U.S. patent number RE46,188 [Application Number 14/315,124] was granted by the patent office on 2016-10-25 for transmitting/receiving system and method of processing broadcasting signal in transmitting/receiving system.
This patent grant is currently assigned to LG ELECTRONICS INC.. The grantee listed for this patent is LG Electronics Inc.. Invention is credited to In Hwan Choi, Byoung Gill Kim, Jin Woo Kim, Kook Yeon Kwak, Hyoung Gon Lee, Chul Kyu Mun, Won Gyu Song.
United States Patent |
RE46,188 |
Kim , et al. |
October 25, 2016 |
Transmitting/receiving system and method of processing broadcasting
signal in transmitting/receiving system
Abstract
A transmitting system, a receiving system, and a method of
processing broadcast signals are disclosed. Herein, the
transmitting system includes an RS frame encoder, a block
processor, a group formatter, and a trellis encoding module. The RS
frame encoder performs error correction encoding on an RS frame
payload including mobile service data so as to form an RS frame,
divides the RS frame into a plurality of portions, and outputs the
divided RS frame portions. The block processor performs one of
1/2-rate encoding and 1/4-rate encoding on each bit of the mobile
service data included in each portion. The group formatter maps a
portion including symbols of the 1/4-rate encoded mobile service
data and symbols of the 1/2-rate encoded mobile service data to a
corresponding region of a data group. And, the trellis encoding
module performs trellis encoding on the symbols of the 1/4-rate
encoded mobile service data and the symbols of the 1/2-rate encoded
mobile service data of the data group.
Inventors: |
Kim; Jin Woo (Seoul,
KR), Kwak; Kook Yeon (Anyang-si, KR), Kim;
Byoung Gill (Seoul, KR), Song; Won Gyu (Seoul,
KR), Mun; Chul Kyu (Seoul, KR), Lee; Hyoung
Gon (Seoul, KR), Choi; In Hwan (Gwacheon-si,
KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG Electronics Inc. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG ELECTRONICS INC. (Seoul,
KR)
|
Family
ID: |
42740135 |
Appl.
No.: |
14/315,124 |
Filed: |
June 25, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61161390 |
Mar 18, 2009 |
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Reissue of: |
12726818 |
Mar 18, 2010 |
8209584 |
Jun 26, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04H
20/72 (20130101); H04L 1/0071 (20130101); H04L
1/0057 (20130101); H04L 1/0065 (20130101); H04L
1/0041 (20130101); H04L 1/0045 (20130101); H04H
60/11 (20130101); H04L 1/006 (20130101); H04N
21/23614 (20130101); H04L 1/0041 (20130101); H04L
1/007 (20130101); H04H 20/30 (20130101); H04H
40/27 (20130101) |
Current International
Class: |
H03M
13/00 (20060101); H04L 1/00 (20060101); H04N
21/236 (20110101) |
Field of
Search: |
;375/343
;715/755,784,792 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-2007-0068960 |
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Jul 2007 |
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KR |
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Other References
US. Appl. No. 14/451,274, Office Action dated Aug. 27, 2015, 19
pages. cited by applicant .
U.S. Appl. No. 14/451,274, Final Office Action dated Feb. 3, 2016,
23 pages. cited by applicant .
Office Action issued in U.S. Appl. No. 14/451,274, Jul. 29, 2016,
21 pages. cited by applicant.
|
Primary Examiner: Sorrell; Eron J
Attorney, Agent or Firm: Lee, Hong, Degerman, Kang &
Waimey Kang; Jonathan Salfelder; Richard
Parent Case Text
This application .Iadd.is a reissue of U.S. Pat. No. 8,209,584 B2,
issued on Jun. 26, 2012 from U.S. application Ser. No. 12/726,818,
filed on Mar. 18, 2010, which .Iaddend.claims the benefit of U.S.
Provisional Application No. 61/161,390, filed on Mar. 18, 2009,
.Iadd.the contents of .Iaddend.which .[.is.]. .Iadd.are all
.Iaddend.hereby incorporated by reference .Iadd.herein in their
entirety.Iaddend.. .Iadd.In addition, more than one reissue
application has been filed for the reissue of U.S. Pat. No.
8,209,584 B2. U.S. application Ser. No. 14/451,274, filed on Aug.
4, 2014, currently pending, is a reissue application of U.S. Pat.
No. 8,209,584 B2.Iaddend..
Claims
What is claimed is:
1. A transmitting system comprising: a Reed-Solomon (RS) frame
encoder for performing error correction encoding on an RS frame
payload including mobile service data so as to form an RS frame and
dividing the RS frame into a plurality of portions; a block
processor for .[.performing one of 1/2-rate encoding and 1/4-rate
encoding on each bit of.]. .Iadd.processing .Iaddend.the mobile
service data included in each portion.[.;.]..Iadd., wherein the
block processor comprises: a byte to bit converter for converting
bytes of mobile service data to bits of the mobile service data;
and a symbol encoder for encoding each bit of the mobile service
data at one of a 1/2 code rate or a 1/4 code rate, wherein the
symbol encoder comprises: a convolutional encoder for convolutional
encoding an input bit of the mobile service data into 5 output
bits; a bit puncturing unit for removing at least one of the 5
output bits; and a bit ordering unit for re-ordering remaining bits
unremoved from the 5 output bits according to the one of the 1/2
code rate or the 1/4 code rate, and outputting one or more
symbols;.Iaddend. a group formatter for mapping .[.a portion
including.]. .Iadd.at least .Iaddend.symbols of the 1/4-.Iadd.code
.Iaddend.rate encoded mobile service data .[.and.]. .Iadd.or
.Iaddend.symbols of the 1/2-.Iadd.code .Iaddend.rate encoded mobile
service data to a corresponding region of a data group; and a
trellis encoding module for performing trellis encoding on the
.[.symbols of the 1/4-rate encoded mobile service data and the
symbols of the 1/2-rate encoded.]. mobile service data .[.of.].
.Iadd.mapped to .Iaddend.the data group.
2. The transmitting system of claim 1, .[.wherein the block
processor comprises.]. .Iadd.further comprising.Iaddend.: .[.a byte
to symbol converter for converting each byte of the mobile service
data to symbols; a symbol encoder for encoding the symbols of the
mobile service data being outputted from the byte to symbol
converter at a coding rate of H1/H2 (wherein H1 and H2 are
integers);.]. a symbol interleaver for performing symbol
interleaving in symbol units on .Iadd.the symbols of .Iaddend.the
.Iadd.encoded .Iaddend.mobile service data .[.encoded at the coding
rate of H1/H2.].; and a symbol to byte converter for converting the
symbol-interleaved symbols to bytes.
.[.3. The transmitting system of claim 2, wherein the symbol
encoder comprises: a convolutional encoder for performing
convolutional encoding on an input bit of the mobile service data,
thereby outputting the convolutionally encoded input bit as 5 bits;
a bit puncturing unit for removing at least one of the 5 bits being
outputted from the convolutional encoder and outputting the
remaining bits; a bit ordering unit for re-ordering the bits being
outputted from the bit puncturing unit; and a bit to symbol
converter for converting the bits being outputted from the bit
ordering unit to symbols..].
4. The transmitting system of claim .[.3.]. .Iadd.1.Iaddend.,
wherein, among the 5 bits being outputted from the convolutional
encoder, the bit puncturing unit removes a fourth bit and outputs
first, second, third, and fifth bits, and wherein the bit ordering
unit outputs .[.the.]. output bits by an order of the first, third,
second, and fifth bits, thereby performing 1/4-.Iadd.code
.Iaddend.rate encoding on the input bit of the mobile service
data.
5. The transmitting system of claim .[.3.]. .Iadd.1.Iaddend.,
wherein, among the 5 bits being outputted from the convolutional
encoder, the bit puncturing unit removes a third bit and outputs
first, second, fourth, and fifth bits, and wherein the bit ordering
unit directly outputs .[.the.]. output bits by the order of the
first, second, fourth, and fifth bits without modification, thereby
performing 1/4-.Iadd.code .Iaddend.rate encoding on the input bit
of the mobile service data.
6. The transmitting system of claim .[.3.]. .Iadd.1.Iaddend.,
wherein, among the 5 bits being outputted from the convolutional
encoder, the bit puncturing unit removes third, fourth, and fifth
bits and outputs first and second bits, and wherein the bit
ordering unit directly outputs the first and second bits outputted
from the bit puncturing unit without modification, thereby
performing 1/2-.Iadd.code .Iaddend.rate encoding on the input bit
of the mobile service data.
7. The transmitting system of claim .[.2.]. .Iadd.1.Iaddend.,
wherein the symbol encoder performs 1/2-.Iadd.code .Iaddend.rate
encoding on one input bit of an odd-numbered input bit and an
even-numbered input bit of the mobile service data, and wherein the
symbol encoder performs 1/4-.Iadd.code .Iaddend.rate encoding on
the other input bit, thereby performing 1/3-.Iadd.code
.Iaddend.rate encoding on the mobile service data.
8. A method of processing a broadcast signal of a transmitting
system, .Iadd.the method .Iaddend.comprising: performing.Iadd., by
a Reed-Solomon (RS) frame encoder, .Iaddend.error correction
encoding on an RS frame payload including mobile service data so as
to form an RS frame, and dividing the RS frame into a plurality of
portions; .[.performing one of 1/2-rate encoding and 1/4-rate
encoding on each bit of the mobile service data included in each
portion;.]. .Iadd.converting, by a byte to bit converter, bytes of
mobile service data to bits of the mobile service data included in
each portion; encoding, by a symbol encoder, each bit of the mobile
service data at one of a 1/2 code rate or a 1/4 code rate, wherein
encoding each bit comprises: convolutional encoding an input bit of
the mobile service data into 5 output bits; removing at least one
of the 5 output bits; and re-ordering remaining bits unremoved from
the 5 output bits according to the one of the 1/2 code rate or the
1/4 code rate, and outputting one or more symbols;.Iaddend. mapping
.[.a portion including.]..Iadd., by a group formatter, at least
.Iaddend.symbols of the 1/4-.Iadd.code .Iaddend.rate encoded mobile
service data .[.and.]. .Iadd.or .Iaddend.symbols of the
1/2-.Iadd.code .Iaddend.rate encoded mobile service data to a
corresponding region of a data group; and performing.Iadd., by a
trellis encoding module, .Iaddend.trellis encoding on the
.[.symbols of the 1/4-rate encoded mobile service data and the
symbols of the 1/2-rate encoded.]. mobile service data .[.of.].
.Iadd.mapped to .Iaddend.the data group.
9. The method of claim 8, .[.wherein performing one of 1/2-rate
encoding and 1/4-rate encoding comprises.]. .Iadd.further
comprising.Iaddend.: .[.converting each byte of the mobile service
data to symbols; encoding the symbols of the converted mobile
service data at a coding rate of H1/H2 (wherein H1 and H2 are
integers);.]. performing.Iadd., by a symbol interleaver,
.Iaddend.symbol interleaving in symbol units on .Iadd.the symbols
of .Iaddend.the .Iadd.encoded .Iaddend.mobile service data
.[.encoded at the coding rate of H1/H2.].; and converting.Iadd., by
a symbol to byte converter, .Iaddend.the symbol-interleaved symbols
to bytes.
.[.10. The method of claim 9, wherein encoding the symbols of the
converted mobile service data comprises: performing convolutional
encoding on an input bit of the mobile service data, thereby
outputting the convolutionally encoded input bit as 5 bits;
removing at least one of the 5 bits being convolutionally encoded
and outputted, and outputting the remaining bits; re-ordering the
bits being inputted without being removed; and converting the
re-ordered bits to symbols..].
11. A receiving system comprising: a tuner receiving for a
broadcast signal including a data group, wherein the data group
includes mobile service data that are encoded at a coding rate of
1/2 and then processed with trellis encoding, mobile service data
that are encoded at a coding rate of 1/4 and then processed with
trellis encoding, and a plurality of known data sequences; a
demodulator for demodulating the received broadcast signal; a first
decoder for matching the mobile service data being outputted from
the demodulator in block sizes for turbo-decoding with mobile
service data that are symbol-decoded and fed-back, and performing
trellis decoding on the matched mobile service data; a first symbol
mapper for converting a corresponding soft-decision value of the
trellis-decoded mobile service data to an input format of a second
decoder, when the soft-decision value of the trellis-decoded mobile
service data corresponds to a soft-decision value of a 1/4-rate
encoded symbol, thereby outputting the converted soft-decision
value to the second decoder; a second decoder for performing
symbol-decoding on the soft-decision value being outputted from the
first symbol mapper; a second symbol mapper for converting a
corresponding soft-decision value of the symbol-decoded mobile
service data to an input format of the first decoder, when the
soft-decision value of the symbol-decoded mobile service data
corresponds to a soft-decision value of a 1/4-rate encoded symbol,
thereby outputting the converted soft-decision value to the first
decoder; and an RS frame decoder for performing error correction
decoding on an RS frame including the mobile service data that are
symbol-decoded by the second decoder.
12. The receiving system of claim 11, further comprising: a symbol
deinterleaver for block-deinterleaving in symbol units the
soft-decision value of the mobile service data that are
trellis-decoded by the first decoder, thereby outputting the
block-deinterleaved soft-decision value to the first symbol mapper;
and a symbol interleaver for block-interleaving in symbol units the
soft-decision value of the mobile service data being outputted from
the second symbol mapper, thereby outputting the block-interleaved
soft-decision value to the first decoder.
13. The receiving system of claim 12, wherein, when the
soft-decision value of the block-deinterleaved mobile service data
corresponds to soft-decision values of two 1/4-rate encoded
symbols, the first symbol mapper adds a corresponding soft-decision
value of an odd-number symbol among the two symbols and a
corresponding soft-decision value of an even-number symbol among
the two symbols, and wherein the first symbol mapper outputs the
added soft-decision value to the second decoder.
14. The receiving system of claim 12, wherein, when the
soft-decision value of the symbol-deinterleaved mobile service data
corresponds to soft-decision value of a 1/2-rate encoded symbol,
the soft-decision value of the input symbol is directly outputted
to the second decoder without modification.
15. The receiving system of claim 11, further comprising: a first
buffer for storing the demodulated mobile service data, and
repeating the stored mobile service data in a block size for
turbo-decoding as many times as a predetermined number of
turbo-decoding iterations, thereby outputting the mobile service
data to the first decoder; and a second buffer for storing the
mobile service data that are symbol-decoded by the second decoder
and outputting the stored mobile service data to the RS frame
decoder.
16. A method of processing a broadcast signal of a receiving
system, comprising: receiving a broadcast signal including a data
group, wherein the data group includes mobile service data that are
encoded at a coding rate of 1/2 and then processed with trellis
encoding, mobile service data that are encoded at a coding rate of
1/4 and then processed with trellis encoding, and a plurality of
known data sequences; demodulating the received broadcast signal;
matching the mobile service data being demodulated and outputted in
block sizes for turbo-decoding with mobile service data being
symbol-decoded and fed-back, and performing trellis decoding on the
matched mobile service data, thereby performing a first decoding
process; converting a corresponding soft-decision value of the
trellis-decoded mobile service data to an input format of a second
decoding process, when the soft-decision value of the
trellis-decoded mobile service data corresponds to a soft-decision
value of a 1/4-rate encoded symbol, thereby performing a first
symbol-mapping process; performing symbol-decoding on the
soft-decision value of the mobile service data being outputted
after being processed with the first symbol-mapping process,
thereby performing the second decoding process; converting a
corresponding soft-decision value of the symbol-decoded mobile
service data to an input format of the first decoding process, when
the soft-decision value of the symbol-decoded mobile service data
corresponds to a soft-decision value of a 1/4-rate encoded symbol,
thereby feeding-back the converted soft-decision value to the first
decoding process, so as to perform the second symbol-mapping
process; and performing error correction decoding on an RS frame
including the symbol-decoded mobile service data.
17. The method of claim 16, further comprising:
block-deinterleaving in symbol units the soft-decision value of the
trellis-decoded mobile service data, thereby outputting the
block-deinterleaved soft-decision value to the first symbol-mapping
process, so as to perform a symbol-deinterleaving process; and
block-interleaving in symbol units the soft-decision value of the
mobile service data being outputted after the second symbol-mapping
process, thereby outputting the block-interleaved soft-decision
value to the first decoding process, so as to perform
symbol-interleaving process.
18. The method of claim 17, wherein, when the soft-decision value
of the symbol-deinterleaved mobile service data corresponds to
soft-decision values of two 1/4-rate encoded symbols, the first
symbol-mapping process adds a corresponding soft-decision value of
an odd-number symbol among the two symbols and a corresponding
soft-decision value of an even-number symbol among the two symbols,
thereby outputting the added soft-decision value to the second
decoding process.
19. The method of claim 17, wherein, when the soft-decision value
of the symbol-deinterleaved mobile service data corresponds to
soft-decision value of a 1/2-rate encoded symbol, the soft-decision
value of the input symbol is directly outputted to the second
decoding process without modification.
20. The method of claim 16, further comprising: storing the
demodulated mobile service data, and repeating the stored mobile
service data in a block size for turbo-decoding as many times as a
predetermined number of turbo-decoding iterations, thereby
outputting the repeated mobile service data to the first decoding
process; and storing the symbol-decoded mobile service data, and
outputting the stored mobile service data for error correction.
.Iadd.21. The transmitting system of claim 1, further comprising: a
signaling encoder for encoding signaling data, wherein the
signaling data include transmission parameter channel (TPC) data,
and wherein the TPC data include information related to the data
group..Iaddend.
.Iadd.22. The method of claim 8, further comprising: encoding
signaling data, wherein the signaling data include transmission
parameter channel (TPC) data, and wherein the TPC data include
information related to the data group..Iaddend.
.Iadd.23. The receiving system of claim 11, further comprising: a
signaling decoder for decoding signaling data in the demodulated
broadcast signal, wherein the signaling data include transmission
parameter channel (TPC) data, and wherein the TPC data include
information related to the data group..Iaddend.
.Iadd.24. The method of claim 16, further comprising: decoding
signaling data in the demodulated broadcast signal, wherein the
signaling data include transmission parameter channel (TPC) data,
and wherein the TPC data include information related to the data
group..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. The Field
The present invention relates to a digital broadcasting system for
transmitting and receiving a digital broadcast signal, and more
particularly, to a transmitting system for processing and
transmitting the digital broadcast signal, and a receiving system
for receiving and processing the digital broadcast signal and, a
method of processing data in the transmitting system and the
receiving system.
2. Description of the Related Art
The Vestigial Sideband (VSB) transmission mode, which is adopted as
the standard for digital broadcasting in North America and the
Republic of Korea, is a system using a single carrier method.
Therefore, the receiving performance of the digital broadcast
receiving system may be deteriorated in a poor channel environment.
Particularly, since resistance to changes in channels and noise is
more highly required when using portable and/or mobile broadcast
receivers, the receiving performance may be even more deteriorated
when transmitting mobile service data by the VSB transmission
mode.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a
transmitting system and a receiving system and a method of
processing a broadcast signal that are highly resistant to channel
changes and noise.
Another object of the present invention is to provide a
transmitting system and a receiving system and a method of
processing a broadcast signal that can enhance the receiving
performance of the receiving system by performing additional
encoding on mobile service data and by transmitting the processed
data to the receiving system.
A further object of the present invention is to provide a
transmitting system and a receiving system and a method of
processing a broadcast signal that can also enhance the receiving
performance of the receiving system by inserting known data already
known in accordance with a pre-agreement between the receiving
system and the transmitting system in a predetermined region within
a data region.
A further aspect of the present invention is to provide a
transmitting system and a receiving system and a method of
processing a broadcast signal that can perform efficiently a block
encoding and a block decoding on mobile service data.
To achieve these objects and other advantages and in accordance
with the purpose of the invention, as embodied and broadly
described herein, a transmitting system may include an RS frame
encoder, a block processor, a group formatter, and a trellis
encoding module. The RS frame encoder performs error correction
encoding on an RS frame payload including mobile service data so as
to form an RS frame and divides the RS frame into a plurality of
portions. The block processor performs one of 1/2-rate encoding and
1/4-rate encoding on each bit of the mobile service data included
in each portion. The group formatter maps a portion including
symbols of the 1/4-rate encoded mobile service data and symbols of
the 1/2-rate encoded mobile service data to a corresponding region
of a data group. And the trellis encoding module performs trellis
encoding on the symbols of the 1/4-rate encoded mobile service data
and the symbols of the 1/2-rate encoded mobile service data of the
data group.
Herein, the block processor may include a byte to symbol converter
for converting each byte of the mobile service data to symbols, a
symbol encoder for encoding the symbols of the mobile service data
being outputted from the byte to symbol converter at a coding rate
of H1/H2 (wherein H1 and H2 are integers), a symbol interleaver for
performing symbol interleaving in symbol units on the mobile
service data encoded at the coding rate of H1/H2, and a symbol to
byte converter for converting the symbol-interleaved symbols to
bytes.
More specifically, the symbol encoder may include a convolutional
encoder for performing convolutional encoding on an input bit of
the mobile service data, thereby outputting the convolutionally
encoded input bit as 5 bits, a bit puncturing unit for removing at
least one of the 5 bits being outputted from the convolutional
encoder and outputting the remaining bits, a bit ordering unit for
re-ordering the bits being outputted from the bit puncturing unit,
and a bit to symbol converter for converting the bits being
outputted from the bit ordering unit to symbols.
In an embodiment according to the present invention, the bit
puncturing unit, among the 5 bits being outputted from the
convolutional encoder, removes a fourth bit and outputs first,
second, third, and fifth bits, and the bit ordering unit outputs
the output bits by an order of the first, third, second, and fifth
bits, thereby performing 1/4-rate encoding on the input bit of the
mobile service data.
In another embodiment according to the present invention, the bit
puncturing unit, among the 5 bits being outputted from the
convolutional encoder, removes a third bit and outputs first,
second, fourth, and fifth bits, and the bit ordering unit directly
outputs the output bits by the order of the first, second, fourth,
and fifth bits without modification, thereby performing 1/4-rate
encoding on the input bit of the mobile service data.
In another embodiment according to the present invention, the bit
puncturing unit, among the 5 bits being outputted from the
convolutional encoder, removes third, fourth, and fifth bits and
outputs first and second bits, and the bit ordering unit directly
outputs the first and second bits outputted from the bit puncturing
unit without modification, thereby performing 1/2-rate encoding on
the input bit of the mobile service data.
Herein, the symbol encoder performs 1/2-rate encoding on one input
bit of an odd-numbered input bit and an even-numbered input bit of
the mobile service data, and the symbol encoder performs 1/4-rate
encoding on the other input bit, thereby performing 1/3-rate
encoding on the mobile service data.
In another aspect of the present invention, a method of processing
a broadcast signal of a transmitting system may include performing
error correction encoding on an RS frame payload including mobile
service data so as to form an RS frame, and dividing the RS frame
into a plurality of portions, performing one of 1/2-rate encoding
and 1/4-rate encoding on each bit of the mobile service data
included in each portion, mapping a portion including symbols of
the 1/4-rate encoded mobile service data and symbols of the
1/2-rate encoded mobile service data to a corresponding region of a
data group, and performing trellis encoding on the symbols of the
1/4-rate encoded mobile service data and the symbols of the
1/2-rate encoded mobile service data of the data group.
In another aspect of the present invention, a receiving system may
include a tuner, a demodulator, a first decoder, a first symbol
mapper, a second decoder, and a second symbol mapper. The tuner
receives a broadcast signal including a data group. Herein the data
group includes mobile service data that are encoded at a coding
rate of 1/2 and then processed with trellis encoding, mobile
service data that are encoded at a coding rate of 1/4 and then
processed with trellis encoding, and a plurality of known data
sequences. The demodulator demodulates the received broadcast
signal. The first decoder matches the mobile service data being
outputted from the demodulator in block sizes for turbo-decoding
with mobile service data that are symbol-decoded and fed-back, and
performs trellis decoding on the matched mobile service data. The
first symbol mapper converts a corresponding soft-decision value of
the trellis-decoded mobile service data to an input format of a
second decoder, when the soft-decision value of the trellis-decoded
mobile service data corresponds to a soft-decision value of a
1/4-rate encoded symbol, thereby outputting the converted
soft-decision value to the second decoder. The second decoder
performs symbol-decoding on the soft-decision value being outputted
from the first symbol mapper. The second symbol mapper converts a
corresponding soft-decision value of the symbol-decoded mobile
service data to an input format of the first decoder, when the
soft-decision value of the symbol-decoded mobile service data
corresponds to a soft-decision value of a 1/4-rate encoded symbol,
thereby outputting the converted soft-decision value to the first
decoder. And the RS frame decoder performs error correction
decoding on an RS frame including the mobile service data that are
symbol-decoded by the second decoder.
In another aspect of the present invention, the receiving system
may further include a symbol deinterleaver for block-deinterleaving
in symbol units the soft-decision value of the mobile service data
that are trellis-decoded by the first decoder, thereby outputting
the block-deinterleaved soft-decision value to the first symbol
mapper, and a symbol interleaver for block-interleaving in symbol
units the soft-decision value of the mobile service data being
outputted from the second symbol mapper, thereby outputting the
block-interleaved soft-decision value to the first decoder.
Herein, when the soft-decision value of the block-deinterleaved
mobile service data corresponds to soft-decision values of two
1/4-rate encoded symbols, the first symbol mapper adds a
corresponding soft-decision value of an odd-number symbol among the
two symbols and a corresponding soft-decision value of an
even-number symbol among the two symbols, and the first symbol
mapper outputs the added soft-decision value to the second
decoder.
In addition, when the soft-decision value of the
symbol-deinterleaved mobile service data corresponds to
soft-decision value of a 1/2-rate encoded symbol, the first symbol
mapper directly outputs the soft-decision value of the input symbol
to the second decoder without modification.
In another aspect of the present invention, the receiving system
may further include a first buffer for storing the demodulated
mobile service data, and repeating the stored mobile service data
in a block size for turbo-decoding as many times as a predetermined
number of turbo-decoding iterations, thereby outputting the mobile
service data to the first decoder, and a second buffer for storing
the mobile service data that are symbol-decoded by the second
decoder and outputting the stored mobile service data to the RS
frame decoder.
In another aspect of the present invention, a method of processing
a broadcast signal of a receiving system may include receiving a
broadcast signal including a data group, the data group including
mobile service data that are encoded at a coding rate of 1/2 and
then processed with trellis encoding, mobile service data that are
encoded at a coding rate of 1/4 and then processed with trellis
encoding, and a plurality of known data sequences, demodulating the
received broadcast signal, matching the mobile service data being
demodulated and outputted in block sizes for turbo-decoding with
mobile service data being symbol-decoded and fed-back, and
performing trellis decoding on the matched mobile service data,
thereby performing a first decoding process, converting a
corresponding soft-decision value of the trellis-decoded mobile
service data to an input format of a second decoding process, when
the soft-decision value of the trellis-decoded mobile service data
corresponds to a soft-decision value of a 1/4-rate encoded symbol,
thereby performing a first symbol-mapping process, performing
symbol-decoding on the soft-decision value of the mobile service
data being outputted after being processed with the first
symbol-mapping process, thereby performing the second decoding
process, converting a corresponding soft-decision value of the
symbol-decoded mobile service data to an input format of the first
decoding process, when the soft-decision value of the
symbol-decoded mobile service data corresponds to a soft-decision
value of a 1/4-rate encoded symbol, thereby feeding-back the
converted soft-decision value to the first decoding process, so as
to perform the second symbol-mapping process; and performing error
correction decoding on an RS frame including the symbol-decoded
mobile service data.
It is to be understood that both the foregoing general description
and the following detailed description of the present invention are
exemplary and explanatory and are intended to provide further
explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a structure of a M/H frame for transmitting and
receiving mobile service data according to the present
invention;
FIG. 2 illustrates an exemplary structure of a VSB frame;
FIG. 3 illustrates a mapping example of the positions to which the
first 4 slots of a sub-frame are assigned with respect to a VSB
frame in a space region;
FIG. 4 illustrates a mapping example of the positions to which the
first 4 slots of a sub-frame are assigned with respect to a VSB
frame in a time region;
FIG. 5 illustrates an alignment of data after being data
interleaved and identified;
FIG. 6 illustrates an enlarged portion of the data group shown in
FIG. 5 for a better understanding of the present invention;
FIG. 7 illustrates an alignment of data before being data
interleaved and identified;
FIG. 8 illustrates an enlarged portion of the data group shown in
FIG. 7 for a better understanding of the present invention;
FIG. 9 illustrates an exemplary assignment order of data groups
being assigned to one of 5 sub-frames according to the present
invention;
FIG. 10 illustrates an example of assigning a single parade to an
M/H frame according to the present invention;
FIG. 11 illustrates an example of assigning 3 parades to an M/H
frame according to the present invention;
FIG. 12 illustrates an example of expanding the assignment process
of 3 parades to 5 sub-frames within an M/H frame;
FIG. 13 illustrates a data transmission structure according to an
embodiment of the present invention, wherein signaling data are
included in a data group so as to be transmitted;
FIG. 14 illustrates a block diagram showing a general structure of
a transmitting system according to an embodiment of the present
invention;
FIG. 15 is a diagram illustrating an example of RS frame payload
according to the present invention;
FIG. 16 is a diagram illustrating a structure of an M/H header
within an M/H service data packet according to the present
invention;
FIG. 17(a) and FIG. 17(b) are diagrams illustrating another example
of RS frame payload according to the present invention; and
FIG. 18 illustrates a block diagram showing an example of a service
multiplexer of FIG. 14;
FIG. 19 illustrates a block diagram showing an embodiment of a
transmitter of FIG. 14;
FIG. 20 illustrates a block diagram showing an example of a
pre-processor of FIG. 19;
FIG. 21 illustrates a conceptual block diagram of the M/H frame
encoder of FIG. 20;
FIG. 22 illustrates a detailed block diagram of an RS frame encoder
of FIG. 21;
FIG. 23(a) and FIG. 23(b) illustrate a process of one or two RS
frame being divided into several portions, based upon an RS frame
mode value, and a process of each portion being assigned to a
corresponding region within the respective data group;
FIG. 24(a) to FIG. 24(c) illustrate error correction encoding and
error detection encoding processes according to an embodiment of
the present invention;
FIG. 25(a) to FIG. 25(d) illustrate an example of performing a row
permutation (or interleaving) process in super frame units
according to the present invention;
FIG. 26(a) and FIG. 26(b) illustrate an example which a parade
consists of two RS frames
FIG. 27(a) and FIG. 27(b) illustrate an exemplary process of
dividing an RS frame for configuring a data group according to the
present invention;
FIG. 28 illustrates a block diagram of a block processor according
to an embodiment of the present invention;
FIG. 29 illustrates a block diagram of a symbol encoder according
to an embodiment of the present invention;
FIG. 30 illustrates a detailed block diagram of a convolution
encoder of the symbol encoder;
FIG. 31 illustrates an exemplary of a bit puncturing process and a
bit ordering process when the symbol encoder operates at a coding
rate of 1/4 according to the present invention;
FIG. 32 illustrates an exemplary of a bit puncturing process and a
bit ordering process when the symbol encoder operates at a coding
rate of 1/2 according to the present invention;
FIG. 33 illustrates a symbol interleaver of the block
processor;
FIG. 34 illustrates a block diagram of a group formatter of FIG. 20
according to an embodiment of the present invention;
FIG. 35 illustrates a block diagram of a trellis encoder according
to an embodiment of the present invention;
FIG. 36 illustrates an example of assigning signaling information
area according to an embodiment of the present invention;
FIG. 37 illustrates a detailed block diagram of a signaling encoder
of FIG. 20 according to the present invention;
FIG. 38 illustrates an example of a syntax structure of TPC data
according to the present invention;
FIG. 39 illustrates an example of a transmission scenario of the
TPC data and the FIC data level according to the present
invention;
FIG. 40 illustrates an example of power saving of in a receiver
when transmitting 3 parades to an M/H frame level according to the
present invention;
FIG. 41 illustrates an example of a training sequence at the byte
level before trellis encoding according to the present
invention;
FIG. 42 illustrates an example of a training sequence at the symbol
level after trellis encoding according to the present
invention;
FIG. 43 illustrates a block diagram of a receiving system according
to an embodiment of the present invention;
FIG. 44 is a block diagram showing an example of a demodulating
unit in the receiving system;
FIG. 45 is a block diagram showing an example of an operation
controller according to the present invention;
FIG. 46 illustrates an example of linear interpolation according to
the present invention;
FIG. 47 illustrates an example of linear extrapolation according to
the present invention;
FIG. 48 illustrates a block diagram of a channel equalizer
according to an embodiment of the present invention;
FIG. 49 illustrates a block diagram of a block decoder according to
an embodiment of the present invention;
FIG. 50(a) to FIG. 50(d) illustrate an exemplary operation process
of an outer mapper in the block decoder of FIG. 49;
FIG. 51(a) and FIG. 51(b) illustrate an exemplary process of
configuring one or two RS frame by collecting a plurality of
portions according to the present invention; and
FIG. 52 and FIG. 53 illustrate process steps of error correction
decoding according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the invention, which can achieve the above
objects, will now be described with reference to the accompanying
drawings. The configuration and operation of the invention,
illustrated in the drawings and described below with reference to
the drawings, will be described using at least one embodiment
without limiting the spirit and the essential configuration and
operation of the invention.
