitter which
comprises a
trellis encoder for performing trellis encoding using internal memories and
resetting
the a value of the internal memories at a beginning location of the known data
in the
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data stream, and wherein the additional data stream is processed by the
digital
broadcasting transmitter to be robust against errors.
According to yet another aspect of the present invention, there is
provided a method by which a digital broadcasting receiver processes streams,
the
method comprising: detecting location of known data from a data stream
comprising
the known data and an additional data stream, if the data stream is received;
and
processing the data stream using the detected location of known data, wherein
the
data stream is received from a digital broadcasting transmitter which
comprises a
trellis encoder for performing trellis encoding using internal memories and
resetting
the a value of the internal memories at a beginning location of the known data
in the
data stream, and wherein the additional data stream is processed by the
digital
broadcasting transmitter to be robust against errors.
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Technical Solution
[121 To achieve an aspect of the present invention, a digital broadcasting
transmitter
comprises a randomizer for receiving and randomizing a dual TS stream of a pre-
determined format in which a robust data packet is inserted at certain
intervals in a
normal data packet, the normal data being inserted with stuff bytes at a
certain
location, a stuff byte replacing part for replacing the stuff bytes of the
data output from
the randomizer with a predetermined known data, a first RS encoder for
performing RS
encoding of the data output from the stuff byte replacing part, a packet
formatter for in-
terleaving the robust packet of the data output from the first RS encoder and
re-
structuring the format, an interleaver for interleaving the data output from
the packet
formatter, a Trellis encoder for Trellis-encoding the data output from the
interleaver, a
second RS encoder for RS-encoding the robust packet of the Trellis-encoded
data to
alter parity and inputting it to the Trellis encoder, and a modulator for
modulating the
data output from the Trellis encoder and performing RF upconverting.
[131 Preferably, the Trellis encoder has a memory for Trellis encoding, and
initializes
the memory of the data which is input from the location where the stuff bytes
are
inserted.
[141 Preferably, the digital broadcasting transmitter further comprises a
stuff byte
controller for generating a control signal to indicate the location
information of the
stuff bytes and control the memory initialization of the Trellis encoder.
[151 Further, the digital broadcasting transmitter further comprises a packet
buffer for
outputting and temporarily storing the data corresponding to the location of
the stuff
bytes of the data output from the first RS encoder.
[161 More preferably, the packet buffer receives the data altered according to
the
memory initialization from the Trellis encoder and updates the temporarily
stored data.
[171 Further, the digital broadcasting transmitter further comprises a parity
restructuring
part for receiving the updated data from the packet buffer, performing RS
encoding of
the data to generate the altered parity, and outputting the altered parity to
the Trellis
encoder to replace the parity added by the first RS encoder.
[181 More preferably, the stuff bytes are inserted in an adaptation field of
the normal
data packet.
[191 Further, the information on the location and length of the inserted stuff
bytes is
inserted at a certain location of the normal data packet.
[201 In addtion, the known data may have a sequence with a predefined certain
pattern.
[211 Meanwhile, a method for signal processing for a digital broadcasting
transmitter
comprises a randomizing step of receiving and randomizing a dual TS stream of
a
certain format in which a robust data packet is inserted at certain intervals
in a normal
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data packet, the normal data being inserted with stuff bytes at a certain
location, a stuff
byte replacing step of replacing the stuff bytes in the data output from the
randomizing
step with predetermined known data, a first RS encoding step of performing RS
encoding of the data output from the stuff byte replacing step, a packet
restructuring
step of interleaving the robust packet in the data output in the first RS
encoding step
and restructuring the format, a interleaving step of interleaving the data
output from the
packet restructuring step, a Trellis encoding step of performing Trellis
encoding of the
interleaved data, a second RS encoding step of performing RS encoding of the
robust
packet of the Trellis encoded data to alter parity and inputting it to the
Trellis encoding
step and a modulating step of modulating the data output from the Trellis
encoding
step and RF upconverting.
