U.S. patent number RE46,288 [Application Number 14/463,547] was granted by the patent office on 2017-01-24 for digital television transmitting system and receiving system and method of processing broadcast data.
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, Jong Moon Kim, Kook Yeon Kwak, Hyoung Gon Lee, Won Gyu Song.
United States Patent |
RE46,288 |
Choi , et al. |
January 24, 2017 |
Digital television transmitting system and receiving system and
method of processing broadcast data
Abstract
A digital television receiving system includes a first known
data detector, a second known data detector, and a selector. The
first known data detector detects a location of a first known data
sequence in a broadcast signal by calculating a first correlation
value between the broadcast signal and a first reference known data
sequence. Similarly, the second known data detector detects a
location of a second known data sequence in the broadcast signal by
calculating a second correlation value between the broadcast signal
and a second reference known data sequence. The selector selects
the location information detected by one of the first and second
known data detectors with a greater correlation value.
Inventors: |
Choi; In Hwan (Gwacheon-si,
KR), Kwak; Kook Yeon (Anyang-si, KR), Kim;
Byoung Gill (Seoul, KR), Kim; Jin Woo (Seoul,
KR), Lee; Hyoung Gon (Seoul, KR), Kim; Jong
Moon (Gwangmyeong-si, KR), Song; Won Gyu (Seoul,
KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG Electronics Inc. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG ELECTRONICS INC. (Seoul,
KR)
|
Family
ID: |
38801623 |
Appl.
No.: |
14/463,547 |
Filed: |
August 19, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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13011805 |
Jan 10, 2012 |
8094750 |
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12851463 |
Mar 8, 2011 |
7903758 |
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11760656 |
Nov 23, 2010 |
7839950 |
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60884200 |
Jan 9, 2007 |
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Reissue of: |
13314068 |
Dec 7, 2011 |
8320498 |
Nov 27, 2012 |
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Foreign Application Priority Data
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Jun 9, 2006 [KR] |
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10-2006-0052095 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N
21/242 (20130101); H04N 21/2362 (20130101); H04N
7/173 (20130101); H04N 21/2662 (20130101); H04N
21/2383 (20130101); H04N 21/2383 (20130101); H04N
7/173 (20130101); H04N 21/2662 (20130101); H04N
21/234327 (20130101); H04N 21/242 (20130101); H04N
21/2362 (20130101); H04N 21/234327 (20130101) |
Current International
Class: |
H04L
25/49 (20060101); H04N 21/242 (20110101); H04N
21/2362 (20110101); H04N 7/173 (20110101); H04N
21/2662 (20110101); H04N 21/2383 (20110101); H04N
21/2343 (20110101) |
Field of
Search: |
;348/723-726,553
;375/295,365,368,265,261,240.27,301,259,260,270
;714/758,755,762,784,800-805 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-2002-0082268 |
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Oct 2002 |
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KR |
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10-0466590 |
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Jan 2005 |
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KR |
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10-2005-0109052 |
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Nov 2005 |
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KR |
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10-2006-0121107 |
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Nov 2006 |
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KR |
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2005-071958 |
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Aug 2005 |
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WO |
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2005-109878 |
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Nov 2005 |
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WO |
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2005-120062 |
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Dec 2005 |
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WO |
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Other References
US. Appl. No. 14/510,521, Office Action dated May 18, 2015, 9
pages. cited by applicant .
Korean Intellectual Property Office Application Serial No.
10-2006-0052095, Notice of Allowance dated Dec. 7, 2012, 2 pages.
cited by applicant .
U.S. Appl. No. 14/510,521, Office Action dated Aug. 2, 2016, 18
pages. cited by applicant.
|
Primary Examiner: Larose; Colin
Attorney, Agent or Firm: Lee, Hong, Degerman, Kang &
Waimey
Parent Case Text
This application .Iadd.is a reissue of U.S. Pat. No. 8,320,498,
which issued on Nov. 27, 2012, from U.S. application Ser. No.
13/314,068, filed on Dec. 7, 2011, which .Iaddend.is a continuation
of U.S. application Ser. No. 13/011,805, filed on Jan. 21, 2011,
now U.S. Pat. No. 8,094,750, which is a continuation of U.S.
application Ser. No. 12/851,463, filed on Aug. 5, 2010, now U.S.
Pat. No. 7,903,758, which is a continuation of U.S. application
Ser. No. 11/760,656, filed on Jun. 8, 2007, now U.S. Pat. No.
7,839,950, which claims the benefit of earlier filing date and
.[.rigt.]. .Iadd.right .Iaddend.of priority to Korean Patent
Application No. 10-2006-0052095, filed on Jun. 9, 2006, and also
claims the benefit of U.S. Provisional Application No. 60/884,200,
filed on Jan. 9, 2007, the contents of all of which are hereby
incorporated by reference herein in their .[.entireties.].
.Iadd.entirety.Iaddend..
Claims
What is claimed is:
.[.1. A digital television (DTV) transmitting system for processing
digital broadcast data, the DTV transmitting system comprising: a
block processor for encoding enhanced data at a code rate of 1/H,
wherein H is greater than 1; a group formatting unit for: mapping
the encoded enhanced data into data groups; adding known data
sequences, signaling information, place holders for first
non-systematic Reed-Solomon (RS) parity and MPEG header data place
holders to each of the data groups; and deinterleaving data in the
data groups; a packet formatter for removing the place holders for
the first non-systematic RS parity in the data groups in which data
is deinterleaved and replacing the MPEG header data place holders
with MPEG header data in the data groups in which data is
deinterleaved in order to output enhanced data packets; a first RS
encoder for performing a first non-systematic RS encoding for first
data when the first data corresponds to the enhanced data packets
and performing a systematic RS encoding for second data when the
second data corresponds to main data packets; an interleaver for
interleaving the first data corresponding to the enhanced data
packets or the second data corresponding to the main data packets;
a trellis encoder for trellis encoding the interleaved first data
or the interleaved second data, wherein the trellis encoder
includes at least one memory that is initialized at a start of each
of the known data sequences; and a second RS encoder for performing
a second non-systematic RS encoding for data changed during the
initialization of the at least one memory in order to output second
non-systematic RS parity..].
.[.2. The DTV transmitting system of claim 1, further comprising: a
parity replacer for replacing the first non-systematic RS parity
with the second non-systematic RS parity..].
3. A method for processing digital broadcast data in a DTV
transmitting system, the method comprising: encoding enhanced data
at a code rate of 1/H, wherein H is greater than 1; mapping the
encoded enhanced data into data groups; adding known data
sequences, signaling information, place holders for first
non-systematic Reed-Solomon (RS) parity and MPEG header data place
holders to each of the data groups; deinterleaving data in the data
groups; removing the place holders for the first non-systematic RS
parity in the data groups in which data is deinterleaved; replacing
the MPEG header data place holders with MPEG header data in the
data groups in which data is deinterleaved in order to output
enhanced data packets; performing a first non-systematic RS
encoding for first data when the first data corresponds to the
enhanced data packets; performing a systematic RS encoding for
second data when the second data corresponds to main data packets;
interleaving the first data corresponding to the enhanced data
packets or the second data corresponding to the main data packets;
trellis encoding the interleaved first data or the interleaved
second data at a trellis encoder; initializing at least one memory
included in the trellis encoder at a start of each of the known
data sequences; and performing a second non-systematic RS encoding
for data changed during the initialization of the at least one
memory in order to output second non-systematic RS parity.
4. The method of claim 3, further comprising: replacing the first
non-systematic RS parity with the second non-systematic RS
parity.
.Iadd.5. The method of claim 3, wherein the known data sequences
are to be used for channel estimation..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to digital television (DTV) systems
and methods of processing broadcast data.
2. Discussion of the Related Art
Presently, the technology for processing digital signals is being
developed at a vast rate, and, as a larger number of the population
uses the Internet, digital electric appliances, computers, and the
Internet are being integrated. Therefore, in order to meet with the
various requirements of the users, a system that can transmit
diverse supplemental information in addition to video/audio data
through a digital television channel needs to be developed.
Some users may assume that supplemental data broadcasting would be
applied by using a PC card or a portable device having a simple
in-door antenna attached thereto. However, when used indoors, the
intensity of the signals may decrease due to a blockage caused by
the walls or disturbance caused by approaching or proximate mobile
objects. Accordingly, the quality of the received digital signals
may be deteriorated due to a ghost effect and noise caused by
reflected waves. However, unlike the general video/audio data, when
transmitting the supplemental data, the data that is to be
transmitted should have a low error ratio. More specifically, in
case of the video/audio data, errors that are not perceived or
acknowledged through the eyes or ears of the user can be ignored,
since they do not cause any or much trouble. Conversely, in case of
the supplemental data (e.g., program execution file, stock
information, etc.), an error even in a single bit may cause a
serious problem. Therefore, a system highly resistant to ghost
effects and noise is required to be developed.
The supplemental data are generally transmitted by a time-division
method through the same channel as the video/audio data. However,
with the advent of digital broadcasting, digital television
receiving systems that receive only video/audio data are already
supplied to the market. Therefore, the supplemental data that are
transmitted through the same channel as the video/audio data should
not influence the conventional receiving systems that are provided
in the market. In other words, this may be defined as the
compatibility of broadcast system, and the supplemental data
broadcast system should be compatible with the broadcast system.
Herein, the supplemental data may also be referred to as enhanced
data. Furthermore, in a poor channel environment, the receiving
performance of the conventional receiving system may be
deteriorated. More specifically, resistance to changes in channels
and noise is more highly required when using portable and/or mobile
receiving systems.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a DTV
transmitting system and a DTV receiving system and a method of
processing broadcast data that substantially obviate one or more
problems due to limitations and disadvantages of the related
art.
An object of the present invention is to provide a DTV transmitting
system and a DTV receiving system and a method of processing
broadcast data that are highly resistant to channel changes and
noise.
Another object of the present invention is to provide a DTV
transmitting system and a DTV receiving system and a method of
processing broadcast data that can efficiently initialize a memory
of a trellis encoder in order to enhance the receiving performance
of a receiving system.
A further object of the present invention is to provide a DTV
transmitting system and a DTV receiving system and a method of
processing broadcast data that can detect known data being
trellis-encoded and transmitted and that can use the detected known
data on frequency synchronization so as to enhance the receiving
performance.
Additional advantages, objects, and features of the invention will
be set forth in part in the description which follows and in part
will become apparent to those having ordinary skill in the art upon
examination of the following or may be learned from practice of the
invention. The objectives and other advantages of the invention may
be realized and attained by the structure particularly pointed out
in the written description and claims hereof as well as the
appended drawings.
To achieve these objects and other advantages and in accordance
with the purpose of the invention, as embodied and broadly
described herein, a digital television (DTV) transmitting system
includes a pre-processor, a multiplexer, a first Reed-Solomon (RS)
encoder, a trellis encoding module, a second Reed-Solomon (RS)
encoder, and a parity replacer. The pre-processor pre-processes
enhanced data and outputs enhanced data packets including a known
data sequence. The multiplexer multiplexes the enhanced data
packets with main data packets. The first RS encoder performs RS
encoding on the multiplexed data packets by adding systematic
parity data to each main data packet and adding first
non-systematic parity data to each enhanced data packet. The
trellis encoding module performs trellis encoding on the RS-encoded
data packets. In addition, the trellis encoding module generates
initialization data to initialize at least one of memories when the
known data sequence is inputted into the trellis encoding module
from the first RS encoder.
The second RS encoder receives an enhanced data packet including
the known data sequence from the first RS encoder and removes the
first parity data from the received enhanced data packet.
Thereafter, the second RS encoder replaces a portion of the known
data sequence with the initialization data and generates second
non-systematic parity data based on the enhanced data packet
including the replaced initialization data. Finally, the parity
replacer receives an enhanced data packet including the known data
sequence from the first RS encoder and replaces the first parity
data in the received enhanced data packet with the second parity
data generated by the second RS encoder.
In another aspect of the present invention, a digital television
(DTV) receiving system includes a first known data detector, a
second known data detector, and a selector. The first known data
detector detects a location of a first known data sequence in a
broadcast signal by calculating a first correlation value between
the broadcast signal and a first reference known data sequence.
Similarly, the second known data detector detects a location of a
second known data sequence in the broadcast signal by calculating a
second correlation value between the broadcast signal and second
reference known data sequence. The detector then selects the
location information detected by one of the first and second known
data detectors with a greater correlation value. The first
reference known data sequence is a known data sequence generated
based on a assumption that an initial state of a memory included in
a trellis encoder of a digital television (DTV) transmitting system
for pre-coding is set to 0, and the second reference known data
sequence is a known data sequence generated based on an assumption
that the initial state of the memory is set to 1.