DEFINITION OF TERMS USED IN THE PRESENT INVENTION
Although most terms of elements in the present invention have been
selected from general ones widely used in the art taking into
consideration their functions in the invention, the terms may be
changed depending on the intention or convention of those skilled
in the art or the introduction of new technology. Some terms have
been arbitrarily selected by the applicant and their meanings are
explained in detail in the following description as needed. Thus,
the definitions of the terms used in the invention should be
determined based on the whole content of this specification
together with the intended meanings of the terms rather than their
simple names or meanings.
Among the terms used in the description of the present invention,
main service data correspond to data that can be received by a
fixed receiving system and may include audio/video (A/V) data. More
specifically, the main service data may include A/V data of high
definition (HD) or standard definition (SD) levels and may also
include diverse data types required for data broadcasting. Also,
the known data correspond to data pre-known in accordance with a
pre-arranged agreement between the receiving system and the
transmitting system.
Additionally, among the terms used in the present invention, "M/H
(or MH)" corresponds to the initials of "mobile" and "handheld" and
represents the opposite concept of a fixed-type system.
Furthermore, the M/H service data may include at least one of
mobile service data and handheld service data, and will also be
referred to as "mobile service data" for simplicity. Herein, the
mobile service data not only correspond to M/H service data but may
also include any type of service data with mobile or portable
characteristics. Therefore, the mobile service data according to
the present invention are not limited only to the M/H service
data.
The above-described mobile service data may correspond to data
having information, such as program execution files, stock
information, and so on, and may also correspond to A/V data. Most
particularly, the mobile service data may correspond to A/V data
having lower resolution and lower data rate as compared to the main
service data. For example, if an A/V codec that is used for a
conventional main service corresponds to a MPEG-2 codec, a MPEG-4
advanced video coding (AVC) or scalable video coding (SVC) having
better image compression efficiency may be used as the A/V codec
for the mobile service. Furthermore, any type of data may be
transmitted as the mobile service data. For example, transport
protocol expert group (TPEG) data for broadcasting real-time
transportation information may be transmitted as the main service
data.
Also, a data service using the mobile service data may include
weather forecast services, traffic information services, stock
information services, viewer participation quiz programs, real-time
polls and surveys, interactive education broadcast programs, gaming
services, services providing information on synopsis, character,
background music, and filming sites of soap operas or series,
services providing information on past match scores and player
profiles and achievements, and services providing information on
product information and programs classified by service, medium,
time, and theme enabling purchase orders to be processed. Herein,
the present invention is not limited only to the services mentioned
above.
In the present invention, the transmitting system provides backward
compatibility in the main service data so as to be received by the
conventional receiving system. Herein, the main service data and
the mobile service data are multiplexed to the same physical
channel and then transmitted.
Furthermore, the transmitting system according to the present
invention performs additional encoding on the mobile service data
and inserts the data already known by the receiving system and
transmitting system (e.g., known data), thereby transmitting the
processed data.
Therefore, when using the transmitting system according to the
present invention, the receiving system may receive the mobile
service data during a mobile state and may also receive the mobile
service data with stability despite various distortion and noise
occurring within the channel.
M/H Frame Structure
In the embodiment of the present invention, the mobile service data
are first multiplexed with main service data in M/H frame units
and, then, modulated in a VSB mode and transmitted to the receiving
system.
At this point, one M/H frame consists of K1 number of sub-frames,
wherein one sub-frame includes K2 number of slots. Also, each slot
may be configured of K3 number of data packets. In the embodiment
of the present invention, K1 will be set to 5, K2 will be set to
16, and K3 will be set to 156 (i.e., K1=5, K2=16, and K3=156). The
values for K1, K2, and K3 presented in this embodiment either
correspond to values according to a preferred embodiment or are
merely exemplary. Therefore, the above-mentioned values will not
limit the scope of the present invention.
FIG. 1 illustrates a structure of an M/H frame for transmitting and
receiving mobile service data according to the present invention.
In the example shown in FIG. 1, one M/H frame consists of 5
sub-frames, wherein each sub-frame includes 16 slots. In this case,
the M/H frame according to the present invention includes 5
sub-frames and 80 slots.
Also, in a packet level, one slot is configured of 156 data packets
(i.e., transport stream packets), and in a symbol level, one slot
is configured of 156 data segments. Herein, the size of one slot
corresponds to one half (1/2) of a VSB field. More specifically,
since one 207-byte data packet has the same amount of data as a
data segment, a data packet prior to being interleaved may also be
used as a data segment.
At this point, two VSB fields are grouped to form a VSB frame.
FIG. 2 illustrates an exemplary structure of a VSB frame, wherein
one VSB frame consists of 2 VSB fields (i.e., an odd field and an
even field). Herein, each VSB field includes a field
synchronization segment and 312 data segments.
The slot corresponds to a basic time period for multiplexing the
mobile service data and the main service data. Herein, one slot may
either include the mobile service data or be configured only of the
main service data.
If one M/H frame is transmitted during one slot, the first 118 data
packets within the slot correspond to a data group. And, the
remaining 38 data packets become the main service data packets. In
another example, when no data group exists in a slot, the
corresponding slot is configured of 156 main service data
packets.
Meanwhile, when the slots are assigned to a VSB frame, an offset
exists for each assigned position.
FIG. 3 illustrates a mapping example of the positions to which the
first 4 slots of a sub-frame are assigned with respect to a VSB
frame in a space region. And, FIG. 4 illustrates a mapping example
of the positions to which the first 4 slots of a sub-frame are
assigned with respect to a VSB frame in a time region.
Referring to FIG. 3 and FIG. 4, a 38.sup.th data packet (TS packet
#37) of a 1.sup.st slot (Slot #0) is mapped to the 1.sup.st data
packet of an odd VSB field. A 38.sup.th data packet (TS packet #37)
of a 2.sup.nd slot (Slot #1) is mapped to the 157.sup.th data
packet of an odd VSB field. Also, a 38.sup.th data packet (TS
packet #37) of a 3.sup.rd slot (Slot #2) is mapped to the 1.sup.st
data packet of an even VSB field. And, a 38.sup.th data packet (TS
packet #37) of a 4.sup.th Slot (Slot #3) is mapped to the
157.sup.th data packet of an even VSB field. Similarly, the
remaining 12 slots within the corresponding sub-frame are mapped in
the subsequent VSB frames using the same method.
Meanwhile, one data group may be divided into at least one or more
hierarchical regions. And, depending upon the characteristics of
each hierarchical region, the type of mobile service data being
inserted in each region may vary. For example, the data group
within each region may be divided (or categorized) based upon the
receiving performance.
In an example given in the present invention, a data group is
divided into regions A, B, C, and D in a data configuration after
data interleaving.
FIG. 5 illustrates an alignment of data after being data
interleaved and identified. FIG. 6 illustrates an enlarged portion
of the data group shown in FIG. 5 for a better understanding of the
present invention. FIG. 7 illustrates an alignment of data before
being data interleaved and identified. And, FIG. 8 illustrates an
enlarged portion of the data group shown in FIG. 7 for a better
understanding of the present invention. More specifically, a data
structure identical to that shown in FIG. 5 is transmitted to a
receiving system. In other words, one data packet is
data-interleaved so as to be scattered to a plurality of data
segments, thereby being transmitted to the receiving system. FIG. 5
illustrates an example of one data group being scattered to 170
data segments. At this point, since one 207-byte packet has the
same amount of data as one data segment, the packet that is not yet
processed with data-interleaving may be used as the data
segment.
FIG. 5 shows an example of dividing a data group prior to being
data-interleaved into 10 M/H blocks (i.e., M/H block 1 (B1) to M/H
block 10 (B10)). In this example, each M/H block has the length of
16 segments. Referring to FIG. 5, only the RS parity data are
allocated to a portion of 5 segments before the M/H block 1 (B1)
and 5 segments behind the M/H block 10 (B10). The RS parity data
are excluded in regions A to D of the data group.
More specifically, when it is assumed that one data group is
divided into regions A, B, C, and D, each M/H block may be included
in any one of region A to region D depending upon the
characteristic of each M/H block within the data group. At this
point, according to an embodiment of the present invention, each
M/H block may be included in any one of region A to region D based
upon an interference level of main service data.
Herein, the data group is divided into a plurality of regions to be
used for different purposes. More specifically, a region of the
main service data having no interference or a very low interference
level may be considered to have a more resistant (or stronger)
receiving performance as compared to regions having higher
interference levels. Additionally, when using a system inserting
and transmitting known data in the data group, wherein the known
data are known based upon an agreement between the transmitting
system and the receiving system, and when consecutively long known
data are to be periodically inserted in the mobile service data,
the known data having a predetermined length may be periodically
inserted in the region having no interference from the main service
data (i.e., a region wherein the main service data are not mixed).
However, due to interference from the main service data, it is
difficult to periodically insert known data and also to insert
consecutively long known data to a region having interference from
the main service data.
Referring to FIG. 5, M/H block 4 (B4) to M/H block 7 (B7)
correspond to regions without interference of the main service
data. M/H block 4 (B4) to M/H block 7 (B7) within the data group
shown in FIG. 5 correspond to a region where no interference from
the main service data occurs. In this example, a long known data
sequence is inserted at both the beginning and end of each M/H
block. In the description of the present invention, the region
including M/H block 4 (B4) to M/H block 7 (B7) will be referred to
as "region A (=B4+B5+B6+B7)". As described above, when the data
group includes region A having a long known data sequence inserted
at both the beginning and end of each M/H block, the receiving
system is capable of performing equalization by using the channel
information that can be obtained from the known data. Therefore,
the strongest equalizing performance may be yielded (or obtained)
from one of region A to region D.
In the example of the data group shown in FIG. 5, M/H block 3 (B3)
and M/H block 8 (B8) correspond to a region having little
interference from the main service data. Herein, a long known data
sequence is inserted in only one side of each M/H block B3 and B8.
More specifically, due to the interference from the main service
data, a long known data sequence is inserted at the end of M/H
block 3 (B3), and another long known data sequence is inserted at
the beginning of M/H block 8 (B8). In the present invention, the
region including M/H block 3 (B3) and M/H block 8 (B8) will be
referred to as "region B(=B3+B8)". As described above, when the
data group includes region B having a long known data sequence
inserted at only one side (beginning or end) of each M/H block, the
receiving system is capable of performing equalization by using the
channel information that can be obtained from the known data.
Therefore, a stronger equalizing performance as compared to region
C/D may be yielded (or obtained).
Referring to FIG. 5, M/H block 2 (B2) and M/H block 9 (B9)
correspond to a region having more interference from the main
service data as compared to region B. A long known data sequence
cannot be inserted in any side of M/H block 2 (B2) and M/H block 9
(B9). Herein, the region including M/H block 2 (B2) and M/H block 9
(B9) will be referred to as "region C(=B2+B9)". Finally, in the
example shown in FIG. 5, M/H block 1 (B1) and M/H block 10 (B10)
correspond to a region having more interference from the main
service data as compared to region C. Similarly, a long known data
sequence cannot be inserted in any side of M/H block 1 (B1) and M/H
block 10 (B10).
Herein, the region including M/H block 1 (B1) and M/H block 10
(B10) will be referred to as "region D (=B1+B10)". Since region C/D
is spaced further apart from the known data sequence, when the
channel environment undergoes frequent and abrupt changes, the
receiving performance of region C/D may be deteriorated.
FIG. 7 illustrates a data structure prior to data interleaving.
More specifically, FIG. 7 illustrates an example of 118 data
packets being allocated to a data group. FIG. 7 shows an example of
a data group consisting of 118 data packets, wherein, based upon a
reference packet (e.g., a 1.sup.st packet (or data segment) or
157.sup.th packet (or data segment) after a field synchronization
signal), when allocating data packets to a VSB frame, 37 packets
are included before the reference packet and 81 packets (including
the reference packet) are included afterwards.
In other words, with reference to FIG. 5, a field synchronization
signal is placed (or assigned) between M/H block 2 (B2) and M/H
block 3 (B3). Accordingly, this indicates that the slot has an
off-set of 37 data packets with respect to the corresponding VSB
field.
The size of the data groups, number of hierarchical regions within
the data group, the size of each region, the number of M/H blocks
included in each region, the size of each M/H block, and so on
described above are merely exemplary. Therefore, the present
invention will not be limited to the examples described above.
FIG. 9 illustrates an exemplary assignment order of data groups
being assigned to one of 5 sub-frames, wherein the 5 sub-frames
configure an M/H frame. For example, the method of assigning data
groups may be identically applied to all M/H frames or differently
applied to each M/H frame. Furthermore, the method of assigning
data groups may be identically applied to all sub-frames or
differently applied to each sub-frame. At this point, when it is
assumed that the data groups are assigned using the same method in
all sub-frames of the corresponding M/H frame, the total number of
data groups being assigned to an M/H frame is equal to a multiple
of `5`.
According to the embodiment of the present invention, a plurality
of consecutive data groups is assigned to be spaced as far apart
from one another as possible within the M/H frame. Thus, the system
can be capable of responding promptly and effectively to any burst
error that may occur within a sub-frame.
For example, when it is assumed that 3 data groups are assigned to
a sub-frame, the data groups are assigned to a 1.sup.st slot (Slot
#0), a 5.sup.th slot (Slot #4), and a 9.sup.th slot (Slot #8) in
the sub-frame, respectively. FIG. 9 illustrates an example of
assigning 16 data groups in one sub-frame using the above-described
pattern (or rule). In other words, each data group is serially
assigned to 16 slots corresponding to the following numbers: 0, 8,
4, 12, 1, 9, 5, 13, 2, 10, 6, 14, 3, 11, 7, and 15.
Equation 1 below shows the above-described rule (or pattern) for
assigning data groups in a sub-frame. j=(4i+0)mod 16 0=0 if i<4,
0=2 else if i<8, Herein, 0=1 else if i<12, 0=3 else. Equation
1
Herein, j indicates the slot number within a sub-frame. The value
of j may range from 0 to 15 (i.e., 0.ltoreq.j.ltoreq.15). Also,
value of i indicates the data group number. The value of i may
range from 0 to 15 (i.e., 0.ltoreq.i.ltoreq.15).
In the present invention, a collection of data groups included in
an M/H frame will be referred to as a "parade". Based upon the RS
frame mode, the parade transmits data of at least one specific RS
frame.
The mobile service data within one RS frame may be assigned either
to all of regions A/B/C/D within the corresponding data group, or
to at least one of regions A/B/C/D. In the embodiment of the
present invention, the mobile service data within one RS frame may
be assigned either to all of regions A/B/C/D, or to at least one of
regions A/B and regions C/D. If the mobile service data are
assigned to the latter case (i.e., one of regions A/B and regions
C/D), the RS frame being assigned to regions A/B and the RS frame
being assigned to regions C/D within the corresponding data group
are different from one another. In the description of the present
invention, the RS frame being assigned to regions A/B within the
corresponding data group will be referred to as a "primary RS
frame", and the RS frame being assigned to regions C/D within the
corresponding data group will be referred to as a "secondary RS
frame", for simplicity. Also, the primary RS frame and the
secondary RS frame form (or configure) one parade. More
specifically, when the mobile service data within one RS frame are
assigned either to all of regions A/B/C/D within the corresponding
data group, one parade transmits one RS frame. In this case, also
the RS frame will be referred to as a "primary RS frame".
Conversely, when the mobile service data within one RS frame are
assigned either to at least one of regions A/B and regions C/D, one
parade may transmit up to 2 RS frames.
More specifically, the RS frame mode indicates whether a parade
transmits one RS frame, or whether the parade transmits two RS
frames.
Table 1 below shows an example of the RS frame mode.
TABLE-US-00001 TABLE 1 RS frame mode (2 bits) Description 00 There
is only one primary RS frame for all group regions 01 There are two
separate RS frames. Primary RS frame for group regions A and B
Secondary RS frame for group regions C and D 10 Reserved 11
Reserved
Table 1 illustrates an example of allocating 2 bits in order to
indicate the RS frame mode. For example, referring to Table 1, when
the RS frame mode value is equal to `00`, this indicates that one
parade transmits one RS frame. And, when the RS frame mode value is
equal to `01`, this indicates that one parade transmits two RS
frames, i.e., the primary RS frame and the secondary RS frame. More
specifically, when the RS frame mode value is equal to `01`, data
of the primary RS frame for regions A/B are assigned and
transmitted to regions A/B of the corresponding data group.
Similarly, data of the secondary RS frame for regions C/D are
assigned and transmitted to regions C/D of the corresponding data
group.
As described in the assignment of data groups, the parades are also
assigned to be spaced as far apart from one another as possible
within the sub-frame. Thus, the system can be capable of responding
promptly and effectively to any burst error that may occur within a
sub-frame.
Furthermore, the method of assigning parades may be identically
applied to all sub-frames or differently applied to each sub-frame.
According to the embodiment of the present invention, the parades
may be assigned differently for each M/H frame and identically for
all sub-frames within an M/H frame. More specifically, the M/H
frame structure may vary by M/H frame units. Thus, an ensemble rate
may be adjusted on a more frequent and flexible basis.
FIG. 10 illustrates an example of multiple data groups of a single
parade being assigned (or allocated) to an M/H frame. More
specifically, FIG. 10 illustrates an example of a plurality of data
groups included in a single parade, wherein the number of data
groups included in a sub-frame is equal to `3`, being allocated to
an M/H frame.
Referring to FIG. 10, 3 data groups are sequentially assigned to a
sub-frame at a cycle period of 4 slots. Accordingly, when this
process is equally performed in the 5 sub-frames included in the
corresponding M/H frame, 15 data groups are assigned to a single
M/H frame. Herein, the 15 data groups correspond to data groups
included in a parade. Therefore, since one sub-frame is configured
of 4 VSB frame, and since 3 data groups are included in a
sub-frame, the data group of the corresponding parade is not
assigned to one of the 4 VSB frames within a sub-frame.
For example, when it is assumed that one parade transmits one RS
frame, and that a RS frame encoder located in a later block
performs RS-encoding on the corresponding RS frame, thereby adding
24 bytes of parity data to the corresponding RS frame and
transmitting the processed RS frame, the parity data occupy
approximately 11.37% (=24/(187+24).times.100) of the total code
word length. Meanwhile, when one sub-frame includes 3 data groups,
and when the data groups included in the parade are assigned, as
shown in FIG. 10, a total of 15 data groups form an RS frame.
Accordingly, even when an error occurs in an entire data group due
to a burst noise within a channel, the percentile is merely 6.67%
(= 1/15.times.100). Therefore, the receiving system may correct all
errors by performing an erasure RS decoding process. More
specifically, when the erasure RS decoding is performed, a number
of channel errors corresponding to the number of RS parity bytes
may be corrected. By doing so, the receiving system may correct the
error of at least one data group within one parade. Thus, the
minimum burst noise length correctable by a RS frame is over 1 VSB
frame.
Meanwhile, when data groups of a parade are assigned as described
above, either main service data may be assigned between each data
group, or data groups corresponding to different parades may be
assigned between each data group. More specifically, data groups
corresponding to multiple parades may be assigned to one M/H
frame.
Basically, the method of assigning data groups corresponding to
multiple parades is very similar to the method of assigning data
groups corresponding to a single parade. In other words, data
groups included in other parades that are to be assigned to an M/H
frame are also respectively assigned according to a cycle period of
4 slots.
At this point, data groups of a different parade may be
sequentially assigned to the respective slots in a circular method.
Herein, the data groups are assigned to slots starting from the
ones to which data groups of the previous parade have not yet been
assigned.
For example, when it is assumed that data groups corresponding to a
parade are assigned as shown in FIG. 10, data groups corresponding
to the next parade may be assigned to a sub-frame starting either
from the 12.sup.th slot of a sub-frame. However, this is merely
exemplary. In another example, the data groups of the next parade
may also be sequentially assigned to a different slot within a
sub-frame at a cycle period of 4 slots starting from the 3.sup.rd
slot.
FIG. 11 illustrates an example of transmitting 3 parades (Parade
#0, Parade #1, and Parade #2) to an M/H frame. More specifically,
FIG. 11 illustrates an example of transmitting parades included in
one of 5 sub-frames, wherein the 5 sub-frames configure one M/H
frame.
When the 1.sup.st parade (Parade #0) includes 3 data groups for
each sub-frame, the positions of each data groups within the
sub-frames may be obtained by substituting values `0` to `2` for i
in Equation 1. More specifically, the data groups of the 1.sup.st
parade (Parade #0) are sequentially assigned to the 1.sup.st,
5.sup.th, and 9.sup.th slots (Slot #0, Slot #4, and Slot #8) within
the sub-frame. Also, when the 2.sup.nd parade includes 2 data
groups for each sub-frame, the positions of each data groups within
the sub-frames may be obtained by substituting values `3` and `4`
for i in Equation 1.
More specifically, the data groups of the 2.sup.nd parade (Parade
#1) are sequentially assigned to the 2.sup.nd and 12.sup.th slots
(Slot #3 and Slot #11) within the sub-frame.
Finally, when the 3.sup.rd parade includes 2 data groups for each
sub-frame, the positions of each data groups within the sub-frames
may be obtained by substituting values `5` and `6` for i in
Equation 1. More specifically, the data groups of the 3.sup.rd
parade (Parade #2) are sequentially assigned to the 7.sup.th and
11.sup.th slots (Slot #6 and Slot #10) within the sub-frame.
As described above, data groups of multiple parades may be assigned
to a single M/H frame, and, in each sub-frame, the data groups are
serially allocated to a group space having 4 slots from left to
right.
Therefore, a number of groups of one parade per sub-frame (NOG) may
correspond to any one integer from `1` to `8`. Herein, since one
M/H frame includes 5 sub-frames, the total number of data groups
within a parade that can be allocated to an M/H frame may
correspond to any one multiple of `5` ranging from `5` to `40`.
FIG. 12 illustrates an example of expanding the assignment process
of 3 parades, shown in FIG. 11, to 5 sub-frames within an M/H
frame.
FIG. 13 illustrates a data transmission structure according to an
embodiment of the present invention, wherein signaling data are
included in a data group so as to be transmitted.
As described above, an M/H frame is divided into 5 sub-frames. Data
groups corresponding to a plurality of parades co-exist in each
sub-frame. Herein, the data groups corresponding to each parade are
grouped by M/H frame units, thereby configuring a single
parade.
Three parades (Parade #0, Parade #1, Parade #2) also exist in one
M/H frame of FIG. 13. At this time, a part (e.g., 37 bytes/data
group) of each data group is used to forward fast information
channel (FIC) information of mobile service data, which is encoded
separately from RS code. An FIC region within a signaling
information area assigned to each data group constitutes one FIC
segment.
Meanwhile, in this embodiment, a collection of services is defined
by concept of M/H ensemble. One M/H ensemble has the same QoS, and
is coded with the same FEC code. Also, the ensemble has unique
identifier (i.e., ensemble id), and is a collection of consecutive
RS frames having the same FEC code.
As shown in FIG. 13, FIC segment corresponding to each data group
describes service information of M/H ensemble to which
corresponding data group belongs.
In other words, the transmitting/receiving system according to one
embodiment of the present invention manages two data channels. One
data channel is an RS frame data channel for contents transmission,
and the other data channel is a fast information channel (FIC) for
service acquisition. The present invention is intended that mapping
information between ensemble and mobile service is signaled using
FIC chunk, which is split in a FIC segment unit and then
transmitted through the FIC, whereby the receiving system can
perform fast service acquisition.
General Description of the Transmitting System
FIG. 14 illustrates a block diagram showing a general structure of
a digital broadcast transmitting system according to an embodiment
of the present invention.
Herein, the digital broadcast transmitting includes a service
multiplexer 100 and a transmitter 200. Herein, the service
multiplexer 100 is located in the studio of each broadcast station,
and the transmitter 200 is located in a site placed at a
predetermined distance from the studio. The transmitter 200 may be
located in a plurality of different locations. Also, for example,
the plurality of transmitters may share the same frequency. And, in
this case, the plurality of transmitters receives the same signal.
This corresponds to data transmission using Single Frequency
Network (SFN). Accordingly, in the receiving system, a channel
equalizer may compensate signal distortion, which is caused by a
reflected wave, so as to recover the original signal. In another
example, the plurality of transmitters may have different
frequencies with respect to the same channel. This corresponds to
data transmission using Multi Frequency Network (MFN).
A variety of methods may be used for data communication each of the
transmitters, which are located in remote positions, and the
service multiplexer. For example, an interface standard such as a
synchronous serial interface for transport of MPEG-2 data
(SMPTE-310M). In the SMPTE-310M interface standard, a constant data
rate is decided as an output data rate of the service multiplexer.
For example, in case of the 8VSB mode, the output data rate is
19.39 Mbps, and, in case of the 16VSB mode, the output data rate is
38.78 Mbps. Furthermore, in the conventional 8VSB mode transmitting
system, a transport stream (TS) packet having a data rate of
approximately 19.39 Mbps may be transmitted through a single
physical channel. Also, in the transmitting system according to the
present invention provided with backward compatibility with the
conventional transmitting system, additional encoding is performed
on the mobile service data. Thereafter, the additionally encoded
mobile service data are multiplexed with the main service data to a
TS packet form, which is then transmitted. At this point, the data
rate of the multiplexed TS packet is approximately 19.39 Mbps.
At this point, the service multiplexer 100 receives at least one
type of main service data and table information (e.g., PSI/PSIP
table data) for each main service and encapsulates the received
data into a transport stream (TS) packet.
Also, according to an embodiment of the present invention, the
service multiplexer 100 receives at least one type of mobile
service data and table information (e.g., PSI/PSIP table data) for
each mobile service and encapsulates the received data into a
transport stream (TS) packet.
According to another embodiment of the present invention, the
service multiplexer 100 receives a RS frame (or RS frame payload),
which is configured of at least one type of mobile service data and
table information for each mobile service, and encapsulates the
received RS frame data into mobile service data packets of a
transport stream (TS) packet format.
And, the service multiplexer 100 multiplexes the encapsulated TS
packets for main service and the encapsulated TS packets for mobile
service based upon a predetermined multiplexing rule, thereby
outputting the multiplexed TS packets to the transmitter 200.
At this point, the RS frame payload (or RS frame) has the size of N
(row).times.187 (column), as shown in FIG. 15. Herein, N represents
the length of a row (i.e., number of columns), and 187 corresponds
to the length of a column (i.e., number of rows.
In the present invention, for convenience of description, each row
of the N bytes will be referred to as M/H service data packet (or
M/H TP packet). The M/H service data packet includes M/H header of
2 bytes, a stuffing region of k bytes, and M/H payload of N-2-k
bytes. At this time, k has a value of 0 or a value greater than 0.
In this case, the M/H header of 2 bytes is only one example, and
corresponding bytes can be varied depending on a designer.
Accordingly, the present invention will not be limited to such
example.
At this time, as the M/H service data packet includes M/H header,
the M/H header may not reach N bytes.
In this case, stuffing bytes can be assigned to the remaining
payload part of the corresponding M/H service data packet. For
example, after program table information is assigned to one M/H
service data packet, if the length of the M/H service data packet
is N-20 bytes including the M/H header, the stuffing bytes can be
assigned to the remaining 20 bytes. In this case, the value k
becomes 20, and the M/H payload region within the corresponding M/H
service data packet includes N-2-20 bytes.
The RS frame payload is generated by collecting signaling table
information corresponding to one or more mobile services and/or IP
datagram of the mobile service data. For example, signaling table
information for two kinds of mobile services called news (for
example, IP datagram for mobile service 1) and the stocks (for
example, IP datagram for mobile service 2) and IP datagram of
mobile service data can be included in one frame payload.
More specifically, in the transmitting system (e.g., mobile
broadcast station), the mobile service data (e.g., A/V steaming)
are packetized based upon a real time protocol (RTP) method. The
RTP packet is then packetized once again based upon a user datagram
protocol (UDP) method. Thereafter, the RTP/UDP packet is in turn
packetized based upon an IP method, thereby being packetized into
RTP/UDP/IP packet data. In the description of the present
invention, the packetized RTP/UDP/IP packet data will be referred
to as an IP datagram for simplicity.
Furthermore, service information for receiving mobile services may
be provided in the form of a signaling table. And, a service
signaling channel transmitting such signaling table is packetized
based upon a UDP method. And, the packetized UDP data are then
packetized based upon an IP method, thereby being packetized into
UDP/IP data. In the description of the present invention, the
packetized UDP/IP packet data will also be referred to as an IP
datagram for simplicity. According to an embodiment of the present
invention, the service signaling channel is encapsulated into an IP
datagram having a well-known destination IP address and a
well-known destination UDP port number.
More specifically, one RS frame payload includes an IP datagram of
mobile service data for at least one or more mobile services and an
IP datagram of a service signaling channel for receiving the mobile
service data.
According to the embodiment of the present invention, among a
service map table (SMT), a guide access table (GAT), a cell
information table (CIT), a service labeling table (SLT), and a
rating region table (RRT), the present invention transmits at least
one signaling table through the service signaling channel. Herein,
the signaling tables presented in the embodiment of the present
invention are merely examples for facilitating the understanding of
the present invention. Therefore, the present invention is not
limited only to the exemplary signaling tables that can be
transmitted through the service signaling channel.
The SMT provides signaling information on ensemble levels. Also,
each SMT provides IP access information for each mobile service
belonging to the corresponding ensemble including each SMT.
Furthermore, the SMT provides IP stream component level information
required for the corresponding mobile service. The RRT transmits
information on region and consultation organs for program ratings.
More specifically, the RRT provides content advisory rating
information. The GAT provides information on SG providers, which
transmit the service guides. Also, the GAT provides service guide
bootstrapping information required for accessing the SG. The CIT
provides channel information of each cell, which corresponds to the
frequency domain of a broadcast signal. Herein, a cell refers to a
scope affected (or influenced) by a transmitter based upon a
physical frequency in a multi-frequency network (MFN) environment
(or condition). More specifically, the CIT provides information on
a carrier wave frequency of an adjacent cell in the current
transmitter (or transmitting system). Therefore, based upon the CIT
information, a receiver (or receiving system) can travel from one
transmitter's (or exciter's) coverage area to another. The SLT
provides minimum required information for an exclusive usage of a
channel scan process. More specifically, according to the
embodiment of the present invention, other than the SMT, by using
the SLT for the exclusive usage of the channel scan process, so as
to configure a set of minimum information for the channel scan
process, the channel scanning speed may be increased.
According to an embodiment of the present invention, each signaling
table is divided into at least one section. Then, each section is
encapsulated to a UDP/IP header, thereby being transmitted through
the service signaling channel. In this case, the number of UDP/IP
packets being transmitted through the service signaling channel may
vary based upon the number of signaling tables being transmitted
through the service signaling channel and the number of sections in
each signaling table.
At this point, all UDP/IP packets transmitted through the service
signaling channel have the same number of well-known target IP
addresses and well-known target UDP port numbers. For example, when
it is assumed that the SMT, RRT, and GAT are transmitted through
the service signaling channel, the target IP address and target UDP
port number of all UDP/IP packets transmitting the SMT, RRT, and
GAT are identical to one another. Furthermore, the target IP
address and the target UDP port number respectively correspond to
well-known values, i.e., values pre-known by the receiving system
based upon an agreement between the receiving system and the
transmitting system.
Therefore, the identification of each signaling table included in
the service signaling data is performed by a table identifier. The
table identifier may correspond to a table_id field existing in the
corresponding signaling table or in the header of the corresponding
signaling table section. And, when required, identification may be
performed by further referring to a table_id_extension field.
FIG. 16 is a diagram illustrating examples of fields allocated to
the M/H header region within the M/H service data packet according
to the present invention. Examples of the fields include
type_indicator field, error_indicator field, stuff_indicator field,
and pointer field.
The type_indicator field can allocate 3 bits, for example, and
represents a type of data allocated to payload within the
corresponding M/H service data packet. In other words, the
type_indicator field indicates whether data of the payload is IP
datagram or program table information. At this time, each data type
constitutes one logical channel In the logical channel which
transmits the IP datagram, several mobile services are multiplexed
and then transmitted. Each mobile service undergoes demultiplexing
in the IP layer.