[221 Further, a digital broadcasting transmitter according to the present
invention
comprises a randomizer for randomizing a dual TS stream of a certain format
having a
normal data packet in which stuff bytes are inserted at a certain location,
and a robust
data packet, a stuff byte replacing part for replacing the stuff bytes of the
data output
from the randomizer with a predetermined known data, a first RS encoder for
performing RS encoding of the data output from the stuff byte replacing part,
an packet
formatter for interleaving the robust packet of the data output from the first
RS encoder
and restructuring a format, an interleaver for interleaving the data output
from the
packet formatter, a Trellis encoder for performing Trellis encoding of the
data output
from the interleaver, a second RS encoder for performing RS encoding of the
robust
packet of the Trellis encoded data to alter parity and inputting the data to
the Trellis
encoder, and a modulator for modulating the data output from the Trellis
encoder and
performing RF upconverting.
[231 In addition, a method for signal processing for a digital broadcasting
transmitter
comprises a randomizing step of randomizing a dual TS stream of a certain
format
having a normal data packet in which the stuff bytes are inserted at a certain
location,
and robust data packet, a stuff byte replacing step of replacing the stuff
bytes of the
data output from the randomizing step with a predetermined known data, a first
RS
encoding step of performing RS encoding of the data output from the stuff byte
replacing step, a packet restructuring step of interleaving the robust packet
of the data
output from the first RS encoding step and restructuring the format, a
interleaving step
of interleaving the data output from the packet restructuring step, a Trellis
encoding
step of performing Trellis encoding of the interleaved data, a second RS
encoding step
of performing RS encoding of the robust packet of the Trellis encoded data to
alter
parity and inputting the data to the Trellis encoding step, and a modulating
step of
modulating the data output from the Trellis encoding step and RF upconverting.
[241 A digital broadcasting receiver according to the present invention
corresponding to
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the above digital broadcasting transmitter comprises a demodulator for
receiving and
demodulating an encoded signal from a digital broadcasting transmitter, the
encoded
signal being encoded by inserting a predetermined known data in a certain
location of
dual stream where stuff bytes are inserted, a known data output part for
detecting the
location of the known data from the demodulated signal and outputting the
known
data, an equalizer for equalizing the demodulated signal, a Viterbi decoder
for error-
correcting and decoding of the equalized signal using the detected known data,
a dein-
terleaver for deinterleaving data output from the Viterbi decoder, and a
derandomizer
for derandomizing data output from the deinterleaver.
[251 Preferably, the known data output part includes a known symbol detector
for
detecting information on the certain location of the received signal where the
known
data is inserted, a segment flag generator for generating data frame which
includes one
or more segments to indicate the certain location with a predetermined
identification
flag, a Trellis interleaver for encoding the data frame according to the
encoding in the
digital broadcasting transmitter, and a known data extractor for inserting and
outputting the known data at the certain location of the interleaved data
frame which is
indicated by the identification flag.
[261 More preferably, the known data output part outputs the detected known
data to the
demodulator, and the demodulator performs demodulation using the known data.
[271 Meanwhile, a method for signal processing for a digital broadcasting
receiver
comprises a demodulating step of receiving and demodulating an encoded signal
from
a digital broadcasting transmitter, the encoded signal being encoded by
inserting a pre-
determined known data in a certain location of dual stream where stuff bytes
are
inserted, a known data outputting step of detecting the location of the known
data from
the demodulated signal and outputting the known data, a equalizing step of
equalizing
the demodulated signal, a decoding step of error-correcting and decoding of
the
equalized singal using the detected known data, a deinterleaving step of
deinterleaving
data output from the decoding step, and a derandomizing step of derandomizing
data
output from the deinterleaving step.
Advantageous Effects
[281 According to the present invention, a digital broadcasting transmitter
inserts stuff
bytes in a MPEG-2 TS packet, replaces the inserted stuff bytes with known data
and
transmits the data, and a digital broadcasting receiver detects and uses the
known data.
Accordingly, there are effects of compatibility with the existing digital
broadcasting
system, lower complexity of hardware, and enhanced digital broadcasting
reception
performance in poor multipath channels.