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
The accompanying drawings, which are included to provide a further
understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
FIG. 1 illustrates a block diagram of a digital broadcast
transmitting system according to an embodiment of the present
invention;
FIG. 2 and FIG. 3 illustrate another examples of data configuration
at before and after ends of a data deinterleaver in a transmitting
system according to the present invention;
FIG. 4 illustrates a detailed block diagram of a trellis-encoding
module shown in FIG. 1;
FIG. 5 and FIG. 6 respectively illustrate a trellis encoder and a
mapper shown in FIG. 4;
FIG. 7 illustrates an input symbol for initializing a memory within
the trellis encoder of FIG. 4 according to an embodiment of the
present invention;
FIG. 8 illustrates an input symbol for initializing a memory within
the trellis encoder of FIG. 4 according to another embodiment of
the present invention;
FIG. 9 illustrates a block diagram showing a structure of a
demodulating unit within a digital broadcast receiving system
according to an embodiment of the present invention;
FIG. 10 illustrates a block diagram showing a known data estimator
of FIG. 9;
FIG. 11 illustrates a block diagram showing a known data detector
of FIG. 10;
FIG. 12 illustrates a block diagram showing a partial correlator of
FIG. 11;
FIG. 13 illustrates a block diagram of a digital broadcast
receiving system according to an embodiment of the present
invention; and
FIG. 14 illustrates a block diagram of a digital broadcast
receiving system according to another embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made in detail to the preferred embodiments
of the present invention, examples of which are illustrated in the
accompanying drawings. Wherever possible, the same reference
numbers will be used throughout the drawings to refer to the same
or like parts. In addition, although the terms used in the present
invention are selected from generally known and used terms, some of
the terms mentioned in the description of the present invention
have been selected by the applicant at his or her discretion, the
detailed meanings of which are described in relevant parts of the
description herein. Furthermore, it is required that the present
invention is understood, not simply by the actual terms used but by
the meaning of each term lying within.
In the present invention, the enhanced data may either consist of
data including information such as program execution files, stock
information, weather forecast, and so on, or consist of video/audio
data. Additionally, the known data refer to data already known
based upon a pre-determined agreement between the transmitting
system and the receiving system. Furthermore, the main data consist
of data that can be received from the conventional receiving
system, wherein the main data include video/audio data. The present
invention relates to a method of inserting known data and
initializing a memory of a trellis encoder in a digital broadcast
receiving system, and to a method of detecting known data in a
digital broadcast transmitting system.
FIG. 1 illustrates an example of a digital broadcast transmitting
system according to the present invention for inserting and
transmitting known data. The transmitting system of FIG. 1 is
merely exemplary proposed to facilitate the understanding of the
present invention. Herein, any transmitting system that requires
the transmission of transmission parameters may be adopted in the
present invention. Therefore, the present invention is not limited
to the example proposed in the description set forth herein.
The digital broadcast transmitting system of FIG. 1 includes a
pre-processor 110, a packet multiplexer 121, a data randomizer 122,
a RS encoder/non-systematic RS encoder 123, a data interleaver 124,
a parity replacer 125, a non-systematic RS encoder 126, a
trellis-encoding module 127, a frame multiplexer 128, and a
transmitting unit 130. The pre-processor 110 includes a randomizer
111, a RS frame encoder 112, a block processor 113, a group
formatter 114, a data deinterleaver 115, and a packet formatter
116. In the above-described structure of the present invention, the
main data are inputted to the packet multiplexer 121, and the
enhanced data are inputted to the pre-processor 110, which performs
additional encoding so that the enhanced data can respond more
effectively to noise and channel environment that undergoes
frequent changes.
The randomizer 111 of the pre-processor 110 receives enhanced data
and randomizes the received data, thereby outputting the processed
enhanced data to the RS frame encoder 112. Then, the randomizer 111
randomizes the received enhanced data and performs byte expansion
on the randomized enhanced data by inserting null data. At this
point, by having the randomizer 111 randomize the enhanced data, a
later randomizing process on the enhanced data performed by a
randomizer 122, which is positioned in a later block, may be
omitted. The randomizer of the conventional ATSC system may be
identically used as the randomizer for randomizing the enhanced
data. Alternatively, any other type of randomizer may also be used
for this process.
The RS frame encoder 112 receives the randomized enhanced data so
as to configure a frame for additional encoding. Then, the RS frame
encoder 112 encodes the newly configured frame which is then
outputted to the block process 113. For example, the RS frame
encoder 112 performs at least one of an error correction encoding
process and an error detection encoding process on the inputted
enhanced data so as to provide robustness on the corresponding
data. Herein, RS encoding is applied as the error correction
encoding process, and cyclic redundancy check (CRC) encoding is
applied as the error detection encoding process. When performing RS
encoding, parity data that are to be used for error correction are
generated. And, when performing CRC encoding, CRC data that are to
be used for error detection are generated. Furthermore, by
scattering a group error that may occur due to a change in the
frequency environment, the RS frame encoder 112 may also perform a
row permutation process, which permutes enhanced data having a
predetermined size in row units, so that the corresponding data can
respond to the severely vulnerable and frequently changing
frequency environment.
The block processor 113 encodes the enhanced data outputted from
the RS frame encoder 112 at a coding rate of M/N and transmits the
encoded data to the group formatter 114. For example, if 1 bit of
the enhanced data is encoded to 2 bits and outputted, then M is
equal to 1 and N is equal to 2 (i.e., M=1 and N=2). Alternatively,
if 1 bit of the enhanced data is encoded to 4 bits and outputted,
then M is equal to 1 and N is equal to 4 (i.e., M=1 and N=4).
The group formatter 114 inserts the enhanced data outputted from
the block processor 113 (herein, the enhanced data may include
supplemental information data such as signaling information
including transmission information) in a corresponding area within
the data group, which is configured according to a pre-defined
rule. Furthermore, in relation with the data deinterleaving
process, various types of places holders or known data are also
inserted in corresponding areas within the data group.
At this point, the data group may be described by at least one
hierarchical area. Herein, the data allocated to the each area may
vary depending upon the characteristic of each hierarchical area.
Additionally, each data group may be configured to include a field
synchronization signal.
In an example given in the present invention, a data group is
divided into A, B, and C regions in a data configuration prior to
data deinterleaving.
FIG. 2 illustrates an alignment of data after being data
interleaved and identified, and FIG. 3 illustrates an alignment of
data before being data interleaved and identified. More
specifically, a data structure identical to that shown in FIG. 2 is
transmitted to a receiving system. Also, the data group configured
to have the same structure as the data structure shown in FIG. 2 is
inputted to the data deinterleaver 115.
As described above, FIG. 2 illustrates a data structure prior to
data deinterleaving that is divided into 3 regions, such as region
A, region B, and region C. Also, in the present invention, each of
the regions A to C is further divided into a plurality of regions.
Referring to FIG. 2, region A is divided into 5 regions (A1 to A5),
region B is divided into 2 regions (B1 and B2), and region C is
divided into 3 regions (C1 to C3). Herein, regions A to C are
identified as regions having similar receiving performances within
the data group. Herein, the type of enhanced data, which are
inputted, may also vary depending upon the characteristic of each
region.
In the example of the present invention, the data structure is
divided into regions A to C based upon the level of interference of
the main 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 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, and when
consecutively long known data are to be periodically inserted in
the enhanced data, the known data having a predetermined length may
be periodically inserted in the region having no interference from
the main data (e.g., region A). However, due to interference from
the main 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 data (e.g., region B and region C).
Hereinafter, examples of allocating data to region A (A1 to A5),
region B (B1 and B2), and region C (C1 to C3) will now be described
in detail with reference to FIG. 2. The data group size, the number
of hierarchically divided regions within the data group and the
size of each region, and the number of enhanced data bytes that can
be inserted in each hierarchically divided region of FIG. 2 are
merely examples given to facilitate the understanding of the
present invention. Herein, the group formatter 114 creates a data
group including places in which field synchronization bytes are to
be inserted, so as to create the data group that will hereinafter
be described in detail.
More specifically, region A is a region within the data group in
which a long known data sequence may be periodically inserted, and
in which includes regions wherein the main data are not mixed
(e.g., A1 to A5). Also, region A includes a region (e.g., A1)
located between a field synchronization region and the region in
which the first known data sequence is to be inserted. The field
synchronization region has the length of one segment (i.e., 832
symbols) existing in an ATSC system.
For example, referring to FIG. 2, 2428 bytes of the enhanced data
may be inserted in region A1, 2580 bytes may be inserted in region
A2, 2772 bytes may be inserted in region A3, 2472 bytes may be
inserted in region A4, and 2772 bytes may be inserted in region A5.
Herein, trellis initialization data or known data, MPEG header, and
RS parity are not included in the enhanced data. As described
above, when region A includes a known data sequence at both ends,
the receiving system uses channel information that can obtain known
data or field synchronization data, so as to perform equalization,
thereby providing enforced equalization performance.
Also, region B includes a region located within 8 segments at the
beginning of a field synchronization region within the data group
(chronologically placed before region A1) (e.g., region B1), and a
region located within 8 segments behind the very last known data
sequence which is inserted in the data group (e.g., region B2). For
example, 930 bytes of the enhanced data may be inserted in the
region B1, and 1350 bytes may be inserted in region B2. Similarly,
trellis initialization data or known data, MPEG header, and RS
parity are not included in the enhanced data. In case of region B,
the receiving system may perform equalization by using channel
information obtained from the field synchronization section.
Alternatively, the receiving system may also perform equalization
by using channel information that may be obtained from the last
known data sequence, thereby enabling the system to respond to the
channel changes.
Region C includes a region located within 30 segments including and
preceding the 9.sup.th segment of the field synchronization region
(chronologically located before region A) (e.g., region C1), a
region located within 12 segments including and following the
9.sup.th segment of the very last known data sequence within the
data group (chronologically located after region A) (e.g., region
C2), and a region located in 32 segments after the region C2 (e.g.,
region C3). For example, 1272 bytes of the enhanced data may be
inserted in the region C1, 1560 bytes may be inserted in region C2,
and 1312 bytes may be inserted in region C3. Similarly, trellis
initialization data or known data, MPEG header, and RS parity are
not included in the enhanced data. Herein, region C (e.g., region
C1) is located chronologically earlier than (or before) region
A.
Since region C (e.g., region C1) is located further apart from the
field synchronization region which corresponds to the closest known
data region, the receiving system may use the channel information
obtained from the field synchronization data when performing
channel equalization. Alternatively, the receiving system may also
use the most recent channel information of a previous data group.
Furthermore, in region C (e.g., region C2 and region C3) located
before region A, the receiving system may use the channel
information obtained from the last known data sequence to perform
equalization. However, when the channels are subject to fast and
frequent changes, the equalization may not be performed perfectly.
Therefore, the equalization performance of region C may be
deteriorated as compared to that of region B.
When it is assumed that the data group is allocated with a
plurality of hierarchically divided regions, as described above,
the block processor 113 may encode the enhanced data, which are to
be inserted to each region based upon the characteristic of each
hierarchical region, at a different coding rate. For example, the
block processor 113 may encode the enhanced data, which are to be
inserted regions Al to A5 of region A, at a coding rate of 1/2.
Then, the group formatter 114 may insert the 1/2-rate encoded
enhanced data to regions A1 to A5.
The block processor 113 may encode the enhanced data, which are to
be inserted in regions B1 and B2 of region B, at a coding rate of
1/4 having higher error correction ability as compared to the
1/2-coding rate. Then, the group formatter 114 inserts the 1/4-rate
coded enhanced data in region B1 and region B2. Furthermore, the
block processor 113 may encode the enhanced data, which are to be
inserted in regions C1 to C3 of region C, at a coding rate of 1/4
or a coding rate having higher error correction ability than the
1/4-coding rate. Then, the group formatter 114 may either insert
the encoded enhanced data to regions C1 to C3, as described above,
or leave the data in a reserved region for future usage.
In addition, the group formatter 114 also inserts supplemental
data, such as signaling information that notifies the overall
transmission information, other than the enhanced data in the data
group. Also, apart from the encoded enhanced data outputted from
the block processor 113, the group formatter 114 also inserts MPEG
header place holders, non-systematic RS parity place holders, main
data place holders, which are related to data deinterleaving in a
later process, as shown in FIG. 2. Herein, the main data place
holders are inserted because the enhanced data bytes and the main
data bytes are alternately mixed with one another in regions B and
C based upon the input of the data deinterleaver, as shown in FIG.
2. 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.
Furthermore, the group formatter 114 either inserts known data
generated in accordance with a pre-determined method or inserts
known data place holders for inserting the known data in a later
process. Additionally, place holders for initializing the trellis
encoder 127 are also inserted in the corresponding regions. For
example, the initialization data place holders may be inserted in
the beginning of the known data sequence. Herein, the size of the
enhanced data that can be inserted in a data group may vary in
accordance with the sizes of the trellis initialization place
holders or known data (or known data place holders), MPEG header
place holders, and RS parity place holders.