The error_indicator field can allocate 1 bit, for example, and
represents whether the corresponding M/H service data packet has an
error. For example, if the error_indicator field has a value of 0,
it means that there is no error in the corresponding M/H service
data packet. If the error_indicator field has a value of 1, it
means that there may be an error in the corresponding M/H service
data packet.
The stuff_indicator field can allocate 1 bit, for example, and
represents whether stuffing byte exists in payload of the
corresponding M/H service data packet. For example, if the
stuff_indicator field has a value of 0, it means that there is no
stuffing byte in the corresponding M/H service data packet. If the
stuff_indicator field has a value of 1, it means that stuffing byte
exists in the corresponding M/H service data packet.
The pointer field can allocate 11 bits, for example, and represents
position information where new data (i.e., new signaling
information or new IP datagram) starts in the corresponding M/H
service data packet.
For example, if IP datagram for mobile service 1 and IP datagram
for mobile service 2 are allocated to the first M/H service data
packet within the RS frame payload as illustrated in FIG. 15, the
pointer field value represents the start position of the IP
datagram for mobile service 2 within the M/H service data
packet.
Also, if there is no new data in the corresponding M/H service data
packet, the corresponding field value is expressed as a maximum
value exemplarily. According to the embodiment of the present
invention, since 11 bits are allocated to the pointer field, if
2047 is expressed as the pointer field value, it means that there
is no new data in the packet. The point where the pointer field
value is 0 can be varied depending on the type_indicator field
value and the stuff_indicator field value.
It is to be understood that the order, the position, and the
meaning of the fields allocated to the header within the M/H
service data packet illustrated in FIG. 16 are exemplarily
illustrated for understanding of the present invention. Since the
order, the position and the meaning of the fields allocated to the
header within the M/H service data packet and the number of
additionally allocated fields can easily be modified by those
skilled in the art, the present invention will not be limited to
the above example.
FIG. 17(a) and FIG. 17(b) illustrate another examples of RS frame
payload according to the present invention. FIG. 17(a) illustrates
an example of primary RS frame payload to be allocated to regions
A/B within the data group, and FIG. 17(b) illustrates an example of
secondary RS frame payload to be allocated to regions C/D within
the data group.
In FIG. 17(a) and FIG. 17(b), a column length (i.e., the number of
rows) of the RS frame payload to be allocated to the regions A/B
and a column length (i.e., the number of rows) of the RS frame
payload to be allocated to the regions C/D are 187 equally.
However, row lengths (i.e., the number of columns) may be different
from each other.
According to the embodiment of the present invention, when the row
length of the primary RS frame payload to be allocated to the
regions A/B within the data group is N1 bytes and the row length of
the secondary RS frame payload to be allocated to the regions C/D
within the data group is N2 bytes, a condition of N1>N2 is
satisfied. In this case, N1 and N2 can be varied depending on the
transmission parameter or a region of the data group, to which the
corresponding RS frame payload will be transmitted.
For convenience of the description, each row of the N1 and N2 bytes
will be referred to as the M/H service data packet. The M/H service
data packet within the RS frame payload to be allocated to the
regions A/B within the data group can be comprised of M/H header of
2 bytes, a stuffing region of k bytes, and M/H payload of N1-2-k
bytes. At this time, k has a value of 0 or a value greater than 0.
Also, the M/H service data packet within the RS frame payload to be
allocated to the regions C/D within the data group can be comprised
of M/H header of 2 bytes, a stuffing region of k bytes, and M/H
payload of N2-2-k bytes. At this time, k has a value of 0 or a
value greater than 0.
In the present invention, the primary RS frame payload for the
regions A/B within the data group and the secondary RS frame
payload for the regions C/D within the data group can include at
least one of IP datagrams of signaling table information and mobile
service data. Also, one RS frame payload can include IP datagram
corresponding to one or more mobile services.
Corresponding parts of FIG. 15 can be applied to the other parts,
which are not described in FIG. 17(a) and FIG. 17(b).
Meanwhile, the value of N, which corresponds to the number of
columns within an RS frame payload, can be decided according to
Equation 2.
.times..times..times..times. ##EQU00001##
Herein, NoG indicates the number of data groups assigned to a
sub-frame. PL represents the number of SCCC payload data bytes
assigned to a data group. And, P signifies the number of RS parity
data bytes added to each column of the RS frame payload. Finally,
[X] is the greatest integer that is equal to or smaller than X.
More specifically, in Equation 2, PL corresponds to the length of
an RS frame portion. The value of PL is equivalent to the number of
SCCC payload data bytes that are assigned to the corresponding data
group. Herein, the value of PL may vary depending upon the RS frame
mode, SCCC block mode, and SCCC outer code mode. Table 2 to Table 5
below respectively show examples of PL values, which vary in
accordance with the RS frame mode, SCCC block mode, and SCCC outer
code mode. The SCCC block mode and the SCCC outer code mode will be
described in detail in a later process.
TABLE-US-00002 TABLE 2 SCCC outer code mode for for for for Region
A Region B Region C Region D PL 00 00 00 00 9624 00 00 00 01 9372
00 00 01 00 8886 00 00 01 01 8634 00 01 00 00 8403 00 01 00 01 8151
00 01 01 00 7665 00 01 01 01 7413 01 00 00 00 7023 01 00 00 01 6771
01 00 01 00 6285 01 00 01 01 6033 01 01 00 00 5802 01 01 00 01 5550
01 01 01 00 5064 01 01 01 01 4812 Others Reserved
Table 2 shows an example of the PL values for each data group
within an RS frame, wherein each PL value varies depending upon the
SCCC outer code mode, when the RS frame mode value is equal to
`00`, and when the SCCC block mode value is equal to `00`.
For example, when it is assumed that each SCCC outer code mode
value of regions A/B/C/D within the data group is equal to `00`
(i.e., the block processor 302 of a later block performs encoding
at a coding rate of 1/2), the PL value within each data group of
the corresponding RS frame may be equal to 9624 bytes. More
specifically, 9624 bytes of mobile service data within one RS frame
may be assigned to regions A/B/C/D of the corresponding data
group.
TABLE-US-00003 TABLE 3 SCCC outer code mode PL 00 9624 01 4812
Others Reserved
Table 3 shows an example of the PL values for each data group
within an RS frame, wherein each PL value varies depending upon the
SCCC outer code mode, when the RS frame mode value is equal to
`00`, and when the SCCC block mode value is equal to `01`.
TABLE-US-00004 TABLE 4 SCCC outer code mode For Region A for Region
B PL 00 00 7644 00 01 6423 01 00 5043 01 01 3822 Others
Reserved
Table 4 shows an example of the PL values for each data group
within a primary RS frame, wherein each PL value varies depending
upon the SCCC outer code mode, when the RS frame mode value is
equal to `01`, and when the SCCC block mode value is equal to `00`.
For example, when each SCCC outer code mode value of regions A/B is
equal to `00`, 7644 bytes of mobile service data within a primary
RS frame may be assigned to regions A/B of the corresponding data
group.
TABLE-US-00005 TABLE 5 SCCC outer code mode For Region C for Region
D PL 00 00 1980 00 01 1728 01 00 1242 01 01 990 Others Reserved
Table 5 shows an example of the PL values for each data group
within a secondary RS frame, wherein each PL value varies depending
upon the SCCC outer code mode, when the RS frame mode value is
equal to `01`, and when the SCCC block mode value is equal to `00`.
For example, when each SCCC outer code mode value of regions C/D is
equal to `00`, 1980 bytes of mobile service data within a secondary
RS frame may be assigned to regions C/D of the corresponding data
group.
Service Multiplexer
FIG. 18 illustrates a block diagram showing an example of the
service multiplexer. The service multiplexer includes a controller
110 for controlling the overall operations of the service
multiplexer, a table information generator 120 for the main
service, a null packet generator 130, an OM packet encapsulator
140, a mobile service multiplexer 150, and a transport multiplexer
160.
The transport multiplexer 160 may include a main service
multiplexer 161 and a transport stream (TS) packet multiplexer
162.
Referring to FIG. 18, at least one type of compression-encoded main
service data and table data generated from the table information
generator 120 for the main services are inputted to the main
service multiplexer 161 of the transport multiplexer 160. According
to the embodiment of the present invention, the table information
generator 120 generates PSI/PSIP table data, which is configured in
the form of an MPEG-2 private section.
The main service multiplexer 161 respectively encapsulates each of
the main service data and the PSI/PSIP table data, which are being
inputted, to MPEG-2 TS packet formats, thereby multiplexing the
encapsulated TS packets and outputting the multiplexed packets to
the TS packet multiplexer 162. Herein, the data packet being
outputted from the main service multiplexer 161 will hereinafter be
referred to as a main service data packet for simplicity.
The mobile service multiplexer 150 receives and respectively
encapsulates at least one type of compression-encoded mobile
service data and the table information (e.g., PSI/PSIP table data)
for mobile services to MPEG-2 TS packet formats. Then, the mobile
service multiplexer 150 multiplexes the encapsulated TS packets,
thereby outputting the multiplexed packets to the TS packet
multiplexer 162. Hereinafter, the data packet being outputted from
the mobile service multiplexer 150 will be referred to as a mobile
service data packet for simplicity.
Alternatively, the mobile service multiplexer 150 receives and
encapsulates an RS frame payload, which is generated by using at
least one type of compression-encoded mobile service data and the
signaling table information for mobile services, to MPEG-2 TS
packet formats. Then, the mobile service multiplexer 150
multiplexes the encapsulated TS packets, thereby outputting the
multiplexed packets to the TS packet multiplexer 162. Hereinafter,
the data packet being outputted from the mobile service multiplexer
150 will be referred to as a mobile service data packet for
simplicity.
According to an embodiment of the present invention, the mobile
service multiplexer 150 encapsulates an RS frame payload, which is
inputted in any one of the formats shown in FIG. 15, FIG. 17(a), or
FIG. 17(b), to a TS packet format.
At this point, the transmitter 200 requires identification
information in order to identify and process the main service data
packet and the mobile service data packet. Herein, the
identification information may use values pre-decided in accordance
with an agreement between the transmitting system and the receiving
system, or may be configured of a separate set of data, or may
modify predetermined location value with in the corresponding data
packet.
As an example of the present invention, a different packet
identifier (PID) may be assigned to identify each of the main
service data packet and the mobile service data packet. More
specifically, by assigning a PID, which does not use for the main
service data packet, to the mobile service data packet, the
transmitter 200 refers to a PID of data packet inputted, thereby
can identify each of the main service data packet and the mobile
service data packet.
In another example, by modifying a synchronization data byte within
a header of the mobile service data, the service data packet may be
identified by using the synchronization data byte value of the
corresponding service data packet. For example, the synchronization
byte of the main service data packet directly outputs the value
decided by the ISO/IEC 13818-1 standard (i.e., 0x47) without any
modification. The synchronization byte of the mobile service data
packet modifies and outputs the value, thereby identifying the main
service data packet and the mobile service data packet. Conversely,
the synchronization byte of the main service data packet is
modified and outputted, whereas the synchronization byte of the
mobile service data packet is directly outputted without being
modified, thereby enabling the main service data packet and the
mobile service data packet to be identified.
A plurality of methods may be applied in the method of modifying
the synchronization byte. For example, each bit of the
synchronization byte may be inversed, or only a portion of the
synchronization byte may be inversed.
As described above, any type of identification information may be
used to identify the main service data packet and the mobile
service data packet. Therefore, the scope of the present invention
is not limited only to the example set forth in the description of
the present invention.
Meanwhile, a transport multiplexer used in the conventional digital
broadcasting system may be used as the transport multiplexer 160
according to the present invention. More specifically, in order to
multiplex the mobile service data and the main service data and to
transmit the multiplexed data, the data rate of the main service is
limited to a data rate of (19.39-K) Mbps. Then, K Mbps, which
corresponds to the remaining data rate, is assigned as the data
rate of the mobile service. Thus, the transport multiplexer which
is already being used may be used as it is without any
modification.
Herein, the transport multiplexer 160 multiplexes the main service
data packet being outputted from the main service multiplexer 161
and the mobile service data packet being outputted from the mobile
service multiplexer 150. Thereafter, the transport multiplexer 160
transmits the multiplexed data packets to the transmitter 200.
However, in some cases, the output data rate of the mobile service
multiplexer 150 may not be equal to K Mbps. For example, when the
service multiplexer 100 assigns K Mbps of the 19.39 Mbps to the
mobile service data, and when the remaining (19.39-K) Mbps is,
therefore, assigned to the main service data, the data rate of the
mobile service data that are multiplexed by the service multiplexer
100 actually becomes lower than K Mbps. This is because, in case of
the mobile service data, the pre-processor of the transmitting
system performs additional encoding, thereby increasing the amount
of data. Eventually, the data rate of the mobile service data,
which may be transmitted from the service multiplexer 100, becomes
smaller than K Mbps.
For example, since the pre-processor of the transmitter performs an
encoding process on the mobile service data at a coding rate of at
least 1/2, the amount of the data outputted from the pre-processor
is increased to more than twice the amount of the data initially
inputted to the pre-processor. Therefore, the sum of the data rate
of the main service data and the data rate of the mobile service
data, both being multiplexed by the service multiplexer 100,
becomes either equal to or smaller than 19.39 Mbps.
In order to set the final output data rate of the mobile service
multiplexer 150 to K Mbps, the service multiplexer 100 of the
present invention may perform various exemplary operations.
According to an embodiment of the present invention, the null
packet generator 130 may generate a null data packet, which is then
outputted to the mobile service multiplexer 150. Thereafter, the
mobile service multiplexer 150 may multiplex the null data packet
and the mobile service data packets, so as to set the output data
rate to K Mbps.
At this point, the null data packet is transmitted to the
transmitter 200, thereby being discarded. More specifically, the
null data packet is not transmitted to the receiving system. In
order to do so, identification information for identifying the null
data is also required. Herein, the identification information for
identifying the null data may also use a value pre-decided based
upon an agreement between the transmitting system and the receiving
system and may also be configured of a separate set of data. And,
the identification information for identifying the null data may
also change a predetermined position value within the null data
packet and use the changed value. For example, the null packet
generator 130 may modify (or change) a synchronization byte value
within the header of the null data packet, thereby using the
changed value as the identification information. Alternatively, the
transport_error_indicator flag may be set to `1`, thereby being
used as the identification information. According to the embodiment
of the present invention, the transport_error_indicator flag within
the header of the null data packet is used as the identification
information for identifying the null data packet. In this case, the
transport_error_indicator flag of the null data packet is set to
`1`, and the transport_error_indicator flag for each of the other
remaining data packets is reset to `0`, so that the null data
packet can be identified (or distinguished). More specifically,
when the null packet generator 130 generated a null data packet,
and if, among the fields included in the header of the null data
packet, the transport_error_indicator flag is set to `1` and then
transmitted, the transmitter 200 may identify and discard the null
data packet corresponding to the transport_error_indicator flag.
Herein, any value that can identify the null data packet may be
used as the identification information for identifying the null
data packet. Therefore, the present invention will not be limited
only to the example proposed in the description of the present
invention.
As another example of setting (or matching) the final output data
rate of the mobile service multiplexer 150 to K Mbps, an operations
and maintenance (OM) packet (also referred to as OMP) may be used.
In this case, the mobile service multiplexer 150 may multiplex the
mobile service data packet, the null data packet, and the OM
packet, so as to set the output data rate to K Mbps.
Meanwhile, signaling data, such as transmission parameters, are
required for enabling the transmitter 200 to process the mobile
service data.
According to an embodiment of the present invention, the
transmission parameter is inserted in the payload region of the OM
packet, thereby being transmitted to the transmitter.
At this point, in order to enable the transmitter 200 to identify
the insertion of the transmission parameter in the OM packet,
identification information that can identify the insertion of the
transmission parameter in the type field of the corresponding OM
packet (i.e., OM_type field).
More specifically, an operations and maintenance packet (OMP) is
defined for the purpose of operating and managing the transmitting
system. For example, the OMP is configured in an MPEG-2 TS packet
format, and the value of its respective PID is equal to `0x1FFA`.
The OMP consists of a 4-byte header and a 184-byte payload. Among
the 184 bytes, the first byte corresponds to the OM_type field
indicating the type of the corresponding OM packet (OMP). And, the
remaining 183 bytes correspond to an OM_payload field, wherein
actual data are inserted.
According to the present invention, among the reserved field values
of the OM_type field, a pre-arranged value is used, thereby being
capable of indicating that a transmission parameter has been
inserted in the corresponding OM packet. Thereafter, the
transmitter 200 may locate (or identify) the corresponding OMP by
referring to the respective PID. Subsequently, by parsing the
OM_type field within the OMP, the transmitter 200 may be able to
know (or recognize) whether or not a transmission parameter has
been inserted in the corresponding OM packet.
The transmission parameters that can be transmitted to the OM
packet include M/H frame information (e.g., M/H frame_index), FIC
information (e.g., next_FIC_version_number), parade information
(e.g., number_of_parades, parade_id, parade_repetition_cycle, and
ensemble_id), group information (e.g., number_of_group and
start_group_number), SCCC information (e.g., SCCC_block_mode and
SCCC_outer_code_mode), RS frame information (e.g., RS_Frame_mode
and RS_frame_continuity_counter), RS encoding information (e.g.,
RS_code_mode), and so on.
At this point, the OM packet in which the transmission parameter is
inserted may be periodically generated by a constant cycle, so as
to be multiplexed with the mobile service data packet.
The multiplexing rules and the generation of null data packets of
the mobile service multiplexer 150, the main service multiplexer
161, and the TS packet multiplexer 160 are controlled by the
controller 110.
The TS packet multiplexer 162 multiplexes a data packet being
outputted from the main service multiplexer 161 at (19.39-K) Mbps
with a data packet being outputted from the mobile service
multiplexer 150 at K Mbps. Thereafter, the TS packet multiplexer
162 transmits the multiplexed data packet to the transmitter 200 at
a data rate of 19.39 Mbps.
Transmitter
FIG. 19 illustrates a block diagram showing an example of the
transmitter 200 according to an embodiment of the present
invention. Herein, the transmitter 200 includes a controller 201, a
demultiplexer 210, a packet jitter mitigator 220, a pre-processor
230, a packet multiplexer 240, a post-processor 250, a
synchronization (sync) multiplexer 260, and a transmission unit
270.
Herein, when a data packet is received from the service multiplexer
100, the demultiplexer 210 should identify whether the received
data packet corresponds to a main service data packet, a mobile
service data packet, a null data packet, or an OM packet.
For example, the demultiplexer 210 uses the PID within the received
data packet so as to identify the main service data packet, the
mobile service data packet, and the null data packet. Then, the
demultiplexer 210 uses a transport_error_indicator field to
identify the null data packet.
If an OM packet is included in the received data packet, the OM
packet may identify using the PID within the received data packet.
And by using the OM_type field included in the identified OM
packet, the demultiplexer 210 may be able to know whether or not a
transmission parameter is included in the payload region of the
corresponding OM packet and, then, received.
The main service data packet identified by the demultiplexer 210 is
outputted to the packet jitter mitigator 220, the mobile service
data packet is outputted to the pre-processor 230, and the null
data packet is discarded. If the transmission parameter is included
in the OM packet, the corresponding transmission parameter is
extracted, so as to be outputted to the corresponding blocks.
Thereafter, the OM packet is discarded. According to an embodiment
of the present invention, the transmission parameter extracted from
the OM packet is outputted to the corresponding blocks through the
controller 201.
The pre-processor 230 performs an additional encoding process of
the mobile service data included in the service data packet, which
is demultiplexed and outputted from the demultiplexer 210. The
pre-processor 230 also performs a process of configuring a data
group so that the data group may be positioned at a specific place
in accordance with the purpose of the data, which are to be
transmitted on a transmission frame. This is to enable the mobile
service data to respond swiftly and strongly against noise and
channel changes. According to one embodiment of the present
invention, RS frame payload of FIG. 15 (or (a) and (b) of FIG. 17)
is encapsulated into TS packet by the service multiplexer 100 and
transmitted to the transmitter. In this case, mobile service data
within the mobile service data packet become a part of data of the
RS frame payload. In the present invention, for convenience of
description, M/H header data of 2 bytes of each M/H service data
packet, stuffing data of k bytes, and M/H payload data of N-2-k
bytes will be referred to as mobile service data. According to one
embodiment of the present invention, the M/H payload data are
signaling table and/or IP datagram of mobile service data.
The pre-processor 230 may also refer to the transmission parameter
extracted in the OM packet when performing the additional encoding
process. Also, the pre-processor 230 groups a plurality of mobile
service data packets to configure a data group. Thereafter, known
data, mobile service data, RS parity data, and MPEG header are
allocated to pre-determined regions within the data group.
Pre-Processor within Transmitter
FIG. 20 illustrates a block diagram showing the structure of a
pre-processor 230 according to the present invention. Herein, the
pre-processor 230 includes an M/H frame encoder 301, a block
processor 302, a group formatter 303, a signaling encoder 304, and
a packet formatter 305.
The M/H frame encoder 301, which is included in the pre-processor
230 having the above-described structure, data-randomizes the
mobile service data that are inputted to the demultiplexer 210,
thereby forming at least one RS frame belonging to an ensemble. The
M/H frame encoder 301 may include at least one RS frame encoder.
More specifically, RS frame encoders may be provided in parallel,
wherein the number of RS frame encoders is equal to the number of
parades within the M/H frame. As described above, the M/H frame is
a basic time cycle period for transmitting at least one parade.
Also, each parade consists of one or two RS frames.
FIG. 21 illustrates a conceptual block diagram of the M/H frame
encoder 301 according to an embodiment of the present invention.
The M/H frame encoder 301 includes an input demultiplexer (DEMUX)
309, M number of RS frame encoders 310 to 31M-1, and an output
multiplexer (MUX) 320. Herein, M represent the number of parades
included in one M/H frame.
The demultiplexer 309 output the inputted mobile service data
packet to a corresponding RS frame encoder among M number of RS
frame encoders in ensemble units.
According to an embodiment of the present invention, each RS frame
encoder forms an RS frame payload using mobile service data
inputted and performs an error correction encoding process in RS
frame payload units, thereby forming an RS frame. Also, each RS
frame encoder divides the error-correction-encoded RS frame into a
plurality of portions, in order to assign the
error-correction-encoded RS frame data to a plurality of data
groups. Based upon the RS frame mode of Table 1, data within one RS
frame may be assigned either to all of regions A/B/C/D within
multiple data groups, or to at least one of regions A/B and regions
C/D within multiple data groups.
When the RS frame mode value is equal to `01`, i.e., when the data
of the primary RS frame are assigned to regions A/B of the
corresponding data group and data of the secondary RS frame are
assigned to regions C/D of the corresponding data group, each RS
frame encoder creates a primary RS frame and a secondary RS frame
for each parade. Conversely, when the RS frame mode value is equal
to `00`, when the data of the primary RS frame are assigned to all
of regions A/B/C/D, each RS frame encoder creates a RS frame (i.e.,
a primary RS frame) for each parade.
Also, each RS frame encoder divides each RS frame into several
portions. Each portion of the RS frame is equivalent to a data
amount that can be transmitted by a data group. The output
multiplexer (MUX) 320 multiplexes portions within M number of RS
frame encoders 310 to 310M-1 are multiplexed and then outputted to
the block processor 302.
For example, if one parade transmits two RS frames, portions of
primary RS frames within M number of RS frame encoders 310 to
310M-1 are multiplexed and outputted. Thereafter, portions of
secondary RS frames within M number of RS frame encoders 310 to
310M-1 are multiplexed and transmitted.
The input demultiplexer (DEMUX) 309 and the output multiplexer
(MUX) 320 operate based upon the control of the controller 201. The
controller 201 may provide necessary (or required) FEC modes to
each RS frame encoder. The FEC mode includes the RS code mode,
which will be described in detail in a later process.
FIG. 22 illustrates a detailed block diagram of an RS frame encoder
among a plurality of RS frame encoders within an M/H frame
encoder.
One RS frame encoder may include a primary encoder 410 and a
secondary encoder 420. Herein, the secondary encoder 420 may or may
not operate based upon the RS frame mode. For example, when the RS
frame mode value is equal to `00`, as shown in Table 1, the
secondary encoder 420 does not operate.
The primary encoder 410 may include a data randomizer 411, a
Reed-Solomon-cyclic redundancy check (RS-CRC) encoder (412), and a
RS frame divider 413. And, the secondary encoder 420 may also
include a data randomizer 421, a RS-CRC encoder (422), and a RS
frame divider 423.
More specifically, the data randomizer 411 of the primary encoder
410 receives mobile service data of a primary RS frame payload
belonging to a primary ensemble outputted from the output
demultiplexer (DEMUX) 309. Then, after randomizing the received
mobile service data, the data randomizer 411 outputs the randomized
data to the RS-CRC encoder 412.
The RS-CRC encoder 412 forms an RS frame payload belonging to the
randomized primary ensemble, and performs forward error collection
(FEC)-encoding in the RS frame payload unit using at least one of a
Reed-Solomon (RS) code and a cyclic redundancy check (CRC) code.
The RS-CRC encoder 412 outputs the FEC-encoded RS frame to the RS
frame divider 413.
The RS-CRC encoder 412 groups a plurality of mobile service data
that is randomized and inputted, so as to form a RS frame payload.
Then, the RS-CRC encoder 412 performs at least one of an error
correction encoding process and an error detection encoding process
in RS frame payload units, thereby forming an RS frame.
Accordingly, robustness may be provided to the mobile service data,
thereby scattering group error that may occur during changes in a
frequency environment, thereby enabling the mobile service data to
respond to the frequency environment, which is extremely vulnerable
and liable to frequent changes.
Also, the RS-CRC encoder 412 groups a plurality of RS frame so as
to create a super frame, thereby performing a row permutation
process in super frame units. The row permutation process may also
be referred to as a "row interleaving process". Hereinafter, the
process will be referred to as "row permutation" for simplicity. In
the present invention, the row permutation process is optional.
More specifically, when the RS-CRC encoder 412 performs the process
of permuting each row of the super frame in accordance with a
pre-determined rule, the position of the rows within the super
frame before and after the row permutation process is changed. If
the row permutation process is performed by super frame units, and
even though the section having a plurality of errors occurring
therein becomes very long, and even though the number of errors
included in the RS frame, which is to be decoded, exceeds the
extent of being able to be corrected, the errors become dispersed
within the entire super frame. Thus, the decoding ability is even
more enhanced as compared to a single RS frame.
At this point, as an example of the present invention, RS-encoding
is applied for the error correction encoding process, and a cyclic
redundancy check (CRC) encoding is applied for the error detection
process in the RS-CRC encoder 412. When performing the RS-encoding,
parity data that are used for the error correction are generated.
And, when performing the CRC encoding, CRC data that are used for
the error detection are generated.
The CRC data generated by CRC encoding may be used for indicating
whether or not the mobile service data have been damaged by the
errors while being transmitted through the channel In the present
invention, a variety of error detection coding methods other than
the CRC encoding method may be used, or the error correction coding
method may be used to enhance the overall error correction ability
of the receiving system.
Herein, the RS-CRC encoder 412 refers to a pre-determined
transmission parameter provided by the controller 201 so as to
perform operations including RS frame configuration, RS encoding,
CRC encoding, super frame configuration, and row permutation in
super frame units.
FIG. 23(a) and FIG. 23(b) illustrate a process of one or two RS
frame being divided into several portions, based upon an RS frame
mode value, and a process of each portion being assigned to a
corresponding region within the respective data group. According to
an embodiment of the present invention, the data assignment within
the data group is performed by the group formatter 303.
More specifically, FIG. 23(a) shows an example of the RS frame mode
value being equal to `00`. Herein, only the primary encoder 410 of
FIG. 22 operates, thereby forming one RS frame for one parade.
Then, the RS frame is divided into several portions, and the data
of each portion are assigned to regions A/B/C/D within the
respective data group.
FIG. 23(b) shows an example of the RS frame mode value being equal
to `01`. Herein, both the primary encoder 410 and the secondary
encoder 420 of FIG. 22 operate, thereby forming two RS frames for
one parade, i.e., one primary RS frame and one secondary RS frame.
Then, the primary RS frame is divided into several portions, and
the secondary RS frame is divided into several portions. At this
point, the data of each portion of the primary RS frame are
assigned to regions A/B within the respective data group. And, the
data of each portion of the secondary RS frame are assigned to
regions C/D within the respective data group.
Detailed Description of the RS Frame
FIG. 24(a) illustrates an example of an RS frame being generated
from the RS-CRC encoder 412 according to the present invention.
When the RS frame payload is formed, as shown in FIG. 24(a), the
RS-CRC encoder 412 performs a (Nc,Kc)-RS encoding process on each
column, so as to generate Nc-Kc (=P) number of parity bytes. Then,
the RS-CRC encoder 412 adds the newly generated P number of parity
bytes after the very last byte of the corresponding column, thereby
creating a column of (187+P) bytes. Herein, as shown in FIG. 24(a),
Kc is equal to 187 (i.e., Kc=187), and Nc is equal to 187+P (i.e.,
Nc=187+P). Herein, the value of P may vary depending upon the RS
code mode. Table 6 below shows an example of an RS code mode, as
one of the RS encoding information.
TABLE-US-00006 TABLE 6 RS code Number of Parity Bytes mode RS code
(P) 00 (211,187) 24 01 (223, 187) 36 10 (235,187) 48 11 Reserved
Reserved
Table 6 shows an example of 2 bits being assigned in order to
indicate the RS code mode. The RS code mode represents the number
of parity bytes corresponding to the RS frame payload.
For example, when the RS code mode value is equal to `10`,
(235,187)-RS-encoding is performed on the RS frame payload of FIG.
24(a), so as to generate 48 parity data bytes. Thereafter, the 48
parity bytes are added after the last data byte of the
corresponding column, thereby creating a column of 235 data
bytes.
When the RS frame mode value is equal to `00` in Table 1 (i.e.,
when the RS frame mode indicates a single RS frame), only the RS
code mode of the corresponding RS frame is indicated. However, when
the RS frame mode value is equal to `01` in Table 1 (i.e., when the
RS frame mode indicates multiple RS frames), the RS code mode
corresponding to a primary RS frame and a secondary RS frame. More
specifically, it is preferable that the RS code mode is
independently applied to the primary RS frame and the secondary RS
frame.
When such RS encoding process is performed on all N number of
columns, a size of N(row).times.(187+P)(column) bytes may be
generated, as shown in FIG. 24(b).
Each row of the RS frame payload is configured of N bytes. However,
depending upon channel conditions between the transmitting system
and the receiving system, error may be included in the RS frame
payload. When errors occur as described above, CRC data (or CRC
code or CRC checksum) may be used on each row unit in order to
verify whether error exists in each row unit.
The RS-CRC encoder 412 may perform CRC encoding on the mobile
service data being RS encoded so as to create (or generate) the CRC
data. The CRC data being generated by CRC encoding may be used to
indicate whether the mobile service data have been damaged while
being transmitted through the channel.
The present invention may also use different error detection
encoding methods other than the CRC encoding method. Alternatively,
the present invention may use the error correction encoding method
to enhance the overall error correction ability of the receiving
system.
FIG. 24(c) illustrates an example of using a 2-byte (i.e., 16-bit)
CRC checksum as the CRC data. Herein, a 2-byte CRC checksum is
generated for N number of bytes of each row, thereby adding the
2-byte CRC checksum at the end of the N number of bytes. Thus, each
row is expanded to (N+2) number of bytes. Equation 3 below
corresponds to an exemplary equation for generating a 2-byte CRC
checksum for each row being configured of N number of bytes.
g(x)=x.sup.16+x.sup.12+x.sup.5+1 Equation 3
The process of adding a 2-byte checksum in each row is only
exemplary. Therefore, the present invention is not limited only to
the example proposed in the description set forth herein. As
described above, when the process of RS encoding and CRC encoding
are completed, the (N.times.187)-byte RS frame payload is converted
into a (N+2).times.(187+P)-byte RS frame. Based upon an error
correction scenario of a RS frame formed as described above, the
data bytes within the RS frame are transmitted through a channel in
a row direction. At this point, when a large number of errors occur
during a limited period of transmission time, errors also occur in
a row direction within the RS frame being processed with a decoding
process in the receiving system. However, in the perspective of RS
encoding performed in a column direction, the errors are shown as
being scattered. Therefore, error correction may be performed more
effectively. At this point, a method of increasing the number of
parity data bytes (P) may be used in order to perform a more
intense error correction process. However, using this method may
lead to a decrease in transmission efficiency. Therefore, a
mutually advantageous method is required. Furthermore, when
performing the decoding process, an erasure decoding process may be
used to enhance the error correction performance.