Brief Description of the Drawings
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[291 Fig. 1 is a block diagram of a transmitter of a conventional U.S-oriented
terrestrial
waves digital broadcasting (ATSC VSB) system,
[301 Fig. 2 is a view showing a format of ATSC VSB data,
[311 Fig. 3 is a view showing a frame structure of a TS packet,
[321 Fig. 4 is a view showing a frame structure of a TS packet including stuff
bytes
according to the present invention,
[331 Fig. 5 is a block diagram of a digital broadcasting transmitter according
to the
present invention,
[341 Fig.6 and Fig. 7 are views showing a format of data output from a
randomizer of
Fig. 5,
[351 Fig. 8 and Fig. 9 are views showing a format of data output from an
interleaver of
Fig. 5,
[361 Fig. 10 and Fig. 11 are views showing a format of data output from a
Trellis
encoder of Fig. 5,
[371 Fig. 12 and Fig. 13 are views showing a format of data with parity
restructured
according to Trellis encoder initialization of Fig. 5,
[381 Fig. 14 is a block diagram of a digital broadcasting transmitter
according to the
present invention, and
[391 Fig. 15 is a view provided to describe a known data output part of Fig.
10.
Best Mode for Carrying Out the Invention
[401 Hereinafter, the present invention will be described in detail with
reference to the
accompanying drawings.
[411 Fig. 5 is a block diagram of a digital broadcasting transmitter according
to the
present invention. The digital broadcasting transmitter of Fig. 5 is
implemented using
the EVSB system of Fig. 1 that Philips proposed. In detail, stuff bytes are
added in a
MPEG-2 packet of a normal stream or robust stream, and the added stuff bytes
are
replaced with known data in the digital broadcasting transmitter and are
transmitted.
Then, the known data are detected in a receiver and used to compensate
distortion by a
channel.
[421 Referring to Fig. 5, the digital broadcasting transmitter has a
randomizer (110) for
randomizing the data when the normal data and robust data are multiplexed and
input,
a stuff byte replacing part (115) for replacing the stuff bytes of the normal
stream or
robust stream of the randomized data with a particular sequence, a first RS
encoder
(120) for performing Reed-Solomon encoding of the data output from the stuff
byte
replacing part (115) to correct errors by a channel, a packet formatter (130)
for in-
terleaving the robust data of the encoded data, restructuring the packet in
1/2 rate,
inserting the PID and multiplexing with the normal data, an interleaver (140)
for in-
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terleaving the data output from the packet formatter (130), a Trellis encoder
(150) for
initializing a memory value of stuff bytes of the data output from the
interleaver (140),
enhanced-coding the robust data and performing general 2/3 rate Trellis
encoding, a
controller (160) for outputting a signal to control the normal data and robust
data, and a
second RS encoder (170) for performing RS re-encoding of the enhanced-coded
robust
data to be compatible with the existing receiver and replacing parity.
[431 In addition, the digital broadcasting transmitter has a stuff byte
controller (125) for
generating a signal to control a location of the stuff bytes, a packet buffer
(135) for
buffering the output of the first RS encoder (120) for the data initialization
of the
Trellis encoder (150), and receiving and updating the data altered according
to the ini-
tialization of the Trellis encoder (150), a parity restructuring part (145)
for performing
RS encoding of the data altered according to the initialization to generate a
parity and
inputting the generated parity to the Trellis encoder (150) to replace the
existing parity,
a multiplexer (180) for inserting field sync and segment sync in the data
which is
Trellis encoded and mapped, and a modulator (190) for adding a pilot to the
signal
output from the multiplexer (180) and performing the VSB modulation and RF up-
converting.
[441 The normal data packets or robust data packets which are input to the
randomizer
(110) according to the present invention include the stuff bytes inserted
therein. Fig. 3
is a view showing a frame structure of a TS stream packet. Fig. 4 is a view
showing a
frame structure of a MPEG-2 TS stream packet including adaptation field with
stuff
bytes according to the present invention. An MPEG-2 packet of 188 bytes
consists of
an information signal (MPEG-2 header) of 4 bytes including MPEG sync,
adaptation
field length information of 1 byte, other information of 1 byte, adaptation
field data
with stuff bytes of n bytes, and ES data of '1 88-(4+2+n)'bytes.