The output of the group formatter 114 is inputted to the data
deinterleaver 115. And, the data deinterleaver 115 deinterleaves
data by performing an inverse process of the data interleaver on
the data and place holders within the data group, which are then
outputted to the packet formatter 116. More specifically, when the
data and place holders within the data group configured, as shown
in FIG. 2, are deinterleaved by the data deinterleaver 115, the
data group being outputted to the packet formatter 116 is
configured to have the structure shown in FIG. 3.
Among the data deinterleaved and inputted, the packet formatter 116
removes the main data place holder and RS parity place holder that
were allocated for the deinterleaving process from the inputted
deinterleaved data. Thereafter, the remaining portion of the
corresponding data is grouped, and 4 bytes of MPEG header are
inserted therein. The 4-byte MPEG header is configured of a 1-byte
MPEG synchronization byte added to the 3-byte MPEG header place
holder.
When the group formatter 114 inserts the known data place holder,
the packet formatter 116 may either insert actual known data in the
known data place holder or output the known data place holder
without any change or modification for a replacement insertion in a
later process. Afterwards, the packet formatter 116 divides the
data within the above-described packet-formatted data group into
188-byte unit enhanced data packets (i.e., MPEG TS packets), which
are then provided to the packet multiplexer 121.
The packet multiplexer 121 multiplexes the 188-byte unit enhanced
data packet and main data packet outputted from the packet
formatter 116 according to a pre-defined multiplexing method.
Subsequently, the multiplexed data packets are outputted to the
data randomizer 122. The multiplexing method may be modified or
altered in accordance with diverse variables of the system design.
One of the multiplexing methods of the packet multiplexer 121 is to
identify an enhanced data burst section and a main data section
along a time axis and alternately repeating the two sections. At
this point, at least one data group may be transmitted from the
enhanced data burst section, and only the main data may be
transmitted from the main data section. Herein, the enhanced data
burst section may also transmit main data.
As described above, if the enhanced data are transmitted in the
burst structure, the receiving system receiving only the enhanced
data turns the power on only during the burst section in order to
receive the enhanced data. Alternatively, the receiving system
turns the power off during the remaining section, which corresponds
to the main data section transmitting only the main data, so that
the receiving system does not receive any portion of the main data.
Thus, power consumption of the receiving system may be reduced.
If the inputted data correspond to the main data packet, the data
randomizer 122 performs the same randomizing process as the
conventional randomizer. More specifically, the data randomizer 122
discards (or removes) the MPEG synchronization byte included in the
main data packet and randomizes the remaining 187 byte by using a
pseudo random byte that is generated by the data randomizer 122.
Then, the randomized data bytes are outputted to the RS
encoder/non-systematic RS encoder 123. However, if the inputted
data correspond to the enhanced data packet, the data randomizer
522 discards (or removes) the MPEG synchronization byte from the
4-byte MPEG header included in the enhanced data packet and
randomizes only the remaining 3 bytes. Also, the data randomizer
122 outputs the remaining portion of enhanced data excluding the
MPEG header to the RS encoder/non-systematic RS encoder 123 without
performing the randomizing process. This is because the randomizer
111 has already performed a randomizing process on the enhanced
data in an earlier process. The known data and the initialization
data place holders included in the enhanced data packet may either
be randomized or not be randomized.
The RS encoder/non-systematic RS encoder 123 RS-encodes the data
randomized by the data randomizer 122 or the data bypassing the
data randomizer 122 so as to add 20 bytes of RS parity to the
corresponding data. Then, the RS encoder/non-systematic RS encoder
123 outputs the processed data to the data interleaver 124. At this
point, if the inputted data correspond to the main data packet, the
RS encoder/non-systematic RS encoder 123 performs a systematic
RS-encoding process identical to that of the conventional
broadcasting system, thereby adding 20 bytes of RS parity at the
end of the 187-byte unit data. Alternatively, if the inputted data
correspond to the enhanced data packet, the RS
encoder/non-systematic RS encoder 123 performs a non-systematic
RS-encoding process at a specific parity byte place within the
enhanced data packet, thereby inserting the 20-byte RS parity.
Herein, the data interleaver 124 corresponds to a byte unit
convolutional interleaver. The output of the data interleaver 124
is inputted to the parity replacer 125 and the non-systematic RS
encoder 126.
Meanwhile, a process of initializing a memory within the
trellis-encoding module 127 is primarily required in order to
decide the output data of the trellis-encoding module 127, which is
located after the parity replacer 125, 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 127 should first be initialized before the
received known data sequence is trellis-encoded. The memory of the
trellis-encoding module 127 is initialized because various types of
sequences may be outputted depending upon the memory status of the
trellis-encoding module 127, even though the known data sequence is
inputted to the trellis-encoding module 127.
At this point, the beginning portion of the known data sequence
that is being received corresponds to the initialization data place
holder and not the actual known data. Herein, the initialization
data place holder has been included in the data by the group
formatter 114 in an earlier process. Therefore, the process of
generating initialization data and replacing the initialization
data place holder of the corresponding memory with the generated
initialization data are required to be performed immediately before
the known data sequence being inputted is trellis-encoded.
Additionally, a value of the initialization data is decided and
generated based upon a memory status of the trellis-encoding module
127. Further, due to the newly replaced initialization data, a
process of newly calculating the RS parity and replacing the RS
parity, which is outputted from the data interleaver 124, with the
newly calculated RS parity is required. Therefore, the
non-systematic RS encoder 126 receives the enhanced data packet
including the initialization data place holder, which is to be
replaced with the actual initialization data, from the data
interleaver 124 and also receives the initialization data from the
trellis-encoding module 127. Among the inputted enhanced data
packet, the initialization data place holder is replaced with the
initialization data, and the RS parity data that are added to the
enhanced data packet are removed. Thereafter, a new non-systematic
RS parity is calculated and outputted to the parity replacer 125.
Accordingly, the parity replacer 125 selects the output of the data
interleaver 124 as the data within the enhanced data packet, and
the parity replacer 125 selects the output of the non-systematic RS
encoder 126 as the RS parity. The selected data are then outputted
to the trellis-encoding module 127.
Meanwhile, if the main data packet is inputted or if the enhanced
data packet, which does not include any initialization data place
holder that is to be replaced, is inputted, the parity replacer 125
selects the data and RS parity that are outputted from the data
interleaver 124. Then, the parity replacer 125 directly outputs the
selected data to the trellis-encoding module 127 without any
modification. The trellis-encoding module 127 receives the output
data of the parity replacer 125 or the initialization data and
converts the received data to symbol units. Then, the
trellis-encoding module 127 pre-codes the upper bit of the
converted symbol and trellis-encodes the lower bit of the converted
symbol. Thereafter, trellis-encoding module 127 outputs the
processed data to the frame multiplexer 128. The operation of the
trellis-encoding module 127 will be described in more detail in a
later process.
The frame multiplexer 128 inserts a field synchronization signal
and a segment synchronization signal to the data outputted from the
trellis-encoding module 127 and, then, outputs the processed data
to the transmitting unit 130. Herein, the transmitting unit 130
includes a pilot inserter 131, a modulator 132, and a radio
frequency (RF) up-converter 133. The operations and roles of the
transmitting unit 130 and its components are identical to those of
the conventional transmitter. Therefore, detailed description of
the same will be omitted for simplicity.
Trellis-Encoding
FIG. 4 illustrates a detailed block diagram of a trellis-encoding
module 127, which can be initialized. Herein, when a known data
symbol sequence in inputted, the memory within the trellis-encoding
module 127 is initialized so that the trellis-encoded known data
symbol sequence becomes the desired known data symbol sequence. In
order to do so, the trellis-encoding module 127 includes a
multiplexer 201, an initialization data generator 202, and a
trellis encoder 203.
Referring to FIG. 4, in the trellis-encoding module 127 having the
above-described structure, when initialization of the memory within
the trellis-encoding module 127 is required, the initialization
data generator 202 generates data required for the initialization
process based upon a value of the memory within the trellis encoder
203. Thereafter, the initialization data generator 202 outputs the
generated initialization data to the multiplexer 201 and a
non-systematic RS encoder 126. More specifically, of the data being
inputted for the trellis-encoding process correspond to
initialization data place holders (or the beginning of the known
data sequence), the initialization data generator 202 generates the
initialization data.
The multiplexer 201 selects one of the output data of the parity
replacer 125 and the initialization data of the initialization data
generator 202. Then, the multiplexer 201 outputs the selected data
to the trellis encoder 203. More specifically, when the memory of
the trellis encoder 203 is required to be initialized, the
initialization data are outputted to the trellis encoder 203
instead of the initialization data place holders (or the beginning
of the known data sequence) outputted from the parity replacer 125.
Accordingly, the memory within the trellis encoder 203 is
initialized to the value decided by the initialization data. Then,
from the point (or moment) the memory of the trellis encoder 203 is
initialized, the data outputted from the trellis encoder 203 may
become a known data sequence encoded to have a data format (or
configuration) desired by the transmitting system and the receiving
system.
FIG. 5 and FIG. 6 respectively illustrate the trellis encoder 203
according to an embodiment of the present invention. Herein, the
output data of the parity replacer 125 or the initialization data
are trellis-encoded in symbol units. Each symbol is configured of 2
bits. More specifically, an upper bit d1 of the input symbol is
pre-coded by using a memory m2 and an adder of a pre-coder, as
shown in FIG. 5 and FIG. 6, so as to be outputted as c2. A lower
bit d0 of the input symbol is trellis-encoded by using memories m1
and m0 and an adder, so as to be outputted as c1 and c0. The output
c2c1c0 of the trellis encoder 203 corresponds to an 8-level signal,
as shown in FIG. 6, which is mapped to a VSB signal and outputted
to a frame multiplexer 128.
Therefore, the memory m2 of the trellis encoder 203 is decided only
based upon d1, and the memories m1 and m0 are decided only based
upon d0. In other words, the upper bit c2 of the output data of the
trellis encoder 203 is decided based upon the memory m2 within the
pre-coder and the upper input bit d1, and the two lower bits c1 and
c0 are decided based upon the memories m1 and m0 and the lower
input bit d0. The present invention will now be described in detail
in accordance with first and second embodiments of the present
invention. The first and second embodiments respectively describe
an example of initializing only memories m1m0 and an example of
initializing all memories m2m1m0.
First Embodiment
When the memory m2 of the pre-coder within the trellis encoder 203
is not initialized, and when only the remaining two memories m1 and
m0 are initialized, regardless of whether known data are inputted
after the initialization process, only the two lower bits c1 and c0
among the 3 bits outputted from the trellis encoder 203 correspond
to the known data. And, the one upper bit c2 may have two different
values depending upon the status of the memory m2 within the
pre-coder. FIG. 7 illustrates the output data of the initialization
data generator 202, when initializing the memories m1 and m0 of the
trellis encoder 203. More specifically, FIG. 7 illustrates the
input data of two symbol sections that are to be initialized to
`00`, when each of the memories m1 and m0 of the trellis encoder
203 is in an arbitrary status. For example, when the memory status
corresponds to m1m0=11, the input bit d0 should be consecutively
inputted as `1` and `1` in order to initialize the memory to `00`.
In this case, the initialization data generator 202 generates data
required for the initialization process based upon the value of the
memory m1m0 of the trellis encoder 203. At this point, if the
memory m1m0 of the trellis encoder 203 is to be initialized to a
status other than `00`, two symbol sequences that are different
from those shown in FIG. 7 are required. Since these two different
symbol sequences may be easily deduced, a detailed description of
the same will be omitted for simplicity.
As described above, when only the memories m1 and m0 of the trellis
encoder 203 are initialized to a decided value, if a known data
symbol sequence is inputted to the trellis encoder 203, c1 and c0
still remain as known data. However, c2 may be modified (or
changed) in accordance with the value of the memory m2 within the
pre-coder. Since the pre-coder is configured to have a feed-back
structure, even though an identical d1 of the data sequence is
inputted, the data sequence of the outputted data may become
opposite to one another if the starting point is not the same.
The operation of the pre-coder will now be described in detail.
When an initial state of the memory m2 within the pre-coder
corresponds to `0`, and when 100111 is inputted as the data
sequence of input bit d1, the data sequence of the output c2 of the
pre-coder becomes 111010. However, when the initial state of the
memory m2 within the pre-coder corresponds to `1`, and when 100111
is inputted as the data sequence of input bit d1, the data sequence
of the output c2 of the pre-coder becomes 000101. More
specifically, when the same data sequence is inputted to the
pre-coder, and when the initial state of the memory m2 within the
pre-coder is opposite to one another, the output c2 also becomes
the opposite of one another. As a result, when the known data
sequence is inputted, and when only the memories m1 and m0 of the
trellis encoder 203 are initialized, two different symbol sequences
may be outputted from the output data of the trellis encoder 203.