Additionally, the RS-CRC encoder 412 according to the present
invention also performs a row permutation (or interleaving) process
in super frame units in order to further enhance the error
correction performance when error correction the RS frame.
FIG. 25(a) to FIG. 25(d) illustrates an example of performing a row
permutation process in super frame units according to the present
invention. More specifically, G number of RS frames RS-CRC-encoded
is grouped to form a super frame, as shown in FIG. 25(a). At this
point, since each RS frame is formed of (N+2).times.(187+P) number
of bytes, one super frame is configured to have the size of
(N+2).times.(187+P).times.G bytes.
When a row permutation process permuting each row of the super
frame configured as described above is performed based upon a
pre-determined permutation rule, the positions of the rows prior to
and after being permuted (or interleaved) within the super frame
may be altered. More specifically, the i.sup.th row of the super
frame prior to the interleaving process, as shown in FIG. 25(b), is
positioned in the j.sup.th row of the same super frame after the
row permutation process, as shown in FIG. 25(c). The
above-described relation between i and j can be easily understood
with reference to a permutation rule as shown in Equation 4 below.
j=G(i mod(187+P))+.left brkt-bot.i/(187+/P).right brkt-bot.
i=(187+P)(j mod G)+.left brkt-bot.i/G.right brkt-bot. where
0.ltoreq.i, j.ltoreq.(187+P)G-1; or where 0.ltoreq.i, j<(187+P)G
Equation 4
Herein, each row of the super frame is configured of (N+2) number
of data bytes even after being row-permuted in super frame
units.
When all row permutation processes in super frame units are
completed, the super frame is once again divided into G number of
row-permuted RS frames, as shown in FIG. 25(d), and then provided
to the RS frame divider 413. Herein, the number of RS parity bytes
and the number of columns should be equally provided in each of the
RS frames, which configure a super frame. As described in the error
correction scenario of a RS frame, in case of the super frame, a
section having a large number of error occurring therein is so long
that, even when one RS frame that is to be decoded includes an
excessive number of errors (i.e., to an extent that the errors
cannot be corrected), such errors are scattered throughout the
entire super frame. Therefore, in comparison with a single RS
frame, the decoding performance of the super frame is more
enhanced.
The above description of the present invention corresponds to the
processes of forming (or creating) and encoding an RS frame, when a
data group is divided into regions A/B/C/D, and when data of an RS
frame are assigned to all of regions A/B/C/D within the
corresponding data group. More specifically, the above description
corresponds to an embodiment of the present invention, wherein one
RS frame is transmitted using one parade. In this embodiment, the
secondary encoder 420 does not operate (or is not active).
Meanwhile, 2 RS frames are transmitting using one parade, the data
of the primary RS frame may be assigned to regions A/B within the
data group and be transmitted, and the data of the secondary RS
frame may be assigned to regions C/D within the data group and be
transmitted. At this point, the primary encoder 410 receives the
mobile service data that are to be assigned to regions A/B within
the data group, forms the primary RS frame payload, and then
performs RS-encoding and CRC-encoding on the primary RS frame
payload, thereby forming the primary RS frame. Similarly, the
secondary encoder 420 receives the mobile service data that are to
be assigned to regions C/D within the data group, forms the
secondary RS frame payload, and then performs RS-encoding and
CRC-encoding on the secondary RS frame payload thereby forming the
secondary RS frame. More specifically, the primary RS frame and the
secondary RS frame are generated independently.
FIG. 26 illustrates examples of receiving the mobile service data
that are to be assigned to regions A/B within the data group, so as
to form the primary RS frame payload, and receives the mobile
service data that are to be assigned to regions C/D within the data
group, so as to form the secondary RS frame payload, thereby
performing error correction encoding and error detection encoding
on each of the first and secondary RS frame payloads.
More specifically, FIG. 26(a) illustrates an example of the RS-CRC
encoder 412 of the primary encoder 410 receiving mobile service
data of the primary ensemble that are to be assigned to regions A/B
within the corresponding data group, so as to create an RS frame
payload having the size of N1(row).times.187(column). Then, in this
example, the primary encoder 410 performs RS-encoding on each
column of the RS frame payload created as described above, thereby
adding P1 number of parity data bytes in each column. Finally, the
primary encoder 410 performs CRC-encoding on each row, thereby
adding a 2-byte checksum in each row, thereby forming an primary RS
frame.
FIG. 26(b) illustrates an example of the RS-CRC encoder 422 of the
secondary encoder 420 receiving mobile service data of the
secondary ensemble that are to be assigned to regions C/D within
the corresponding data group, so as to create an RS frame payload
having the size of N2(row).times.187 (column). Then, in this
example, the secondary encoder 420 performs RS-encoding on each
column of the RS frame payload created as described above, thereby
adding P2 number of parity data bytes in each column. Finally, the
secondary encoder 420 performs CRC-encoding on each row, thereby
adding a 2-byte checksum in each row, thereby forming an secondary
RS frame.
At this point, each of the RS-CRC encoders 412 and 422 may refer to
a pre-determined transmission parameter provided by the controller
201, the RS-CRC encoders 412 and 422 may be informed of M/H frame
information, FIC information, RS frame information (including RS
frame mode information), RS encoding information (including RS code
mode), SCCC information (including SCCC block mode information and
SCCC outer code mode information), data group information, and
region information within a data group. The RS-CRC encoders 412 and
422 may refer to the transmission parameters for the purpose of RS
frame configuration, error correction encoding, error detection
encoding. Furthermore, the transmission parameters should also be
transmitted to the receiving system so that the receiving system
can perform a normal decoding process. At this point, as an example
of the present invention, the transmission parameter is transmitted
through transmission parameter channel (TPC) to a receiving system.
The TPC will be described in detail in a later.
The data of the primary RS frame, which is encoded by RS frame
units and row-permuted by super frame units from the RS-CRC encoder
412 of the primary encoder 410, are outputted to the RS frame
divider 413. If the secondary encoder 420 also operates in the
embodiment of the present invention, the data of the secondary RS
frame, which is encoded by RS frame units and row-permuted by super
frame units from the RS-CRC encoder 422 of the secondary encoder
420, are outputted to the RS frame divider 423. The RS frame
divider 413 of the primary encoder 410 divides the primary RS frame
into several portions, which are then outputted to the output
multiplexer (MUX) 320. Each portion of the primary RS frame is
equivalent to a data amount that can be transmitted by one data
group. Similarly, the RS frame divider 423 of the secondary encoder
420 divides the secondary RS frame into several portions, which are
then outputted to the output multiplexer (MUX) 320.
Hereinafter, the RS frame divider 413 of the primary RS encoder 410
will now be described in detail. Also, in order to simplify the
description of the present invention, it is assumed that an RS
frame payload having the size of N(row).times.187 (column), as
shown in FIG. 24(a) to FIG. 24(c), that P number of parity data
bytes are added to each column by RS-encoding the RS frame payload,
and that a 2-byte checksum is added to each row by CRC-encoding the
RS frame payload. As a result, an RS frame having the size of (N+2)
(row).times.187+P (column) is formed. Accordingly, the RS frame
divider 413 divides (or partitions) the RS frame having the size of
(N+2) (row).times.187+P (column) into several portions, each having
the size of PL (wherein PL corresponds to the length of the RS
frame portion).
At this point, as shown in Table 2 to Table 5, the value of PL may
vary depending upon the RS frame mode, SCCC block mode, and SCCC
outer coder mode. Also, the total number of data bytes of the
RS-encoded and CRC-encoded RS frame is equal to or smaller than
5.times.NoG.times.PL. In this case, the RS frame is divided (or
partitioned) into ((5.times.NoG)-1) number of portions each having
the size of PL and one portion having a size equal to smaller than
PL. More specifically, with the exception of the last portion of
the RS frame, each of the remaining portions of the RS frame has an
equal size of PL. If the size of the last portion is smaller than
PL, a stuffing byte (or dummy byte) may be inserted in order to
fill (or replace) the lacking number of data bytes, thereby
enabling the last portion of the RS frame to also be equal to PL.
Each portion of an RS frame corresponds to the amount of data that
are to be SCCC-encoded and mapped into a single data group of a
parade.
FIG. 27(a) and FIG. 27(b) respectively illustrate examples of
adding S number of stuffing bytes, when an RS frame having the size
of (N+2) (row).times.(187+P) (column) is divided into 5.times.NoG
number of portions, each having the size of PL. More specifically,
the RS-encoded and CRC-encoded RS frame, shown in FIG. 27(a), is
divided into several portions, as shown in FIG. 27(b). The number
of divided portions at the RS frame is equal to (5.times.NoG).
Particularly, the first ((5.times.NoG)-1) number of portions each
has the size of PL, and the last portion of the RS frame may be
equal to or smaller than PL. If the size of the last portion is
smaller than PL, a stuffing byte (or dummy byte) may be inserted in
order to fill (or replace) the lacking number of data bytes, as
shown in Equation 5 below, thereby enabling the last portion of the
RS frame to also be equal to PL.
S=(5.times.NoG.times.PL)-((N+2).times.(187+P)) Equation 5
Herein, each portion including data having the size of PL passes
through the output multiplexer 320 of the M/H frame encoder 301,
which is then outputted to the block processor 302.
At this point, the mapping order of the RS frame portions to a
parade of data groups in not identical with the group assignment
order defined in Equation 1. When given the group positions of a
parade in an M/H frame, the SCCC-encoded RS frame portions will be
mapped in a time order (i.e., in a left-to-right direction).
For example, as shown in FIG. 11, data groups of the 2.sup.nd
parade (Parade #1) are first assigned (or allocated) to the
13.sup.th slot (Slot #12) and then assigned to the 3.sup.rd slot
(Slot #2). However, when the data are actually placed in the
assigned slots, the data are placed in a time sequence (or time
order, i.e., in a left-to-right direction). More specifically, the
1.sup.st data group of Parade #1 is placed in Slot #2, and the
2.sup.nd data group of Parade #1 is placed in Slot #12.
Block Processor
Meanwhile, the block processor 302 performs an SCCC outer encoding
process on the output of the M/H frame encoder 301. More
specifically, the block processor 302 receives the data of each
error correction encoded portion. Then, the block processor 302
encodes the data once again at a coding rate of H1/H2 (wherein H1
is a natural number equal to or greater than 1 and H2 is a natural
number equal to or greater than 2), thereby outputting the
H1/H2-rate encoded data to the group formatter 303. For example, if
1 bit of the input data is coded to 2 bits and outputted, then H1
is equal to 1 and H2 is equal to 2. Alternatively, if 1 bit of the
input data is coded to 4 bits and outputted, then H1 is equal to 1
and H2 is equal to 4. Hereinafter, the former coding rate will be
referred to a coding rate of 1/2 (also referred to as "1/2-rate
encoding"), and the latter coding rate will be referred to as a
coding rate of 1/4 (also referred to as "1/4-rate encoding"), for
simplicity. Similarly, if 7 bits of the input data is coded to 16
bits and outputted, then H1 is equal to 7 and H2 is equal to 16.
Hereinafter, the coding rate will be referred to a coding rate of
7/16 (also referred to as " 7/16-rate encoding"), for
simplicity.
The data of each portion outputted from the M/H frame encoder 301
may include at least one of mobile service data, RS parity data,
CRC data, and stuffing data. However, in a broader meaning, the
data included in each portion may correspond to data for mobile
services. Therefore, the data included in each portion will all be
considered as mobile service data and described accordingly.
The group formatter 303 inserts the mobile service data
SCCC-outer-encoded and outputted from the block processor 302 in
the corresponding region within the data group, which is formed in
accordance with a pre-defined rule. Also, in association with the
data deinterleaving process, the group formatter 303 inserts
various place holders (or known data place holders) in the
corresponding region within the data group. Thereafter, the group
formatter 303 deinterleaves the data within the data group and the
place holders.
According to the present invention, with reference to data after
being data-interleaved, as shown in FIG. 5, a data groups is
configured of 10 M/H blocks (B1 to B10) and divided into 4 regions
(A, B, C, and D).
Also, as shown in FIG. 5, when it is assumed that the data group is
divided into a plurality of hierarchical regions, as described
above, the block processor 302 may encode the mobile service data,
which are to be inserted to each region based upon the
characteristic of each hierarchical region, at different coding
rates.
For example, the block processor 302 may encode the mobile service
data, which are to be inserted in region A/B within the
corresponding data group, at a coding rate of 1/2. Then, the group
formatter 303 may insert the 1/2-rate encoded mobile service data
to region A/B. Also, the block processor 302 may encode the mobile
service data, which are to be inserted in region C/D within the
corresponding data group, at a coding rate of 1/4 having higher (or
stronger) error correction ability than the 1/2-coding rate.
Thereafter, the group formatter 303 may insert the 1/2-rate encoded
mobile service data to region C/D. In another example, the block
processor 302 may encode the mobile service data, which are to be
inserted in region C/D, at a coding rate having higher error
correction ability than the 1/4-coding rate. Then, the group
formatter 303 may either insert the encoded mobile service data to
region C/D, as described above, or leave the data in a reserved
region for future usage.
According to another embodiment of the present invention, the block
processor 302 may perform a H1/H2-rate encoding process in SCCC
block units. Herein, the SCCC block includes at least one M/H
block. At this point, when H1/H2-rate encoding is performed in M/H
block units, the M/H blocks (B1 to B10) and the SCCC block (SCB1 to
SCB10) become identical to one another (i.e., SCB1=B1, SCB2=B2,
SCB3=B3, SCB4=B4, SCB5=B5, SCB6=B6, SCB7=B7, SCB8=B8, SCB9=B9, and
SCB10=B10). For example, the M/H block 1 (B1) may be encoded at the
coding rate of 1/2, the M/H block 2 (B2) may be encoded at the
coding rate of 1/4, and the M/H block 3 (B3) may be encoded at the
coding rate of 1/2. The coding rates are applied respectively to
the remaining M/H blocks.
Alternatively, a plurality of M/H blocks within regions A, B, C,
and D may be grouped into one SCCC block, thereby being encoded at
a coding rate of H1/H2 in SCCC block units. Accordingly, the
receiving performance of region C/D may be enhanced. For example,
M/H block 1 (B1) to M/H block 5 (B5) may be grouped into one SCCC
block and then encoded at a coding rate of 1/2. Thereafter, the
group formatter 303 may insert the 1/2-rate encoded mobile service
data to a section starting from M/H block 1 (B1) to M/H block 5
(B5). Furthermore, M/H block 6 (B6) to M/H block 10 (B10) may be
grouped into one SCCC block and then encoded at a coding rate of
1/4. Thereafter, the group formatter 303 may insert the 1/4-rate
encoded mobile service data to another section starting from M/H
block 6 (B6) to M/H block 10 (B10). In this case, one data group
may consist of two SCCC blocks.
According to another embodiment of the present invention, one SCCC
block may be formed by grouping two M/H blocks. For example, M/H
block 1 (B1) and M/H block 6 (B6) may be grouped into one SCCC
block (SCB1). Similarly, M/H block 2 (B2) and M/H block 7 (B7) may
be grouped into another SCCC block (SCB2). Also, M/H block 3 (B3)
and M/H block 8 (B8) may be grouped into another SCCC block (SCB3).
And, M/H block 4 (B4) and M/H block 9 (B9) may be grouped into
another SCCC block (SCB4). Furthermore, M/H block 5 (B5) and M/H
block 10 (B10) may be grouped into another SCCC block (SCB5). In
the above-described example, the data group may consist of 10 M/H
blocks and 5 SCCC blocks. Accordingly, in a data (or signal)
receiving environment undergoing frequent and severe channel
changes, the receiving performance of regions C and D, which is
relatively more deteriorated than the receiving performance of
region A, may be reinforced. Furthermore, since the number of
mobile service data symbols increases more and more from region A
to region D, the error correction encoding performance becomes more
and more deteriorated. Therefore, when grouping a plurality of M/H
block to form one SCCC block, such deterioration in the error
correction encoding performance may be reduced.
As described-above, when the block processor 302 performs encoding
at a H1/H2-coding rate, information associated with SCCC should be
transmitted to the receiving system in order to accurately recover
the mobile service data.
Table 7 below shows an example of a SCCC block mode, which
indicating the relation between an M/H block and an SCCC block,
among diverse SCCC block information.
TABLE-US-00007 TABLE 7 SCCC Block Mode 00 01 10 11 Description One
M/H Block Two M/H Blocks per SCCC Block per SCCC Block Reserved
Reserved SCB SCB input, SCB input, M/H Block M/H Blocks SCB1 B1 B1
+ B6 SCB2 B2 B2 + B7 SCB3 B3 B3 + B8 SCB4 B4 B4 + B9 SCB5 B5 B5 +
B10 SCB6 B6 -- SCB7 B7 -- SCB8 B8 -- SCB9 B9 -- SCB10 B10 --
More specifically, Table 4 shows an example of 2 bits being
allocated in order to indicate the SCCC block mode. For example,
when the SCCC block mode value is equal to `00`, this indicates
that the SCCC block and the M/H block are identical to one another.
Also, when the SCCC block mode value is equal to `01`, this
indicates that each SCCC block is configured of 2 M/H blocks.
As described above, if one data group is configured of 2 SCCC
blocks, although it is not indicated in Table 7, this information
may also be indicated as the SCCC block mode. For example, when the
SCCC block mode value is equal to `10`, this indicates that each
SCCC block is configured of 5 M/H blocks and that one data group is
configured of 2 SCCC blocks. Herein, the number of M/H blocks
included in an SCCC block and the position of each M/H block may
vary depending upon the settings made by the system designer.
Therefore, the present invention will not be limited to the
examples given herein. Accordingly, the SCCC mode information may
also be expanded.
An example of a coding rate information of the SCCC block, i.e.,
SCCC outer code mode, is shown in Table 8 below.
TABLE-US-00008 TABLE 8 SCCC outer code mode (2 bits) Description 00
Outer code rate of SCCC block is 1/2 rate 01 Outer code rate of
SCCC block is 1/4 rate 10 Reserved 11 Reserved
More specifically, Table 8 shows an example of 2 bits being
allocated in order to indicate the coding rate information of the
SCCC block. For example, when the SCCC outer code mode value is
equal to `00`, this indicates that the coding rate of the
corresponding SCCC block is 1/2. And, when the SCCC outer code mode
value is equal to `01`, this indicates that the coding rate of the
corresponding SCCC block is 1/4.
If the SCCC block mode value of Table 7 indicates `00`, the SCCC
outer code mode may indicate the coding rate of each M/H block with
respect to each M/H block. In this case, since it is assumed that
one data group includes 10 M/H blocks and that 2 bits are allocated
for each SCCC block mode, a total of bits are required for
indicating the SCCC block modes of the 10 M/H modes. In another
example, when the SCCC block mode value of Table 7 indicates `00`,
the SCCC outer code mode may indicate the coding rate of each
region with respect to each region within the data group. In this
case, since it is assumed that one data group includes 4 regions
(i.e., regions A, B, C, and D) and that 2 bits are allocated for
each SCCC block mode, a total of 8 bits are required for indicating
the SCCC block modes of the 4 regions. In another example, when the
SCCC block mode value of Table 7 is equal to `01`, each of the
regions A, B, C, and D within the data group has the same SCCC
outer code mode.
Meanwhile, an example of an SCCC output block length (SOBL) for
each SCCC block, when the SCCC block mode value is equal to `00`,
is shown in Table 9 below.
TABLE-US-00009 TABLE 9 SIBL 1/2 1/4 SCCC Block SOBL rate rate SCB1
(Bl) 528 264 132 SCB2 (B2) 1536 768 384 SCB3 (B3) 2376 1188 594
SCB4 (B4) 2388 1194 597 SCB5 (B5) 2772 1386 693 SCB6 (B6) 2472 1236
618 SCB7 (B7) 2772 1386 693 SCB8 (B8) 2508 1254 627 SCB9 (B9) 1416
708 354 SCB10 (B10) 480 240 120
More specifically, when given the SCCC output block length (SOBL)
for each SCCC block, an SCCC input block length (SIBL) for each
corresponding SCCC block may be decided based upon the outer coding
rate of each SCCC block. The SOBL is equivalent to the number of
SCCC output (or outer-encoded) bytes for each SCCC block. And, the
SIBL is equivalent to the number of SCCC input (or payload) bytes
for each SCCC block. Table 10 below shows an example of the SOBL
and SIBL for each SCCC block, when the SCCC block mode value is
equal to `01`.
TABLE-US-00010 TABLE 10 SIBL 1/2 1/4 SCCC Block SOBL rate rate SCB1
(B1 + B6) 528 264 132 SCB2 (B2 + B7) 1536 768 384 SCB3 (B3 + B8)
2376 1188 594 SCB4 (B4 + B9) 2388 1194 597 SCB5 (B5 + B10) 2772
1386 693
In order to do so, as shown in FIG. 28, the block processor 302
includes a RS frame portion-SCCC block converter 511, a byte-bit
converter 512, a symbol encoder 513, a symbol interleaver 514, a
symbol-byte converter 515, and an SCCC block-M/H block converter
516.
The symbol encoder 513 and the symbol interleaver 514 are virtually
concatenated with the trellis encoding module in the post-processor
in order to configure an SCCC block.
More specifically, the RS frame portion-SCCC block converter 511
divides the RS frame portions, which are being inputted, into
multiple SCCC blocks using the SIBL of Table 9 and Table 10 based
upon the RS code mode, SCCC block mode, and SCCC outer code mode.
Herein, the M/H frame encoder 301 may output only primary RS frame
portions or both primary RS frame portions and secondary RS frame
portions in accordance with the RS frame mode.
When the RS Frame mode is set to `00`, a portion of the primary RS
Frame equal to the amount of data, which are to be SCCC outer
encoded and mapped to 10 M/H blocks (B1 to B10) of a data group,
will be provided to the block processor 302. When the SCCC block
mode value is equal to `00`, then the primary RS frame portion will
be split into 10 SCCC Blocks according to Table 9. Alternatively,
when the SCCC block mode value is equal to `01`, then the primary
RS frame will be split into 5 SCCC blocks according to Table
10.
When the RS frame mode value is equal to `01`, then the block
processor 302 may receive two RS frame portions. The RS frame mode
value of `01` will not be used with the SCCC block mode value of
`01`. The first portion from the primary RS frame will be
SCCC-outer-encoded as SCCC Blocks SCB3, SCB4, SCB5, SCB6, SCB7, and
SCB8 by the block processor 302. The SCCC Blocks SCB3 and SCB8 will
be mapped to region B and the SCCC blocks SCB4, SCB5, SCB6, and
SCB7 shall be mapped to region A by the group formatter 303. The
second portion from the secondary RS frame will also be
SCCC-outer-encoded, as SCB1, SCB2, SCB9, and SCB10, by the block
processor 302. The group formatter 303 will map the SCCC blocks
SCB1 and SCB10 to region D as the M/H blocks B1 and B10,
respectively. Similarly, the SCCC blocks SCB2 and SCB9 will be
mapped to region C as the M/H blocks B2 and B9.
The byte to bit converter 512 divides the mobile service data byte
of each SCCC block being outputted from the RS frame portion to
SCCC block converter 511 into 8 bits. Then, the byte-to-bit
converter 512 outputs the divided 8 bits to a symbol encoder
513.
The symbol encoder 513 performs H1/H2 encoding on the mobile
service data bits that are being inputted. More specifically, the
symbol encoder 513 encodes the inputted data bits by using a
convolutional encoding method. Thereafter, the symbol encoder 513
outputs symbols in accordance with a pre-selected coding rate. For
example, when a coding rate of 1/4 (or 1/4-coding rate) is
selected, the symbol encoder 513 encodes an inputted data bit so as
to output 4 data bits, i.e., 2 symbols. Herein, according to the
present invention, the symbol encoder 513 may be used as a 1/2-rate
encoder (or 1/2-encoder), a 1/3-rate encoder (or 1/3-encoder), or a
1/4-rate encoder (or 1/4-encoder). Alternatively, the symbol
encoder 513 may also be used as an encoder of a completely
different coding rate, such as 7/16, in other words, the symbol
encoder 513 may also be used as a 7/16-rate encoder (or
7/16-encoder).
FIG. 29 illustrates a detailed block diagram of a symbol encoder
513 according to an embodiment of the present invention. Herein,
the symbol encoder 513 includes a Convolutional encoder 5131, a
Parallel to Serial converter 5132, a Bit Puncturing unit 5133, a
Bit Ordering unit 5134, and a Bit to Symbol converter 5135.
FIG. 30 illustrates a detailed block diagram of the convolutional
encoder 5131 according to the embodiment of the present invention.
Herein, the convolutional encoder 5131 consists of 2 delay units
521 and 523 and three adders 522, 524, and 525. The convolutional
encoder 511 encodes an input data bit U and outputs 5 bits (u0 to
u4). At this point, the input data bit U is directly outputted as
the uppermost bit u0 without being modified, and, at the same time,
the input data bit U is encoded so as to be outputted as lower bits
u1u2u3u4.
More specifically, the input data bit U is directly outputted as
the uppermost bit u0 without being modified, and, at the same time,
the input data bit U is outputted to the first and third adders 522
and 525. The first adder 522 adds the input data bit U to the
output of the first delay unit 521, thereby outputting the
processed data bits to the second delay unit 523. Thereafter, data
that are delayed by a predetermined period of time (e.g., 1 clock)
by the second delay unit 523 are outputted as the lower bit u1 and
simultaneously fed-back to the first delay unit 521. The first
delay unit 521 delays the data being fed-back from the second delay
unit 523 by a predetermined period of time (e.g., 1 clock), thereby
outputting the delayed data bit as the lower bit u2 and
simultaneously outputting the processed data bits to the first
adder 522 and the second adder 524.
The second adder 524 adds the output data bits of the first and
second adders 522 and 524 and, then, outputs the added data bits as
the lower bit u3. The third adder 525 adds the input data bit U and
the output of the second adder 524 and, then, outputs the added
data bits as the lowermost bit u4.
At this point, the first and second delay units 521 and 523 are
reset to `0` at the beginning (or starting point) of each SCCC
block.
More specifically, the convolutional encoder 5131 performs
convolutional encoding on the input data bit U, so as to output 5
bits (u0 to u4) to the parallel to serial converter 5132. The
parallel to serial converter 5132 converts the 5 bits that are
being inputted in parallel to serial bits. Then, the parallel to
serial converter 5132 outputs the 5 converted parallel bits to the
bit puncturing unit 5133. Among the 5 bits being serially inputted,
the bit puncturing unit 5133 removes some of the bits in accordance
with a pre-determined coding rate. Thereafter, the bit puncturing
unit 5133 outputs the processed data bits to the bit ordering unit
5134.
For example, when the predetermined coding rate is 1/2, among the 5
inputted bits, the bit puncturing unit 5133 removes the third,
fourth, and fifth bits (u2, u3, and u4) and outputs the first and
second bits u0 and u1 as a single bundle, as shown in FIG. 32. For
example, the first and second bits u0 and u1 being outputted from
the bit puncturing unit 5133 bypass the bit ordering unit 5134 and
are outputted to the bit to symbol converter 5135. The bit to
symbol converter 5135 converts the first and second bits u0 and u1,
which are outputted from the bit puncturing unit 5133, to a symbol,
thereby outputting the converted symbol to the symbol interleaver
514.
In another example, when the predetermined coding rate is 1/4,
among the 5 inputted bits, the bit puncturing unit 5133 removes the
fourth bit (u3) and outputs the first, second, third, and fifth
bits u0 to u2 and u4 as a single bundle, as shown in FIG. 31. The
bit ordering unit 5134 reorders the input bits to the outputted
bundle units in accordance with a predetermined rule, thereby
outputting the reordered bits to the bit to symbol converter 5135.
For example, when the coding rate is 1/4, the bit ordering unit
5134 reorders the 4 bits u0 to u2, and u4 that are outputted from
the bit puncturing unit 5133 to the bit to symbol converter
5135.
Referring to FIG. 31, the bit ordering unit 5134 receives the
first, second, third, and fifth bits u0 to u2, and u4 and reorders
the received bits by an order of the first bit u0, the second bit
u1, the fifth bit u4, and the third bit u2, thereby outputting the
reordered bits to the bit to symbol converter 5135.
In light of the FEC, when removing the fourth bit u3, among the 5
bits being outputted from the bit puncturing unit 5133, and
outputting the first, second, third, and fifth bit u0 to u2, and
u4, and when having the bit ordering unit 5134 output the processed
bits by the order of the first bit u0, the second bit u1, the fifth
bit u4, and the third bit u2, the receiving performance (or
capability) is most outstanding.
In a 1/4-rate encoding process according to another embodiment of
the present invention, the bit puncturing unit 5133 may also remove
the third bit u2, among the 5 bits being outputted from the
convolutional encoder 5131, and may output the first, second,
fourth, and fifth bit u0, u1, u3, and u4, and the bit ordering unit
5134 may reorder the output bits by the order of the first bit u0,
the second bit u1, the fourth bit u3, and the fifth bit u4.
However, the above-described examples are merely embodiments
proposed in order to facilitate the understanding of the present
invention. Therefore, among the 5 bits, the bit puncturing unit
5133 may remove data bits other than the ones mentioned in the
examples proposed above. And, the bit ordering unit 5134 may
perform reordering of the input bits by an order different from the
orders proposed in the above-described examples.
The bit to symbol converter 5135 converts the two bits being
outputted from the bit ordering unit 5134 to one symbol and, then,
outputs the converted symbol to the symbol interleaver 514. More
specifically, the output bits of the bit ordering unit 5134 are
outputted to the symbol interleaver 514 in 2-bit units.
Table 11 below shows an example of the output symbols of the symbol
interleaver 513, when the symbol encoder 513 operates as a 1/2-rate
encoder or a 1/4-rate encoder.
TABLE-US-00011 TABLE 11 1/2 1/4 rate Region rate SCCC Block mode =
`00` SCCC Block mode = `01` A, B (u0, u1) (u0, u2), (u1, u4) (u0,
u2), (u1, u4) C, D (u0, u1), (u3, u4)
For example, when the coding rate is 1/2, 1 output symbol, i.e.,
the output bits u0 and u1 are outputted to the symbol interleaver
514. Also, in case the coding rate is 1/4, depending upon the SCCC
block mode, 2 output symbols, i.e., 4 output bits are outputted to
the symbol interleaver 514. More specifically, for example, when
the SCCC block mode is `00`, an output symbol configured of bits u0
and u2 and an output symbol configured of bits u1 and u4 for
regions A and B within the data group are sequentially outputted to
the symbol interleaver 514. Also, an output symbol configured of
bits u0 and u1 and an output symbol configured of bits u3 and u4
for regions C and D within the data group are sequentially
outputted to the symbol interleaver 514. More specifically, the bit
puncturing and the bit re-ordering of the data that are to be
allocated to regions A and B within the data group are different
from the bit puncturing and the bit re-ordering of the data that
are to be allocated to regions C and D within the data group.
However, this is merely exemplary, and, therefore, when the SCCC
block mode is `00`, an output symbol configured of bits u0 and u2
and an output symbol configured of bits u1 and u4 for regions A, B,
C, and D may also be sequentially outputted to the symbol
interleaver 514. Alternatively, when the SCCC block mode is `01`,
an output symbol configured of bits u0 and u2 and an output symbol
configured of bits u1 and u4 are sequentially outputted to the
symbol interleaver 514.
Meanwhile, the symbol encoder 513 according to the present
invention may be operated as a 1/3-rate encoder (or
1/3-encoder).
According to a first embodiment of the present invention, the
1/3-rate encoding process may be performed by using a method of
having the bit puncturing unit 5133 remove 2 bits, among the 5 bits
u0 to u4 that are outputted through the convolutional encoder 5131
and the serial to parallel converter 5132, and to output the
remaining 3 bits to the bit to symbol converter 5135 through the
bit ordering unit 5134. For example, the bit to symbol converter
5135 uses an odd-numbered input bit, which is inputted to the
convolutional encoder 5131 so as to be encoded and outputted as 3
bits, and also uses an even-numbered input bit, which is inputted
to the convolutional encoder 5131 so as to be encoded and outputted
as 3 bits, thereby outputting 3 symbols, i.e., 6 bits. More
specifically, when the 2 bits that are inputted to the symbol
encoder 513, the processed bits are outputted from the symbol
encoder 513 as 6 bits (i.e., 3 symbols). At this point, according
to the embodiment of the present invention, the 3 bits that are
outputted from the bit puncturing unit 5133 may be reordered in
accordance with a predetermined rule by using the bit ordering unit
5134, or the output bits may bypass the bit ordering unit 5134.