[451 A TS stream packet frame of Fig. 3 consists of MPEG-2 header and
adaptation field
or ES data. The normal data packet or robust data packet according to the
present
invention, as shown in Fig. 4, has structure in which stuff bytes are inserted
in the
adaptation field so that all the TS stream includes the adaptation field. Such
an MPEG-
2 TS packet is input as the normal data or robust data of Fig. 5.
[461 In Fig. 5, the robust data are processed in a robust data pre-processor
(not shown)
and are multiplexed with the normal data to be sent to the randomizer (110).
[471 The randomizer (110) randomizes the data whose the nomal data and robust
data
are multiplexed as described above.
[481 The data randomized through the randomizer (110) are input to the the
stuff byte
replacing part (115) and the stuff bytes of the normal data and robust data
are replaced
with a particular sequence generated by a particular sequence generator (not
shown)
and are output. The particular sequence is data having a predefined pattern
that the
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transmitter and the receiver already know, and is hereinafter referred to as
'known
data'.
[491 When the stuff bytes are inserted in a normal data packet, Fig.6 shows a
format of
data output from the randomizer (120) in which n stuff bytes inserted in the
normal
data packet are replaced with the particular sequence data, that is, with the
known data.
Referring to Fig. 6, normal data packets and robust data packets are arranged
at certain
intervals and known data are inserted instead of stuff bytes in the adaptation
fields of
the normal data packets.
[501 Fig. 7 shows the data format when stuff bytes are inserted in a normal
data packet
and robust data packet respectively, and n stuff bytes inserted in the normal
data packet
and robust data packet among the data output from the mdomizer (120) are
replaced
with the particular sequence data, that is, with the known data. Referring to
Fig. 7, the
normal data packet and robust data packet are arranged at certain intervals
and known
data are inserted instead of stuff bytes in the adaptation fields of the
normal data packet
and robust data packet.
[511 In addition, as described above, the header of MPEG-2 packet data output
from in
the randomizer (120) includes the first byte of a sync and 3 bytes of the PID.
The first
2 bytes of adaptation field of certain bytes include information on adaptation
field
length.
[521 In other words, the first 2 bytes of the adaptation field have
information on length
of stuff bytes, that is, the known data inserted in the adaptation field. As
the beginning
location of the known data in a packet is fixed, the receiver can know the
information
on location and length, that is, quantity of the known data according to the
information
inserted in the first 2 bytes of the adaptation field.
[531 The data output from the stuff byte replacing part (115) are outer-coded
through the
first RS encoder (120) to correct errors by a channel. The robust data of the
outer
coded data are interleaved by the packet formatter (130), the packet of the
robust data
is restructured at 1/2 rate and the PID is inserted. Then, the robust data are
multiplexed
with the normal data and the data are interleaved in the interleaver (140).
[541 Fig. 8 shows a format of data after replacing the stuff bytes inserted in
the normal
data with the known data and interleaving by the interleaver (140). MPEG-2
packets of
Fig. 6 are dispersed in 52 units by the interleaver (140) as shown in Fig. 8.
Data of the
same byte location in an MPEG-2 packet construct the same column after data in-
terleaving, as shown in Fig. 8.
[551 Furthermore, Fig. 9 shows a format of data after replacing stuff bytes
inserted in the
normal data and robust data with the known data and interleaving by the
interleaver
(140). MPEG-2 packets of Fig. 7 are dispersed in 52 units by the interleaver
(140) as in
Fig. 9. Data of the same byte location in an MPEG-2 packet construct the same
column
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after data interleaving, as shown in Fig. 9.
[561 Then, the robust data of the data output by the the interleaver (140) are
enhanced-
coded and processed with the existing 2/3 rate Trellis encoding by the Trellis
encoder
(150).
[571 Fig. 10 shows the output data formats after a data stream of Fig. 8 is
Trellis-
encoded by the Trellis encoder (150). One field includes six convolutional
interleavers
so that six sequences including stuff bytes are generated. In other words, if
TS stream
has 10 stuff bytes, known symbol sequences of '0*6=60' are generated in one
field.
[581 Fig. 11 shows the output data formats after a data stream of Fig. 9 is
Trellis-
encoded by the Trellis encoder (150).