And, at this point, only c2 of the two output symbol sequences is
the opposite of one another, and c1 and c0 are identical to one
another, respectively.
Therefore, the known data symbol being trellis-encoded and mapped
to 8 levels may correspond to level +7 (c2c1c0=111) or level -1
(c2c1c0=011), or correspond to level +5 (c2c1c0=110) or level -3
(c2c1c0=010) or correspond to level +3 (c2c1c0=101) or level -5
(c2c1c0=001), or correspond to level +1 (c2c1c0=100) or level -7
(c2c1c0=000). More specifically, when c1c0 is equal to 00, the
signal level being mapped to 8 different levels may only correspond
to -7 and +1. As described above, depending upon the status of the
memory m2 within the pre-coder, two different known data symbol
sequences may be outputted from the trellis encoder 203. If one of
the two known data symbol sequence corresponds to -7, +5, -5, +1,
+7, +3, -1, -3, the other known data symbol sequence corresponds to
+1, -3, +3, -7, -1, -5, +7, +5.
Second Embodiment
As shown in FIG. 5 and FIG. 6, in order to initialize the memory m2
of the trellis encoder 203 to a decided value, one d1 may be used.
Alternatively, in order to initialize each of the memories m1 and
m0 to a decided value, two d0s are required. Therefore, it is
apparent that in order to initialize memories m2, m1, and m0 of the
trellis encoder 203, at least two input symbols are required. FIG.
8 illustrates the output of the initialization data generator 202
when initializing the memories m2, m1, and m0 of the trellis
encoder 203. More specifically, FIG. 8 illustrates the input data
of two symbol sections that are to be initialized to `000`, when
each of the memories m2, m1, and m0 of the trellis encoder 203 is
in an arbitrary status.
For example, when the memory status corresponds to m2m1m0=111, the
input symbol d1d0 should be consecutively inputted either as `01`
and `11` or as `11` and `01` in order to initialize the memory to
`000`. In this case, the initialization data generator 202
generates data required for the initialization process based upon
the value of the memory m2m1m0 of the trellis encoder 203. At this
point, if the memory m2m1m0 of the trellis encoder 203 is to be
initialized to a status other than `000`, two symbol sequences that
are different from those shown in FIG. 8 are required. Since these
two different symbol sequences may be easily deduced, a detailed
description of the same will be omitted for simplicity.
Receiving System
FIG. 9 illustrates a block diagram showing a demodulating unit of a
digital broadcast receiving system according to an embodiment of
the present invention, wherein the demodulating unit is used for
receiving data transmitted from the transmitting system,
demodulating and equalizing the received data, so as to recover the
processed data back to the initial (or original) data. Referring to
FIG. 9, the demodulating unit of the digital broadcast receiving
system includes a demodulator 601, an equalizer 602, a known data
estimator 603, a block decoder 604, a data deformatter 605, a RS
frame decoder 606, a derandomizer 607, a data deinterleaver 608, a
RS decoder 609, and a data derandomizer 610.
More specifically, an intermediate frequency (IF) signal of a
particular channel that is tuned by a tuner is inputted to the
demodulator 601 and the known data detector 603. The demodulator
601 performs self gain control, carrier recovery, and timing
recovery processes on the inputted IF signal, thereby modifying the
IF signal to a baseband signal. Then, the demodulator 601 outputs
the newly created baseband signal to the equalizer 602 and the
known data estimator 603. The equalizer 602 compensates the
distortion of the channel included in the demodulated signal and
then outputs the error-compensated signal to the block decoder
604.
At this point, the known data estimator 603 detects the known
sequence place inserted by the transmitting end from the
input/output data of the demodulator 601 (i.e., the data prior to
the demodulation or the data after the modulation). Thereafter, the
known data place information is outputted to the demodulator 601
and the equalizer 602. Simultaneously, a coarse frequency offset is
estimated and outputted to the demodulator 601. The processes of
detecting the known data place and detecting the coarse frequency
offset will be described in more detail in a later process.
Also, the known data estimator 603 outputs a set of information to
the block decoder 604. This set of information is used to allow the
block decoder 604 of the receiving system to identify the enhanced
data that are processed with additional encoding from the
transmitting system and the main data that are not processed with
additional encoding. This set of information is also used to
indicate a stating point of a block in the enhanced encoder. Also,
the information detected from the known data estimator 603 may be
used throughout the entire receiving system and may also be used by
the data deformatter 605 and the RS frame decoder 606.
The demodulator 601 uses the known data during the timing and/or
carrier recovery, thereby enhancing the demodulating performance.
Similarly, the equalizer 602 uses the known data sequence, thereby
enhancing the equalizing quality. Particularly, the demodulator 601
may use the known data place information and the estimated value of
the coarse frequency offset both outputted from the known data
estimator 603, thereby estimating and compensating the frequency
offset with more accuracy. Moreover, the decoding result of the
block decoder 604 may be fed-back to the equalizer 602, thereby
enhancing the equalizing performance.
The equalizer 602 may perform channel equalization by using a
plurality of methods. An example of estimating a channel impulse
response (CIR) so as to perform channel equalization will be given
in the description of the present invention. 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. Furthermore, by using the known
data, the place and contents of which is known in accordance with
an agreement between the transmitting system and the receiving
system, and the field synchronization data, so as to estimate the
CIR, the present invention may be able to perform channel
equalization with more stability.
Herein, the data group that is inputted for the equalization
process is divided into regions A to C, as shown in FIG. 2. More
specifically, in the example of the present invention, each region
A, B, and C are further divided into regions A1 to A5, regions B1
and B2, and regions C1 to C3, respectively. Referring to FIG. 2,
the CIR that is estimated from the field synchronization data in
the data structure is referred to as CIR_FS. Alternatively, the
CIRs that are estimated from each of the 5 known data sequences
existing in region A are sequentially referred to as CIR_N0,
CIR_N1, CIR_N2, CIR_N3, and CIR_N4.
As described above, the present invention uses the CIR estimated
from the field synchronization data and the known data sequences 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. The linear interpolation described
herein is merely exemplary among a wide range of possible
interpolation methods. And, therefore, the present invention is not
limited only to the examples set forth 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, extrapolation refers to estimating a function
value of a point outside of the section between points Q and S.
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.
More specifically, in case of region C1, any one of the CIR_N4
estimated from a previous data group, the CIR_FS estimated from the
current data group that is to be processed with channel
equalization, and a new CIR generated by extrapolating the CIR_FS
of the current data group and the CIR_N0 may be used to perform
channel equalization. Alternatively, in case of region B1, a
variety of methods may be applied as described in the case for
region C1. For example, a new CIR created by linearly extrapolating
the CIR_FS estimated from the current data group and the CIR_N0 may
be used to perform channel equalization. Also, the CIR_FS estimated
from the current data group may also be used to perform channel
equalization. Finally, in case of region A1, a new CIR may be
created by interpolating the CIR_FS estimated from the current data
group and CIR_N0, which is then used to perform channel
equalization. Furthermore, any one of the CIR_FS estimated from the
current data group and CIR_N0 may be used to perform channel
equalization.
In case of regions A2 to A5, CIR_N(i-1) estimated from the current
data group and CIR_N(i) may be interpolated to create a new CIR and
use the newly created CIR to perform channel equalization. Also,
any one of the CIR_N(i-1) estimated from the current data group and
the CIR_N(i) may be used to perform channel equalization.
Alternatively, in case of regions B2, C2, and C3, CIR_N3 and CIR_N4
both estimated from the current data group may be extrapolated to
create a new CIR, which is then used to perform the channel
equalization process. Furthermore, the CIR_N4 estimated from the
current data group may be used to perform the channel equalization
process. Accordingly, an optimum performance may be obtained when
performing channel equalization on the data inserted in the data
group. The methods of obtaining the CIRs required for performing
the channel equalization process in each region within the data
group, as described above, are merely examples given to facilitate
the understanding of the present invention. A wider range of
methods may also be used herein. And, therefore, the present
invention will not only be limited to the examples given in the
description set forth herein.
Meanwhile, if the data being channel equalized and then inputted to
the block decoder 604 correspond to the enhanced data on which
additional encoding and trellis encoding are both performed by the
transmitting system, trellis-decoding and additional decoding
processes are performed as inverse processes of the transmitting
system. Alternatively, if the data being channel equalized and then
inputted to the block decoder 604 correspond to the main data on
which additional encoding is not performed and only
trellis-encoding is performed by the transmitting system, only the
trellis-decoding process is performed.
The data group decoded by the block decoder 604 is inputted to the
enhanced data deformatter 605, and the main data packet is inputted
to the data deinterleaver 608.
More specifically, if the inputted data correspond to the main
data, the block decoder 604 performs Viterbi decoding on the
inputted data, so as to either output a hard decision value or
hard-decide a soft decision value and output the hard-decided
result. On the other hand, if the inputted correspond to the
enhanced data, the block decoder 604 outputs either a hard decision
value or a soft decision value on the inputted enhanced data. In
other words, if the data inputted to the block decoder 604
correspond to the enhanced data, the block decoder 604 performs a
decoding process on the data encoded by the block processor and the
trellis encoder of the transmitting system. At this point, the
output of the RS frame encoder included in the pre-processor of the
transmitting system becomes an external code, and the output of the
block processor and the trellis encoder becomes an internal code.
In order to show maximum performance of the external code when
decoding such connection codes, the decoder of the internal code
should output a soft decision value. Therefore, the block decoder
604 may output a hard decision value on the enhanced data. However,
when required, it is more preferable that the block decoder 604
outputs a soft decision value.
More specifically, depending upon the system design or conditions,
the block decoder 604 outputs any one of the soft decision value
and the hard decision value with respect to the enhanced data, and
the block decoder 604 outputs the hard decision value with respect
to the main data.
Meanwhile, the data deinterleaver 608, the RS decoder 609, and the
data derandomizer 610 are blocks required for receiving the main
data. Therefore, the above-mentioned blocks may not be required in
the structure of a receiving system that is designed to receive
only the enhanced data. The data deinterleaver 608 performs an
inverse process of the data interleaver included in the
transmitting system by deinterleaving the main data. Then, the data
deinterleaver 608 outputs the deinterleaved data to the RS decoder
609. The RS decoder 609 performs a systematic RS decoding process
on the deinterleaved data and outputs the processed data to the
data derandomizer 610.
The data derandomizer 610 received the data outputted from the RS
decoder 609 and generates a pseudo random data byte identical to
that of the randomizer included in the digital broadcast
transmitting system (or DTV transmitter). Thereafter, the data
derandomizer 610 performs a bitwise exclusive OR (XOR) operation
between the generated pseudo random data byte and the data packet
outputted from the RS decoder 609, thereby inserting the MPEG
synchronization bytes to the beginning of each packet so as to
output the data in 188-byte main data packet units.
Meanwhile, the data being outputted from the block decoder 604 are
inputted to the data deformatter 605 in an data group format. At
this point, the data deformatter 605 already knows the
configuration of the inputted data. Therefore, the data deformatter
605 is capable of identifying the signaling information, which
includes system information, and the enhanced data within the A
area. Herein, the data deformatter 605 removes the known data,
trellis initialization data, and MPEG header that have been
inserted in the main data and data group, and also removes the RS
parity data that have been inserted by the RS
encoder/non-systematic RS encoder or the non-systematic RS encoder
of the transmitting system. Thereafter, the data deformatter 605
outputs the processed data to the RS frame decoder 606.
The RS frame decoder 606 performs an inverse process of the RS
frame encoder included in the transmitting system on the output
data of the data deformatter 605. Then, the RS frame decoder 606
outputs the processed data to the derandomizer 607. More
specifically, the RS frame decoder 606 performs at least one of
error detection decoding, inversed row permutation, and error
correction decoding on the input data so as to recover the enhanced
data to the initial (or original) enhanced data. The derandomizer
607 derandomizes the inputted enhanced data by performing an
inverse process of the randomizer 111 included in the transmitting
system. Meanwhile, the known data estimator 603 estimates the known
data place inserted by the transmitting system and, at the same
time, estimates the coarse frequency offset while estimating the
known data. At this point, as shown in the first embodiment, the
transmitting system may only initialize the memories m1 and m0 of
the trellis encoder at the initialization data place holder (or the
starting point of the known data sequence). Alternatively, as shown
in the second embodiment, the transmitting system may initialize
all three memories m2, m1, and m0 of the trellis encoder.
Particularly, as shown in the first embodiment, when initializing
only the memories m1 and m0 of the trellis encoder (i.e., when the
memory m2 within the pre-coder is not initialized), and when the
known data are trellis-encoded and outputted, two different known
data sequences may be outputted based upon the initial state of the
memory m2 within the pre-coder. Therefore, the known data estimator
603 of the digital broadcast receiving system (or digital
television receiver) may estimate the status (or state) of the
pre-coder so as to detect the known data.
In order to do so, the known data estimator 603 as shown in FIG. 10
includes a first known data detector 701, a second known data
detector 702, and a selector 703.
The first known data detector 701 detects a known data symbol
sequence that is generated when the initial state of the memory m2
within the pre-coder of the trellis encoder included in the
transmitting system is `0`. The second known data detector 702
detects a known data symbol sequence that is generated when the
initial state of the memory m2 is `1`. For this, the first known
data detector 701 calculates a partial correlation between the
received signal and a first reference known data sequence, thereby
detecting the place of the corresponding known data and estimating
the coarse frequency offset, which are then outputted.
Additionally, the second known data detector 702 calculates a
partial correlation between the received signal and a second
reference known data sequence, thereby detecting the place of the
corresponding known data and estimating the coarse frequency
offset, which are then outputted. Herein, the first reference known
data sequence corresponds to a reference data sequence that is
generated from or stored in the receiving system, when it is
assumed that the initial state of the pre-coder memory m2 within
the trellis encoder included in the transmitting system is `0`. The
second reference known data sequence corresponds to a reference
data sequence that is generated from or stored in the receiving
system, when it is assumed that the initial state of the pre-coder
memory m2 within the trellis encoder included in the transmitting
system is `1`.
The selector 703 compares each peak value of the partial
correlation values respectively outputted from the first known data
detector 701 and the second known data detector 702. Thereafter,
the selector 703 selects the known data detector having the higher
(or greater) peak value. The, the selector 703 outputs the known
data place information, frequency offset, and selected information
(e.g., estimated initial state value of the pre-coder memory),
which are outputted from the selected known data detector. Since
the components and operation of the first known data detector 701
and the second known data detector 702 are identical to one
another, the description of only one known data detector according
to the present invention will be provided herein.
FIG. 11 illustrates a block diagram shown the structure of a known
data detector. More specifically, FIG. 11 illustrates an example an
inputted signal being oversampled to N times its initial state.
Herein, N represents a sampling rate of the received signal.
Referring to FIG. 11, the known sequence detector includes N number
of partial correlators 811 to 81N configured in parallel, and a
known data place detector and frequency offset decider 820. Herein,
the first partial correlator 811 consists of a 1/N decimator, and a
partial correlator. The second partial correlator 812 consists of a
1 sample delay, a 1/N decimator, and a partial correlator. And, the
N.sup.th partial correlator 81N consists of a N-1 sample delay, a
1/N decimator, and a partial correlator. These are used to match
(or identify) the phase of each of the samples within the
oversampled symbol with the phase of the original symbol, and to
decimate the samples of the remaining phases, thereby performing
partial correlation on each sample. More specifically, the input
signal is decimated at a rate of 1/N for each sampling phase, so as
to pass through each partial correlator.
For example, when the input signal is oversampled to 2 times (i.e.,
when N=2), this indicates that two samples are included in one
signal. In this case, two partial correlators are required, and
each 1/N decimator becomes a 1/2 decimator. At this point, the 1/N
decimator of the first partial correlator 811 decimates (or
removes), among the input samples, the samples located in-between
symbol places (or positions). Then, the corresponding 1/N decimator
outputs the decimated sample to the partial correlator.
Furthermore, the 1 sample delay of the second partial correlator
812 delays the input sample by 1 sample (i.e., performs a 1 sample
delay on the input sample) and outputs the delayed input sample to
the 1/N decimator. Subsequently, among the samples inputted from
the 1 sample delay, the 1/N decimator of the second partial
correlator 812 decimates (or removes) the samples located
in-between symbol places (or positions). Thereafter, the
corresponding 1/N decimator outputs the decimated sample to the
partial correlator.
After each predetermined period of the symbol, each of the partial
correlators outputs a correlation value and an estimation value of
the frequency offset estimated at that particular moment to the
known data place detector and frequency offset decider 820. The
known data place detector and frequency offset decider 820 stores
the output of the partial correlators corresponding to each
sampling phase during an data group cycle or a pre-decided cycle.
Thereafter, the known data place detector and frequency offset
decider 820 decides a position (or place) corresponding to the
highest correlation value, among the stored values, as the place
(or position) for receiving the known data. Simultaneously, the
known data place detector and frequency offset decider 820 finally
decides the estimation value of the frequency offset estimated at
the moment corresponding to the highest correlation value as the
coarse frequency offset value of the receiving system.
FIG. 12 illustrates a block diagram showing the structure of one of
the partial correlators shown in FIG. 11. During the step of
detecting known data, since a frequency offset is included in the
received signal, each partial correlator divides the known data,
which is known according to an agreement between the transmitting
system and the receiving system, to K number of parts each having
an L symbol length, thereby correlating each divided part with the
corresponding part of the received signal. In order to do so, each
partial correlator includes K number of phase and size detector 911
to 91K each formed in parallel, an adder 920, and a coarse
frequency offset estimator 930.
The first phase and size detector 911 includes an L symbol buffer
911-2, a multiplier 911-3, an accumulator 911-4, and a squarer
911-5. Herein, the first phase and size detector 911 calculates the
correlation value of the known data having a first L symbol length
among the K number of sections. Also, the second phase and size
detector 912 includes an L symbol delay 912-1, an L symbol buffer
912-2, a multiplier 912-3, an accumulator 912-4, and a squarer
912-5. Herein, the second phase and size detector 912 calculates
the correlation value of the known data having a second L symbol
length among the K number of sections. Finally, the N.sup.th phase
and size detector 91K includes a (K-1)L symbol delay 91K-1, an L
symbol buffer 91K-2, a multiplier 91K-3, an accumulator 91K-4, and
a squarer 91K-5. Herein, the N.sup.th phase and size detector 91K
calculates the correlation value of the known data having an
N.sup.th L symbol length among the K number of sections.
Referring to FIG. 12, {P.sub.0, P.sub.1, . . . , P.sub.KL-1} each
being multiplied with the received signal in the multiplier
represents the reference known data sequence known by both the
transmitting system and the receiving system. And, * represents a
complex conjugate. For example, in the first phase and size
detector 911, the signal outputted from the 1/N decimator of the
first partial correlator 811, shown in FIG. 11, is temporarily
stored in the L symbol buffer 911-2 of the first phase and size
detector 911 and then inputted to the multiplier 911-3. The
multiplier 911-3 multiplies the output of the L symbol buffer 911-2
with the complex conjugate of the known data parts P.sub.0,
P.sub.1, . . . , P.sub.KL-1, each having a first L symbol length
among the known K number of sections. Then, the multiplied result
is outputted to the accumulator 911-4. During the L symbol period,
the accumulator 911-4 accumulates the output of the multiplier
911-3 and, then, outputs the accumulated value to the squarer 911-5
and the coarse frequency offset estimator 930. The output of the
accumulator 911-4 is a correlation value having a phase and a size.
Accordingly, the squarer 911-5 calculates an absolute value of the
output of the multiplier 911-4 and squares the calculated absolute
value, thereby obtaining the size of the correlation value. The
obtained size is then inputted to the adder 920.
The adder 920 adds the output of the squarers corresponding to each
size and phase detector 911 to 91K. Then, the adder 920 outputs the
added result to the known data place detector and frequency offset
decider 820. Also, the coarse frequency offset estimator 930
receives the output of the accumulator corresponding to each size
and phase detector 911 to 91K, so as to estimate the coarse
frequency offset at each corresponding sampling phase. Thereafter,
the coarse frequency offset estimator 930 outputs the estimated
offset value to the known data place detector and frequency offset
decider 820. When the K number of inputs that are outputted from
the accumulator of each phase and size detector 911 to 91K are each
referred to as {Z.sub.0, Z.sub.1, . . . , Z.sub.K-1}, the output of
the coarse frequency offset estimator 930 may be obtained by using
Equation 1 shown below.
.omega..times..times..times..times..times..times..times.
##EQU00001##
The known data place detector and frequency offset decider 820
stores the output of the partial correlator corresponding to each
sampling phase during an data group cycle or a pre-decided cycle.
Then, among the stored correlation values, the known data place
detector and frequency offset decider 820 decides the place (or
position) corresponding to the highest correlation value as the
place for receiving the known data. Furthermore, the known data
place detector and frequency offset decider 820 decides the
estimated value of the frequency offset taken (or estimated) at the
point of the highest correlation value as the coarse frequency
offset value of the receiving system. For example, if the output of
the partial correlator corresponding to the second partial
correlator 812 is the highest value, the place corresponding to the
highest value is decided as the known data place. Thereafter, the
coarse frequency offset estimated by the second partial correlator
812 is decided as the final coarse frequency offset, which is then
outputted to the selector 703.
FIG. 13 illustrates a block diagram showing the structure of a
digital broadcast receiving system according to an embodiment of
the present invention. Referring to FIG. 13, the digital broadcast
receiving system includes a tuner 1001, a demodulating unit 1002, a
demultiplexer 1003, an audio decoder 1004, a video decoder 1005, a
native TV application manager 1006, a channel manager 1007, a
channel map 1008, a first memory 1009, a data decoder 1010, a
second memory 1011, a system manager 1012, a data broadcasting
application manager 1013, a storage controller 1014, and a third
memory 1015. Herein, the third memory 1015 is a mass storage
device, such as a hard disk drive (HDD) or a memory chip. The tuner
1001 tunes a frequency of a specific channel through any one of an
antenna, cable, and satellite. Then, the tuner 1001 down-converts
the tuned frequency to an intermediate frequency (IF), which is
then outputted to the demodulating unit 1002. At this point, the
tuner 1001 is controlled by the channel manager 1007. Additionally,
the result and strength of the broadcast signal of the tuned
channel are also reported to the channel manager 1007. The data
that are being received by the frequency of the tuned specific
channel include main data, enhanced data, and table data for
decoding the main data and enhanced data.
In the embodiment of the present invention, examples of the
enhanced data may include data provided for data service, such as
Java application data, HTML application data, XML data, and so on.
The data provided for such data services may correspond either to a
Java class file for the Java application, or to a directory file
designating positions (or locations) of such files. Furthermore,
such data may also correspond to an audio file and/or a video file
used in each application. The data services may include weather
forecast services, traffic information services, stock information
services, services providing information quiz programs providing
audience participation services, real time poll, user interactive
education programs, gaming services, services providing information
on soap opera (or TV series) synopsis, characters, original sound
track, filing sites, services providing information on past sports
matches, profiles and accomplishments of sports players, product
information and product ordering services, services providing
information on broadcast programs by media type, airing time,
subject, and so on. The types of data services described above are
only exemplary and are not limited only to the examples given
herein. Furthermore, depending upon the embodiment of the present
invention, the enhanced data may correspond to meta data. For
example, the meta data use the XML application so as to be
transmitted through a DSM-CC protocol.
The demodulating unit 1002 performs VSB-demodulation and channel
equalization on the signal being outputted from the tuner 1001,
thereby identifying the main data and the enhanced data.
Thereafter, the identified main data and enhanced data are
outputted in TS packet units. Example of the demodulating unit 1002
is shown in FIG. 9. The demodulating unit shown in FIG. 9 is merely
exemplary and the scope of the present invention is not limited to
the examples set forth herein. In the embodiment given as an
example of the present invention, only the enhanced data packet
outputted from the demodulating unit 1002 is inputted to the
demultiplexer 1003. In this case, the main data packet is inputted
to another demultiplexer (not shown) that processes main data
packets. Herein, the storage controller 1014 is also connected to
the other demultiplexer in order to store the main data after
processing the main data packets. The demultiplexer of the present
invention may also be designed to process both enhanced data
packets and main data packets in a single demultiplexer.
The storage controller 1014 is interfaced with the demultiplexer so
as to control instant recording, reserved (or pre-programmed)
recording, time shift, and so on of the enhanced data and/or main
data. For example, when one of instant recording, reserved (or
pre-programmed) recording, and time shift is set and programmed in
the receiving system (or receiver) shown in FIG. 13, the
corresponding enhanced data and/or main data that are inputted to
the demultiplexer are stored in the third memory 1015 in accordance
with the control of the storage controller 1014. The third memory
1015 may be described as a temporary storage area and/or a
permanent storage area. Herein, the temporary storage area is used
for the time shifting function, and the permanent storage area is
used for a permanent storage of data according to the user's choice
(or decision).
When the data stored in the third memory 1015 need to be reproduced
(or played), the storage controller 1014 reads the corresponding
data stored in the third memory 1015 and outputs the read data to
the corresponding demultiplexer (e.g., the enhanced data are
outputted to the demultiplexer 1003 shown in FIG. 13). At this
point, according to the embodiment of the present invention, since
the storage capacity of the third memory 1015 is limited, the
compression encoded enhanced data and/or main data that are being
inputted are directly stored in the third memory 1015 without any
modification for the efficiency of the storage capacity. In this
case, depending upon the reproduction (or reading) command, the
data read from the third memory 1015 pass trough the demultiplexer
so as to be inputted to the corresponding decoder, thereby being
restored to the initial state.
The storage controller 1014 may control the reproduction (or play),
fast-forward, rewind, slow motion, instant replay functions of the
data that are already stored in the third memory 1015 or presently
being buffered. Herein, the instant replay function corresponds to
repeatedly viewing scenes that the viewer (or user) wishes to view
once again. The instant replay function may be performed on stored
data and also on data that are currently being received in real
time by associating the instant replay function with the time shift
function. If the data being inputted correspond to the analog
format, for example, if the transmission mode is NTSC, PAL, and so
on, the storage controller 1014 compression encodes the inputted
data and stored the compression-encoded data to the third memory
1015. In order to do so, the storage controller 1014 may include an
encoder, wherein the encoder may be embodied as one of software,
middleware, and hardware. Herein, an MPEG encoder may be used as
the encoder according to an embodiment of the present invention.
The encoder may also be provided outside of the storage controller
1014.
Meanwhile, in order to prevent illegal duplication (or copies) of
the input data being stored in the third memory 1015, the storage
controller 1014 scrambles the input data and stores the scrambled
data in the third memory 1015. Accordingly, the storage controller
1014 may include a scramble algorithm for scrambling the data
stored in the third memory 1015 and a descramble algorithm for
descrambling the data read from the third memory 1015. Herein, the
definition of scramble includes encryption, and the definition of
descramble includes decryption. The scramble method may include
using an arbitrary key (e.g., control word) to modify a desired set
of data, and also a method of mixing signals.
Meanwhile, the demultiplexer 1003 receives the real-time data
outputted from the demodulating unit 1002 or the data read from the
third memory 1015 and demultiplexes the received data. In the
example given in the present invention, the demultiplexer 1003
performs demultiplexing on the enhanced data packet. Therefore, in
the present invention, the receiving and processing of the enhanced
data will be described in detail. It should also be noted that a
detailed description of the processing of the main data will be
omitted for simplicity starting from the description of the
demultiplexer 1003 and the subsequent elements.
The demultiplexer 1003 demultiplexes enhanced data and program
specific information/program and system information protocol
(PSI/PSIP) tables from the enhanced data packet inputted in
accordance with the control of the data decoder 1010. Thereafter,
the demultiplexed enhanced data and PSI/PSIP tables are outputted
to the data decoder 1010 in a section format. In order to extract
the enhanced data from the channel through which enhanced data are
transmitted and to decode the extracted enhanced data, system
information is required. Such system information may also be
referred to as service information. The system information may
include channel information, event information, etc. In the
embodiment of the present invention, the PSI/PSIP tables are
applied as the system information. However, the present invention
is not limited to the example set forth herein. More specifically,
regardless of the name, any protocol transmitting system
information in a table format may be applied in the present
invention.
The PSI table is an MPEG-2 system standard defined for identifying
the channels and the programs. The PSIP table is an advanced
television systems committee (ATSC) standard that can identify the
channels and the programs. The PSI table may include a program
association table (PAT), a conditional access table (CAT), a
program map table (PMT), and a network information table (NIT).
Herein, the PAT corresponds to special information that is
transmitted by a data packet having a PID of `0`. The PAT transmits
PID information of the PMT and PID information of the NIT
corresponding to each program. The CAT transmits information on a
paid broadcast system used by the transmitting system. The PMT
transmits PID information of a transport stream (TS) packet, in
which program identification numbers and individual bit sequences
of video and audio data configuring the corresponding program are
transmitted, and the PID information, in which PCR is transmitted.
The NIT transmits information of the actual transmission
network.
The PSIP table may include a virtual channel table (VCT), a system
time table (STT), a rating region table (RRT), an extended text
table (ETT), a direct channel change table (DCCT), an event
information table (EIT), and a master guide table (MGT). The VCT
transmits information on virtual channels, such as channel
information for selecting channels and information such as packet
identification (PID) numbers for receiving the audio and/or video
data. More specifically, when the VCT is parsed, the PID of the
audio/video data of the broadcast program may be known. Herein, the
corresponding audio/video data are transmitted within the channel
along with the channel name and the channel number. The STT
transmits information on the current data and timing information.
The RRT transmits information on region and consultation organs for
program ratings. The ETT transmits additional description of a
specific channel and broadcast program. The EIT transmits
information on virtual channel events (e.g., program title, program
start time, etc.). The DCCT/DCCSCT transmits information associated
with automatic (or direct) channel change. And, the MGT transmits
the versions and PID information of the above-mentioned tables
included in the PSIP.
Each of the above-described tables included in the PSI/PSIP is
configured of a basic unit referred to as a "section", and a
combination of one or more sections forms a table. For example, the
VCT may be divided into 256 sections. Herein, one section may
include a plurality of virtual channel information. However, a
single set of virtual channel information is not divided into two
or more sections. At this point, the receiving system may parse and
decode the data for the data service that are transmitting by using
only the tables included in the PSI, or only the tables included in
the PSIP, or a combination of tables included in both the PSI and
the PSIP. In order to parse and decode the data for the data
service, at least one of the PAT and PMT included in the PSI, and
the VCT included in the PSIP is required. For example, the PAT may
include the system information for transmitting the data
corresponding to the data service, and the PID of the PMT
corresponding to the data service data (or program number). The PMT
may include the PID of the TS packet used for transmitting the data
service data. The VCT may include information on the virtual
channel for transmitting the data service data, and the PID of the
TS packet for transmitting the data service data.
Meanwhile, depending upon the embodiment of the present invention,
a DVB-SI may be applied instead of the PSIP. The DVB-SI may include
a network information table (NIT), a service description table
(SDT), an event information table (EIT), and a time and data table
(TDT). The DVB-SI may be used in combination with the
above-described PSI. Herein, the NIT divides the services
corresponding to particular network providers by specific groups.
The NIT includes all tuning information that is used during the IRD
set-up. The NIT may be used for informing or notifying any change
in the tuning information. The SDT includes the service name and
different parameters associated with each service corresponding to
a particular MPEG multiplex. The EIT is used for transmitting
information associated with all events occurring in the MPEG
multiplex. The EIT includes information on the current transmission
and also includes information selectively containing different
transmission streams that may be received by the IRD. And, the TDT
is used for updating the clock included in the IRD.
Furthermore, three selective SI tables (i.e., a bouquet associate
table (BAT), a running status table (RST), and a stuffing table
(ST)) may also be included. More specifically, the bouquet
associate table (BAT) provides a service grouping method enabling
the IRD to provide services to the viewers. Each specific service
may belong to at least one `bouquet` unit. A running status table
(RST) section is used for promptly and instantly updating at least
one event execution status. The execution status section is
transmitted only once at the changing point of the event status.
Other SI tables are generally transmitted several times. The
stuffing table (ST) may be used for replacing or discarding a
subsidiary table or the entire SI tables.
In the present invention, the enhanced data included in the payload
within the TS packet consist of a digital storage media-command and
control (DSM-CC) section format. However, the TS packet including
the data service data may correspond either to a packetized
elementary stream (PES) type or to a section type. More
specifically, either the PES type data service data configure the
TS packet, or the section type data service data configure the TS
packet. The TS packet configured of the section type data will be
given as the example of the present invention. At this point, the
data service data are includes in the digital storage media-command
and control (DSM-CC) section. Herein, the DSM-CC section is then
configured of a 188-byte unit TS packet.
Furthermore, the packet identification of the TS packet configuring
the DSM-CC section is included in a data service table (DST). When
transmitting the DST, `0x95` is assigned as the value of a stream
type field included in the service location descriptor of the PMT
or the VCT. More specifically, when the PMT or VCT stream_type
field value is `0x95`, the receiving system may acknowledge that
data broadcasting including enhanced data (i.e., the enhanced data)
is being received. At this point, the enhanced data may be
transmitted by a data carousel method. The data carousel method
corresponds to repeatedly transmitting identical data on a regular
basis.
At this point, according to the control of the data decoder 1010,
the demultiplexer 1003 performs section filtering, thereby
discarding repetitive sections and outputting only the
non-repetitive sections to the data decoder 1010. The demultiplexer
1003 may also output only the sections configuring desired tables
(e.g., VCT) to the data decoder 1010 by section filtering. Herein,
the VCT may include a specific descriptor for the enhanced data.
However, the present invention does not exclude the possibilities
of the enhanced data being included in other tables, such as the
PMT. The section filtering method may include a method of verifying
the PID of a table defined by the MGT, such as the VCT, prior to
performing the section filtering process. Alternatively, the
section filtering method may also include a method of directly
performing the section filtering process without verifying the MGT,
when the VCT includes a fixed PID (i.e., a base PID). At this
point, the demultiplexer 1003 performs the section filtering
process by referring to a table_id field, a version_number field, a
section_number field, etc.
As described above, the method of defining the PID of the VCT
broadly includes two different methods. Herein, the PID of the VCT
is a packet identifier required for identifying the VCT from other
tables. The first method consists of setting the PID of the VCT so
that it is dependent to the MGT. In this case, the receiving system
cannot directly verify the VCT among the many PSI and/or PSIP
tables. Instead, the receiving system must check the PID defined in
the MGT in order to read the VCT. Herein, the MGT defines the PID,
size, version number, and so on, of diverse tables. The second
method consists of setting the PID of the VCT so that the PID is
given a base PID value (or a fixed PID value), thereby being
independent from the MGT. In this case, unlike in the first method,
the VCT according to the present invention may be identified
without having to verify every single PID included in the MGT.
Evidently, an agreement on the base PID must be previously made
between the transmitting system and the receiving system.
Meanwhile, in the embodiment of the present invention, the
demultiplexer 1003 may output only an application information table
(AIT) to the data decoder 1010 by section filtering. The AIT
includes information on an application being operated in the
receiving system for the data service. The AIT may also be referred
to as an XAIT, and an AMT. Therefore, any table including
application information may correspond to the following
description. When the AIT is transmitted, a value of `0x05` may be
assigned to a stream_type field of the PMT. The AIT may include
application information, such as application name, application
version, application priority, application ID, application status
(i.e., auto-start, user-specific settings, kill, etc.), application
type (i.e., Java or HTML), position (or location) of stream
including application class and data files, application platform
directory, and location of application icon.
In the method for detecting application information for the data
service by using the AIT, component_tag, original_network_id,
transport_stream_id, and service_id fields may be used for
detecting the application information. The component_tag field
designates an elementary stream carrying a DSI of a corresponding
object carousel. The original_network_id field indicates a DVB-SI
original_network_id of the TS providing transport connection. The
transport_stream_id field indicates the MPEG TS of the TS providing
transport connection, and the service_id field indicates the DVB-SI
of the service providing transport connection. Information on a
specific channel may be obtained by using the original_network_id
field, the transport_stream_id field, and the service_id field. The
data service data, such as the application data, detected by using
the above-described method may be stored in the second memory 1011
by the data decoder 1010.
The data decoder 1010 parses the DSM-CC section configuring the
demultiplexed enhanced data. Then, the enhanced data corresponding
to the parsed result are stored as a database in the second memory
1011. The data decoder 1010 groups a plurality of sections having
the same table identification (table_id) so as to configure a
table, which is then parsed. Thereafter, the parsed result is
stored as a database in the second memory 1011. At this point, by
parsing data and/or sections, the data decoder 1010 reads all of
the remaining actual section data that are not section-filtered by
the demultiplexer 1003. Then, the data decoder 1010 stores the read
data to the second memory 1011. The second memory 1011 corresponds
to a table and data carousel database storing system information
parsed from tables and enhanced data parsed from the DSM-CC
section. Herein, a table_id field, a section_number field, and a
last_section_number field included in the table may be used to
indicate whether the corresponding table is configured of a single
section or a plurality of sections. For example, TS packets having
the PID of the VCT are grouped to form a section, and sections
having table identifiers allocated to the VCT are grouped to form
the VCT.
When the VCT is parsed, information on the virtual channel to which
enhanced data are transmitted may be obtained. The obtained
application identification information, service component
identification information, and service information corresponding
to the data service may either be stored in the second memory 1011
or be outputted to the data broadcasting application manager 1013.
In addition, reference may be made to the application
identification information, service component identification
information, and service information in order to decode the data
service data. Alternatively, such information may also prepare the
operation of the application program for the data service.
Furthermore, the data decoder 1010 controls the demultiplexing of
the system information table, which corresponds to the information
table associated with the channel and events. Thereafter, an A.V
PID list may be transmitted to the channel manager 1007.
The channel manager 1007 may refer to the channel map 1008 in order
to transmit a request for receiving system-related information data
to the data decoder 1010, thereby receiving the corresponding
result. In addition, the channel manager 1007 may also control the
channel tuning of the tuner 1001. Furthermore, the channel manager
1007 may directly control the demultiplexer 1003, so as to set up
the A/V PID, thereby controlling the audio decoder 1004 and the
video decoder 1005. The audio decoder 1004 and the video decoder
1005 may respectively decode and output the audio data and video
data demultiplexed from the main data packet. Alternatively, the
audio decoder 1004 and the video decoder 1005 may respectively
decode and output the audio data and video data demultiplexed from
the enhanced data packet. Meanwhile, when the enhanced data include
data service data, and also audio data and video data, it is
apparent that the audio data and video data demultiplexed by the
demultiplexer 1003 are respectively decoded by the audio decoder
1004 and the video decoder 1005. For example, an audio-coding
(AC)-3 decoding algorithm may be applied to the audio decoder 1004,
and a MPEG-2 decoding algorithm may be applied to the video decoder
1005.
Meanwhile, the native TV application manager 1006 operates a native
application program stored in the first memory 1009, thereby
performing general functions such as channel change. The native
application program refers to software stored in the receiving
system upon shipping of the product. More specifically, when a user
request (or command) is transmitted to the receiving system through
a user interface (UI), the native TV application manger 1006
displays the user request on a screen through a graphic user
interface (GUI), thereby responding to the user's request. The user
interface receives the user request through an input device, such
as a remote controller, a key pad, a jog controller, an a
touchscreen provided on the screen, and then outputs the received
user request to the native TV application manager 1006 and the data
broadcasting application manager 1013. Furthermore, the native TV
application manager 1006 controls the channel manager 1007, thereby
controlling channel-associated, such as the management of the
channel map 1008, and controlling the data decoder 1010. The native
TV application manager 1006 also controls the GUI of the overall
receiving system, thereby storing the user request and status of
the receiving system in the first memory 1009 and restoring the
stored information.
The channel manager 1007 controls the tuner 1001 and the data
decoder 1010, so as to managing the channel map 1008 so that it can
respond to the channel request made by the user. More specifically,
channel manager 1007 sends a request to the data decoder 1010 so
that the tables associated with the channels that are to be tuned
are parsed. The results of the parsed tables are reported to the
channel manager 1007 by the data decoder 1010. Thereafter, based on
the parsed results, the channel manager 1007 updates the channel
map 1008 and sets up a PID in the demultiplexer 1003 for
demultiplexing the tables associated with the data service data
from the enhanced data.
The system manager 1012 controls the booting of the receiving
system by turning the power on or off. Then, the system manager
1012 stores ROM images (including downloaded software images) in
the first memory 1009. More specifically, the first memory 1009
stores management programs such as operating system (OS) programs
required for managing the receiving system and also application
program executing data service functions. The application program
is a program processing the data service data stored in the second
memory 1011 so as to provide the user with the data service. If the
data service data are stored in the second memory 1011, the
corresponding data service data are processed by the
above-described application program or by other application
programs, thereby being provided to the user. The management
program and application program stored in the first memory 1009 may
be updated or corrected to a newly downloaded program. Furthermore,
the storage of the stored management program and application
program is maintained without being deleted even if the power of
the system is shut down. Therefore, when the power is supplied the
programs may be executed without having to be newly downloaded once
again.
The application program for providing data service according to the
present invention may either be initially stored in the first
memory 1009 upon the shipping of the receiving system, or be stored
in the first 1009 after being downloaded. The application program
for the data service (i.e., the data service providing application
program) stored in the first memory 1009 may also be deleted,
updated, and corrected. Furthermore, the data service providing
application program may be downloaded and executed along with the
data service data each time the data service data are being
received.
When a data service request is transmitted through the user
interface, the data broadcasting application manager 1013 operates
the corresponding application program stored in the first memory
1009 so as to process the requested data, thereby providing the
user with the requested data service. And, in order to provide such
data service, the data broadcasting application manager 1013
supports the graphic user interface (GUI). Herein, the data service
may be provided in the form of text (or short message service
(SMS)), voice message, still image, and moving image. The data
broadcasting application manager 1013 may be provided with a
platform for executing the application program stored in the first
memory 1009. The platform may be, for example, a Java virtual
machine for executing the Java program. Hereinafter, an example of
the data broadcasting application manager 1013 executing the data
service providing application program stored in the first memory
1009, so as to process the data service data stored in the second
memory 1011, thereby providing the user with the corresponding data
service will now be described in detail.
Assuming that the data service corresponds to a traffic information
service, the data service according to the present invention is
provided to the user of a receiving system that is not equipped
with an electronic map and/or a GPS system in the form of at least
one of a text (or short message service (SMS)), a voice message, a
graphic message, a still image, and a moving image. In this case,
is a GPS module is mounted on the receiving system shown in FIG.
13, the GPS module receives satellite signals transmitted from a
plurality of low earth orbit satellites and extracts the current
position (or location) information (e.g., longitude, latitude,
altitude), thereby outputting the extracted information to the data
broadcasting application manager 1013.
At this point, it is assumed that the electronic map including
information on each link and nod and other diverse graphic
information are stored in one of the second memory 1011, the first
memory 1009, and another memory that is not shown. More
specifically, according to the request made by the data
broadcasting application manager 1013, the data service data stored
in the second memory 1011 are read and inputted to the data
broadcasting application manager 1013. The data broadcasting
application manager 1013 translates (or deciphers) the data service
data read from the second memory 1011, thereby extracting the
necessary information according to the contents of the message
and/or a control signal.
FIG. 14 illustrates a block diagram showing the structure of a
digital broadcast (or television) receiving system according to
another embodiment of the present invention. Referring to FIG. 14,
the digital broadcast receiving system includes a tuner 2001, a
demodulating unit 2002, a demultiplexer 2003, a first descrambler
2004, an audio decoder 2005, a video decoder 2006, a second
descrambler 2007, an authentication unit 2008, a native TV
application manager 2009, a channel manager 2010, a channel map
2011, a first memory 2012, a data decoder 2013, a second memory
2014, a system manager 2015, a data broadcasting application
manager 2016, a storage controller 2017, a third memory 2018, and a
telecommunication module 2019. Herein, the third memory 2018 is a
mass storage device, such as a hard disk drive (HDD) or a memory
chip. Also, during the description of the digital broadcast (or
television or DTV) receiving system shown in FIG. 14, the
components that are identical to those of the digital broadcast
receiving system of FIG. 13 will be omitted for simplicity.
As described above, in order to provide services for preventing
illegal duplication (or copies) or illegal viewing of the enhanced
data and/or main data that are transmitted by using a broadcast
network, and to provide paid broadcast services, the transmitting
system may generally scramble and transmit the broadcast contents.
Therefore, the receiving system needs to descramble the scrambled
broadcast contents in order to provide the user with the proper
broadcast contents. Furthermore, the receiving system may generally
be processed with an authentication process with an authentication
means before the descrambling process. Hereinafter, the receiving
system including an authentication means and a descrambling means
according to an embodiment of the present invention will now be
described in detail.
According to the present invention, the receiving system may be
provided with a descrambling means receiving scrambled broadcasting
contents and an authentication means authenticating (or verifying)
whether the receiving system is entitled to receive the descrambled
contents. Hereinafter, the descrambling means will be referred to
as first and second descramblers 2004 and 2007, and the
authentication means will be referred to as an authentication unit
2008. Such naming of the corresponding components is merely
exemplary and is not limited to the terms suggested in the
description of the present invention. For example, the units may
also be referred to as a decryptor. Although FIG. 14 illustrates an
example of the descramblers 2004 and 2007 and the authentication
unit 2008 being provided inside the receiving system, each of the
descramblers 2004 and 2007 and the authentication unit 2008 may
also be separately provided in an internal or external module.
Herein, the module may include a slot type, such as a SD or CF
memory, a memory stick type, a USB type, and so on, and may be
detachably fixed to the receiving system.
As described above, when the authentication process is performed
successfully by the authentication unit 2008, the scrambled
broadcasting contents are descrambled by the descramblers 2004 and
2007, thereby being provided to the user. At this point, a variety
of the authentication method and descrambling method may be used
herein. However, an agreement on each corresponding method should
be made between the receiving system and the transmitting system.
Hereinafter, the authentication and descrambling methods will now
be described, and the description of identical components or
process steps will be omitted for simplicity.
The receiving system including the authentication unit 2008 and the
descramblers 2004 and 2007 will now be described in detail. The
receiving system receives the scrambled broadcasting contents
through the tuner 2001 and the demodulating unit 2002. Then, the
system manager 2015 decides whether the received broadcasting
contents have been scrambled. Herein, the demodulating unit 2002
may be included as a demodulating unit according to embodiments of
the present invention as described in FIG. 9. However, the present
invention is not limited to the examples given in the description
set forth herein. If the system manager 2015 decides that the
received broadcasting contents have been scrambled, then the system
manager 2015 controls the system to operate the authentication unit
2008. As described above, the authentication unit 2008 performs an
authentication process in order to decide whether the receiving
system according to the present invention corresponds to a
legitimate host entitled to receive the paid broadcasting service.
Herein, the authentication process may vary in accordance with the
authentication methods.
For example, the authentication unit 2008 may perform the
authentication process by comparing an IP address of an IP datagram
within the received broadcasting contents with a specific address
of a corresponding host. At this point, the specific address of the
corresponding receiving system (or host) may be a MAC address. More
specifically, the authentication unit 2008 may extract the IP
address from the decapsulated IP datagram, thereby obtaining the
receiving system information that is mapped with the IP address. At
this point, the receiving system should be provided, in advance,
with information (e.g., a table format) that can map the IP address
and the receiving system information. Accordingly, the
authentication unit 2008 performs the authentication process by
determining the conformity between the address of the corresponding
receiving system and the system information of the receiving system
that is mapped with the IP address. In other words, if the
authentication unit 2008 determines that the two types of
information conform to one another, then the authentication unit
2008 determines that the receiving system is entitled to receive
the corresponding broadcasting contents.
In another example, standardized identification information is
defined in advance by the receiving system and the transmitting
system. Then, the identification information of the receiving
system requesting the paid broadcasting service is transmitted by
the transmitting system. Thereafter, the receiving system
determines whether the received identification information conforms
with its own unique identification number, so as to perform the
authentication process. More specifically, the transmitting system
creates a database for storing the identification information (or
number) of the receiving system requesting the paid broadcasting
service. Then, if the corresponding broadcasting contents are
scrambled, the transmitting system includes the identification
information in the EMM, which is then transmitted to the receiving
system.
If the corresponding broadcasting contents are scrambled, messages
(e.g., entitlement control message (ECM), entitlement management
message (EMM)), such as the CAS information, mode information,
message position information, that are applied to the scrambling of
the broadcasting contents are transmitted through a corresponding
data header or anther data packet. The ECM may include a control
word (CW) used for scrambling the broadcasting contents. At this
point, the control word may be encoded with an authentication key.
The EMM may include an authentication key and entitlement
information of the corresponding data. Herein, the authentication
key may be encoded with a receiving system-specific distribution
key. In other words, assuming that the enhanced data are scrambled
by using the control word, and that the authentication information
and the descrambling information are transmitted from the
transmitting system, the transmitting system encodes the CW with
the authentication key and, then, includes the encoded CW in the
entitlement control message (ECM), which is then transmitted to the
receiving system. Furthermore, the transmitting system includes the
authentication key used for encoding the CW and the entitlement to
receive data (or services) of the receiving system (i.e., a
standardized serial number of the receiving system that is entitled
to receive the corresponding broadcasting service or data) in the
entitlement management message (EMM), which is then transmitted to
the receiving system.
Accordingly, the authentication unit 2008 of the receiving system
extracts the identification information of the receiving system and
the identification information included in the EMM of the
broadcasting service that is being received. Then, the
authentication unit 2008 determines whether the identification
information conform to each other, so as to perform the
authentication process. More specifically, if the authentication
unit 2008 determines that the information conform to each other,
then the authentication unit 2008 eventually determines that the
receiving system is entitled to receive the request broadcasting
service.
In yet another example, the authentication unit 2008 of the
receiving system may be detachably fixed to an external module. In
this case, the receiving system is interfaced with the external
module through a common interface (CI). In other words, the
external module may receive the data scrambled by the receiving
system through the common interface, thereby performing the
descrambling process of the received data. Alternatively, the
external module may also transmit only the information required for
the descrambling process to the receiving system. The common
interface is configured on a physical layer and at least one
protocol layer. Herein, in consideration of any possible expansion
of the protocol layer in a later process, the corresponding
protocol layer may be configured to have at least one layer that
can each provide an independent function.
The external module may either consist of a memory or card having
information on the key used for the scrambling process and other
authentication information but not including any descrambling
function, or consist of a card having the above-mentioned key
information and authentication information and including the
descrambling function. Both the receiving system and the external
module should be authenticated in order to provide the user with
the paid broadcasting service provided (or transmitted) from the
transmitting system. Therefore, the transmitting system can only
provide the corresponding paid broadcasting service to the
authenticated pair of receiving system and external module.
Additionally, an authentication process should also be performed
between the receiving system and the external module through the
common interface. More specifically, the module may communicate
with the system manager 2015 included in the receiving system
through the common interface, thereby authenticating the receiving
system. Alternatively, the receiving system may authenticate the
module through the common interface. Furthermore, during the
authentication process, the module may extract the unique ID of the
receiving system and its own unique ID and transmit the extracted
IDs to the transmitting system. Thus, the transmitting system may
use the transmitted ID values as information determining whether to
start the requested service or as payment information. Whenever
necessary, the system manager 2015 transmits the payment
information to the remote transmitting system through the
telecommunication module 2019.
The authentication unit 2008 authenticates the corresponding
receiving system and/or the external module. Then, if the
authentication process is successfully completed, the
authentication unit 2008 certifies the corresponding receiving
system and/or the external module as a legitimate system and/or
module entitled to receive the requested paid broadcasting service.
In addition, the authentication unit 2008 may also receive
authentication-associated information from a mobile
telecommunications service provider to which the user of the
receiving system is subscribed, instead of the transmitting system
providing the requested broadcasting service. In this case, the
authentication-association information may either be scrambled by
the transmitting system providing the broadcasting service and,
then, transmitted to the user through the mobile telecommunications
service provider, or be directly scrambled and transmitted by the
mobile telecommunications service provider. Once the authentication
process is successfully completed by the authentication unit 2008,
the receiving system may descramble the scrambled broadcasting
contents received from the transmitting system. At this point, the
descrambling process is performed by the first and second
descramblers 2004 and 2007. Herein, the first and second
descramblers 2004 and 2007 may be included in an internal module or
an external module of the receiving system.
The receiving system is also provided with a common interface for
communicating with the external module including the first and
second descramblers 2004 and 2007, so as to perform the
descrambling process. More specifically, the first and second
descramblers 2004 and 2007 may be included in the module or in the
receiving system in the form of hardware, middleware or software.
Herein, the descramblers 2004 and 2007 may be included in any one
of or both of the module and the receiving system. If the first and
second descramblers 2004 and 2007 are provided inside the receiving
system, it is advantageous to have the transmitting system (i.e.,
at least any one of a service provider and a broadcast station)
scramble the corresponding data using the same scrambling
method.
Alternatively, if the first and second descramblers 2004 and 2007
are provided in the external module, it is advantageous to have
each transmitting system scramble the corresponding data using
different scrambling methods. In this case, the receiving system is
not required to be provided with the descrambling algorithm
corresponding to each transmitting system. Therefore, the structure
and size of receiving system may be simplified and more compact.
Accordingly, in this case, the external module itself may be able
to provide CA functions, which are uniquely and only provided by
each transmitting systems, and functions related to each service
that is to be provided to the user. The common interface enables
the various external modules and the system manager 2015, which is
included in the receiving system, to communicate with one another
by a single communication method. Furthermore, since the receiving
system may be operated by being connected with at least one or more
modules providing different services, the receiving system may be
connected to a plurality of modules and controllers.
In order to maintain successful communication between the receiving
system and the external module, the common interface protocol
includes a function of periodically checking the status of the
opposite correspondent. By using this function, the receiving
system and the external module is capable of managing the status of
each opposite correspondent. This function also reports the user or
the transmitting system of any malfunction that may occur in any
one of the receiving system and the external module and attempts
the recovery of the malfunction.
In yet another example, the authentication process may be performed
through software. More specifically, when a memory card having CAS
software downloaded, for example, and stored therein in advanced is
inserted in the receiving system, the receiving system receives and
loads the CAS software from the memory card so as to perform the
authentication process. In this example, the CAS software is read
out from the memory card and stored in the first memory 2012 of the
receiving system. Thereafter, the CAS software is operated in the
receiving system as an application program. According to an
embodiment of the present invention, the CAS software is mounted on
(or stored) in a middleware platform and, then executed. A Java
middleware will be given as an example of the middleware included
in the present invention. Herein, the CAS software should at least
include information required for the authentication process and
also information required for the descrambling process.
Therefore, the authentication unit 2008 performs authentication
processes between the transmitting system and the receiving system
and also between the receiving system and the memory card. At this
point, as described above, the memory card should be entitled to
receive the corresponding data and should include information on a
normal receiving system that can be authenticated. For example,
information on the receiving system may include a unique number,
such as a standardized serial number of the corresponding receiving
system. Accordingly, the authentication unit 2008 compares the
standardized serial number included in the memory card with the
unique information of the receiving system, thereby performing the
authentication process between the receiving system and the memory
card.
If the CAS software is first executed in the Java middleware base,
then the authentication between the receiving system and the memory
card is performed. For example, when the unique number of the
receiving system stored in the memory card conforms to the unique
number of the receiving system read from the system manager 2015,
then the memory card is verified and determined to be a normal
memory card that may be used in the receiving system. At this
point, the CAS software may either be installed in the first memory
2012 upon the shipping of the present invention, or be downloaded
to the first memory 2012 from the transmitting system or the module
or memory card, as described above. Herein, the descrambling
function may be operated by the data broadcasting application
manger 2016 as an application program.
Thereafter, the CAS software parses the EMM/ECM packets outputted
from the demultiplexer 2003, so as to verify whether the receiving
system is entitled to receive the corresponding data, thereby
obtaining the information required for descrambling (i.e., the CW)
and providing the obtained CW to the descramblers 2004 and 2007.
More specifically, the CAS software operating in the Java
middleware platform first reads out the unique (or serial) number
of the receiving system from the corresponding receiving system and
compares it with the unique number of the receiving system
transmitted through the EMM, thereby verifying whether the
receiving system is entitled to receive the corresponding data.
Once the receiving entitlement of the receiving system is verified,
the corresponding broadcasting service information transmitted to
the ECM and the entitlement of receiving the corresponding
broadcasting service are used to verify whether the receiving
system is entitled to receive the corresponding broadcasting
service. Once the receiving system is verified to be entitled to
receive the corresponding broadcasting service, the authentication
key transmitted to the EMM is used to decode (or decipher) the
encoded CW, which is transmitted to the ECM, thereby transmitting
the decoded CW to the descramblers 2004 and 2007. Each of the
descramblers 2004 and 2007 uses the CW to descramble the
broadcasting service.
Meanwhile, the CAS software stored in the memory card may be
expanded in accordance with the paid service which the broadcast
station is to provide. Additionally, the CAS software may also
include other additional information other than the information
associated with the authentication and descrambling. Furthermore,
the receiving system may download the CAS software from the
transmitting system so as to upgrade (or update) the CAS software
originally stored in the memory card. As described above,
regardless of the type of broadcast receiving system, as long as an
external memory interface is provided, the present invention may
embody a CAS system that can meet the requirements of all types of
memory card that may be detachably fixed to the receiving system.
Thus, the present invention may realize maximum performance of the
receiving system with minimum fabrication cost, wherein the
receiving system may receive paid broadcasting contents such as
broadcast programs, thereby acknowledging and regarding the variety
of the receiving system. Moreover, since only the minimum
application program interface is required to be embodied in the
embodiment of the present invention, the fabrication cost may be
minimized, thereby eliminating the manufacturer's dependence on CAS
manufacturers. Accordingly, fabrication costs of CAS equipments and
management systems may also be minimized.
Meanwhile, the descramblers 2004 and 2007 may be included in the
module either in the form of hardware or in the form of software.
In this case, the scrambled data that being received are
descrambled by the module and then demodulated. Also, if the
scrambled data that are being received are stored in the third
memory 2018, the received data may be descrambled and then stored,
or stored in the memory at the point of being received and then
descrambled later on prior to being played (or reproduced).
Thereafter, in case scramble/descramble algorithms are provided in
the storage controller 2017, the storage controller 2017 scrambles
the data that are being received once again and then stores the
re-scrambled data to the third memory 2018.
In yet another example, the descrambled broadcasting contents
(transmission of which being restricted) are transmitted through
the broadcasting network. Also, information associated with the
authentication and descrambling of data in order to disable the
receiving restrictions of the corresponding data are transmitted
and/or received through the telecommunications module 2019. Thus,
the receiving system is able to perform reciprocal (or two-way)
communication. The receiving system may either transmit data to the
telecommunication module within the transmitting system or be
provided with the data from the telecommunication module within the
transmitting system. Herein, the data correspond to broadcasting
data that are desired to be transmitted to or from the transmitting
system, and also unique information (i.e., identification
information) such as a serial number of the receiving system or MAC
address.
The telecommunication module 2019 included in the receiving system
provides a protocol required for performing reciprocal (or two-way)
communication between the receiving system, which does not support
the reciprocal communication function, and the telecommunication
module included in the transmitting system. Furthermore, the
receiving system configures a protocol data unit (PDU) using a
tag-length-value (TLV) coding method including the data that are to
be transmitted and the unique information (or ID information).
Herein, the tag field includes indexing of the corresponding PDU.
The length field includes the length of the value field. And, the
value field includes the actual data that are to be transmitted and
the unique number (e.g., identification number) of the receiving
system.
The receiving system may configure a platform that is equipped with
the Java platform and that is operated after downloading the Java
application of the transmitting system to the receiving system
through the network. In this case, a structure of downloading the
PDU including the tag field arbitrarily defined by the transmitting
system from a storage means included in the receiving system and
then transmitting the downloaded PDU to the telecommunication
module 2019 may also be configured. Also, the PDU may be configured
in the Java application of the receiving system and then outputted
to the telecommunication module 2019. The PDU may also be
configured by transmitting the tag value, the actual data that are
to be transmitted, the unique information of the corresponding
receiving system from the Java application and by performing the
TLV coding process in the receiving system. This structure is
advantageous in that the firmware of the receiving system is not
required to be changed even if the data (or application) desired by
the transmitting system is added.
The telecommunication module within the transmitting system either
transmits the PDU received from the receiving system through a
wireless data network or configures the data received through the
network into a PDU which is transmitted to the host. At this point,
when configuring the PDU that is to be transmitted to the host, the
telecommunication module within the transmitting end may include
unique information (e.g., IP address) of the transmitting system
which is located in a remote location. Additionally, in receiving
and transmitting data through the wireless data network, the
receiving system may be provided with a common interface, and also
provided with a WAP, CDMA 1.times. EV-DO, which can be connected
through a mobile telecommunication base station, such as CDMA and
GSM, and also provided with a wireless LAN, mobile internet, WiBro,
WiMax, which can be connected through an access point. The
above-described receiving system corresponds to the system that is
not equipped with a telecommunication function. However, a
receiving system equipped with telecommunication function does not
require the telecommunication module 2019.
The broadcasting data being transmitted and received through the
above-described wireless data network may include data required for
performing the function of limiting data reception. Meanwhile, the
demultiplexer 2003 receives either the real-time data outputted
from the demodulating unit 2002 or the data read from the third
memory 2018, thereby performing demultiplexing. In this embodiment
of the present invention, the demultiplexer 2003 performs
demultiplexing on the enhanced data packet. Similar process steps
have already been described earlier in the description of the
present invention. Therefore, a detailed of the process of
demultiplexing the enhanced data will be omitted for
simplicity.
The first descrambler 2004 receives the demultiplexed signals from
the demultiplexer 2003 and then descrambles the received signals.
At this point, the first descrambler 2004 may receive the
authentication result received from the authentication unit 2008
and other data required for the descrambling process, so as to
perform the descrambling process. The audio decoder 2005 and the
video decoder 2006 receive the signals descrambled by the first
descrambler 2004, which are then decoded and outputted.
Alternatively, if the first descrambler 2004 did not perform the
descrambling process, then the audio decoder 2005 and the video
decoder 2006 directly decode and output the received signals. In
this case, the decoded signals are received and then descrambled by
the second descrambler 2007 and processed accordingly.
As described above, the digital broadcasting systems and methods of
processing broadcast data according to the present invention have
the following advantages. More specifically, the digital
broadcasting receiving system and method of processing broadcast
data according to the present invention is highly protected against
(or resistant to) any error that may occur when transmitting
supplemental data through a channel. And, the present invention is
also highly compatible to the conventional receiving system.
Moreover, the present invention may also receive the supplemental
data without any error even in channels having severe ghost effect
and noise.
Additionally, when a known data sequence is inputted to a trellis
encoder, by having the transmitting system initialize a memory
within the trellis encoder and trellis-encode the inputted data,
thereby outputted the processed data, and by having the receiving
system estimate known data information, which is to be used for
frequency synchronization, symbol timing synchronization, frame
synchronization, and channel equalization, the receiving
performance of the receiving system may be enhanced in a situation
undergoing severe and frequent channel changes. Furthermore, 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.
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