According to a second embodiment of the present invention, the
symbol encoder 513, i.e., the convolutional encoder 5131, the
parallel to serial converter 5132, the bit puncturing unit 5133,
the bit ordering unit 5134, and the bit to symbol converter 5135
may be used to perform a 1/3-rate encoding process by using a
method of alternately performing 1/4-rate encoding and 1/2-rate
encoding. For example, the bit to symbol converter 5135 uses an
odd-numbered input bit, which is inputted to the convolutional
encoder 5131 so as to be encoded and outputted as 4 bits, and also
uses an even-numbered input bit, which is inputted to the
convolutional encoder 5131 so as to be encoded and outputted as 2
bits, thereby outputting 3 symbols, i.e., 6 bits.
In other words, the symbol encoder 513 performs encoding at a
coding rate of 1/4 on the odd-numbered input bit and performs
encoding at a coding rate of 1/2 on the even-numbered input bit.
Herein, the encoding of each input bit may be performed in the
opposite order. More specifically, the symbol encoder 513 may
perform encoding at a coding rate of 1/2 on the odd-numbered input
bit and may perform encoding at a coding rate of 1/4 on the
even-numbered input bit. In the description according to the
embodiment of the present invention, 1/4-rate encoding is performed
on the odd-numbered input bit, and 1/2-rate encoding is performed
on the even-numbered input bit. As described above, when the
1/4-rate encoding and the 1/2-rate encoding are alternately
performed by the symbol encoder 513, the 2 input bits become 6
bits, i.e., 3 symbols. Accordingly, as a result, the symbol encoder
513 is operated as a 1/3-rate encoder (or 1/3-encoder).
At this point, according to the embodiment of the present
invention, when the symbol encoder 513 is operated at a coding rate
of 1/4, the bit puncturing process and the bit reordering process
of FIG. 31 may be directly performed without modification. More
specifically, as shown in FIG. 31, among the 5 bits u0 to u4, the
bit puncturing unit 5133 removes the fourth bit u3 and outputs the
first, second, third, and fifth bits u0 to u2, and u4 as one bundle
to the bit ordering unit 5134. Thereafter, the bit ordering unit
5134 reorders the first, second, third, and fifth bits u0 to u2,
and u4 outputted from the bit puncturing unit 5133 by the order of
the first bit u0, the second bit u1, the fifth bit u4, and the
third bit u2. Subsequently, the bit ordering unit 5134 outputs the
reordered bits to the bit to symbol converter 5135. Alternatively,
according to the embodiment of the present invention, when the
symbol encoder 513 is operated as a 1/2-rate encoder, the bit
puncturing process of FIG. 32 is directly used without
modification, whereas the bit reordering process is omitted.
In the method of multiplexing a symbol encoded at a coding rate of
1/2 (or a 1/2-rate encoded symbol) and a symbol encoded at a coding
rate of 1/4 (or a 1/2-rate encoded symbol) within one transmission
block according to the present invention, the ordering of the
symbols is not limited provided that a sum of the number of
1/4-rate encoded symbols and the number of 1/2-rate encoded symbols
is greater than or equal to the size of one transmission block.
As described above, according to the first embodiment of the
present invention, 1/3-rate encoding is performed on each input
bit, and, according to the second embodiment of the present
invention, 1/4-rate encoding is performed on the odd-numbered input
bit and 1/2-rate encoding is performed on the even-numbered input
bit. Thus, the symbol encoder 513 may be operated as a 1/3-rate
encoder.
Meanwhile, in the present invention, the symbol encoder 513 of the
block processor 302 and the TCM encoder (or also referred to as the
trellis encoder) of the trellis encoding module 256 are virtually
concatenated in order to configure the SCCC. More specifically, the
most significant bit (MSB) and the least significant bit (LSB) of
the symbol being encoded and outputted from the symbol encoder 513
of the block processor 302 are virtually concatenated in series
with the TCM encoder of the trellis encoding module 256, thereby
configuring a turbo encoder. The TCM encoder of the trellis
encoding module 256 performs trellis encoding on the symbol, i.e.,
2 bits being encoded and outputted from the bit to symbol converter
5135 of the block processor 302, thereby outputting the processed
symbol (or 2 bits) as 3 bits.
At this point, depending upon the method of the most significant
bit (MSB) and the least significant bit (LSB) that are encoded by
the symbol encoder 513 being concatenated with the inputted most
significant bit (MSB) and the inputted least significant bit (LSB)
of the TCM encoder included in the trellis encoding module 256,
when the receiving system performs turbo decoding, a difference in
the error correction performance (or capability) may occur.
For example, when the first embodiment of the present invention may
be applied to the symbol encoder 513 so that the symbol encoder 513
can be operated as a 1/3-rate encoder, among the 3 output bits of
the bit puncturing unit 5133 within the symbol encoder 513, the
uppermost (or most significant) bit may be concatenated with the
uppermost (or most significant) bit of the input symbol of the TCM
encoder included in the trellis encoding module 256. Alternatively,
the uppermost (or most significant) bit among the 3 output bits of
the bit puncturing unit 5133 may be concatenated with the lowermost
(or least significant) bit of the input symbol of the TCM encoder.
More specifically, in the first embodiment of the present
invention, 1 bit is inputted so as to be encoded and outputted as 3
bits. Herein, among the 3 output bits respective to the
odd-numbered input bit, if the uppermost (or most significant) bit
is concatenated with the uppermost (or most significant) bit of the
input symbol of the TCM encoder included in the trellis encoding
module 256, the uppermost (or most significant) bit among the 3
output bits respective to the even-numbered input bit is
concatenated with the lowermost (or least significant) bit of the
input symbol of the TCM encoder included in the trellis encoding
module 256.
In another example, when the second embodiment of the present
invention may be applied to the symbol encoder 513 so that the
symbol encoder 513 can be operated as a 1/3-rate encoder, according
to the embodiment of the present invention, the rule of
concatenating the conventional 1/4-rate encoded symbol and 1/2-rate
encoded symbol with the input symbol of the TCM encoder is directly
used without modification. More specifically, the uppermost (or
most significant) bit of the output symbol of the symbol encoder
513 is always concatenated with the uppermost (or most significant)
bit of the TCM encoder included in the trellis encoding module 256.
And, the lowermost (or least significant) bit of the output symbol
of the symbol encoder 513 is concatenated with the lowermost (or
least significant) bit of the TCM encoder included in the trellis
encoding module 256.
Accordingly, the error correction performance (or capability) in
the case of performing 1/3-rate encoding by applying the first
embodiment of the present invention is more degraded (or deficient)
than the error correction performance (or capability) in the case
of performing 1/3-rate encoding by applying the second embodiment
of the present invention. In other words, the performance of the
receiving system is more exceeding when the 1/3-rate encoding
process is performed by applying the second embodiment of the
present invention.
Meanwhile, apart from performing 1/3-rate encoding by applying the
second embodiment of the present invention, a random coding rate
ranging between the 1/2 coding rate and the 1/4 coding rate may
also be used in combination. As described above, in the present
invention, when 1 bit inputted to the symbol encoder 513 is encoded
at the coding rate of 1/2, 1 symbol is outputted to the symbol
interleaver 514. However, when 1 bit inputted to the symbol encoder
513 is encoded at the coding rate of 1/4, 2 symbols are outputted
to the symbol interleaver 514.
Therefore, when the symbol encoder 513 outputs the 1/2-rate encoded
symbol to the symbol interleaver 514 during the 1/3 section of one
symbol interleaving block (i.e., B), and when the symbol encoder
513 outputs the 1/4-rate encoded symbol to the symbol interleaver
514 during the remaining 2/3 section, the total coding rate of the
symbol interleaver block becomes equal to 1/3(=1/2*1/3+1/4*2/3).
However, when 1/4 of one symbol interleaver block is filled with a
symbol that is 1/4-rate encoded and outputted, and when the
remaining 3/4 of the symbol interleaver block is filled with a
symbol that is 1/2-rate encoded and outputted, the total coding
rate of the symbol interleaver block becomes equal to
7/16(=1/4*1/4+1/2*3/4).
Furthermore, by positioning a 1/2-rate encoded symbol in a region
(or SCCC block) showing an excellent equalization performance
within a data group configured (or formed) by the group formatter,
and by positioning a 1/4-rate encoded symbol in a region (or SCCC
block) showing a poor equalization performance, thereby
transmitting the corresponding symbols, the present invention may
be capable of optimizing the receiving performance. Alternatively,
by positioning a 1/4-rate encoded symbol in a section showing poor
(or deficient) equalization within one region (or SCCC block), and
by positioning a 1/2-rate encoded symbol in a section showing
robust (or excellent) equalization within one region (or SCCC
block), thereby transmitting the corresponding symbols, the present
invention may be capable of optimizing the receiving
performance.
The symbol interleaver 514 performs block interleaving, in symbol
units, on the output data symbol of the symbol encoder 513. More
specifically, the symbol interleaver 514 is a type of block
interleaver. Any interleaver performing structural rearrangement
(or realignment) may be applied as the symbol interleaver 514 of
the block processor. However, in the present invention, a variable
length symbol interleaver that can be applied even when a plurality
of lengths is provided for the symbol, so that its order may be
rearranged, may also be used.
FIG. 33 illustrates a symbol interleaver according to an embodiment
of the present invention. Particularly, FIG. 33 illustrates an
example of the symbol interleaver when B=2112 and L=4096. Herein, B
indicates a block length in symbols that are outputted for symbol
interleaving from the symbol encoder 513. And, L represents a block
length in symbols that are actually interleaved by the symbol
interleaver 514. At this point, the block length in symbols B
inputted to the symbol interleaver 514 is equivalent to
4.times.SOBL. More specifically, since one symbol is configured of
2 bits, the value of B may be set to be equal to 4.times.SOBL.
In the present invention, when performing the symbol-interleaving
process, the conditions of L=2.sup.m (wherein m is an integer) and
of L.gtoreq.B should be satisfied. If there is a difference in
value between B and L, (L-B) number of null (or dummy) symbols is
added, thereby creating an interleaving pattern, as shown in P'(i)
of FIG. 33. Therefore, B becomes a block size of the actual symbols
that are inputted to the symbol interleaver 514 in order to be
interleaved. L becomes an interleaving unit when the interleaving
process is performed by an interleaving pattern created from the
symbol interleaver 514.
Equation 6 shown below describes the process of sequentially
receiving B number of symbols, the order of which is to be
rearranged, and obtaining an L value satisfying the conditions of
L=2.sup.m (wherein m is an integer) and of L.gtoreq.B, thereby
creating the interleaving so as to realign (or rearrange) the
symbol order. In relation to all places, wherein
0.ltoreq.i.ltoreq.B-1, P(i)={89.times.i.times.(i+1)/2} mod L
Herein, L.gtoreq.B, L=2.sup.m, wherein m is an integer. Equation
6
As shown in P'(i) of FIG. 33, the order of B number of input
symbols and (L-B) number of null symbols is rearranged by using the
above-mentioned Equation 6. Then, as shown in P(i) of FIG. 33, the
null byte places are removed, so as to rearrange the order.
Starting with the lowest value of i, the P(i) are shifted to the
left in order to fill the empty entry locations. Thereafter, the
symbols of the aligned interleaving pattern P(i) are outputted to
the symbol-byte converter 515 in order.
Herein, the symbol-byte converter 515 converts to bytes the mobile
service data symbols, having the rearranging of the symbol order
completed and then outputted in accordance with the rearranged
order, and thereafter outputs the converted bytes to the SCCC
block-M/H block converter 516. The SCCC block-M/H block converter
516 converts the symbol-interleaved SCCC blocks to M/H blocks,
which are then outputted to the group formatter 303.
If the SCCC block mode value is equal to `00`, the SCCC block is
mapped at a one-to-one (1:1) correspondence with each M/H block
within the data group. In another example, if the SCCC block mode
value is equal to `01`, each SCCC block is mapped with two M/H
blocks within the data group. For example, the SCCC block SCB1 is
mapped with (B1, B6), the SCCC block SCB2 is mapped with (B2, B7),
the SCCC block SCB3 is mapped with (B3, B8), the SCCC block SCB4 is
mapped with (B4, B9), and the SCCC block SCB5 is mapped with (B5,
B10). The M/H block that is outputted from the SCCC block-M/H block
converter 516 is configured of mobile service data and FEC
redundancy. In the present invention, the mobile service data as
well as the FEC redundancy of the M/H block will be collectively
considered as mobile service data.
For example, in a 1/3 section of a block corresponding to B, the
1/2-rate encoded symbol is inputted to the symbol interleaver 514,
and, in the remaining 2/3 section of the block corresponding to B,
the 1/4-rate encoded symbol is also inputted to the symbol
interleaver 514. Thereafter, when the inputted symbols are
interleaved and then outputted, the total encoding rate of the
block processor 302 becomes 1/3. In another example, in a 1/4
section of a block corresponding to B, the 1/4-rate encoded symbol
is inputted to the symbol interleaver 514, and, in the 3/4 section
of a block corresponding to B, the 1/2-rate encoded symbol is
inputted to the symbol interleaver 514. Thereafter, when the
inputted symbols are interleaved and then outputted, the total
encoding rate of the block processor 302 becomes 7/16.
Group Formatter
The group formatter 303 inserts data of M/H blocks outputted from
the block processor 302 to the corresponding M/H blocks within the
data group, which is formed in accordance with a pre-defined rule.
Also, in association with the data-deinterleaving process, the
group formatter 303 inserts various place holders (or known data
place holders) in the corresponding region within the data group.
More specifically, apart from the encoded mobile service data
outputted from the block processor 302, the group formatter 303
also inserts MPEG header place holders, non-systematic RS parity
place holders, main service data place holders, which are
associated with the data deinterleaving in a later process, as
shown in FIG. 5.
Herein, the main service data place holders are inserted because
the mobile service data bytes and the main service data bytes are
alternately mixed with one another in regions B to D based upon the
input of the data deinterleaver, as shown in FIG. 5. For example,
based upon the data outputted after data deinterleaving, the place
holder for the MPEG header may be allocated at the very beginning
of each packet. Also, in order to configure an intended group
format, dummy bytes may also be inserted. Furthermore, the group
formatter 303 inserts initialization data (i.e., trellis
initialization byte) of the trellis encoding module 256 in the
corresponding regions. For example, the initialization data may be
inserted in the beginning of the known data sequence. The
initialization data is used for initializing memories within the
trellis encoding module 256, and is not transmitted to the
receiving system.
Additionally, the group formatter 303 may also insert signaling
information, which are encoded and outputted from the signaling
encoder 304, in corresponding regions within the data group. At
this point, reference may be made to the signaling information when
the group formatter 303 inserts each data type and respective place
holders in the data group. The process of encoding the signaling
information and inserting the encoded signaling information to the
data group will be described in detail in a later process.
After inserting each data type and respective place holders in the
data group, the group formatter 303 may deinterleave the data and
respective place holders, which have been inserted in the data
group, as an inverse process of the data interleaver, thereby
outputting the deinterleaved data and respective place holders to
the packet formatter 305. The group formatter 303 may include a
group format organizer 527, and a data deinterleaver 529, as shown
in FIG. 34. The group format organizer 527 inserts data and
respective place holders in the corresponding regions within the
data group, as described above. And, the data deinterleaver 529
deinterleaves the inserted data and respective place holders as an
inverse process of the data interleaver.
The packet formatter 305 removes the main service data place
holders and the RS parity place holders that were allocated for the
deinterleaving process from the deinterleaved data being inputted.
Then, the packet formatter 305 groups the remaining portion and
inserts the 3-byte MPEG header place holder in an MPEG header
having a null packet PID (or an unused PID from the main service
data packet). Furthermore, the packet formatter 305 adds a
synchronization data byte at the beginning of each 187-byte data
packet. Also, when the group formatter 303 inserts known data place
holders, the packet formatter 303 may insert actual known data in
the known data place holders, or may directly output the known data
place holders without any modification in order to make replacement
insertion in a later process. Thereafter, the packet formatter 305
identifies the data within the packet-formatted data group, as
described above, as a 188-byte unit mobile service data packet
(i.e., MPEG TS packet), which is then provided to the packet
multiplexer 240.
Based upon the control of the controller 201, the packet
multiplexer 240 multiplexes the data group packet-formatted and
outputted from the packet formatter 306 and the main service data
packet outputted from the packet jitter mitigator 220. Then, the
packet multiplexer 240 outputs the multiplexed data packets to the
data randomizer 251 of the post-processor 250. More specifically,
the controller 201 controls the time-multiplexing of the packet
multiplexer 240. If the packet multiplexer 240 receives 118 mobile
service data packets from the packet formatter 305, 37 mobile
service data packets are placed before a place for inserting VSB
field synchronization. Then, the remaining 81 mobile service data
packets are placed after the place for inserting VSB field
synchronization. The multiplexing method may be adjusted by diverse
variables of the system design. The multiplexing method and
multiplexing rule of the packet multiplexer 240 will be described
in more detail in a later process.
Also, since a data group including mobile service data in-between
the data bytes of the main service data is multiplexed (or
allocated) during the packet multiplexing process, the shifting of
the chronological position (or place) of the main service data
packet becomes relative. Also, a system object decoder (i.e., MPEG
decoder) for processing the main service data of the receiving
system, receives and decodes only the main service data and
recognizes the mobile service data packet as a null data
packet.
Therefore, when the system object decoder of the receiving system
receives a main service data packet that is multiplexed with the
data group, a packet jitter occurs.
At this point, since a multiple-level buffer for the video data
exists in the system object decoder and the size of the buffer is
relatively large, the packet jitter generated from the packet
multiplexer 240 does not cause any serious problem in case of the
video data. However, since the size of the buffer for the audio
data in the object decoder is relatively small, the packet jitter
may cause considerable problem. More specifically, due to the
packet jitter, an overflow or underflow may occur in the buffer for
the main service data of the receiving system (e.g., the buffer for
the audio data). Therefore, the packet jitter mitigator 220
re-adjusts the relative position of the main service data packet so
that the overflow or underflow does not occur in the system object
decoder.
In the present invention, examples of repositioning places for the
audio data packets within the main service data in order to
minimize the influence on the operations of the audio buffer will
be described in detail. The packet jitter mitigator 220 repositions
the audio data packets in the main service data section so that the
audio data packets of the main service data can be as equally and
uniformly aligned and positioned as possible. Additionally, when
the positions of the main service data packets are relatively
re-adjusted, associated program clock reference (PCR) values may
also be modified accordingly. The PCR value corresponds to a time
reference value for synchronizing the time of the MPEG decoder.
Herein, the PCR value is inserted in a specific region of a TS
packet and then transmitted.
In the example of the present invention, the packet jitter
mitigator 220 also performs the operation of modifying the PCR
value. The output of the packet jitter mitigator 220 is inputted to
the packet multiplexer 240. As described above, the packet
multiplexer 240 multiplexes the main service data packet outputted
from the packet jitter mitigator 220 with the mobile service data
packet outputted from the pre-processor 230 into a burst structure
in accordance with a pre-determined multiplexing rule. Then, the
packet multiplexer 240 outputs the multiplexed data packets to the
data randomizer 251 of the post-processor 250.
If the inputted data correspond to the main service data packet,
the data randomizer 251 performs the same randomizing process as
that of the conventional randomizer. More specifically, the
synchronization byte within the main service data packet is
deleted. Then, the remaining 187 data bytes are randomized by using
a pseudo random byte generated from the data randomizer 251.
Thereafter, the randomized data are outputted to the RS
encoder/non-systematic RS encoder 252. On the other hand, if the
inputted data correspond to the mobile service data packet, the
data randomizer 251 may not perform a randomizing process on the
mobile service data packet.
The RS encoder/non-systematic RS encoder 252 performs an RS
encoding process on the data being randomized by the data
randomizer 251 or on the data bypassing the data randomizer 251, so
as to add 20 bytes of RS parity data. Thereafter, the processed
data are outputted to the data interleaver 253. Herein, if the
inputted data correspond to the main service data packet, the RS
encoder/non-systematic RS encoder 252 performs the same systematic
RS encoding process as that of the conventional broadcasting
system, thereby adding the 20-byte RS parity data at the end of the
187-byte data. Alternatively, if the inputted data correspond to
the mobile service data packet, the RS encoder/non-systematic RS
encoder 252 performs a non-systematic RS encoding process. At this
point, the 20-byte RS parity data obtained from the non-systematic
RS encoding process are inserted in a pre-decided parity byte place
within the mobile service data packet.
The data interleaver 253 corresponds to a byte unit convolutional
interleaver. The output of the data interleaver 253 is inputted to
the parity replacer 254 and to the non-systematic RS encoder
255.
Meanwhile, a process of initializing a memory of a trellis code
modulation (TCM) encoder (or trellis encoder) within the trellis
encoding module 256 is primarily required in order to decide the
output data of the trellis encoding module 256, which is located
after the parity replacer 254, as the known data pre-defined
according to an agreement between the receiving system and the
transmitting system. More specifically, the memory of the trellis
encoding module 256 should first be initialized before the received
known data sequence is trellis-encoded.
At this point, the beginning portion of the known data sequence
that is received corresponds to the initialization data and not to
the actual known data. Herein, the initialization data has been
included in the data by the group formatter within the
pre-processor 230 in an earlier process. Therefore, the process of
replacing the initialization data with memory values within the
trellis encoding module 256 are required to be performed
immediately before the inputted known data sequence is
trellis-encoded.
More specifically, the initialization data are replaced with the
memory value within the trellis encoding module 256, thereby being
inputted to the trellis encoding module 256. At this point, the
memory value replacing the initialization data are process with (or
calculated by) an exclusive OR (XOR) operation with the respective
memory value within the trellis encoding module 256, so as to be
inputted to the corresponding memory. Therefore, the corresponding
memory is initialized to `0`. Additionally, a process of using the
memory value replacing the initialization data to re-calculate the
RS parity, so that the re-calculated RS parity value can replace
the RS parity being outputted from the data interleaver 253, is
also required.
Therefore, the non-systematic RS encoder 255 receives the mobile
service data packet including the initialization data from the data
interleaver 253 and also receives the memory value from the trellis
encoding module 256.
Among the inputted mobile service data packet, the initialization
data are replaced with the memory value, and the RS parity data
that are added to the mobile service data packet are removed and
processed with non-systematic RS encoding. Thereafter, the new RS
parity obtained by performing the non-systematic RS encoding
process is outputted to the parity replacer 255. Accordingly, the
parity replacer 255 selects the output of the data interleaver 253
as the data within the mobile service data packet, and the parity
replacer 255 selects the output of the non-systematic RS encoder
255 as the RS parity. The selected data are then outputted to the
trellis encoding module 256.
Meanwhile, if the main service data packet is inputted or if the
mobile service data packet, which does not include any
initialization data that are to be replaced, is inputted, the
parity replacer 254 selects the data and RS parity that are
outputted from the data interleaver 253. Then, the parity replacer
254 directly outputs the selected data to the trellis encoding
module 256 without any modification. The trellis encoding module
256 converts the byte-unit data to symbol units and performs a
12-way interleaving process so as to trellis-encode the received
data. Thereafter, the processed data are outputted to the
synchronization multiplexer 260.
FIG. 35 illustrates a detailed diagram of one of 12 trellis
encoders (or TCM encoders) included in the trellis encoding module
256. Herein, the trellis encoder includes first and second
multiplexers 531 and 541, first and second exclusive OR (XOR) gates
532 and 542, and first to third memories 533, 542, and 544.
More specifically, the first to third memories 533, 542, and 544
are initialized by the memory value instead of the initialization
data from the parity replacer 254. More specifically, when the
first symbol (i.e., two bits), which are converted from
initialization data (i.e., each trellis initialization data byte),
are inputted, the input bits of the trellis encoder will be
replaced by the memory values of the trellis encoder, as shown in
FIG. 35.
Since 2 symbols (i.e., 4 bits) are required for trellis
initialization, the last 2 symbols (i.e., 4 bits) from the trellis
initialization bytes are not used for trellis initialization and
are considered as a symbol from a known data byte and processed
accordingly.
When the trellis encoder is in the initialization mode, the input
comes from an internal trellis status (or state) and not from the
parity replacer 254. When the trellis encoder is in the normal
mode, the input symbol (X2X1) provided from the parity replacer 254
will be processed. The trellis encoder provides the converted (or
modified) input data for trellis initialization to the
non-systematic RS encoder 255.
More specifically, when a selection signal designates a normal
mode, the first multiplexer 531 selects an upper bit X2 of the
input symbol. And, when a selection signal designates an
initialization mode, the first multiplexer 531 selects the output
of the first memory 533 and outputs the selected output data to the
first XOR gate 532. The first XOR gate 532 performs XOR operation
on the output of the first multiplexer 531 and the output of the
first memory 533, thereby outputting the added result to the first
memory 533 and, at the same time, as a most significant (or
uppermost) bit Z2. The first memory 533 delays the output data of
the first XOR gate 532 by 1 clock, thereby outputting the delayed
data to the first multiplexer 531 and the first XOR gate 532.
Meanwhile, when a selection signal designates a normal mode, the
second multiplexer 541 selects a lower bit X1 of the input symbol.
And, when a selection signal designates an initialization mode, the
second multiplexer 541 selects the output of the second memory 542,
thereby outputting the selected result to the second XOR gate 543
and, at the same time, as a lower bit Z1. The second XOR gate 543
performs XOR operation on the output of the second multiplexer 541
and the output of the second memory 542, thereby outputting the
added result to the third memory 544. The third memory 544 delays
the output data of the second XOR gate 543 by 1 clock, thereby
outputting the delayed data to the second memory 542 and, at the
same time, as a least significant (or lowermost) bit Z0. The second
memory 542 delays the output data of the third memory 544 by 1
clock, thereby outputting the delayed data to the second XOR gate
543 and the second multiplexer 541.
The select signal designates an initialization mode during the
first two symbols that are converted from the initialization
data.
For example, when the select signal designates an initialization
mode, the first XOR gate 532 performs an XOR operation on the value
of the first memory 533, which is provided through the first
multiplexer 531, and on a memory value that is directly provided
from the first memory 533. That is, the first XOR gate 532 performs
an XOR operation on 2 bits having the same value. Generally, when
only one of the two bits belonging to the operand is `1`, the
result of the XOR gate is equal to `1` . Otherwise, the result of
the XOR gate becomes equal to `0`. Therefore, when the value of the
first memory 533 is processed with an XOR operation, the result is
always equal to `0`. Furthermore, since the output of the first XOR
gate 532, i.e., `0`, is inputted to the first memory 533, the first
memory 533 is initialized to `0`.
Similarly, when the select signal designates an initialization
mode, the second XOR gate 543 performs an XOR operation on the
value of the second memory 542, which is provided through the
second multiplexer 541, and on a memory value that is directly
provided from the second memory 542. Therefore, the output of the
second XOR gate 543 is also always equal to `0`. Since the output
of the second XOR gate 543, i.e., `0`, is inputted to the third
memory 544, the third memory 544 is also initialized to `0`. The
output of the third memory 544 is inputted to the second memory 542
in the next clock, thereby initializing the second memory 542 to
`0`. In this case also, the select signal designates the
initialization mode.
More specifically, when the first symbol being converted from the
initialization data byte replaces the values of the first memory
533 and the second memory 542, thereby being inputted to the
trellis encoder, each of the first and third memories 533 and 544
within the trellis encoder is initialized to `00`. Following the
process, when the second symbol being converted from the
initialization data byte replaces the values of the first memory
533 and the second memory 542, thereby being inputted to the
trellis encoder, each of the first, second, and third memories 533,
542, and 544 within the trellis encoder is initialized to
`000`.
As described above, 2 symbols are required to initialize the memory
of the trellis encoder. At this point, while the select signal
designates an initialization mode, the output bits (X2'X1') of the
first and second memories 533 and 542 are inputted to the
non-systematic RS encoder 255, so as to perform a new RS parity
calculation process.
The synchronization multiplexer 260 inserts a field synchronization
signal and a segment synchronization signal to the data outputted
from the trellis encoding module 256 and, then, outputs the
processed data to the pilot inserter 271 of the transmission unit
270.
Herein, the data having a pilot inserted therein by the pilot
inserter 271 are modulated by the modulator 272 in accordance with
a pre-determined modulating method (e.g., a VSB method).
Thereafter, the modulated data are transmitted to each receiving
system though the radio frequency (RF) up-converter 273.
Multiplexing Method of Packet Multiplexer
Data of the error correction encoded and H1/H2-rate encoded primary
RS frame (i.e., when the RS frame mode value is equal to `00`) or
primary/secondary RS frame (i.e., when the RS frame mode value is
equal to `01`), are divided into a plurality of data groups by the
group formatter 303. Then, the divided data portions are assigned
to at least one of regions A to D of each data group or to an M/H
block among the M/H blocks B1 to B10, thereby being deinterleaved.
Then, the deinterleaved data group passes through the packet
formatter 305, thereby being multiplexed with the main service data
by the packet multiplexer 240 based upon a de-decided multiplexing
rule. The packet multiplexer 240 multiplexes a plurality of
consecutive data groups, so that the data groups are assigned to be
spaced as far apart from one another as possible within the
sub-frame. For example, when it is assumed that 3 data groups are
assigned to a sub-frame, the data groups are assigned to a 1.sup.st
slot (Slot #0), a 5.sup.th slot (Slot #4), and a 9.sup.th slot
(Slot #8) in the sub-frame, respectively.
As described-above, in the assignment of the plurality of
consecutive data groups, a plurality of parades are multiplexed and
outputted so as to be spaced as far apart from one another as
possible within a sub-frame. For example, the method of assigning
data groups and the method of assigning parades may be identically
applied to all sub-frames for each M/H frame or differently applied
to each M/H frame.
FIG. 10 illustrates an example of a plurality of data groups
included in a single parade, wherein the number of data groups
included in a sub-frame is equal to `3`, and wherein the data
groups are assigned to an M/H frame by the packet multiplexer 240.
Referring to FIG. 10, 3 data groups are sequentially assigned to a
sub-frame at a cycle period of 4 slots. Accordingly, when this
process is equally performed in the 5 sub-frames included in the
corresponding M/H frame, 15 data groups are assigned to a single
M/H frame. Herein, the 15 data groups correspond to data groups
included in a parade.
When data groups of a parade are assigned as shown in FIG. 10, the
packet multiplexer 240 may either assign main service data to each
data group, or assign data groups corresponding to different
parades between each data group. More specifically, the packet
multiplexer 240 may assign data groups corresponding to multiple
parades to one M/H frame. Basically, the method of assigning data
groups corresponding to multiple parades is very similar to the
method of assigning data groups corresponding to a single parade.
In other words, the packet multiplexer 240 may assign data groups
included in other parades to an M/H frame according to a cycle
period of 4 slots. At this point, data groups of a different parade
may be sequentially assigned to the respective slots in a circular
method. Herein, the data groups are assigned to slots starting from
the ones to which data groups of the previous parade have not yet
been assigned. For example, when it is assumed that data groups
corresponding to a parade are assigned as shown in FIG. 10, data
groups corresponding to the next parade may be assigned to a
sub-frame starting either from the 12.sup.th slot of a
sub-frame.
FIG. 11 illustrates an example of assigning and transmitting 3
parades (Parade #0, Parade #1, and Parade #2) to an M/H frame. For
example, when the 1.sup.st parade (Parade #0) includes 3 data
groups for each sub-frame, the packet multiplexer 240 may obtain
the positions of each data groups within the sub-frames by
substituting values `0` to `2` for i in Equation 1. More
specifically, the data groups of the 1.sup.st parade (Parade #0)
are sequentially assigned to the 1.sup.st, 5.sup.th, and 9.sup.th
slots (Slot #0, Slot #4, and Slot #8) within the sub-frame. Also,
when the 2.sup.nd parade includes 2 data groups for each sub-frame,
the packet multiplexer 240 may obtain the positions of each data
groups within the sub-frames by substituting values `3` and `4` for
i in Equation 1. More specifically, the data groups of the 2.sup.nd
parade (Parade #1) are sequentially assigned to the 2.sup.nd and
12.sup.th slots (Slot #3 and Slot #11) within the sub-frame.
Finally, when the 3.sup.rd parade includes 2 data groups for each
sub-frame, the packet multiplexer 240 may obtain the positions of
each data groups within the sub-frames by substituting values `5`
and `6` for i in Equation 1. More specifically, the data groups of
the 3.sup.rd parade (Parade #2) are sequentially assigned and
outputted to the 7.sup.th and 11.sup.th slots (Slot #6 and Slot
#10) within the sub-frame.