[591 Referring to Fig. 10 and Fig. 11, data of the same byte location in MPEG-
2 packet
are included in one data segment after Trellis encoding. Therefore, if stuff
bytes are
consecutively added in a certain location of MPEG-2 packet and randomized, and
the
stuff bytes are replaced with a particular sequence and Trellis encoded, the
stuff bytes
inserted in the same byte location form one data segment, which is a known
signal. In
result, the digital broadcasting receiver can detect and use the known data to
improve
reception performance.
[601 In addition, the second RS encoder (170) carries out RS re-encoding of
the
enhanced-coded robust data to be compatible with the existing receiver and
carries out
non-systematic RS encoding to replace the parity.
[611 The Trellis encoder (150) has its memory (now shown) for Trellis
encoding. The
Trellis encoder (150) performs initialization of the memory from the beginning
location of the stuff bytes or known data.
[621 Meanwhile, the packet buffer (135) receives and buffers the data
corresponding to
the location of memory initialization of the Trellis encoder (150) from the
first RS
encoder (120), and afterwards, receives the new data altered by the memory ini-
tialization of the Trellis encoder (150) and updates the previously buffered
data, and
inputs the updated data to the parity restructuring part (145). Accordingly,
the parity
restructuring part (145) performs RS encoding of the data altered by the
memory ini-
tialization to generate the parity and the generated parity is input to the
Trellis encoder
(150) to replace the previous parity.
[631 Furthermore, the controller (160) outputs a signal to control the normal
data and
robust data, and the stuff byte controller (125) generates a signal to control
the location
of stuff bytes.
[641 The encoded data are mapped in an 8 level symbol and inserted with the
field sync
and segment sync to data formats as shown in Fig. 2 and Fig. 8. Then, DC
offset is
given and VSB modulation is performed to generate pilot by the modulator
(190), and
the data are converted into RF and transmitted.
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[651 Meanwhile, the stuff byte controller (125) detects the adaptation field
length of Fig.
4, and generates and outputs a flag signal to indicate the location of the
stuff bytes or
known sequence data of Fig. 6 to Fig. 13, based on the detection.
[661 The Trellis encoder (150) of Fig. 5 performs the 12 Trellis encoder
initialization at
the beginning location of the known data to initialize the value of a memory
element of
the encoder. The altered data by the initialization replaces the previous
value stored in
the packet buffer (135) and replaces the value of the previous parity location
using the
new parity generated by the parity restructuring part (145) according to the
altered
data.
[671 Fig. 12 shows a data format after RS encoding and parity restructuring by
the parity
restructuring part (145) of Fig. 5 with respect to data with a format as shown
in Fig. 10.
Additionally, Fig. 13 shows a data format after RS encoding and parity
restructuring
by the parity restructuring part (145) of Fig. 5 with respect to data with a
format as
shown in Fig. 11.
[681 Referring to Fig. 12 and Fig. 13, when the Trellis encoder (150) is
initialized at the
beginning location of the symbol sequence of the known data, the data value is
altered
by the initialization so that the output parity of the first RS encoder (120)
is altered.
Accordingly, the parity restructuring part (145) updates the previous parity
with the
altered parity to perform Trellis encoding so that there will be no problem
when an RS
decoder of a digital broadcasting receiver to be described later decodes the
data.
[691 In other words, memory initialization of the Trellis encoder (150) is
performed in
order for Trellis-encoded data to form a predefined particular sequence during
symbol
sequence section of the known data. Then, in order to alter parity
corresponding to the
altered data of the memory initialization location, RS encoding of the altered
data is
performed so that new parity is generated and the altered parity replaces the
previous
parity. Fig. 12 shows a process to replace a corresponding parity according to
the
altered data value by the memory initialization.
[701 Fig. 14 is a block diagram of a digital broadcasting receiver
corresponding to the
digital broadcasting transmitter of Fig. 5 according to the present invention.
If the
received signal includes the normal data, robust data and stuff bytes, the
digital
broadcasting receiver has elements to decode them.
[711 The digital broadcasting receiver of Fig. 14 includes a demodulator (310)
for
lowering an RF signal to baseband and demodulating it, an equalizer (320) for
deleting
inter-symbol interference, a Viterbi decoder (330) for correcting errors in
the equalized
signals and performing decoding, a deinterleaver (340), a packet formatter
(350) for
demultiplexing the output of the deinterleaver (340) and performing packet re-
formatting and deinterleaving of the robust data, a control signal generator
(360) for
generating a control signal to control a dual stream, an RS decoder (370) for
RS
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correction and decoding of the data output from the packet formatter (350), a
de-
randomizer (380) and a known data output part (400) for generating location of
stuff
bytes and processing known data.