As described above, the packet multiplexer 240 may multiplex and
output data groups of multiple parades to a single M/H frame, and,
in each sub-frame, the multiplexing process of the data groups may
be performed serially with a group space of 4 slots from left to
right. Therefore, a number of groups of one parade per sub-frame
(NOG) may correspond to any one integer from `1` to `8`. Herein,
since one M/H frame includes 5 sub-frames, the total number of data
groups within a parade that can be allocated to an M/H frame may
correspond to any one multiple of `5` ranging from `5` to `40`.
Signaling Information Encoding
The present invention assigns signaling information areas for
inserting signaling information to some areas within each data
group.
FIG. 36 illustrates an example of assigning signaling information
areas for inserting signaling information starting from the
1.sup.st segment of the 4.sup.th M/H block (B4) to a portion of the
2.sup.nd segment. More specifically, 276(=207+69) bytes of the
4.sup.th M/H block (B4) in each data group are assigned as the
signaling information area. In other words, the signaling
information area consists of 207 bytes of the 1.sup.st segment and
the first 69 bytes of the 2.sup.nd segment of the 4.sup.th M/H
block (B4). For example, the 1.sup.st segment of the 4.sup.th M/H
block (B4) corresponds to the 17.sup.th or 173.sup.rd segment of a
VSB field.
For example, the data group includes 6 numbers of known data
sequences as shown in FIG. 41 and FIG. 42, the signaling
information area is positioned between a first known data sequence
(i.e., first training sequence) and a second known data sequence
(i.e., second training sequence). At this point, the first known
data sequence is inserted into the last two segments of the M/H
block B3, and the second known data sequence is inserted into the
second and third segments of the M/H block B4. Also, the third to
sixth known data sequences is inserted into the last two segments
of the M/H blocks B4, B5, B6, and B7, respectively. The first,
third to sixth known data sequences are spaced 16 segments apart
from one another.
The signaling information that is to be inserted in the signaling
information area is FEC-encoded by the signaling encoder 304,
thereby inputted to the group formatter 303. The signaling
information may include a transmission parameter which is included
in the payload region of an OM packet, and then received to the
demultiplexer 210.
The group formatter 303 inserts the signaling information, which is
FEC-encoded and outputted by the signaling encoder 304, in the
signaling information area within the data group.
Herein, the signaling information may be identified by two
different types of signaling channels: a transmission parameter
channel (TPC) and a fast information channel (FIC).
Herein, the TPC data corresponds to signaling information including
transmission parameters, such as RS frame information, RS encoding
information, FIC information, data group information, SCCC
information, and M/H frame information and so on. However, the TPC
data presented herein is merely exemplary. And, since the adding or
deleting of signaling information included in the TPC may be easily
adjusted and modified by one skilled in the art, the present
invention will, therefore, not be limited to the examples set forth
herein.
Furthermore, the FIC data is provided to enable a fast service
acquisition of data receivers, and the FIC data includes cross
layer information between the physical layer and the upper
layer(s).
FIG. 37 illustrates a detailed block diagram of the signaling
encoder 304 according to the present invention. Referring to FIG.
37, the signaling encoder 304 includes a TPC encoder 561, an FIC
encoder 562, a block interleaver 563, a multiplexer 564, a
signaling randomizer 565, and an iterative turbo encoder 566.
The TPC encoder 561 receives 10-bytes of TPC data and performs
(18,10)-RS encoding on the 10-bytes of TPC data, thereby adding 8
bytes of RS parity data to the 10 bytes of TPC data. The 18 bytes
of RS-encoded TPC data are outputted to the multiplexer 564.
The FIC encoder 562 receives 37-bytes of FIC data and performs
(51,37)-RS encoding on the 37-bytes of FIC data, thereby adding 14
bytes of RS parity data to the 37 bytes of FIC data. Thereafter,
the 51 bytes of RS-encoded FIC data are inputted to the block
interleaver 563, thereby being interleaved in predetermined block
units. Herein, the block interleaver 563 corresponds to a variable
length block interleaver. The block interleaver 563 interleaves the
FIC data within each sub-frame in TNoG(column).times.51(row) block
units and then outputs the interleaved data to the multiplexer 564.
Herein, the TNoG corresponds to the total number of data groups
being assigned to a sub-frame. The block interleaver 563 is
synchronized with the first set of FIC data in each sub-frame.
The block interleaver 563 writes 51 bytes of incoming (or inputted)
RS codewords in a row direction (i.e., row-by-row) and
left-to-right and up-to-down directions and reads 51 bytes of RS
codewords in a column direction (i.e., column-by-column) and
left-to-right and up-to-down directions, thereby outputting the RS
codewords.
The multiplexer 564 multiplexes the RS-encoded TPC data from the
TPC encoder 561 and the block-interleaved FIC data from the block
interleaver 563 along a time axis. Then, the multiplexer 564
outputs 69 bytes of the multiplexed data to the signaling
randomizer 565.
The signaling randomizer 565 randomizes the multiplexed data and
outputs the randomized data to the iterative turbo encoder 566. The
signaling randomizer 565 may use the same generator polynomial of
the randomizer used for mobile service data. Also, initialization
occurs in each data group.
The iterative turbo encoder 566 corresponds to an inner encoder
performing iterative turbo encoding in a PCCC method on the
randomized data (i.e., signaling information data).
For example, if the iterative turbo encoder 566 performs encoding
of data at a coding rate of 1/4, 69 bytes applied to the iterative
turbo encoder 566 are extended to 276 bytes by the iterative
turbo-encoding process, such that the iterative turbo encoder 566
outputs the resultant 276 bytes. The 276 bytes generated from the
iterative turbo encoder 566 are transferred to the group formatter
303, such that they are inserted into a signaling information area
of a corresponding data group. The iterative turbo encoder 566 may
include 6 numbers of even component encoders and 6 numbers of odd
component encoders.
FIG. 38 illustrates an example of a syntax structure of TPC data
being inputted to the TPC encoder 561. The TPC data are inserted in
the signaling information area of each data group and then
transmitted.
The TPC data may include a sub-frame number field, a slot_number
field, a parade_id field, a starting_group_number (SGN) field, a
number_of_groups (NoG) field, a parade_repetition_cycle (PRC)
field, an RS_frame_mode field, an RS_code_mode_primary field, an
RS_code_mode_secondary field, an SCCC_block_mode field, an
SCCC_outer_code_mode_A field, an SCCC_outer_code_mode_B field, an
SCCC_outer_code_mode_C field, an SCCC_outer_code_mode_D field, an
FIC_version field, a parade_continuity_counter field, and a TNoG
field.
The Sub-Frame_number field corresponds to the current Sub-Frame
number within the M/H frame, which is transmitted for M/H frame
synchronization. The value of the Sub-Frame_number field may range
from 0 to 4. The Slot_number field indicates the current slot
number within the sub-frame, which is transmitted for M/H frame
synchronization. Also, the value of the Sub-Frame_number field may
range from 0 to 15.
The Parade_id field identifies the parade to which this group
belongs. The value of this field may be any 7-bit value. Each
parade in a M/H transmission shall have a unique Parade_id field.
Communication of the Parade_id between the physical layer and the
management layer may be performed by means of an Ensemble_id field
formed by adding one bit to the left of the Parade_id field. If the
Ensemble_id field is used for the primary Ensemble delivered
through this parade, the added MSB shall be equal to `0`.
Otherwise, if the Ensemble_id field is used for the secondary
ensemble, the added MSB shall be equal to `1`. Assignment of the
Parade_id field values may occur at a convenient level of the
system, usually in the management layer.
The starting_group_number (SGN) field shall be the first
Slot_number for a parade to which this group belongs, as determined
by Equation 1 (i.e., after the Slot numbers for all preceding
parades have been calculated). The SGN and NoG shall be used
according to Equation 1 to obtain the slot numbers to be allocated
to a parade within the sub-frame.
The number_of_Groups (NoG) field shall be the number of groups in a
sub-frame assigned to the parade to which this group belongs, minus
1, e.g., NoG=0 implies that one group is allocated (or assigned) to
this parade in a sub-frame. The value of NoG may range from 0 to 7.
This limits the amount of data that a parade may take from the main
(legacy) service data, and consequently the maximum data that can
be carried by one parade. The slot numbers assigned to the
corresponding Parade can be calculated from SGN and NoG, using
Equation 1.
The Parade_repetition_cycle (PRC) field corresponds to the cycle
time over which the parade is transmitted, minus 1, specified in
units of M/H frames, as described in Table 12.
TABLE-US-00012 TABLE 12 PRC Description 000 This parade shall be
transmitted once every M/H frame. 001 This parade shall be
transmitted once every 2 M/H frames. 010 This parade shall be
transmitted once every 3 M/H frames. 011 This parade shall be
transmitted once every 4 M/H frames. 100 This parade shall be
transmitted once every 5 M/H frames. 101 This parade shall be
transmitted once every 6 M/H frames. 110 This parade shall be
transmitted once every 7 M/H frames. 111 Reserved
For example, if PRC field value is equal to `001`, this indicates
that the parade shall be transmitted once every 2 M/H frame.
The RS_Frame_mode field shall be as defined in Table 1. The
RS_Frame_mode field represents that one parade transmits one RS
frame or two RS frames.
The RS_code_mode_primary field shall be the RS code mode for the
primary RS frame. Herein, the RS_code_mode_primary field is defined
in Table 6.
The RS_code_mode_secondary field shall be the RS code mode for the
secondary RS frame. Herein, the RS_code_mode_secondary field is
defined in Table 6.
The SCCC_Block_mode field represents how M/H blocks within a data
group are assigned to SCCC block. The SCCC_Block_mode field shall
be as defined in Table 7.
The SCCC_outer_code_mode_A field corresponds to the SCCC outer code
mode for Region A within a data group. The SCCC outer code mode is
defined in Table 8.
The SCCC_outer_code_mode_B field corresponds to the SCCC outer code
mode for Region B within the data group. The SCCC_outer_code_mode_C
field corresponds be the SCCC outer code mode for Region C within
the data group. And, the SCCC_outer_code_mode_D field corresponds
to the SCCC outer code mode for Region D within the data group.
The FIC_version field represents a version of FIC data.
The Parade_continuity_counter field counter may increase from 0 to
15 and then repeat its cycle. This counter shall increment by 1
every (PRC+1) M/H frames. For example, as shown in Table 12,
PRC=011 (decimal 3) implies that Parade.sub.-- continuity_counter
increases every fourth M/H frame.
The TNoG field may be identical for all sub-frames in an M/H
Frame.
However, the information included in the TPC data presented herein
is merely exemplary. And, since the adding or deleting of
information included in the TPC may be easily adjusted and modified
by one skilled in the art, the present invention will, therefore,
not be limited to the examples set forth herein.
Since the TPC data (excluding the Sub-Frame_number field and the
Slot_number field) for each parade do not change their values
during an M/H frame, the same information is repeatedly transmitted
through all M/H groups belonging to the corresponding parade during
an M/H frame. This allows very robust and reliable reception of the
TPC data. Because the Sub-Frame_number and the Slot_number are
increasing counter values, they also are robust due to the
transmission of regularly expected values.
FIG. 39 illustrates an example of a transmission scenario of the
TPC data and the FIC data. The values of the Sub-Frame_number
field, Slot_number field, Parade_id field, Parade_repetition_cycle
field, and Parade_continuity_counter field may corresponds to the
current M/H frame throughout the sub-frames within a specific M/H
frame. Some of TPC parameters and FIC data are signaled in
advance.
The SGN, NoG and all FEC modes may have values corresponding to the
current M/H frame in the first two sub-frames. The SGN, NoG and all
FEC modes may have values corresponding to the frame in which the
parade next appears throughout the 3.sup.rd, 4.sup.th, and 5.sup.th
sub-frames of the current M/H frame. This enables the M/H receivers
to receive (or acquire) the transmission parameters in advance very
reliably.
For example, when Parade_repetition_cycle=`000`, the values of the
3.sup.rd, 4.sup.th, and 5.sup.th sub-frames of the current M/H
frame correspond to the next M/H frame. Also, when
Parade_repetition_cycle=`011`, the values of the 3.sup.rd,
4.sup.th, and 5.sup.th sub-frames of the current M/H frame
correspond to the 4.sup.th M/H frame and beyond.
The FIC_version field and the FIC_data field may have values that
apply to the current M/H Frame during the 1.sup.st sub-frame and
the 2.sup.nd sub-frame, and they shall have values corresponding to
the M/H frame immediately following the current M/H frame during
the 3.sup.rd, 4.sup.th, and 5.sup.th sub-frames of the current M/H
frame.
Meanwhile, the receiving system may turn the power on only during a
slot to which the data group of the designated (or desired) parade
is assigned, and the receiving system may turn the power off during
the remaining slots, thereby reducing power consumption of the
receiving system. Such characteristic is particularly useful in
portable or mobile receivers, which require low power consumption.
For example, it is assumed that data groups of a 1.sup.st parade
with NOG=3, a 2.sup.nd parade with NOG=2, and a 3.sup.rd parade
with NOG=3 are assigned to one M/H frame, as shown in FIG. 40. It
is also assumed that the user has selected a mobile service
included in the 1.sup.st parade using the keypad provided on the
remote controller or terminal. In this case, the receiving system
turns the power on only during a slot that data groups of the
1.sup.st parade is assigned, as shown in FIG. 40, and turns the
power off during the remaining slots, thereby reducing power
consumption, as described above. At this point, the power is
required to be turned on briefly earlier than the slot to which the
actual designated data group is assigned (or allocated). This is to
enable the tuner or demodulator to converge in advance.
Assignment of Known Data (or Training Signal)
In addition to the payload data, the M/H transmission system
inserts long and regularly spaced training sequences into each
group. The regularity is an especially useful feature since it
provides the greatest possible benefit for a given number of
training symbols in high-Doppler rate conditions. The length of the
training sequences is also chosen to allow fast acquisition of the
channel during bursted power-saving operation of the demodulator.
Each group contains 6 training sequences. The training sequences
are specified before trellis-encoding. The training sequences are
then trellis-encoded and these trellis-encoded sequences also are
known sequences. This is because the trellis encoder memories are
initialized to pre-determined values at the beginning of each
sequence. The form of the 6 training sequences at the byte level
(before trellis-encoding) is shown in FIG. 41. This is the
arrangement of the training sequence at the group formatter
303.
The 1.sup.st training sequence is located at the last 2 segments of
the 3.sup.rd M/H block (B3). The 2.sup.nd training sequence may be
inserted at the 2.sup.nd and 3.sup.rd segments of the 4.sup.th M/H
block (B4). The 2.sup.nd training sequence is next to the signaling
area, as shown in FIG. 5. Then, the 3.sup.rd training sequence, the
4.sup.th training sequence, the 5.sup.th training sequence, and the
6.sup.th training sequence may be placed at the last 2 segments of
the 4.sup.th, 5.sup.th, 6.sup.th, and 7.sup.th M/H blocks (B4, B5,
B6, and B7), respectively. As shown in FIG. 41, the 1.sup.st
training sequence, the 3.sup.rd training sequence, the 4.sup.th
training sequence, the 5.sup.th training sequence, and the 6.sup.th
training sequence are spaced 16 segments apart from one another.
Referring to FIG. 41, the dotted area indicates trellis
initialization data bytes, the lined area indicates training data
bytes, and the white area includes other bytes such as the
FEC-coded M/H service data bytes, FEC-coded signaling data, main
service data bytes, RS parity data bytes (for backwards
compatibility with legacy ATSC receivers) and/or dummy data
bytes.
FIG. 42 illustrates the training sequences (at the symbol level)
after trellis-encoding by the trellis encoder. Referring to FIG.
42, the dotted area indicates data segment sync symbols, the lined
area indicates training data symbols, and the white area includes
other symbols, such as FEC-coded mobile service data symbols,
FEC-coded signaling data, main service data symbols, RS parity data
symbols (for backwards compatibility with legacy ATSC receivers),
dummy data symbols, trellis initialization data symbols, and/or the
first part of the training sequence data symbols. Due to the
intra-segment interleaving of the trellis encoder, various types of
data symbols will be mixed in the white area.
After the trellis-encoding process, the last 1416 (=588+828)
symbols of the 1.sup.st training sequence, the 3.sup.rd training
sequence, the 4.sup.th training sequence, the 5.sup.th training
sequence, and the 6.sup.th training sequence commonly share the
same data pattern. Including the data segment synchronization
symbols in the middle of and after each sequence, the total length
of each common training pattern is 1424 symbols. The 2.sup.nd
training sequence has a first 528-symbol sequence and a second
528-symbol sequence that have the same data pattern. More
specifically, the 528-symbol sequence is repeated after the
4-symbol data segment synchronization signal. At the end of each
training sequence, the memory contents of the twelve modified
trellis encoders shall be set to zero (0).
Receiving System
FIG. 43 is a block diagram illustrating a receiving system
according to an embodiment of the present invention.
The receiving system of FIG. 43 includes an antenna 1300, a tuner
1301, a demodulating unit 1302, a demultiplexer 1303, a program
table buffer 1304, a program table decoder 1305, a program table
storage unit 1306, a data handler 1307, a middleware engine 1308,
an A/V decoder 1309, an A/V post-processor 1310, an application
manager 1311, and a user interface 1314. The application manager
1311 may include a channel manager 1312 and a service manager
1313.
In FIG. 43, solid lines indicate data flows and dotted lines
indicate control flows.
The tuner 1301 tunes to a frequency of a specific channel through
any of an antenna, a cable, or a satellite and down-converts the
frequency to an Intermediate Frequency (IF) signal and outputs the
IF signal to the demodulating unit 1302.
In one embodiment of the present invention, the tuner 1301 may
select a frequency of a specific mobile broadcasting channel from
among broadcasting channels transmitted via the antenna 1300. For
example, if it is assumed that the receiving system is a terminal
having both a communication function such as a phone function and a
broadcast function such as a mobile broadcasting function, the
antenna 1300 may be used as a broadcasting antenna, and an
additional communication antenna may also be included in the
receiving system. That is, the broadcasting antenna may be
physically different than the communication antenna. For another
example, one antenna may be used as both the broadcasting antenna
and the communication antenna. For still another example, a
plurality of antennas having different polarization characteristics
may be used as a substitute for the broadcasting antenna, so that a
multi-path diversity scheme is made available. In this case,
although a quality of a received broadcast signal increases in
proportion to the number of used antennas, power consumption
excessively increases and the size of a space occupied by an
overall system also increases. Therefore, it is preferable that a
proper number of diversity antennas be used in consideration of the
above-mentioned limitations.
Herein, the tuner 1301 is controlled by the channel manager 1312 in
the application manager 1311 and reports the result and strength of
a broadcast signal of the tuned channel to the channel manager
1312. Data received through the frequency of the specific channel
includes main service data, mobile service data, a transmission
parameter, and program table information (or signaling information)
for decoding the main service data and the mobile service data.
The demodulating unit 1302 performs VSB demodulation, channel
equalization, etc., on the signal output from the tuner 1301 and
identifies and separately outputs main service data and mobile
service data. The demodulating unit 1302 will be described in
detail in a later.
On the other hand, the transmitter can transmit signaling
information (or TPC information) including transmission parameters
by inserting the signaling information into at least one of a field
synchronization region, a known data region, and a mobile service
data region. Accordingly, the demodulating unit 1302 can extract
the transmission parameters from the field synchronization region,
the known data region, and the mobile service data region.
The transmission parameters may include M/H frame information,
sub-frame information, slot information, parade-related information
(for example, a parade_id, a parade repeat period, etc.),
information of data groups in a sub-frame, RS frame mode
information, RS code mode information, SCCC block mode information,
SCCC outer code mode information, FIC version information, etc.
The demodulating unit 1302 performs block decoding, RS frame
decoding, etc., using the extracted transmission parameters. For
example, the demodulating unit 1302 performs block decoding of each
region in a data group with reference to SCCC-related information
(for example, SCCC block mode information or an SCCC outer code
mode) included in the transmission parameters and performs RS frame
decoding of each region included in the data group with reference
to RS-related information (for example, an RS code mode).
In the embodiment of the present invention, an RS frame including
mobile service data demodulated by the demodulating unit 1302 is
input to the demultiplexer 1303.
That is, data inputted to the demultiplexer 1303 has an RS frame
payload format as shown in FIG. 17(a) or FIG. 17(b). More
specifically, the RS frame decoder of the demodulating unit 1302
performs the reverse of the encoding process performed at the RS
frame encoder of the transmission system to correct errors in the
RS frame and then outputs the error-corrected RS frame payload to a
data derandomizer. The data derandomizer then performs
derandomizing on the error-corrected RS frame payload through the
reverse of the randomizing process performed at the transmission
system to obtain an RS frame payload as shown in FIG. 17(a) or FIG.
17(b).
The demultiplexer 1303 may receive RS frame payloads of all parades
and may also receive only an RS frame payload of a parade including
a mobile service that the user desires to receive through power
supply control. For example, when RS frame payloads of all parades
are received, the demultiplexer 1303 can demultiplex a parade
including a mobile service that the user desires to receive using a
parade_id.
When one parade carries two RS frames, the demultiplexer 1303 needs
to identify an RS frame carrying an ensemble including mobile
service data to be decoded from a parade containing a mobile
service that the user desires to receive. That is, when a received
single parade or a parade demultiplexed from a plurality of parades
carries a primary ensemble and a secondary ensemble, the
demultiplexer 1303 selects one of the primary and secondary
ensembles.
In an embodiment, the demultiplexer 1303 can demultiplex an RS
frame carrying an ensemble including mobile service data to be
decoded using an ensemble_id created by adding one bit to a left
position of the parade_id.
The demultiplexer 1303 refers to the M/H header of the M/H service
data packet within the RS frame payload belonging to the ensemble
including the mobile service data that are to be decoded, thereby
identifying when the corresponding M/H service data packet is the
program table information (or signaling information) or the IP
datagram of the mobile service data. Alternatively, when the
program table information (or signaling information) and the mobile
service data are both configured in the form of IP datagrams, the
demultiplexer 1303 may use the IP address in order to identify the
IP datagram of the program table information (or signaling
information) and the mobile service data.
Herein, the identified program table information (or signaling
information) is outputted to the program table buffer 1304. And,
audio/video/data streams are separated from the IP datagram of
mobile service data that are to be selected among the IP datagrams
of the identified mobile service data, thereby being respectively
outputted to the A/V decoder 1309 and/or the data handler 1307.
According to an embodiment of the present invention, when the
stuff_indicator field within the M/H header of the M/H service data
packet indicates that stuffing bytes are inserted in the payload of
the corresponding M/H service data packet, the demultiplexer 1303
removes the stuffing bytes from the payload of the corresponding
M/H service data packet. Then, the demultiplexer 1303 identifies
the program table information and the mobile service data.
Thereafter, the demultiplexer 1303 identifies A/V/D streams from
the identified mobile service data.
The program table buffer 1304 temporarily stores the section-type
program table information and then outputs the section-type program
table information to the program table decoder 1305.
The program table decoder 1305 identifies tables using a table_id
and a section_length in the program table information and parses
sections of the identified tables and produces and stores a
database of the parsed results in the program table storage unit
1306. For example, the program table decoder 1305 collects sections
having the same table identifier (table_id) to construct a table.
The program table decoder 1305 then parses the table and produces
and stores a database of the parsed results in the program table
storage unit 1306.
The A/V decoder 1309 decodes the audio and video streams outputted
from the demultiplexer 1303 using audio and video decoding
algorithms, respectively. The decoded audio and video data is
outputted to the A/V post-processor 1310. Here, at least one of an
AC-3 decoding algorithm, an MPEG 2 audio decoding algorithm, an
MPEG 4 audio decoding algorithm, an AAC decoding algorithm, an AAC+
decoding algorithm, an HE AAC decoding algorithm, an AAC SBR
decoding algorithm, an MPEG surround decoding algorithm, and a BSAC
decoding algorithm can be used as the audio decoding algorithm and
at least one of an MPEG 2 video decoding algorithm, an MPEG 4 video
decoding algorithm, an H.264 decoding algorithm, an SVC decoding
algorithm, and a VC-1 decoding algorithm can be used as the audio
decoding algorithm.
The data handler 8507 processes data stream packets required for
data broadcasting among data stream packets separated (or
identified) by the demultiplexer 1303 and provides the processed
data stream packets to the middleware engine 1310 to allow the
middleware engine 1310 to be multiplexed them with A/V data. In an
embodiment, the middleware engine 1310 is a Java middleware
engine.
The application manager 1311 receives a key input from the TV
viewer and displays a Graphical User Interface (GUI) on the TV
screen in response to a viewer request through a User Interface
(UI). The application manager 1311 also writes and reads
information regarding overall GUI control of the TV, user requests,
and TV system states to and from a memory (for example, NVRAM or
flash memory). In addition, the application manager 1311 can
receive parade-related information (for example, a parade_id) from
the demodulating unit 1302 to control the demultiplexer 1303 to
select an RS frame of a parade including a required mobile service.
The application manager 1311 can also receive an ensemble_id to
control the demultiplexer 1303 to select an RS frame of an ensemble
including mobile service data to be decoded from the parade. The
application manager 1311 also controls the channel manager 1312 to
perform channel-related operations (for example, channel map
management and program table decoder operations).
The channel manager 1312 manages physical and logical channel maps
and controls the tuner 1301 and the program table decoder 1305 to
respond to a channel-related request of the viewer. The channel
manager also requests that the program table decoder 1305 parse a
channel-related table of a channel to be tuned and receives the
parsing results from the program table decoder 1305.
Demodulating Unit within Receiving System
FIG. 44 illustrates an example of a demodulating unit in a digital
broadcast receiving system according to the present invention. The
demodulating unit of FIG. 44 uses known data information, which is
inserted in the mobile service data section and, then, transmitted
by the transmitting system, so as to perform carrier
synchronization recovery, frame synchronization recovery, and
channel equalization, thereby enhancing the receiving performance.
Also the demodulating unit may turn the power on only during a slot
to which the data group of the designated (or desired) parade is
assigned, thereby reducing power consumption of the receiving
system.
Referring to FIG. 44, the demodulating unit includes an operation
controller 2000, a demodulator 2002, an equalizer 2003, a known
sequence detector 2004, a block decoder 2005, and a RS frame
decoder 2006. The demodulating unit may further include a main
service data processor 2008. The main service data processor 2008
may include a data deinterleaver, a RS decoder, and a data
derandomizer. The demodulating unit may further include a signaling
decoder 2013. The receiving system also may further include a power
controller 5000 for controlling power supply of the demodulating
unit.
More specifically, a frequency of a particular channel tuned by a
tuner down converts to an intermediate frequency (IF) signal. Then,
the down-converted data 2001 outputs the down-converted IF signal
to the demodulator 2002 and the known sequence detector 2004. At
this point, the down-converted data 2001 is inputted to the
demodulator 2002 and the known sequence detector 2004 via
analog/digital converter ADC (not shown). The ADC converts
pass-band analog IF signal into pass-band digital IF signal.
The demodulator 2002 performs self gain control, carrier recovery,
and timing recovery processes on the inputted pass-band digital IF
signal, thereby modifying the IF signal to a base-band signal.
Then, the demodulator 2002 outputs the newly created base-band
signal to the equalizer 2003 and the known sequence detector
2004.
The equalizer 2003 compensates the distortion of the channel
included in the demodulated signal and then outputs the
error-compensated signal to the block decoder 2005.
At this point, the known sequence detector 2004 detects the known
sequence position information inserted by the transmitting end from
the input/output data of the demodulator 2002 (i.e., the data prior
to the demodulation process or the data after the demodulation
process). Thereafter, the position information along with the
symbol sequence of the known data, which are generated from the
detected position, is outputted to the operation controller 2000,
the demodulator 2002, the equalizer 2003, and the signaling decoder
2013. Also, the known sequence detector 2004 outputs a set of
information to the block decoder 2005. This set of information is
used to allow the block decoder 2005 of the receiving system to
identify the mobile service data that are processed with additional
encoding from the transmitting system and the main service data
that are not processed with additional encoding.
In addition, although the connection status is not shown in FIG.
44, the information detected from the known sequence detector 2004
may be used throughout the entire receiving system and may also be
used in the RS frame decoder 2006.
The data demodulated in the demodulator 2002 or the data equalized
in the channel equalizer 2003 is inputted to the signaling decoder
2013. The known data position information detected in the known
sequence detector 2004 is inputted to the signaling decoder
2013.
The signaling decoder 2013 extracts and decodes signaling
information (e.g., TPC information), which inserted and transmitted
by the transmitting end, from the inputted data, the decoded
signaling information provides to blocks requiring the signaling
information.
More specifically, the signaling decoder 2013 extracts and decodes
TPC data and FIC data, which inserted and transmitted by the
transmitting end, from the equalized data, and then the decoded TPC
data and FIC data outputs to the operation controller 2000, the
known sequence detector 2004, and the power controller 5000. For
example, the TPC data and FIC data is inserted in a signaling
information region of each data group, and then is transmitted to a
receiving system.
The signaling decoder 2013 performs signaling decoding as an
inverse process of the signaling encoder shown in FIG. 37, so as to
extract TPC data and FIC data. For example, the signaling decoder
2013 decodes the inputted data using the PCCC method and
derandomizes the decoded data, thereby dividing the derandomized
data into TPC data and FIC data. At this point, the signaling
decoder 2013 performs RS-decoding on the divided TPC data, so as to
correct the errors occurring in the TPC data. Subsequently, the
signaling decoder 2013 deinterleaves the divided FIC data and then
performs RS-decoding on the deinterleaved FIC data, so as to
correct the error occurring in the FIC data. The error-corrected
TPC data are then outputted to the operation controller 2000, the
known sequence detector 2004, and the power controller 5000.
The TPC data may also include a transmission parameter which is
inserted into the payload region of an OM packet by the service
multiplexer 100, and then is transmitted to transmitter 200.
Herein, the TPC data may include RS frame information, SCCC
information, M/H frame information, and so on, as shown in FIG. 38.
The RS frame information may include RS frame mode information and
RS code mode information. The SCCC information may include SCCC
block mode information and SCCC outer code mode information. The
M/H frame information may include M/H frame index information, and
the TPC data may include sub-frame count information, slot count
information, parade_id information, SGN information, NoG
information, and so on.
At this time, the signaling information area within the data group
can be identified using known data information output from the
known data detector 2004. More specifically, the first known data
sequence (i.e., first training sequence) is inserted into the last
two segments of the M/H block B3, and the second known data
sequence (i.e., second training sequence) is inserted into the
second and third segments of the M/H block B4. At this time, since
the second known data sequence is received subsequently to the
signaling information area, the signaling decoder 2013 can decode
the signaling information of the signaling information area by
extracting the same from the data output from the demodulator 2002
or the channel equalizer 2003.
The power controller 5000 is inputted the M/H frame-associated
information from the signaling decoder 2013, and controls power of
the tuner and the demodulating unit. Alternatively, the power
controller 5000 is inputted a power control information from the
operation controller 2000, and controls power of the tuner and the
demodulating unit.
According to the embodiment of the present invention, the power
controller 5000 turns the power on only during a slot to which a
slot of the parade including user-selected mobile service is
assigned. The power controller 5000 then turns the power off during
the remaining slots.
For example, it is assumed that data groups of a 1.sup.st parade
with NOG=3, a 2.sup.nd parade with NOG=2, and a 3.sup.rd parade
with NOG=3 are assigned to one M/H frame, as shown in FIG. 40. It
is also assumed that the user has selected a mobile service
included in the 1.sup.st parade using the keypad provided on the
remote controller or terminal. In this case, the power controller
5000 turns the power on during a slot that data groups of the
1.sup.st parade is assigned, as shown in FIG. 40, and turns the
power off during the remaining slots, thereby reducing power
consumption.
The demodulator 2002 uses the known data symbol sequence during the
timing and/or carrier recovery, thereby enhancing the demodulating
performance. Similarly, the equalizer 2003 uses the known data so
as to enhance the equalizing performance. Moreover, the decoding
result of the block decoder 2005 may be fed-back to the equalizer
2003, thereby enhancing the equalizing performance.
Demodulator and Known Sequence Detector
At this point, the transmitting system may receive a data frame (or
VSB frame) including a data group which known data sequence (or
training sequence) is periodically inserted therein, as shown in
FIG. 5. Herein, the data group is divided into regions A to D, as
shown in FIG. 5. More specifically, in the example of the present
invention, each region A, B, C, and D are further divided into M/H
blocks B4 to B7, M/H blocks B3 and B8, M/H blocks B2 and B9, M/H
blocks B1 and B10, respectively.
Referring to FIG. 41 and FIG. 42, known data sequence having the
same pattern are included in each known data section that is being
periodically inserted. Herein, the length of the known data
sequence having identical data patterns may be either equal to or
different from the length of the entire (or total) known data
sequence of the corresponding known data section (or block). If the
two lengths are different from one another, the length of the
entire known data sequence should be longer than the length of the
known data sequence having identical data patterns. In this case,
the same known data sequences are included in the entire known data
sequence.
As described above, when the known data are periodically inserted
in-between the mobile service data, the channel equalizer of the
receiving system may use the known data as training sequences,
which may be used as accurate discriminant values. According to
another embodiment of the present invention, the channel equalizer
estimates a channel impulse response. Herein, the known data may be
used in the process. According to yet another embodiment of the
present invention, the channel equalizer may use the known data for
updating filter coefficients (i.e., equalization coefficients).
Meanwhile, when known data sequence having the same pattern is
periodically inserted, each known data sequence may be used as a
guard interval in a channel equalizer according to the present
invention. Herein, the guard interval prevents interference that
occurs between blocks due to a multiple path channel This is
because the known data sequence located behind a mobile service
data section (i.e., data block) may be considered as being copied
in front of the mobile service data section.
The above-described structure is referred to as a cyclic prefix.
This structure provides circular convolution in a time domain
between a data block transmitted from the transmitting system and a
channel impulse response. Accordingly, this facilitates the channel
equalizer of the receiving system to perform channel equalization
in a frequency domain by using a fast fourier transform (FFT) and
an inverse fast fourier transform (IFFT).
More specifically, when viewed in the frequency domain, the data
block received by the receiving system is expressed as a
multiplication of the data block and the channel impulse response.
Therefore, when performing the channel equalization, by multiplying
the inverse of the channel in the frequency domain, the channel
equalization may be performed more easily.
The known sequence detector 2004 detects the position of the known
data being periodically inserted and transmitted as described
above. At the same time, the known sequence detector 2004 may also
estimate initial frequency offset during the process of detecting
known data. In this case, the demodulator 2002 may estimate with
more accuracy carrier frequency offset from the information on the
known data position information and initial frequency offset
estimation value, thereby compensating the estimated carrier
frequency offset.
Meanwhile, when known data is transmitted, as shown in FIG. 5, the
known sequence detector 2004 detects a position of second known
data region by using known data of the second known data region
that the same pattern is repeated twice.
At this point, since the known sequence detector 2004 is
well-informed of the data group structure, when the position of the
second known data region is detected, the known sequence detector
2004 can estimate positions of the first, third, fourth, fifth, and
sixth known data regions of a corresponding data group by counting
symbols or segments based upon the second known data region
position. If the corresponding data group is a data group including
field synchronization segment, the known sequence detector 2004 can
estimate the position of the field synchronization segment of the
corresponding data group, which is positioned chronologically
before the second known data region, by counting symbols or
segments based upon the second known data region position. Also,
the known sequence detector 2004 may estimate the known data
position information and the field synchronization position
information from the parade including mobile service selected by a
user based on the M/H frame-associated information outputted from
the signaling decoder 2013.
At least one of the estimated known data poison information and
field synchronization information is provided to the demodulator
2002, the channel equalizer 2003, the signaling decoder 2013, and
the operation controller 2000.
Also, the known sequence detector 2004 may estimate initial
frequency offset by using known data inserted in the second known
data region (i.e., ACQ known data region). In this case, the
demodulator 2002 may estimate with more accuracy carrier frequency
offset from the information on the known data position information
and initial frequency offset estimation value, thereby compensating
the estimated carrier frequency offset.
Operation Controller
The operation controller 2000 receives the known data position
information and the transmission parameter information and then
forwards M/H frame time information, a presence or non-presence of
a data group of a selected parade, position information of known
data within the data group, power control information and the like
to each block of the demodulating unit. The operation controller
2000, as shown in FIG. 44, controls operations of the demodulator
2002, the channel equalizer 2003, the block decoder 2005 and the RS
frame decoder 2006. And, the operation controller 2000 is able to
overall operations of the demodulating unit (not shown in the
drawing). Moreover, the operation controller 2000 can be
implemented with the separate block or can be included within a
prescribed one of the blocks of the demodulating unit shown in FIG.
44.
FIG. 45 is an overall block diagram of an operation controller
2000.
Referring to FIG. 45, the operation controller 2000 can include a
parade ID checker 3101, a frame synchronizer 3102, a parade mapper
3103, a group controller 3104 and a known sequence indication
controller 3105.
The operation controller 2000 receives known data position
information from the known sequence detector 2004 and receives
transmission parameter information from the signaling decoder 2013.
The operation controller 2000 then generates a control signal
necessary for a demodulating unit of a receiving system. For
instance, the known data position information detected by the known
sequence detector 2004 is inputted to the known sequence indication
controller 3105. And, the transmission parameter information (i.e.,
TPC data) decoded by the signaling decoder 2013 is inputted to the
parade ID checker 3101.
The parade ID checker 3101 compares a parade ID (parade ID selected
by a user) contained in the user control signal to a parade ID
inputted from the signaling decoder 2013. If the two parade IDs are
not identical to each other, the parade ID checker stands by until
a next transmission parameter is inputted from the signaling
decoder 2013.
If the two parade IDs are identical to each other, the parade ID
checker 3101 outputs the transmission parameter information to the
blocks within the operation controller 2000 and the overall
system.
If it is checked that the parade ID in the transmission parameter
information inputted to the parade ID checker 3101 is identical to
the parade ID selected by a user, the parade ID checker 3101
outputs starting_group_number (SGN) and number_of_groups (NOG) to
the parade mapper 3103, outputs sub_frame_number, slot_number and
parade_repetition_cycle PRC) to the frame synchronizer 3102,
outputs SCCC_block_mode, SCCC_outer_code_mode_A,
SCCC_outer_code_mode_B, SCCC_outer_code_mode_C and
SCCC_outer_code_mode_D to the block decoder 2005, and outputs
RS_frame_mode, RS_code_mode_primary and Rs_code_mode_secondary to
the RS frame decoder 2006.
The parade mapper 3103 receives the SGN and the NOG from the parade
ID checker as inputs, decides a data group is carried by which one
of sixteen slots within a Sub-frame, and then outputs the
corresponding information. Data group number transmitted every
sub-frame is set to an integer consecutive between SGN and
(SGN+NOG-1). For instance, if SGN=3 and NOG=4, four groups, of
which group numbers are 3, 4, 5 and 6, are transmitted for the
corresponding sub-frames, respectively. The parade mapper finds a
slot number j for transmitting a data group according to Equation 1
with a group number i obtained from SGN and NOG.
In the above example, in case of SGN=3 and NOG=4, if they are
inserted in Equation 1, slot numbers of groups transmitted
according to the above formula sequentially become 12, 2, 6 and
10.
The parade mapper 3103 then outputs the found slot number
information. The slot number information may be outputted to the
signaling decoder 2013. In this case, the signaling decoder 2013
may identify a start of a subframe or a end of the subframe by
using the slot number information.
For example of outputting slot numbers, a method of using a bit
vector having 16 bits is available.
A bit vector SNi (i=0.about.15) can be set to 1 if there exists a
group transmitted for an i.sup.th slot. A bit vector SNi
(i=0.about.15) can be set to 0 if a group transmitted for an
i.sup.th slot does not exist. And, this bit vector can be outputted
as slot number information.
The frame synchronizer 3102 receives the sub_frame_number,
slot-number and PRC from the parade ID checker and then sends
slot_counter and frame_mask signals as outputs. The slot_counter is
the signal indicating a slot_number at a current timing point at
which a receiver is operating. And, the frame_mask is the signal
indicating whether a corresponding parade is transmitted for a
current frame. The frame synchronizer 3102 performs a process for
initializing slot_counter, sub_frame_number and frame_counter in
receiving signaling information initially. A counter value of a
current timing point is generated from adding a delayed slot number
L according to a time taken to decode signaling from demodulation
together with the signaling information inputted in this process.
After completion of the initialization process, slot_counter is
updated every
single slot period, updates sub_frame_counter every period of the
slot_counter value, and updates frame_counter every period of the
sub_frame_counter. By referring to the frame_counter information
and the PRC information, a frame_mask signal is generated. For
example, if a corresponding parade is being transmitted for a
current frame, `1` is outputted as the frame_mask. Otherwise, it is
able to output `0`.
The group controller 3104 receives the slot number information from
the parade mapper 3103. The group controller 3104 receives the
slot_counter and frame_mask information from the frame synchronizer
3102. The group controller 3104 then outputs
group_presence_indicator indicating whether an M/H group is being
transmitted. For instance, if the slot number information inputted
from the parade mapper 3103 corresponds to 12, 2, 6 and 10, when
the frame_mask information inputted from the frame synchronizer
3102 is 1 and the slot_counter inputted from the frame synchronizer
3102 includes 2, 6, 10 and 12, `1` is outputted as the
group_presence_indicator. Otherwise, it is able to output 0.
The group_presence_indicator may be outputted to the signaling
decoder 2013. In this case, the signaling decoder 2013 may use the
group_presence_indicator to identify whether a data group
exits.
The known sequence indication controller 3105 outputs position
information of another known data, group start position information
and the like with position information of specific inputted known
data. In this case, since the known data are present at a
previously appointed position within the data group, if position
data of one of a plurality of known data sequences, it is able to
know data position information of another known sequence, data
group start position information and the like. The known sequence
indication controller 3105 can output known data and data group
position information necessary for the demodulating unit of the
receiving system using the group_presence_indicator information
only if the data group is transmitted. Alternatively, the known
sequence detector 2004 can perform operations of the known sequence
indication controller 3105.
Channel Equalizer
The data demodulated by the demodulator 2002 by using the known
data are inputted to the equalizer 2003. Additionally, the
demodulated data may also be inputted to the known sequence
detector 2004. At this point, a data group that is inputted for the
equalization process may be divided into region A to region D, as
shown in FIG. 5. More specifically, according to the embodiment of
the present invention, region A includes M/H block B4 to M/H block
B7, region B includes M/H block B3 and M/H block B8, region C
includes M/H block B2 and M/H block B9, and region D includes M/H
block B1 and M/H block B10. In other words, one data group is
divided into M/H blocks from B1 to B10, each M/H block having the
length of 16 segments. Also, a long training sequence (i.e., known
data sequence) is inserted at the starting portion of the M/H
blocks B4 to B8. Furthermore, two data groups may be allocated (or
assigned) to one VSB field. In this case, field synchronization
data are positioned in the 37.sup.th segment of one of the two data
groups.
The present invention may use known data, which have position and
content information based upon an agreement between the
transmitting system and the receiving system, and/or field
synchronization data for the channel equalization process.
The channel equalizer 2003 may perform channel equalization using a
plurality of methods. According to the present invention, the
channel equalizer 2003 uses known data and/or field synchronization
data, so as to estimate a channel impulse response (CIR), thereby
performing channel equalization.
Most particularly, an example of estimating the CIR in accordance
with each region within the data group, which is hierarchically
divided and transmitted from the transmitting system, and applying
each CIR differently will also be described herein.
At this point, a data group can be assigned and transmitted a
maximum the number of 4 in a VSB frame in the transmitting system.
In this case, all data group do not include field synchronization
data. In the present invention, the data group including the field
synchronization data performs channel-equalization using the field
synchronization data and known data. And the data group not
including the field synchronization data performs
channel-equalization using the known data.
For example, the data of the M/H block B3 including the field
synchronization data performs channel-equalization using the CIR
calculated from the field synchronization data area and the CIR
calculated from the first known data area. Also, the data of the
M/H blocks B1 and B2 performs channel-equalization using the CIR
calculated from the field synchronization data area and the CIR
calculated from the first known data area. Meanwhile, the data of
the M/H blocks B1 to B3 not including the field synchronization
data performs channel-equalization using CIRS calculated from the
first known data area and the third known data area.
As described above, the present invention uses the CIR estimated
from the known data region in order to perform channel equalization
on data within the data group. At this point, each of the estimated
CIRs may be directly used in accordance with the characteristics of
each region within the data group. Alternatively, a plurality of
the estimated CIRs may also be either interpolated or extrapolated
so as to create a new CIR, which is then used for the channel
equalization process.
Herein, when a value F(Q) of a function F(x) at a particular point
Q and a value F(S) of the function F(x) at another particular point
S are known, interpolation refers to estimating a function value of
a point within the section between points Q and S. Linear
interpolation corresponds to the simplest form among a wide range
of interpolation operations.
FIG. 46 illustrates an example of linear interpolation. More
specifically, in a random function F(x), when given the values F(Q)
and F(S) each from points x=Q and x=S, respectively, the
approximate value {circumflex over (F)}(P) of the F(x) function at
point x=P may be estimated by using Equation 7 below. In other
words, since the values of F(Q) and F(S) respective to each point
x=Q and x=S are known (or given), a straight line passing through
the two points may be calculated so as to obtain the approximate
value {circumflex over (F)}(P) of the corresponding function value
at point P. At this point, the straight line passing through points
(Q,F (Q)) and (S,F(S)) may be obtained by using Equation 7
below.
.function..function..function..times..function..times..times.
##EQU00002##
Accordingly, Equation 8 below shows the process of substituting p
for x in Equation 7, so as to calculate the approximate value
{circumflex over (F)}(P) of the function value at point P.
.function..function..function..times..function..times..times..function..t-
imes..function..times..function..times..times. ##EQU00003##
The linear interpolation method of Equation 8 is merely the
simplest example of many other linear interpolation methods.
Therefore, since any other linear interpolation method may be used,
the present invention will not be limited only to the examples
given herein.
Alternatively, when a value F(Q) of a function F(x) at a particular
point Q and a value F(S) of the function F(x) at another particular
point S are known (or given), extrapolation refers to estimating a
function value of a point outside of the section between points Q
and S. Herein, the simplest form of extrapolation corresponds to
linear extrapolation.
FIG. 47 illustrates an example of linear extrapolation. As
described above, for linear extrapolation as well as linear
interpolation, in a random function F(x), when given the values
F(Q) and F(S) each from points x=Q and x=S, respectively, the
approximate value {circumflex over (F)}(P) of the corresponding
function value at point P may be obtained by calculating a straight
line passing through the two points. Herein, linear extrapolation
is the simplest form among a wide range of extrapolation
operations. Similarly, the linear extrapolation described herein is
merely exemplary among a wide range of possible extrapolation
methods. And, therefore, the present invention is not limited only
to the examples set forth herein.
FIG. 48 illustrates a block diagram of a channel equalizer
according to an embodiment of the present invention. Referring to
FIG. 48, the channel equalizer includes a first frequency domain
converter 4100, a channel estimator 4110, a second frequency domain
converter 4121, a coefficient calculator 4122, a distortion
compensator 4130, and a time domain converter 4140.
Herein, the channel equalizer may further include a remaining
carrier phase error remover, a noise canceller (NC), and a decision
unit.
The first frequency domain converter 4100 includes an overlap unit
4101 overlapping inputted data, and a fast fourier transform (FFT)
unit 4102 converting the data outputted from the overlap unit 4101
to frequency domain data.
The channel estimator 4110 includes a CIR estimator 4111, a first
cleaner 4113, a CIR calculator 4114, a second cleaner, and a
zero-padding unit. herein, the channel estimator 4110 may further
include a phase compensator compensating a phase of the CIR which
estimated in the CIR estimator 4111.
The second frequency domain converter 4121 includes a fast fourier
transform (FFT) unit converting the CIR being outputted from the
channel estimator 4110 to frequency domain CIR.
The time domain converter 4140 includes an IFFT unit 4141
converting the data having the distortion compensated by the
distortion compensator 4130 to time domain data, and a save unit
4142 extracting only valid data from the data outputted from the
IFFT unit 4141. The output data from the save unit 4142 corresponds
to the channel-equalized data.
If the remaining carrier phase error remover is connected to an
output terminal of the time domain converter 4140, the remaining
carrier phase error remover estimates the remaining carrier phase
error included in the channel-equalized data, thereby removing the
estimated error. If the noise remover is connected to an output
terminal of the time domain converter 4140, the noise remover
estimates noise included in the channel-equalized data, thereby
removing the estimated noise.
More specifically, the receiving data demodulated in FIG. 48 are
overlapped by the overlap unit 4101 of the first frequency domain
converter 4100 at a pre-determined overlapping ratio, which are
then outputted to the FFT unit 4102. The FFT unit 4102 converts the
overlapped time domain data to overlapped frequency domain data
through by processing the data with FFT. Then, the converted data
are outputted to the distortion compensator 4130.
The distortion compensator 4130 performs a complex number
multiplication on the overlapped frequency domain data outputted
from the FFT unit 4102 included in the first frequency domain
converter 4100 and the equalization coefficient calculated from the
coefficient calculator 4122, thereby compensating the channel
distortion of the overlapped data outputted from the FFT unit 4102.
Thereafter, the compensated data are outputted to the IFFT unit
4141 of the time domain converter 4140. The IFFT unit 4141 performs
IFFT on the overlapped data having the channel distortion
compensated, thereby converting the overlapped data to time domain
data, which are then outputted to the save unit 4142. The save unit
4142 extracts valid data from the data of the channel-equalized and
overlapped in the time domain, and outputs the extracted valid
data.
Meanwhile, the received data are inputted to the overlap unit 4101
of the first frequency domain converter 4100 included in the
channel equalizer and, at the same time, inputted to the CIR
estimator 4111 of the channel estimator 4110.
The CIR estimator 4111 uses a training sequence, for example, data
being inputted during the known data section and the known data in
order to estimate the CIR. If the data to be channel-equalizing is
the data within the data group including field synchronization
data, the training sequence using in the CIR estimator 4111 may
become the field synchronization data and known data. Meanwhile, if
the data to be channel-equalizing is the data within the data group
not including field synchronization data, the training sequence
using in the CIR estimator 4111 may become only the known data.
For example, the CIR estimator 4111 estimates CIR using the known
data correspond to reference known data generated during the known
data section by the receiving system in accordance with an
agreement between the receiving system and the transmitting system.
For this, the CIR estimator 4111 is provided known data position
information from the known sequence detector 2004. Also the CIR
estimator 4111 may be provided field synchronization position
information from the known sequence detector 2004.
The estimated CIR passes through the first cleaner (or pre-CIR
cleaner) 4113 or bypasses the first cleaner 4113, thereby being
inputted to the CIR calculator (or CIR interpolator-extrapolator)
4114. The CIR calculator 4114 either interpolates or extrapolates
an estimated CIR, which is then outputted to the second cleaner (or
post-CIR cleaner) 4115.
The first cleaner 4113 may or may not operate depending upon
whether the CIR calculator 4114 interpolates or extrapolates the
estimated CIR. For example, if the CIR calculator 4114 interpolates
the estimated CIR, the first cleaner 4113 does not operate.
Conversely, if the CIR calculator 4114 extrapolates the estimated
CIR, the first cleaner 4113 operates.
More specifically, the CIR estimated from the known data includes a
channel element that is to be obtained as well as a jitter element
caused by noise. Since such jitter element deteriorates the
performance of the equalizer, it preferable that a coefficient
calculator 4122 removes the jitter element before using the
estimated CIR. Therefore, according to the embodiment of the
present invention, each of the first and second cleaners 4113 and
4115 removes a portion of the estimated CIR having a power level
lower than the predetermined threshold value (i.e., so that the
estimated CIR becomes equal to `0`). Herein, this removal process
will be referred to as a "CIR cleaning" process.
The CIR calculator 4114 performs CIR interpolation by multiplying
CIRs estimated from the CIR estimator 4111 by each of coefficients,
thereby adding the multiplied values. At this point, some of the
noise elements of the CIR may be added to one another, thereby
being cancelled. Therefore, when the CIR calculator 4114 performs
CIR interpolation, the original (or initial) CIR having noise
elements remaining therein. In other words, when the CIR calculator
4114 performs CIR interpolation, the estimated CIR bypasses the
first cleaner 4113 and is inputted to the CIR calculator 4114.
Subsequently, the second cleaner 4115 cleans the CIR interpolated
by the CIR interpolator-extrapolator 4114.
Conversely, the CIR calculator 4114 performs CIR extrapolation by
using a difference value between two CIRs, so as to estimate a CIR
positioned outside of the two CIRs. Therefore, in this case, the
noise element is rather amplified. Accordingly, when the CIR
calculator 4114 performs CIR extrapolation, the CIR cleaned by the
first cleaner 4113 is used. More specifically, when the CIR
calculator 4114 performs CIR extrapolation, the extrapolated CIR
passes through the second cleaner 4115, thereby being inputted to
the zero-padding unit 4116.
Meanwhile, when a second frequency domain converter (or fast
fourier transform (FFT2)) 4121 converts the CIR, which has been
cleaned and outputted from the second cleaner 4115, to a frequency
domain, the length and of the inputted CIR and the FFT size may not
match (or be identical to one another). In other words, the CIR
length may be smaller than the FFT size. In this case, the
zero-padding unit 4116 adds a number of zeros `0`s corresponding to
the difference between the FFT size and the CIR length to the
inputted CIR, thereby outputting the processed CIR to the second
frequency domain converter (FFT2) 4121. Herein, the zero-padded CIR
may correspond to one of the interpolated CIR, extrapolated CIR,
and the CIR estimated in the known data section.
The second frequency domain converter 4121 performs FFT on the CIR
being outputted from the zero padding unit 4116, thereby converting
the CIR to a frequency domain CIR. Then, the second frequency
domain converter 4121 outputs the converted CIR to the coefficient
calculator 4122.
The coefficient calculator 4122 uses the frequency domain CIR being
outputted from the second frequency domain converter 4121 to
calculate the equalization coefficient. Then, the coefficient
calculator 4122 outputs the calculated coefficient to the
distortion compensator 4130. Herein, for example, the coefficient
calculator 4122 calculates a channel equalization coefficient of
the frequency domain that can provide minimum mean square error
(MMSE) from the CIR of the frequency domain, which is outputted to
the distortion compensator 4130.
The distortion compensator 4130 performs a complex number
multiplication on the overlapped data of the frequency domain being
outputted from the FFT unit 4102 of the first frequency domain
converter 4100 and the equalization coefficient calculated by the
coefficient calculator 4122, thereby compensating the channel
distortion of the overlapped data being outputted from the FFT unit
4102.
Block Decoder
Meanwhile, if the data being inputted to the block decoder 2005,
after being channel-equalized by the equalizer 2003, correspond to
the data having both block encoding and trellis encoding performed
thereon (i.e., the data within the RS frame, the signaling
information data, etc.) by the transmitting system, trellis
decoding and block decoding processes are performed on the inputted
data as inverse processes of the transmitting system.
Alternatively, if the data being inputted to the block decoder 2005
correspond to the data having only trellis encoding performed
thereon (i.e., the main service data), and not the block encoding,
only the trellis decoding process is performed on the inputted data
as the inverse process of the transmitting system.
The trellis decoded and block decoded data by the block decoder
2005 are then outputted to the RS frame decoder 2006. More
specifically, the block decoder 2005 removes the known data, data
used for trellis initialization, and signaling information data,
MPEG header, which have been inserted in the data group, and the RS
parity data, which have been added by the RS encoder/non-systematic
RS encoder or non-systematic RS encoder of the transmitting system.
Then, the block decoder 2005 outputs the processed data to the RS
frame decoder 2006. Herein, the removal of the data may be
performed before the block decoding process, or may be performed
during or after the block decoding process.
Meanwhile, the data trellis-decoded by the block decoder 2005 are
outputted to the data deinterleaver of the main service data
processor 2008. At this point, the data being trellis-decoded by
the block decoder 2005 and outputted to the data deinterleaver may
not only include the main service data but may also include the
data within the RS frame and the signaling information.
Furthermore, the RS parity data that are added by the transmitting
system after the pre-processor 230 may also be included in the data
being outputted to the data deinterleaver.
According to another embodiment of the present invention, data that
are not processed with block decoding and only processed with
trellis encoding by the transmitting system may directly bypass the
block decoder 2005 so as to be outputted to the data deinterleaver.
In this case, a trellis decoder should be provided before the data
deinterleaver.
More specifically, if the inputted data correspond to the data
having only trellis encoding performed thereon and not block
encoding, the block decoder 2005 performs Viterbi (or trellis)
decoding on the inputted data so as to output a hard decision value
or to perform a hard-decision on a soft decision value, thereby
outputting the result.
Meanwhile, if the inputted data correspond to the data having both
block encoding process and trellis encoding process performed
thereon, the block decoder 2005 outputs a soft decision value with
respect to the inputted data.
In other words, if the inputted data correspond to data being
processed with block encoding by the block processor 302 and being
processed with trellis encoding by the trellis encoding module 256,
in the transmitting system, the block decoder 2005 performs a
decoding process and a trellis decoding process on the inputted
data as inverse processes of the transmitting system. At this
point, the RS frame encoder of the pre-processor included in the
transmitting system may be viewed as an outer (or external)
encoder. And, the trellis encoder may be viewed as an inner (or
internal) encoder.
When decoding such concatenated codes, in order to allow the block
decoder 2005 to maximize its performance of decoding externally
encoded data, the decoder of the internal code should output a soft
decision value.
FIG. 49 illustrates a detailed block diagram of the block decoder
2005 according to an embodiment of the present invention. Referring
to FIG. 49, the block decoder 2005 includes a feedback controller
5010, an input buffer 5011, a trellis decoding unit (or 12-way
trellis coded modulation (TCM) decoder or inner decoder) 5012, a
symbol-byte converter 5013, an outer block extractor 5014, a
feedback deformatter 5015, a symbol deinterleaver 5016, an outer
symbol mapper 5017, a symbol decoder 5018, an inner symbol mapper
5019, a symbol interleaver 5020, a feedback formatter 5021, and an
output buffer 5022. Herein, just as in the transmitting system, the
trellis decoding unit 5012 may be viewed as an inner (or internal)
decoder. And, the symbol decoder 5018 may be viewed as an outer (or
external) decoder.
The input buffer 5011 temporarily stores the mobile service data
symbols being channel-equalized and outputted from the equalizer
2003. (Herein, the mobile service data symbols may include symbols
corresponding to the signaling information, RS parity data symbols
and CRC data symbols added during the encoding process of the RS
frame.) Thereafter, the input buffer 5011 repeatedly outputs the
stored symbols for M number of times to the trellis decoding unit
5012 in a turbo block (TDL) size required for the turbo decoding
process.
The turbo decoding length (TDL) may also be referred to as a turbo
block. Herein, a TDL should include at least one SCCC block size.
Therefore, as defined in FIG. 5, when it is assumed that one M/H
block is a 16-segment unit, and that a combination of 10 M/H blocks
form one SCCC block, a TDL should be equal to or larger than the
maximum possible combination size. For example, when it is assumed
that 2 M/H blocks form one SCCC block, the TDL may be equal to or
larger than 32 segments (i.e., 828.times.32=26496 symbols).
Herein, M indicates a number of repetitions for turbo-decoding
pre-decided by the feed-back controller 5010.
Also, M represents a number of repetitions of the turbo decoding
process, the number being predetermined by the feedback controller
5010.
Additionally, among the values of symbols being channel-equalized
and outputted from the equalizer 2003, the input symbol values
corresponding to a section having no mobile service data symbols
(including RS parity data symbols during RS frame encoding and CRC
data symbols) included therein, bypass the input buffer 5011
without being stored. More specifically, since trellis-encoding is
performed on input symbol values of a section wherein SCCC
block-encoding has not been performed, the input buffer 5011 inputs
the inputted symbol values of the corresponding section directly to
the trellis encoding module 5012 without performing any storage,
repetition, and output processes.
The storage, repetition, and output processes of the input buffer
5011 are controlled by the feedback controller 5010. Herein, the
feedback controller 5010 refers to SCCC-associated information
(e.g., SCCC block mode and SCCC outer code mode), which are
outputted from the signaling decoder 2013 or the operation
controller 2000, in order to control the storage and output
processes of the input buffer 5011.
The trellis decoding unit 5012 includes a 12-way TCM decoder.
Herein, the trellis decoding unit 5012 performs 12-way trellis
decoding as inverse processes of the 12-way trellis encoder.
More specifically, the trellis decoding unit 5012 receives a number
of output symbols of the input buffer 5011 and soft-decision values
of the feedback formatter 5021 equivalent to each TDL, so as to
perform the TCM decoding process.
At this point, based upon the control of the feedback controller
5010, the soft-decision values outputted from the feedback
formatter 5021 are matched with a number of mobile service data
symbol places so as to be in a one-to-one (1:1) correspondence.
Herein, the number of mobile service data symbol places is
equivalent to the TDL being outputted from the input buffer
5011.
More specifically, the mobile service data being outputted from the
input buffer 5011 are matched with the turbo decoded data being
inputted, so that each respective data place can correspond with
one another. Thereafter, the matched data are outputted to the
trellis decoding unit 5012. For example, if the turbo decoded data
correspond to the third symbol within the turbo block, the
corresponding symbol (or data) is matched with the third symbol
included in the turbo block, which is outputted from the input
buffer 5011. Subsequently, the matched symbol (or data) is
outputted to the trellis decoding unit 5012.
In order to do so, while the regressive turbo decoding is in
process, the feedback controller 5010 controls the input buffer
5011 so that the input buffer 5011 stores the corresponding turbo
block data. Also, by delaying data (or symbols), the soft decision
value (e.g., LLR) of the symbol outputted from the symbol
interleaver 5020 and the symbol of the input buffer 5011
corresponding to the same place (or position) within the block of
the output symbol are matched with one another to be in a
one-to-one correspondence. Thereafter, the matched symbols are
controlled so that they can be inputted to the TCM decoder through
the respective path.
This process is repeated for a predetermined number of turbo
decoding cycle periods. Then, the data of the next turbo block are
outputted from the input buffer 5011, thereby repeating the turbo
decoding process.
The output of the trellis decoding unit 5012 signifies a degree of
reliability of the transmission bits configuring each symbol. For
example, in the transmitting system, since the input data of the
trellis encoding module correspond to two bits as one symbol, a log
likelihood ratio (LLR) between the likelihood of a bit having the
value of `1` and the likelihood of the bit having the value of `0`
may be respectively outputted (in bit units) to the upper bit and
the lower bit. Herein, the log likelihood ratio corresponds to a
log value for the ratio between the likelihood of a bit having the
value of `1` and the likelihood of the bit having the value of `0`.
Alternatively, a LLR for the likelihood of 2 bits (i.e., one
symbol) being equal to "00", "01", "10", and "11" may be
respectively outputted (in symbol units) to all 4 combinations of
bits (i.e., 00, 01, 10, 11). Consequently, this becomes the soft
decision value that indicates the degree of reliability of the
transmission bits configuring each symbol. A maximum a posteriori
probability (MAP) or a soft-out Viterbi algorithm (SOYA) may be
used as a decoding algorithm of each TCM decoder within the trellis
decoding unit 5012.
The output of the trellis decoding unit 5012 is inputted to the
symbol-byte converter 5013 and the outer block extractor 5014.
The symbol-byte converter 5013 performs a hard-decision process of
the soft decision value that is trellis decoded and outputted from
the trellis decoding unit 5012. Thereafter, the symbol-byte
converter 5013 groups 4 symbols into byte units, which are then
outputted to the data deinterleaver of the main service data
processor 2008 of FIG. 44. More specifically, the symbol-byte
converter 5013 performs hard-decision in bit units on the soft
decision value of the symbol outputted from the trellis decoding
unit 5012. Therefore, the data processed with hard-decision and
outputted in bit units from the symbol-byte converter 5013 not only
include main service data, but may also include mobile service
data, known data, RS parity data, and MPEG headers.
Among the soft decision values of TDL size of the trellis decoding
unit 5012, the outer block extractor 5014 identifies the soft
decision values of B size of corresponding to the mobile service
data symbols (wherein symbols corresponding to signaling
information, RS parity data symbols that are added during the
encoding of the RS frame, and CRC data symbols are included) and
outputs the identified soft decision values to the feedback
deformatter 5015.
The feedback deformatter 5015 changes the processing order of the
soft decision values corresponding to the mobile service data
symbols. This is an inverse process of an initial change in the
processing order of the mobile service data symbols, which are
generated during an intermediate step, wherein the output symbols
outputted from the block processor 302 of the transmitting system
are being inputted to the trellis encoding module 256 (e.g., when
the symbols pass through the group formatter, the data
deinterleaver, the packet formatter, and the data interleaver).
Thereafter, the feedback deformatter 2015 performs reordering of
the process order of soft decision values corresponding to the
mobile service data symbols and, then, outputs the processed mobile
service data symbols to the symbol deinterleaver 5016.
This is because a plurality of blocks exist between the block
processor 302 and the trellis encoding module 256, and because, due
to these blocks, the order of the mobile service data symbols being
outputted from the block processor 302 and the order of the mobile
service data symbols being inputted to the trellis encoding module
256 are not identical to one another. Therefore, the feedback
deformatter 5015 reorders (or rearranges) the order of the mobile
service data symbols being outputted from the outer block extractor
5014, so that the order of the mobile service data symbols being
inputted to the symbol deinterleaver 5016 matches the order of the
mobile service data symbols outputted from the block processor 302
of the transmitting system. The reordering process may be embodied
as one of software, middleware, and hardware.