[721 The demodulator (310) converts the RF signal received via channel into a
baseband
signal through tuner/IF (not shown), detects and demodulates sync of the
converted
baseband signal. The equalizer (320) compensates multipath channel distortion
of the
demodulated signal.
[731 Meanwhile, the known data output part (400) detects information on stuff
byte
quantity inserted in the reserved part of field sync data segment section to
acquire
location information on known symbol, and outputs the known data from the
acquired
location information.
[741 Fig. 15 shows the known data output part (400) for detecting the known
data of the
digital broadcasting receiver.
[751 The known data output part (400) includes a known symbol detector(410), a
segment flag generator (420), a Trellis interleaver (430), and a known data
extractor
(440).
[761 If the information on the quantity (the number) of stuff bytes is
inserted in the
reserved part of field sync data segment section, the known symbol detector
(410) of
the known data output part (400) in the digital broadcasting receiver detects
the in-
formation on quantity of the known data. Based on the detected information,
the
segment flag generator (420) and the Trellis interleaver (430) acquire
information on
the location of the known symbol. From the acquired location information, the
known
data extractor (440) ouputs the known data for use in improving reception
performance
of the digital broadcasting receiver is improved. As the location of stuff
bytes is fixed
all the time, if quantity of stuff bytes can be detected, the segment flag
generator (420)
and the Trellis interleaver (430) can be implemented using a counter and a
control
logic.
[771 That is, the known symbol detector (410) extracts information on the
known data
location from control information bit including information on adaptation
field length
of the demodulated data header. The information on the known data location
includes
the information on known data length. As the known data location is preset,
the
location and number of the known symbols according to encoding of known data
can
be acquired by knowing the length.
[781 According to the location and number of the known symbols, the segment
flag
generator (420) marks with a predetermined flag of length corresponding to the
number of symbols at the corresponding location and generates at least one
segment
and a MPEG-2 transmission frame including the segment.
[791 The Trellis interleaver (430) encodes the transmission frame generated in
the
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segment flag generator (420) according to the interleaving in the digital
broadcasting
transmitter.
[801 The known data extractor (440) inserts the predefined known data at the
location of
the known symbol which is identified by the flag of the transmission frames
which are
encoded and output from the Trellis interleaver (430), and outputs the known
data-
inserted data.
[811 Meanwhile, the signal equalized by the equalizer (320) is error-corrected
through
the Viterbi decoder (330) and decoded into symbol data. The decoded data
rearranges
the data dispersed by the interleaver (140) of the transmitter of Fig. 5
through the dein-
terleaver (340). The deinterleaved data are de-multiplexed by the packet
formatter
(350) to be devided into the normal data and robust data. The robust data go
through
packet reformatting and deinterleaving and are input to the RS decoder (370)
with the
normal data, and error-corrected. The control signal generator (360) generates
a control
signal to process the normal data and robust data. The data output from the RS
decoder
(370) are derandomized through the derandomizer (380).
[821 As described above, stuff bytes are generated and inserted in MPEG-2 TS
packet,
and the inserted stuff bytes are replaced with known data and transmitted from
the
digital broadcasting transmitter. Then the digital broadcasting receiver
detects and uses
the known data. Accordingly, reception performance of the digital broadcasting
receiver, such as sync acquisition and equalizing performance, can be
improved.
[831 Furthermore, the stuff bytes are inserted in the existing transmission
frame structure
and only a reserved part is altered so that there are advantages that
compatibility with
the existing system is provided and additional hardware is easily implemented.
[841 According to the present invention, stuff bytes are inserted in normal
data or robust
data of the MPEG-2 packet in the digital broadcasting transmitter, and the
inserted
stuff bytes are replaced with known data and transmitted, so that the digital
broadcasting receiver detects and uses the known data. In result,
implementation of
hardware is not complicated and digital broadcasting reception performance at
poor
multipath channels can be improved.
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