The symbol deinterleaver 5016 performs deinterleaving on the mobile
service data symbols having their processing orders changed and
outputted from the feedback deformatter 5015, as an inverse process
of the symbol interleaving process of the symbol interleaver 514
included in the transmitting system. The size of the block used by
the symbol deinterleaver 5016 during the deinterleaving process is
identical to interleaving size of an actual symbol (i.e., B) of the
symbol interleaver 514, which is included in the transmitting
system. This is because the turbo decoding process is performed
between the trellis decoding unit 5012 and the symbol decoder 5018.
Both the input and output of the symbol deinterleaver 5016
correspond to soft decision values, and the deinterleaved soft
decision values are outputted to the outer symbol mapper 5017.
The operations of the outer symbol mapper 5017 may vary depending
upon the structure and coding rate of the symbol encoder 513
included in the transmitting system. For example, when data are
1/2-rate encoded by the symbol encoder 513 and then transmitted,
the outer symbol mapper 5017 directly outputs the input data
without modification. In another example, when data are 1/4-rate
encoded by the symbol encoder 513 and then transmitted, the outer
symbol mapper 5017 converts the input data so that it can match the
input data format of the symbol decoder 5018. For this, the outer
symbol mapper 5017 may be inputted SCCC-associated information
(i.e., SCCC block mode and SCCC outer code mode) from the signaling
decoder 2013. Then, the outer symbol mapper 5017 outputs the
converted data to the symbol decoder 5018.
The symbol decoder 5018 (i.e., the outer decoder) receives the data
outputted from the outer symbol mapper 5017 and performs symbol
decoding as an inverse process of the symbol encoder 513 included
in the transmitting system. At this point, two different soft
decision values are outputted from the symbol decoder 5018. One of
the outputted soft decision values corresponds to a soft decision
value matching the output symbol of the symbol encoder 513
(hereinafter referred to as a "first decision value"). The other
one of the outputted soft decision values corresponds to a soft
decision value matching the input bit of the symbol encoder 513
(hereinafter referred to as a "second decision value"). More
specifically, the first decision value represents a degree of
reliability the output symbol (i.e., 2 bits) of the symbol encoder
513. Herein, the first soft decision value may output (in bit
units) a LLR between the likelihood of 1 bit being equal to `1` and
the likelihood of 1 bit being equal to `0` with respect to each of
the upper bit and lower bit, which configures a symbol.
Alternatively, the first soft decision value may also output (in
symbol units) a LLR for the likelihood of 2 bits being equal to
"00", "01", "10", and "11" with respect to all possible
combinations. The first soft decision value is fed-back to the
trellis decoding unit 5012 through the inner symbol mapper 5019,
the symbol interleaver 5020, and the feedback formatter 5021. On
the other hand, the second soft decision value indicates a degree
of reliability the input bit of the symbol encoder 513 included in
the transmitting system. Herein, the second soft decision value is
represented as the LLR between the likelihood of 1 bit being equal
to `1` and the likelihood of 1 bit being equal to `0`. Thereafter,
the second soft decision value is outputted to the outer buffer
5022. In this case, a maximum a posteriori probability (MAP) or a
soft-out Viterbi algorithm (SOYA) may be used as the decoding
algorithm of the symbol decoder 5018.
The first soft decision value that is outputted from the symbol
decoder 5018 is inputted to the inner symbol mapper 5019. The inner
symbol mapper 5019 converts the first soft decision value to a data
format corresponding the input data of the trellis decoding unit
5012. Thereafter, the inner symbol mapper 5019 outputs the
converted soft decision value to the symbol interleaver 5020. The
operations of the inner symbol mapper 5019 may also vary depending
upon the structure and coding rate of the symbol encoder 513
included in the transmitting system.
In the following description, when the symbol encoder 513 of the
transmitting system operates as at least one of a 1/4-rate encoder
(or 1/4-encoder) and a 1/2-rate encoder (or 1/2-encoder), the
operations of the outer symbol mapper 5017 and the inner symbol
mapper 5019 will now be described in detail.
According to an embodiment of the present invention, the symbol
encoder 513 performs 1/4-rate encoding on one bit U so as to output
4 bits u0, u2, u1, and u4. At this point, it is assumed that 4
bits, i.e., 2 symbols are sequentially outputted one by one twice.
In the description of the present invention, the symbol that is
outputted first will be referred to as an odd-number symbol and the
symbol that is outputted next (or in second place) will be referred
to as an even-number symbol, for simplicity. Also, in the
description of the present invention,
(a) to (d) of FIG. 50 respectively show exemplary operations of the
outer symbol mapper 5017, when the symbol encoder 513 of the
transmitting system performs 1/4-rate encoding.
(a) of FIG. 50 shows an exemplary log-likelihood ratio (LLR) value
of 2 symbols being inputted to the outer symbol mapper 5017, and
(d) of FIG. 50 shows an exemplary LLR value of 1 symbol being
outputted from the outer symbol mapper 5017.
For example, when the input and/or output units of the outer symbol
mapper 5017 and the inner symbol mapper 5019 corresponds to symbol
units, the number of soft-decision values that are to be outputted
from the outer symbol mapper 5017 is equal to 16 (2.sup.4=16). At
this point, the 16 (2.sup.4=16) soft-decision values that are to be
outputted from the outer symbol mapper 5017 correspond to a result
of adding the corresponding soft-decision value of the odd-number
symbol and the corresponding soft-decision value of the even-number
symbol, as shown in (c) of FIG. 50. More specifically, among the 16
(2.sup.4=16) soft-decision values that are to be outputted from the
outer symbol mapper 5017, for example, the soft-decision value of
s=(0, 0, 1, 1) (i.e., LLR (0011).sub.2k) is calculated by adding
the soft-decision value of the odd-number symbol m.sub.0=(0, 0)
(i.e., LLR(00).sub.3k) and the soft-decision value of the
even-number symbol m.sub.1=(1, 1) (i.e., LLR(11).sub.3k+1). And,
the calculated soft-decision value is inputted to the symbol
decoder 5018.
Also, the number of soft-decision values that are to be outputted
from the inner symbol mapper 5019 is equal to 4 (2.sup.2=4). Among
the 4 (2.sup.2=4) soft-decision values that are to be outputted
from the inner symbol mapper 5019, for example, the soft-decision
value of an odd-number symbol m.sub.0=(1, 1) is obtained by taking
the largest soft-decision value among the soft-decision values of
the output symbols s=(1, 1, X, X) of the symbol decoder 5018. And,
the soft-decision value of an even-number symbol m.sub.0=(0, 0) is
obtained by taking the largest soft-decision value among the
soft-decision values of the output symbols s=(X, X, 0, 0) of the
symbol decoder 5018. Herein, `X` randomly corresponds to one of `1`
and `0`. The output of the inner symbol mapper 5019 is provided to
the symbol interleaver 5020.
Meanwhile, when the input and/or output units of the outer symbol
mapper 5017 and the inner symbol mapper 5019 corresponds to bit
units, the number of soft-decision values that are to be outputted
from the outer symbol mapper 5017 is equal to 4.
More specifically, the outer symbol mapper 5017 simultaneously
outputs two soft-decision values of an odd-number input bit (i.e.,
soft-decision values respective to an upper bit and a lower bit
configuring the odd-number input bit) and two soft-decision values
of an even-number input bit (i.e., soft-decision values respective
to an upper bit and a lower bit configuring the even-number input
bit). And, with respect to the 4 inputs provided from the symbol
decoder 5018, the inner symbol mapper 5019 identifies two
soft-decision values of an odd-number output bit (i.e.,
soft-decision values respective to an upper bit and a lower bit
configuring the odd-number output bit of the symbol decoder 5018)
and two soft-decision values of an even-number output bit (i.e.,
soft-decision values respective to an upper bit and a lower bit
configuring the even-number output bit of the symbol decoder 5018).
Thereafter, the inner symbol mapper 5019 outputs the identified
soft-decision values to the symbol interleaver 5020.
More specifically, when the symbol encoder 513 performs 1/4-rate
encoding, the LLR for each of the 16 different symbols may be
received and symbol-decoded. Then, the LLRs for the 16 symbols may
be outputted as first soft-decision values. Alternatively, the LLR
for each of the 4 bits may be received and symbol-decoded.
Thereafter, the LLRs for the 4 bits may be outputted as the first
soft-decision values.
According to another embodiment of the present invention, the
symbol encoder 513 performs 1/2-rate encoding on one bit U, so as
to output 2 bits u0 and u1. And, in this case, it is assumed that 2
bits are outputted as one symbol.
At this point, when the input and/or output units of the outer
symbol mapper 5017 and the inner symbol mapper 5019 corresponds to
symbol units, the number of soft-decision values that are to be
outputted from the outer symbol mapper 5017 is equal to 4
(2.sup.2=4), as shown in (d) of FIG. 50. More specifically, among
the 4 (2.sup.2=4) soft-decision values that are to be outputted
from the outer symbol mapper 5017, for example, the soft-decision
value of s=(1, 0) (i.e., LLR (10).sub.2k+1) corresponds to the
soft-decision value (LLR (10).sub.3k+2) of the inputted symbol
m.sub.0=(1, 0). Thereafter, this value is provided to the symbol
decoder 5018. The number of soft-decision values that are to be
outputted from the inner symbol mapper 5019 is also equal to 4
(2.sup.2=4), and the 4 soft-decision value become the soft-decision
value of the input symbol s=(1, 1) of the symbol decoder 5018.
Subsequently, this soft-decision value is outputted to the symbol
interleaver 5020.
Meanwhile, when the input and/or output units of the outer symbol
mapper 5017 and the inner symbol mapper 5019 corresponds to bit
units, the number of soft-decision values that are to be outputted
from the outer symbol mapper 5017 is equal to 2, i.e.,
soft-decision value for each of the upper bit and the lower bit.
The inner symbol mapper 5019 receives the soft-decision value for
the upper bit and the soft-decision value for the lower bit from
the symbol decoder 5018 and outputs the received soft-decision
values as soft-decision values of 2 output bits (i.e.,
soft-decision values respective to an upper bit and a lower bit
being outputted from the symbol decoder 5018).
More specifically, when 1/2-rate encoding is performed by the
symbol encoder 513, the LLR for each of the 4 different symbols may
be received and symbol-decoded. Then, the LLRs for the 4 symbols
may be outputted as first soft-decision values. Alternatively, the
LLR for each of the 2 bits may be received and symbol-decoded.
Thereafter, the LLRs for the 2 bits may be outputted as the first
soft-decision values.
Meanwhile, when it is assumed that the second embodiment of the
present invention is applied to the block processor 302 of the
transmitting system so as to perform the 1/3-rate encoding process,
the block decoder 2005 should alternately perform 1/4-rate block
decoding and 1/2-rate block decoding. More specifically, 1/2-rate
encoded symbols and 1/4-rate encoded symbols are inter-mixed and
outputted from the block processor 302 and inputted to the trellis
encoding module 256, thereby being processed with TCM encoding. In
this case, based upon a pre-defined symbol position information,
the outer symbol mapper 5017 receives 2 symbol values at the
1/4-rate encoded symbol position so as to calculate 16 different
soft-decision values for symbol decoding, as shown in (c) of FIG.
50. And, the outer symbol mapper 5017 receives 1 symbol value at
the 1/2-rate encoded symbol position so as to directly output the 4
soft-decision values for symbol decoding without modification, as
shown in (d) of FIG. 50. The outputted soft-decision values, as
described above, are inputted to the symbol decoder 5018 so as to
be used for the symbol decoding process.
In other words, among the consecutive output symbol values of the
TCM decoder 5012, two of the corresponding 1/4-rate encoded symbol
values may be combined to yield 4*4=16 soft-decision values.
Accordingly, the symbol decoder 5018 calculates 2.sup.4 branch
metrics so as to perform symbol-decoding. Herein, `2.sup.4`
corresponds to a number of cases of the output bits outputted from
the symbol encoder 513 operating as a 1/4-rate encoder.
Additionally, among the consecutive output symbol values of the TCM
decoder 5012, one of the corresponding 1/2-rate encoded symbol
values may be combined to yield 4 soft-decision values.
Accordingly, the symbol decoder 5018 calculates 2.sup.2 branch
metrics so as to perform symbol-decoding. Herein, `2.sup.2`
corresponds to a number of cases of the output bits outputted from
the symbol encoder 513 operating as a 1/2-rate encoder. The related
art MAP, SOVA, MAX-log MAP, and so on are used as the decoding
algorithm performed by the TCM decoder 5012 and the symbol decoder
5018. Also, according to an embodiment of the present invention,
since a symbol interleaver was used between the symbol encoder and
the TCM encoder of the transmitting system, a symbol log-likelihood
ratio (LLR) is used as the log-likelihood ratio (LLR) being
inputted and/or outputted to and/or from the TCM decoder 5012 and
the symbol decoder 5018.
The symbol interleaver 5020 performs symbol interleaving, as shown
in FIG. 33, on the first soft decision value that is outputted from
the inner symbol mapper 5019. Then, the symbol interleaver 5020
outputs the symbol-interleaved first soft decision value to the
feedback formatter 5021. Herein, the output of the symbol
interleaver 5020 also corresponds to a soft decision value.
With respect to the changed processing order of the soft decision
values corresponding to the symbols that are generated during an
intermediate step, wherein the output symbols outputted from the
block processor 302 of the transmitting system are being inputted
to the trellis encoding module (e.g., when the symbols pass through
the group formatter, the data deinterleaver, the packet formatter,
the RS encoder, and the data interleaver), the feedback formatter
5021 alters (or changes) the order of the output values outputted
from the symbol interleaver 5020. Subsequently, the feedback
formatter 5020 outputs values to the trellis decoding unit 5012 in
the changed order. The reordering process of the feedback formatter
5021 may configure at least one of software, hardware, and
middleware.
The soft decision values outputted from the symbol interleaver 5020
are matched with the positions of mobile service data symbols each
having the size of TDL, which are outputted from the input buffer
5011, so as to be in a one-to-one correspondence. Thereafter, the
soft decision values matched with the respective symbol position
are inputted to the trellis decoding unit 5012. At this point,
since the main service data symbols or the RS parity data symbols
and known data symbols of the main service data do not correspond
to the mobile service data symbols, the feedback formatter 5021
inserts null data in the corresponding positions, thereby
outputting the processed data to the trellis decoding unit 5012.
Additionally, each time the symbols having the size of TDL are
turbo decoded, no value is fed-back by the symbol interleaver 5020
starting from the beginning of the first decoding process.
Therefore, the feedback formatter 5021 is controlled by the
feedback controller 5010, thereby inserting null data into all
symbol positions including a mobile service data symbol. Then, the
processed data are outputted to the trellis decoding unit 5012.
The output buffer 5022 receives the second soft decision value from
the symbol decoder 5018 based upon the control of the feedback
controller 5010. Then, the output buffer 5022 temporarily stores
the received second soft decision value. Thereafter, the output
buffer 5022 outputs the second soft decision value to the RS frame
decoder 2006. For example, the output buffer 5022 overwrites the
second soft decision value of the symbol decoder 5018 until the
turbo decoding process is performed for M number of times. Then,
once all M number of turbo decoding processes is performed for a
single TDL, the corresponding second soft decision value is
outputted to the RS frame decoder 2006.
The feedback controller 5010 controls the number of turbo decoding
and turbo decoding repetition processes of the overall block
decoder, shown in FIG. 49. More specifically, once the turbo
decoding process has been repeated for a predetermined number of
times, the second soft decision value of the symbol decoder 5018 is
outputted to the RS frame decoder 2006 through the output buffer
5022. Thus, the block decoding process of a turbo block is
completed. In the description of the present invention, this
process is referred to as a regressive turbo decoding process for
simplicity.
At this point, the number of regressive turbo decoding rounds
between the trellis decoding unit 5012 and the symbol decoder 5018
may be defined while taking into account hardware complexity and
error correction performance. Accordingly, if the number of rounds
increases, the error correction performance may be enhanced.
However, this may lead to a disadvantageous of the hardware
becoming more complicated (or complex).
Meanwhile, the main service data processor 2008 corresponds to
block required for receiving the main service data. Therefore, the
above-mentioned blocks may not be necessary (or required) in the
structure of a digital broadcast receiving system for receiving
mobile service data only.
The data deinterleaver of the main service data processor 2008
performs an inverse process of the data interleaver included in the
transmitting system. In other words, the data deinterleaver
deinterleaves the main service data outputted from the block
decoder 2005 and outputs the deinterleaved main service data to the
RS decoder. The data being inputted to the data deinterleaver
include main service data, as well as mobile service data, known
data, RS parity data, and an MPEG header. At this point, among the
inputted data, only the main service data and the RS parity data
added to the main service data packet may be outputted to the RS
decoder. Also, all data outputted after the data derandomizer may
all be removed with the exception for the main service data. In the
embodiment of the present invention, only the main service data and
the RS parity data added to the main service data packet are
inputted to the RS decoder.
The RS decoder performs a systematic RS decoding process on the
deinterleaved data and outputs the processed data to the data
derandomizer.
The data derandomizer receives the output of the RS decoder and
generates a pseudo random data byte identical to that of the
randomizer included in the digital broadcast transmitting system.
Thereafter, the data derandomizer performs a bitwise exclusive OR
(XOR) operation on the generated pseudo random data byte, thereby
inserting the MPEG synchronization bytes to the beginning of each
packet so as to output the data in 188-byte main service data
packet units.
RS Frame Decoder
The data outputted from the block decoder 2005 are in portion
units. More specifically, in the transmitting system, the RS frame
is divided into several portions, and the mobile service data of
each portion are assigned either to regions A/B/C/D within the data
group or to any one of regions A/B and regions C/D, thereby being
transmitted to the receiving system. Therefore, the RS frame
decoder 2006 groups several portions included in a parade so as to
form an RS frame. Alternatively, the RS frame decoder 2006 may also
group several portions included in a parade so as to form two RS
frames. Thereafter, error correction decoding is performed in RS
frame units.
For example, when the RS frame mode value is equal to `00`, then
one parade transmits one RS frame. At this point, one RS frame is
divided into several portions, and the mobile service data of each
portion are assigned to regions A/B/C/D of the corresponding data
group, thereby being transmitted. In this case, the RS frame
decoder 2006 extracts mobile service data from regions A/B/C/D of
the corresponding data group, as shown in FIG. 51(a). Subsequently,
the RS frame decoder 2006 may perform the process of forming (or
creating) a portion on a plurality of data group within a parade,
thereby forming several portions. Then, the several portions of
mobile service data may be grouped to form an RS frame. Herein, if
stuffing bytes are added to the last portion, the RS frame may be
formed after removing the stuffing byte.
In another example, when the RS frame mode value is equal to `01`,
then one parade transmits two RS frames (i.e., a primary RS frame
and a secondary RS frame). At this point, a primary RS frame is
divided into several primary portions, and the mobile service data
of each primary portion are assigned to regions A/B of the
corresponding data group, thereby being transmitted. Also, a
secondary RS frame is divided into several secondary portions, and
the mobile service data of each secondary portion are assigned to
regions C/D of the corresponding data group, thereby being
transmitted.
In this case, the RS frame decoder 2006 extracts mobile service
data from regions A/B of the corresponding data group, as shown in
FIG. 51(b). Subsequently, the RS frame decoder 2006 may perform the
process of forming (or creating) a primary portion on a plurality
of data group within a parade, thereby forming several primary
portions. Then, the several primary portions of mobile service data
may be grouped to form a primary RS frame. Herein, if stuffing
bytes are added to the last primary portion, the primary RS frame
may be formed after removing the stuffing byte. Also, the RS frame
decoder 2006 extracts mobile service data from regions C/D of the
corresponding data group. Subsequently, the RS frame decoder 2006
may perform the process of forming (or creating) a secondary
portion on a plurality of data group within a parade, thereby
forming several secondary portions. Then, the several secondary
portions of mobile service data may be grouped to form a secondary
RS frame. Herein, if stuffing bytes are added to the last secondary
portion, the secondary RS frame may be formed after removing the
stuffing byte.
More specifically, the RS frame decoder 2006 receives the
RS-encoded and/or CRC-encoded mobile service data of each portion
from the block decoder 2005. Then, the RS frame decoder 2006 groups
several portions, which are inputted based upon RS frame-associated
information outputted from the signaling decoder 2013 or the
operation controller 2000, thereby performing error correction. By
referring to the RS frame mode value included in the RS
frame-associated information, the RS frame decoder 2006 may form an
RS frame and may also be informed of the number of RS code parity
data bytes and the code size. Herein, the RS code is used to
configure (or form) the RS frame.
The RS frame decoder 2006 also refers to the RS frame-associated
information in order to perform an inverse process of the RS frame
encoder, which is included in the transmitting system, thereby
correcting the errors within the RS frame. In addition, the RS
frame decoder 2006 performs a derandomizing process on a payload of
the error-corrected RS frame.
FIG. 52 illustrates, when the RS frame mode value is equal to `00`,
an exemplary process of grouping several portion being transmitted
to a parade, thereby forming an RS frame and an RS frame
reliability map.
More specifically, the RS frame decoder 2006 receives and groups a
plurality of mobile service data bytes, so as to form an RS frame.
According to the present invention, in transmitting system, the
mobile service data correspond to data RS-encoded in RS frame
units. At this point, the mobile service data may already be error
correction encoded (e.g., CRC-encoded). Alternatively, the error
correction encoding process may be omitted.
It is assumed that, in the transmitting system, an RS frame having
the size of (N+2).times.(187+P) bytes is divided into M number of
portions, and that the M number of mobile service data portions are
assigned and transmitted to regions A/B/C/D in M number of data
groups, respectively. In this case, in the receiving system, each
mobile service data portion is grouped, as shown in FIG. 52(a),
thereby forming an RS frame having the size of (N+2).times.(187+P)
bytes. At this point, when stuffing bytes (S) are added to at least
one portion included in the corresponding RS frame and then
transmitted, the stuffing bytes are removed, thereby configuring an
RS frame and an RS frame reliability map. For example, as shown in
FIG. 27, when S number of stuffing bytes are added to the
corresponding portion, the S number of stuffing bytes are removed,
thereby configuring the RS frame and the RS frame reliability
map.
Herein, when it is assumed that the block decoder 2005 outputs a
soft decision value for the decoding result, the RS frame decoder
2006 may decide the `0` and `1` of the corresponding bit by using
the codes of the soft decision value. 8 bits that are each decided
as described above are grouped to create 1 data byte. If the
above-described process is performed on all soft decision values of
several portions (or data groups) included in a parade, the RS
frame having the size of (N+2).times.(187+P) bytes may be
configured.
Additionally, the present invention uses the soft decision value
not only to configure the RS frame but also to configure a
reliability map.
Herein, the reliability map indicates the reliability of the
corresponding data byte, which is configured by grouping 8 bits,
the 8 bits being decided by the codes of the soft decision
value.
For example, when the absolute value of the soft decision value
exceeds a pre-determined threshold value, the value of the
corresponding bit, which is decided by the code of the
corresponding soft decision value, is determined to be reliable.
Conversely, when the absolute value of the soft decision value does
not exceed the pre-determined threshold value, the value of the
corresponding bit is determined to be unreliable. Thereafter, if
even a single bit among the 8 bits, which are decided by the codes
of the soft decision value and group to configure one data byte, is
determined to be unreliable, the corresponding data byte is marked
on the reliability map as an unreliable data byte.
Herein, determining the reliability of one data byte is only
exemplary. More specifically, when a plurality of data bytes (e.g.,
at least 4 data bytes) are determined to be unreliable, the
corresponding data bytes may also be marked as unreliable data
bytes within the reliability map. Conversely, when all of the data
bits within the one data byte are determined to be reliable (i.e.,
when the absolute value of the soft decision values of all 8 bits
included in the one data byte exceed the predetermined threshold
value), the corresponding data byte is marked to be a reliable data
byte on the reliability map. Similarly, when a plurality of data
bytes (e.g., at least 4 data bytes) are determined to be reliable,
the corresponding data bytes may also be marked as reliable data
bytes within the reliability map. The numbers proposed in the
above-described example are merely exemplary and, therefore, do not
limit the scope or spirit of the present invention.
The process of configuring the RS frame and the process of
configuring the reliability map both using the soft decision value
may be performed at the same time. Herein, the reliability
information within the reliability map is in a one-to-one
correspondence with each byte within the RS frame. For example, if
a RS frame has the size of (N+2).times.(187+P) bytes, the
reliability map is also configured to have the size of
(N+2).times.(187+P) bytes. FIG. 52(a') and FIG. 52(b') respectively
illustrate the process steps of configuring the reliability map
according to the present invention.
Subsequently, the RS frame reliability map is used on the RS frames
so as to perform error correction.
FIG. 53 illustrates example of the error correction processed
according to embodiments of the present invention. FIG. 53
illustrates an example of performing an error correction process
when the transmitting system has performed both RS encoding and CRC
encoding processes on the RS frame.
As shown in FIG. 53(a) and FIG. 53(d), when the RS frame having the
size of (N+2).times.(187+P) bytes and the RS frame reliability map
having the size of (N+2).times.(187+P) bytes are created, a CRC
syndrome checking process is performed on the created RS frame,
thereby verifying whether any error has occurred in each row.
Subsequently, as shown in FIG. 53(b), a 2-byte checksum is removed
to configure an RS frame having the size of N.times.(187+P) bytes.
Herein, the presence (or existence) of an error is indicated on an
error flag corresponding to each row. Similarly, since the portion
of the reliability map corresponding to the CRC checksum has hardly
any applicability, this portion is removed so that only
N.times.(187+P) number of the reliability information bytes remain,
as shown in FIG. 53(b').
After performing the CRC syndrome checking process, as described
above, a RS decoding process is performed in a column direction.
Herein, a RS erasure correction process may be performed in
accordance with the number of CRC error flags. More specifically,
as shown in FIG. 53(c), the CRC error flag corresponding to each
row within the RS frame is verified. Thereafter, the RS frame
decoder 2006 determines whether the number of rows having a CRC
error occurring therein is equal to or smaller than the maximum
number of errors on which the RS erasure correction may be
performed, when performing the RS decoding process in a column
direction. The maximum number of errors corresponds to P number of
parity bytes inserted when performing the RS encoding process. In
the embodiment of the present invention, it is assumed that 48
parity bytes have been added to each column (i.e., P=48).
If the number of rows having the CRC errors occurring therein is
smaller than or equal to the maximum number of errors (i.e., 48
errors according to this embodiment) that can be corrected by the
RS erasure decoding process, a (235,187)-RS erasure decoding
process is performed in a column direction on the RS frame having
(187+P) number of N-byte rows (i.e., 235 N-byte rows), as shown in
FIG. 53(d). Thereafter, as shown in FIG. 53(e), the 48-byte parity
data that have been added at the end of each column are removed.
Conversely, however, if the number of rows having the CRC errors
occurring therein is greater than the maximum number of errors
(i.e., 48 errors) that can be corrected by the RS erasure decoding
process, the RS erasure decoding process cannot be performed. In
this case, the error may be corrected by performing a general RS
decoding process. In addition, the reliability map, which has been
created based upon the soft decision value along with the RS frame,
may be used to further enhance the error correction ability (or
performance) of the present invention.
More specifically, the RS frame decoder 2006 compares the absolute
value of the soft decision value of the block decoder 2005 with the
pre-determined threshold value, so as to determine the reliability
of the bit value decided by the code of the corresponding soft
decision value. Also, 8 bits, each being determined by the code of
the soft decision value, are grouped to form one data byte.
Accordingly, the reliability information on this one data byte is
indicated on the reliability map. Therefore, as shown in FIG.
53(c), even though a particular row is determined to have an error
occurring therein based upon a CRC syndrome checking process on the
particular row, the present invention does not assume that all
bytes included in the row have errors occurring therein. The
present invention refers to the reliability information of the
reliability map and sets only the bytes that have been determined
to be unreliable as erroneous bytes. In other words, with disregard
to whether or not a CRC error exists within the corresponding row,
only the bytes that are determined to be unreliable based upon the
reliability map are set as erasure points.
According to another method, when it is determined that CRC errors
are included in the corresponding row, based upon the result of the
CRC syndrome checking result, only the bytes that are determined by
the reliability map to be unreliable are set as errors. More
specifically, only the bytes corresponding to the row that is
determined to have errors included therein and being determined to
be unreliable based upon the reliability information, are set as
the erasure points. Thereafter, if the number of error points for
each column is smaller than or equal to the maximum number of
errors (i.e., 48 errors) that can be corrected by the RS erasure
decoding process, an RS erasure decoding process is performed on
the corresponding column. Conversely, if the number of error points
for each column is greater than the maximum number of errors (i.e.,
48 errors) that can be corrected by the RS erasure decoding
process, a general decoding process is performed on the
corresponding column.
More specifically, if the number of rows having CRC errors included
therein is greater than the maximum number of errors (i.e., 48
errors) that can be corrected by the RS erasure decoding process,
either an RS erasure decoding process or a general RS decoding
process is performed on a column that is decided based upon the
reliability information of the reliability map, in accordance with
the number of erasure points within the corresponding column. For
example, it is assumed that the number of rows having CRC errors
included therein within the RS frame is greater than 48. And, it is
also assumed that the number of erasure points decided based upon
the reliability information of the reliability map is indicated as
40 erasure points in the first column and as erasure points in the
second column. In this case, a (235,187)-RS erasure decoding
process is performed on the first column. Alternatively, a
(235,187)-RS decoding process is performed on the second column.
When error correction decoding is performed on all column
directions within the RS frame by using the above-described
process, the 48-byte parity data which were added at the end of
each column are removed, as shown in FIG. 53(e).
As described above, even though the total number of CRC errors
corresponding to each row within the RS frame is greater than the
maximum number of errors that can be corrected by the RS erasure
decoding process, when the number of bytes determined to have a low
reliability level, based upon the reliability information on the
reliability map within a particular column, while performing error
correction decoding on the particular column.
Herein, the difference between the general RS decoding process and
the RS erasure decoding process is the number of errors that can be
corrected. More specifically, when performing the general RS
decoding process, the number of errors corresponding to half of the
number of parity bytes (i.e., (number of parity bytes)/2) that are
inserted during the RS encoding process may be error corrected
(e.g., 24 errors may be corrected). Alternatively, when performing
the RS erasure decoding process, the number of errors corresponding
to the number of parity bytes that are inserted during the RS
encoding process may be error corrected (e.g., 48 errors may be
corrected).
After performing the error correction decoding process, as
described above, a RS frame payload configured of 187 N-byte rows
(or packet) may be obtained as shown in FIG. 53(e). Also,
derandomizing is performed on a (N+187)-byte payload of the RS
frame as an inverse process of the transmitting system. Each M/H
service data packet (i.e., M/H TP packet) of the derandomized RS
frame payload is outputted to the demultiplexer 1303. As described
above, each of the M/H service data packets may consist of a 2-byte
M/H header, a k-byte stuffing region, and a (N-2-k)-byte M/H
payload. At this point, the value of k may be equal to or greater
than `0`. And, the M/H header includes a type_indicator field, an
error_indicator field, a stuff_indicator field, and a pointer
field.
The present invention may be provided with a number of RS frame
decoders corresponding to a number (=M) of parades within a single
M/H frame. Herein, the M number of RS frame decoders is provided in
parallel. Each of the M number of RS frame decoders may be
configured by equipping the RS frame decoder with a multiplexer
multiplexing a plurality of portion at the inputting end, and by
equipping the RS frame decoder with a demultiplexer at the
outputting end.
As described above, the transmitting system and the receiving
system and the broadcast signal processing method of the same
according to the present invention have the following
advantages.
When transmitting mobile service data through a channel, the
present invention may be robust against errors and backward
compatible with the conventional digital broadcast receiving
system.
Moreover, the present invention may also receive the mobile service
data without any error even in channels having severe ghost effect
and noise.
Furthermore, by inserting known data in a particular position (or
place) within a data region and transmitting the processed data,
the receiving performance of the receiving system may be enhanced
even in a channel environment that is liable to frequent
changes.
By performing a 1/2-rate encoding process on one of an odd-numbered
bit and an even-numbered bit of the mobile service data, and by
performing a 1/4-rate encoding process on the other one of the
odd-numbered bit and the even-numbered bit of the mobile service
data, the present invention may perform 1/3-rate encoding process
on the mobile service data.
Finally, the present invention is even more effective when applied
to mobile and portable receivers, which are also liable to a
frequent change in channel and which require protection (or
resistance) against intense noise.
It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *