U.S. patent number RE46,312 [Application Number 14/514,141] was granted by the patent office on 2017-02-14 for transmitting/receiving system and method of processing broadcast signal in transmitting/receiving system.
This patent grant is currently assigned to LG ELECTRONICS INC.. The grantee listed for this patent is LG ELECTRONICS INC.. Invention is credited to In Hwan Choi, Byoung Gill Kim, Jin Woo Kim, Hyoung Gon Lee, Won Gyu Song.
United States Patent |
RE46,312 |
Lee , et al. |
February 14, 2017 |
Transmitting/receiving system and method of processing broadcast
signal in transmitting/receiving system
Abstract
An apparatus and method for transmitting digital broadcast
signal are provided. The apparatus includes a group formatter to
format a data group including mobile service data, where the group
formatter further maps the mobile service data into a data group of
interleaved format, adds N training sequences into a corresponding
location of the data group of interleaved format, adds signaling
data into the data group of interleaved format, inserts place
holder bytes for MPEG header and non-systematic Reed-Solomon (RS)
parity into the data group of interleaved format, and deinterleaves
the mobile service data in the data group of interleaved format, a
non-systematic RS encoder to non-systematic RS encode the mobile
service data in the formatted data group and insert non-systematic
RS parity obtained from the non-systematic RS encoding into the
formatted data group.
Inventors: |
Lee; Hyoung Gon (Seoul,
KR), Kim; Byoung Gill (Seoul, KR), Song;
Won Gyu (Seoul, KR), Choi; In Hwan (Gwacheon-si,
KR), Kim; Jin Woo (Seoul, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG ELECTRONICS INC. (Seoul,
KR)
|
Family
ID: |
42222789 |
Appl.
No.: |
14/514,141 |
Filed: |
October 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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12613918 |
Feb 21, 2012 |
8121232 |
|
|
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61111733 |
Nov 6, 2008 |
|
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61112192 |
Nov 7, 2008 |
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Reissue of: |
13350685 |
Jan 13, 2012 |
8494083 |
Jul 23, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
1/005 (20130101); H04L 25/0212 (20130101); H04L
1/0071 (20130101); H04L 1/0041 (20130101); H04L
25/067 (20130101); H04L 27/06 (20130101); H04L
25/03019 (20130101); H04L 25/0234 (20130101); H04L
1/007 (20130101); H04L 1/0041 (20130101); H04L
1/0005 (20130101); H04L 1/006 (20130101); H04L
25/0212 (20130101); H04L 1/0057 (20130101); H04L
25/0234 (20130101); H04L 25/067 (20130101); H04L
1/0071 (20130101); H04L 25/03019 (20130101); H04L
1/0065 (20130101); H04L 25/0226 (20130101); H04L
27/06 (20130101); H04L 1/007 (20130101); H04L
1/0065 (20130101); H04L 1/0057 (20130101); H04L
25/0226 (20130101); H04L 1/006 (20130101); H04L
25/0242 (20130101); H04L 2025/03382 (20130101); H04L
25/03159 (20130101); H04L 2027/0095 (20130101); H04L
25/03203 (20130101); H04L 25/03159 (20130101); H04L
25/03203 (20130101); H04L 25/0242 (20130101); H04L
2025/03382 (20130101); H04L 2027/0095 (20130101) |
Current International
Class: |
H04L
27/04 (20060101); H04L 25/03 (20060101); H04L
27/06 (20060101); H04L 25/06 (20060101); H04L
1/00 (20060101); H04L 25/02 (20060101); H04L
27/12 (20060101); H04L 27/20 (20060101); H04L
27/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Ge; Yuzhen
Attorney, Agent or Firm: Lee, Hong, Degerman, Kang &
Waimey
Parent Case Text
This application .Iadd.is a reissue application of U.S. Pat. No.
8,494,083 B2, issued from U.S. application Ser. No. 13/350,685,
filed Jan. 13, 2012, which .Iaddend.is a continuation of U.S.
application Ser. No. 12/613,918, filed Nov. 6, 2009, now U.S. Pat.
No. 8,121,232, which pursuant to 35 U.S.C. .sctn.119(a) claims the
benefit of U.S. Provisional Application No. 61/111,733, filed on
Nov. 6, 2008, and U.S. Provisional Application No. 61/112,192,
filed on Nov. 7, 2008, the contents of all of which are hereby
incorporated by reference .[.as if fully set forth.]. herein
.Iadd.in their entireties.Iaddend..
.Iadd.More than one reissue application has been filed for the
reissue of U.S. Pat. No. 8,494,083 B2. The other reissue
application is U.S. application Ser. No. 14/552,126, filed Nov. 24,
2014 which is a continuation of reissue application Ser. No.
14/514,141, filed Oct. 14, 2014, which is a reissue application of
U.S. application Ser. No. 13/350,685, filed Jan. 13, 2012, which is
a continuation of U.S. application Ser. No. 12/613,918, filed on
Nov. 6, 2009, now U.S. Pat. No. 8,121,232, which pursuant to 35
U.S.C. .sctn.119(a) claims the benefit of U.S. Provisional
Application No. 61/111,733, filed on Nov. 6, 2008, and U.S.
Provisional Application No. 61/112,192, filed on Nov. 7, 2008.
.Iaddend.
Claims
The invention claimed is:
1. A method for processing a digital broadcast signal at a
transmitter, the method comprising: formatting .[.the.]. .Iadd.a
.Iaddend.data group including mobile service data, wherein
formatting the data group comprises: mapping the mobile service
data into .[.a.]. .Iadd.the .Iaddend.data group; adding training
sequences into corresponding locations of the data group, wherein
at least 5 of the training sequences are spaced M segments apart in
the data group, wherein at least 1 of the training sequences is
inserted between a first training sequence and a second training
sequence of the at least 5 training sequences, and wherein M is an
integer; adding signaling data into the data group, wherein the
signaling data are added .[.between.]. .Iadd.following .Iaddend.the
first training sequence of the at least 5 training sequences .[.and
the at least 1 of the training sequences.].; inserting place holder
bytes for MPEG header and non-systematic Reed-Solomon (RS) parity
into the data group; and deinterleaving data in the data group;
non-systematic RS encoding the mobile service data in the formatted
data group to insert the non-systematic RS parity into locations
where the place holder bytes for the non-systematic RS parity were
inserted in the formatted data group; and transmitting .[.a.].
.Iadd.the .Iaddend.digital broadcast signal including the
non-systematic RS-encoded mobile service data.
2. The method of claim 1, further comprising: Interleaving the
non-systematic RS encoded mobile service data.
3. The method of claim 1, wherein: the at least 1 of the training
sequences in the .[.digital broadcast signal.]. .Iadd.data group
.Iaddend.has a first K-symbol sequence and a second L-symbol
sequence; K is identical to L; and the first K-symbol sequence and
the second L-symbol sequence have a same data pattern.
4. The method of claim 1, wherein the at least 5 of the training
sequences in the .[.digital broadcast signal.]. .Iadd.data group
.Iaddend.have a same data pattern in common.
.[.5. An apparatus for transmitting a digital broadcast signal, the
apparatus comprising: a group formatter configured to format a data
group including mobile service data, wherein the group formatter is
further configured to: map the mobile service data into a data
group; add N training sequences into corresponding locations of the
data group, wherein at least 5 of the training sequences are spaced
M segments apart in the data group, wherein at least 1 of the
training sequences is inserted between a first training sequence
and a second training sequence of the at least 5 training
sequences, and wherein M is an integer; add signaling data into the
data group, wherein the signaling data are added between the first
training sequence of the at least 5 training sequences and the at
least 1 of the training sequences; insert place holder bytes for
MPEG header and non-systematic Reed-Solomon (RS) parity into the
data group; and deinterleave data in the data group; a
non-systematic RS encoder configured to non-systematic RS encode
the mobile service data in the formatted data group and to insert
the non-systematic RS parity into locations where the place holder
bytes for the non-systematic RS parity were inserted in the
formatted data group; and a transmission unit configured to
transmit a digital broadcast signal including the non-systematic
RS-encoded mobile service data..].
.[.6. The apparatus of claim 5, further comprising: a data
interleaver configured to Interleave the non-systematic RS encoded
mobile service data..].
.[.7. The apparatus of claim 5, wherein: the at least 1 of the
training sequences in the digital broadcast signal has a first
K-symbol sequence and a second L-symbol sequence; K is identical to
L; and the first K-symbol sequence and the second L-symbol sequence
have a same data pattern..].
.[.8. The apparatus of claim 5, wherein the at least 5 of the
training sequences in the digital broadcast signal have a same data
pattern in common..].
.Iadd.9. The method of claim 1, further comprising randomizing the
mobile service data. .Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital broadcasting system for
transmitting and receiving digital broadcast signal, and more
particularly, to a transmitting system for processing and
transmitting digital broadcast signal, and a receiving system for
receiving and processing digital broadcast signal and, a method of
processing data in the transmitting system and the receiving
system.
2. Discussion of the Related Art
The Vestigial Sideband (VSB) transmission mode, which is adopted as
the standard for digital broadcasting in North America and the
Republic of Korea, is a system using a single carrier method.
Therefore, the receiving performance of the digital broadcast
receiving system may be deteriorated in a poor channel environment.
Particularly, since resistance to changes in channels and noise is
more highly required when using portable and/or mobile broadcast
receivers, the receiving performance may be even more deteriorated
when transmitting mobile service data by the VSB transmission
mode.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a transmitting
system and a receiving system and a method of processing broadcast
signal 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 transmitting
system and a receiving system and a method of processing broadcast
signal that are highly resistant to channel changes and noise.
Another object of the present invention is to provide a
transmitting system and a receiving system and a method of
processing broadcast signal that can enhance the receiving
performance of the receiving system by performing additional
encoding on mobile service data and by transmitting the processed
data to the receiving system.
A further object of the present invention is to provide a
transmitting system and a receiving system and a method of
processing broadcast signal that can also enhance the receiving
performance of the receiving system by inserting known data already
known in accordance with a pre-agreement between the receiving
system and the transmitting system in a predetermined region within
a data region.
A further object of the present invention is to provide a
transmitting system and a receiving system and a method of
processing broadcast signal that can enhanced the receiving
performance of the receiving system, by using the known data so as
to perform channel equalization, therein the known data are
inserted in a data region and then received.
Another object of the present invention is to provide a receiving
system and method for processing a broadcast signal that can
enhance channel-equalizing performance by estimating a channel
impulse response (CIR) of a general data section located between
training sections using cubic spline interpolation, in performing
channel-equalization using training sequences that are inserted in
data regions and received accordingly.
A further object of the present invention is to provide a receiving
system and method for processing a broadcast signal that can
enhance channel-equalizing performance by estimating a channel
impulse response (CIR) of a general data section located outside of
the training sections using extrapolation, in performing
channel-equalization using training sequences that are inserted in
data regions and received accordingly.
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 broadcast transmitting system may
include a service multiplexer and a transmitter. The service
multiplexer may multiplex mobile service data and main service data
at a predetermined data rate and may transmit the multiplexed data
to the transmitter. The transmitter may perform additional encoding
on the mobile service data being transmitted from the service
multiplexer. The transmitter may also group a plurality of
additionally encoded mobile service data packets so as to form a
data group. The transmitter may multiplex mobile service data
packets including mobile service data and main service data packets
including main service data and may transmit the multiplexed data
packets to a receiving system.
Herein, the data group may be divided into a plurality of regions
depending upon a degree of interference of the main service data.
Also, a long known data sequence may be periodically inserted in
regions without interference of the main service data. Also, a
receiving system according to an embodiment of the present
invention may be used for demodulating and channel equalizing the
known data sequence.
In another aspect of the present invention, a receiving system
includes a signal receiving unit, a detector, a channel equalizer,
a block decoder, and an error correction unit. The signal receiving
unit receives a broadcast signal including mobile service data and
a data group including N number of training sequences. The detector
detects N number of training sequences from the broadcast signal
(wherein N.gtoreq.5), wherein the detected N number of training
sequences are received during N number of training sections. The
equalizer estimates a channel impulse response (CIR) of N number of
training sections, based upon the detected N number of training
sequences, applies the channel impulse response estimated in M
number of training sections (wherein N.gtoreq.M) to a cubic spline
interpolation function, so as to generate a channel impulse
response of (N-1) number of mobile service data sections located
between the N number of training sections, thereby performing
channel-equalization on the mobile service data of the
corresponding mobile service data section. The block decoder
performs turbo-decoding in block units on the channel-equalized
mobile service data. And, the error correction unit performs error
correction decoding on the turbo-decoded mobile service data,
thereby correcting errors occurring in the mobile service data.
Herein, each of the N number of training sequences may be located
at constant intervals within the data group. The data group that is
being received may correspond to one of a data group including
field synchronization data and a data group not including any field
synchronization data. More specifically, in the data group
including field synchronization data, N may be equal to 6, and 6
training sequences may correspond to 1 field synchronization data
sequence and 5 known data sequences. And, in data group not
including any field synchronization data, N may be equal to 5, and
5 training sequences may correspond to 5 known data sequences.
The equalizer may apply channel impulse responses (CIRs) estimated
in 5 training sections to each cubic spline interpolation function
of (N-1) number of mobile service data sections, so as to generate
a CIR for each mobile service data section.
When the mobile service data are not located between training
sections, the equalizer may generate a CIR of an extrapolation
section including the mobile service data by applying channel
impulse responses (CIRs) estimated in at least 2 training sections
to an extrapolation function, and may perform channel-equalization
on the mobile service data of the extrapolation section. Herein,
the equalizer may compensate a power of a CIR of the extrapolation
section, so that a proportional relation between a power of a
signal and the compensated power of the CIR both measured in the
extrapolation section can become identical to a proportional
relation between a power of a signal and a power of a CIR both
measured in at least one training section.
In a further aspect of the present invention, a broadcast signal
processing method in a digital broadcast receiving system includes
the steps of receiving a broadcast signal including mobile service
data and a data group including N number of training sequences,
detecting N number of training sequences from the broadcast signal
(wherein N.gtoreq.5), the detected N number of training sequences
being received during N number of training sections, estimating a
channel impulse response (CIR) of N number of training sections,
based upon the detected N number of training sequences, applying
the channel impulse response estimated in M number of training
sections (wherein N.gtoreq.M) to a cubic spline interpolation
function, so as to generate a channel impulse response of (N-1)
number of mobile service data sections located between the N number
of training sections, thereby performing channel-equalization on
the mobile service data of the corresponding mobile service data
section, performing turbo-decoding in block units on the
channel-equalized mobile service data, and performing error
correction decoding on the turbo-decoded mobile service data,
thereby correcting errors occurring in the mobile service data.
It is to be understood that both the foregoing general description
and the following detailed description of the present invention are
exemplary and explanatory and are intended to provide further
explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
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 structure of a M/H frame for transmitting and
receiving mobile service data according to the present
invention;
FIG. 2 illustrates an exemplary structure of a VSB frame;
FIG. 3 illustrates a mapping example of the positions to which the
first 4 slots of a sub-frame are assigned with respect to a VSB
frame in a space region;
FIG. 4 illustrates a mapping example of the positions to which the
first 4 slots of a sub-frame are assigned with respect to a VSB
frame in a time region;
FIG. 5 illustrates an alignment of data after being data
interleaved and identified;
FIG. 6 illustrates an enlarged portion of the data group shown in
FIG. 5 for a better understanding of the present invention;
FIG. 7 illustrates an alignment of data before being data
interleaved and identified;
FIG. 8 illustrates an enlarged portion of the data group shown in
FIG. 7 for a better understanding of the present invention;
FIG. 9 illustrates an exemplary assignment order of data groups
being assigned to one of 5 sub-frames according to the present
invention;
FIG. 10 illustrates an example of assigning a single parade to an
M/H frame according to the present invention;
FIG. 11 illustrates an example of assigning 3 parades to an M/H
frame according to the present invention;
FIG. 12 illustrates an example of expanding the assignment process
of 3 parades to 5 sub-frames within an M/H frame;
FIG. 13 illustrates a data transmission structure according to an
embodiment of the present invention, wherein signaling data are
included in a data group so as to be transmitted;
FIG. 14 illustrates a block diagram showing a general structure of
a transmitting system according to an embodiment of the present
invention;
FIG. 15 is a diagram illustrating an example of RS frame according
to the present invention;
FIG. 16 is a diagram illustrating a structure of an M/H header
within an M/H service data packet according to the present
invention;
FIG. 17(a) and FIG. 17(b) are diagrams illustrating another example
of RS frame according to the present invention; and
FIG. 18 illustrates a block diagram showing an example of a service
multiplexer of FIG. 14;
FIG. 19 illustrates a block diagram showing an embodiment of a
transmitter of FIG. 14;
FIG. 20 illustrates a block diagram showing an example of a
pre-processor of FIG. 19;
FIG. 21 illustrates a conceptual block diagram of the M/H frame
encoder of FIG. 20;
FIG. 22 illustrates a detailed block diagram of an RS frame encoder
of FIG. 21;
FIG. 23(a) and FIG. 23(b) illustrate a process of one or two RS
frame being divided into several portions, based upon an RS frame
mode value, and a process of each portion being assigned to a
corresponding region within the respective data group;
FIG. 24(a) to FIG. 24(c) illustrate error correction encoding and
error detection encoding processes according to an embodiment of
the present invention;
FIG. 25(a) to FIG. 25(d) illustrate an example of performing a row
permutation (or interleaving) process in super frame units
according to the present invention;
FIG. 26(a) and FIG. 26(b) illustrate an example which a parade
consists of two RS frames
FIG. 27(a) and FIG. 27(b) illustrate an exemplary process of
dividing an RS frame for configuring a data group according to the
present invention;
FIG. 28 illustrates a block diagram of a block processor according
to an embodiment of the present invention;
FIG. 29 illustrates a detailed block diagram of a convolution
encoder of the block processor;
FIG. 30 illustrates a symbol interleaver of the block
processor;
FIG. 31 illustrates a block diagram of a group formatter according
to an embodiment of the present invention;
FIG. 32 illustrates a block diagram of a trellis encoder according
to an embodiment of the present invention;
FIG. 33 illustrates an example of assigning signaling information
area according to an embodiment of the present invention;
FIG. 34 illustrates a detailed block diagram of a signaling encoder
according to the present invention;
FIG. 35 illustrates an example of a syntax structure of TPC data
according to the present invention;
FIG. 36 illustrates an example of a transmission scenario of the
TPC data and the FIC data level according to the present
invention;
FIG. 37 illustrates an example of power saving of in a receiver
when transmitting 3 parades to an M/H frame level according to the
present invention;
FIG. 38 illustrates an example of a training sequence at the byte
level according to the present invention;
FIG. 39 illustrates an example of a training sequence at the symbol
according to the present invention;
FIG. 40 illustrates a block diagram of a receiving system according
to an embodiment of the present invention;
FIG. 41 is a block diagram showing an example of a demodulating
unit in the receiving system;
FIG. 42 is a block diagram showing an example of an operation
controller of FIG. 41;
FIG. 43 illustrates an example of linear interpolation according to
the present invention;
FIG. 44 illustrates the relation between a segment and a channel
impulse response (CIR) in a data group including field
synchronization data according to the present invention;
FIG. 45 illustrates the relation between a segment and a channel
impulse response (CIR) in a data group not including any field
synchronization data according to the present invention;
FIG. 46 illustrates the relation between a segment and a channel
impulse response (CIR) in a data group, which is used for
estimating the CIR of a general data section located between
training sections, among data sections including field
synchronization data according to the present invention;
FIG. 47 illustrates an example of linear extrapolation according to
the present invention;
FIG. 48 illustrates the relation between a power of a CIR and a
signal power in a data group including field synchronization data
according to the present invention;
FIG. 49 illustrates a block diagram of a channel equalizer
according to an embodiment of the present invention;
FIG. 50 illustrates a block diagram of a block decoder according to
an embodiment of the present invention;
FIG. 51(a) and FIG. 51(b) illustrate an exemplary process of
configuring one or two RS frame by collecting a plurality of
portions according to the present invention;
FIG. 52 and FIG. 53 illustrate process steps of error correction
decoding according to an embodiment of the present invention;
FIG. 54 to FIG. 61 illustrate an exemplary of a data group format
represented using numbers before (prior) data interleaving
according to the present invention;
FIG. 62 to FIG. 72 illustrate an exemplary of a data group format
represented using numbers before (prior) data interleaving
according to the present invention;
FIG. 73 illustrates an example of a training sequence represented
using numbers at the byte level according to the present invention;
and
FIG. 74 illustrates an example of a training sequence represented
using numbers at the symbol according to 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.
Among the terms used in the description of the present invention,
main service data correspond to data that can be received by a
fixed receiving system and may include audio/video (A/V) data. More
specifically, the main service data may include A/V data of high
definition (HD) or standard definition (SD) levels and may also
include diverse data types required for data broadcasting. Also,
the known data correspond to data pre-known in accordance with a
pre-arranged agreement between the receiving system and the
transmitting system.
Additionally, among the terms used in the present invention, "M/H
(or MH)" corresponds to the initials of "mobile" and "handheld" and
represents the opposite concept of a fixed-type system.
Furthermore, the M/H service data may include at least one of
mobile service data and handheld service data, and will also be
referred to as "mobile service data" for simplicity. Herein, the
mobile service data not only correspond to M/H service data but may
also include any type of service data with mobile or portable
characteristics. Therefore, the mobile service data according to
the present invention are not limited only to the M/H service
data.
The above-described mobile service data may correspond to data
having information, such as program execution files, stock
information, and so on, and may also correspond to A/V data. Most
particularly, the mobile service data may correspond to A/V data
having lower resolution and lower data rate as compared to the main
service data. For example, if an A/V codec that is used for a
conventional main service corresponds to a MPEG-2 codec, a MPEG-4
advanced video coding (AVC) or scalable video coding (SVC) having
better image compression efficiency may be used as the A/V codec
for the mobile service. Furthermore, any type of data may be
transmitted as the mobile service data. For example, transport
protocol expert group (TPEG) data for broadcasting real-time
transportation information may be transmitted as the main service
data.
Also, a data service using the mobile service data may include
weather forecast services, traffic information services, stock
information services, viewer participation quiz programs, real-time
polls and surveys, interactive education broadcast programs, gaming
services, services providing information on synopsis, character,
background music, and filming sites of soap operas or series,
services providing information on past match scores and player
profiles and achievements, and services providing information on
product information and programs classified by service, medium,
time, and theme enabling purchase orders to be processed. Herein,
the present invention is not limited only to the services mentioned
above.
In the present invention, the transmitting system provides backward
compatibility in the main service data so as to be received by the
conventional receiving system. Herein, the main service data and
the mobile service data are multiplexed to the same physical
channel and then transmitted.
Furthermore, the transmitting system according to the present
invention performs additional encoding on the mobile service data
and inserts the data already known by the receiving system and
transmitting system (e.g., known data), thereby transmitting the
processed data.
Therefore, when using the transmitting system according to the
present invention, the receiving system may receive the mobile
service data during a mobile state and may also receive the mobile
service data with stability despite various distortion and noise
occurring within the channel.
M/H Frame Structure
In the embodiment of the present invention, the mobile service data
are first multiplexed with main service data in M/H frame units
and, then, modulated in a VSB mode and transmitted to the receiving
system.
At this point, one M/H frame consists of K1 number of sub-frames,
wherein one sub-frame includes K2 number of slots. Also, each slot
may be configured of K3 number of data packets. In the embodiment
of the present invention, K1 will be set to 5, K2 will be set to
16, and K3 will be set to 156 (i.e., K1=5, K2=16, and K3=156). The
values for K1, K2, and K3 presented in this embodiment either
correspond to values according to a preferred embodiment or are
merely exemplary. Therefore, the above-mentioned values will not
limit the scope of the present invention.
FIG. 1 illustrates a structure of an M/H frame for transmitting and
receiving mobile service data according to the present invention.
In the example shown in FIG. 1, one M/H frame consists of 5
sub-frames, wherein each sub-frame includes 16 slots. In this case,
the M/H frame according to the present invention includes 5
sub-frames and 80 slots. Also, in a packet level, one slot is
configured of 156 data packets (i.e., transport stream packets),
and in a symbol level, one slot is configured of 156 data segments.
Herein, the size of one slot corresponds to one half (1/2) of a VSB
field. More specifically, since one 207-byte data packet has the
same amount of data as a data segment, a data packet prior to being
interleaved may also be used as a data segment.
At this point, two VSB fields are grouped to form a VSB frame.
FIG. 2 illustrates an exemplary structure of a VSB frame, wherein
one VSB frame consists of 2 VSB fields (i.e., an odd field and an
even field). Herein, each VSB field includes a field
synchronization segment and 312 data segments.
The slot corresponds to a basic time period for multiplexing the
mobile service data and the main service data. Herein, one slot may
either include the mobile service data or be configured only of the
main service data.
If one M/H frame is transmitted during one slot, the first 118 data
packets within the slot correspond to a data group. And, the
remaining 38 data packets become the main service data packets. In
another example, when no data group exists in a slot, the
corresponding slot is configured of 156 main service data
packets.
Meanwhile, when the slots are assigned to a VSB frame, an offset
exists for each assigned position.
FIG. 3 illustrates a mapping example of the positions to which the
first 4 slots of a sub-frame are assigned with respect to a VSB
frame in a space region. And, FIG. 4 illustrates a mapping example
of the positions to which the first 4 slots of a sub-frame are
assigned with respect to a VSB frame in a time region.
Referring to FIG. 3 and FIG. 4, a 38.sup.th data packet (TS packet
#37) of a 1.sup.st slot (Slot #0) is mapped to the 1.sup.st data
packet of an odd VSB field. A 38.sup.th data packet (TS packet #37)
of a 2.sup.nd slot (Slot #1) is mapped to the 157.sup.th data
packet of an odd VSB field. Also, a 38.sup.th data packet (TS
packet #37) of a 3.sup.rd slot (Slot #2) is mapped to the 1.sup.st
data packet of an even VSB field. And, a 38.sup.th data packet (TS
packet #37) of a 4.sup.th slot (Slot #3) is mapped to the
157.sup.th data packet of an even VSB field. Similarly, the
remaining 12 slots within the corresponding sub-frame are mapped in
the subsequent VSB frames using the same method.
Meanwhile, one data group may be divided into at least one or more
hierarchical regions. And, depending upon the characteristics of
each hierarchical region, the type of mobile service data being
inserted in each region may vary. For example, the data group
within each region may be divided (or categorized) based upon the
receiving performance.
In an example given in the present invention, a data group is
divided into regions A, B, C, and D in a data configuration after
data interleaving.
FIG. 5 illustrates an alignment of data after being data
interleaved and identified. FIG. 6 illustrates an enlarged portion
of the data group shown in FIG. 5 for a better understanding of the
present invention. FIG. 7 illustrates an alignment of data before
being data interleaved and identified. And, FIG. 8 illustrates an
enlarged portion of the data group shown in FIG. 7 for a better
understanding of the present invention. More specifically, a data
structure identical to that shown in FIG. 5 is transmitted to a
receiving system. In other words, one data packet is
data-interleaved so as to be scattered to a plurality of data
segments, thereby being transmitted to the receiving system. FIG. 5
illustrates an example of one data group being scattered to 170
data segments. At this point, since one 207-byte packet has the
same amount of data as one data segment, the packet that is not yet
processed with data-interleaving may be used as the data
segment.
FIG. 5 shows an example of dividing a data group prior to being
data-interleaved into 10 M/H blocks (i.e., M/H block (B1) to M/H
block 10 (B10)). In this example, each M/H block has the length of
16 segments. Referring to FIG. 5, only the RS parity data are
allocated to a portion of 5 segments before the M/H block 1 (B1)
and 5 segments behind the M/H block 10 (B10). The RS parity data
are excluded in regions A to D of the data group.
More specifically, when it is assumed that one data group is
divided into regions A, B, C, and D, each M/H block may be included
in any one of region A to region D depending upon the
characteristic of each M/H block within the data group. At this
point, according to an embodiment of the present invention, each
M/H block may be included in any one of region A to region D based
upon an interference level of main service data.
Herein, the data group is divided into a plurality of regions to be
used for different purposes. More specifically, a region of the
main service data having no interference or a very low interference
level may be considered to have a more resistant (or stronger)
receiving performance as compared to regions having higher
interference levels. Additionally, when using a system inserting
and transmitting known data in the data group, wherein the known
data are known based upon an agreement between the transmitting
system and the receiving system, and when consecutively long known
data are to be periodically inserted in the mobile service data,
the known data having a predetermined length may be periodically
inserted in the region having no interference from the main service
data (i.e., a region wherein the main service data are not mixed).
However, due to interference from the main service data, it is
difficult to periodically insert known data and also to insert
consecutively long known data to a region having interference from
the main service data.
Referring to FIG. 5, M/H block 4 (B4) to M/H block 7 (B7)
correspond to regions without interference of the main service
data. M/H block 4 (B4) to M/H block 7 (B7) within the data group
shown in FIG. 5 correspond to a region where no interference from
the main service data occurs. In this example, a long known data
sequence is inserted at both the beginning and end of each M/H
block. In the description of the present invention, the region
including M/H block 4 (B4) to M/H block 7 (B7) will be referred to
as "region A (=B4+B5+B6+B7)". As described above, when the data
group includes region A having a long known data sequence inserted
at both the beginning and end of each M/H block, the receiving
system is capable of performing equalization by using the channel
information that can be obtained from the known data. Therefore,
the strongest equalizing performance may be yielded (or obtained)
from one of region A to region D.
In the example of the data group shown in FIG. 5, M/H block 3 (B3)
and M/H block 8 (B8) correspond to a region having little
interference from the main service data. Herein, a long known data
sequence is inserted in only one side of each M/H block B3 and B8.
More specifically, due to the interference from the main service
data, a long known data sequence is inserted at the end of M/H
block 3 (B3), and another long known data sequence is inserted at
the beginning of M/H block 8 (B8). In the present invention, the
region including M/H block 3 (B3) and M/H block 8 (B8) will be
referred to as "region B(=B3+B8)". As described above, when the
data group includes region B having a long known data sequence
inserted at only one side (beginning or end) of each M/H block, the
receiving system is capable of performing equalization by using the
channel information that can be obtained from the known data.
Therefore, a stronger equalizing performance as compared to region
C/D may be yielded (or obtained).
Referring to FIG. 5, M/H block 2 (B2) and M/H block 9 (B9)
correspond to a region having more interference from the main
service data as compared to region B. A long known data sequence
cannot be inserted in any side of M/H block 2 (B2) and M/H block 9
(B9). Herein, the region including M/H block (B2) and M/H block 9
(B9) will be referred to as "region C(=B2+B9)". Finally, in the
example shown in FIG. 5, M/H block 1 (B1) and M/H block 10 (B10)
correspond to a region having more interference from the main
service data as compared to region C. Similarly, a long known data
sequence cannot be inserted in any side of M/H block 1 (B1) and M/H
block 10 (B10).
Herein, the region including M/H block 1 (B1) and M/H block 10
(B10) will be referred to as "region D (=B1+B10)". Since region C/D
is spaced further apart from the known data sequence, when the
channel environment undergoes frequent and abrupt changes, the
receiving performance of region C/D may be deteriorated.
FIG. 7 illustrates a data structure prior to data interleaving.
More specifically, FIG. 7 illustrates an example of 118 data
packets being allocated to a data group. FIG. 7 shows an example of
a data group consisting of 118 data packets, wherein, based upon a
reference packet (e.g., a 1st packet (or data segment) or
157.sup.th packet (or data segment) after a field synchronization
signal), when allocating data packets to a VSB frame, 37 packets
are included before the reference packet and 81 packets (including
the reference packet) are included afterwards.
In other words, with reference to FIG. 5, a field synchronization
signal is placed (or assigned) between M/H block 2 (B2) and M/H
block 3 (B3). Accordingly, this indicates that the slot has an
off-set of 37 data packets with respect to the corresponding VSB
field.
FIG. 54 to FIG. 61 illustrate an exemplary data group format
represented using numbers before (prior) data interleaving. In FIG.
54 to FIG. 61, the 207 variable bytes of each 208-byte MPEG-2
transport stream packet are shown. The initial MPEG-2 sync byte of
each packet is not shown. Referring to FIG. 54 to FIG. 61, number 0
corresponds to main service data (i.e., normal VSB data), number 1
corresponds to signaling data (or signling bytes or signaling
information), number 2 corresponds to dummy data bytes, number 3
corresponds to trellis initialization bytes, number 4 corresponds
to MPEG header, number 5 corresponds to known (training) data
sequence, number 6 corresponds to mobile service data (i.e., M/H
Data), and number 9 corresponds to RS parity bytes.
FIG. 62 to FIG. 72 illustrate an exemplary data group format
represented using numbers after data interleaving. In FIG. 62 to
FIG. 72, the 207 variable bytes of each 208-byte MPEG-2 transport
stream packet are shown. The initial MPEG-2 sync byte of each
packet is not shown. In a data group containing a field
synchronization segment, the field syncronization segment shall be
inserted between data group segments #36 and #37; i.e., 37 data
group segments precede a data field syncronization segment.
Referring to FIG. 62 to FIG. 72, number 0 corresponds to main
service data (i.e., normal VSB data), number 1 corresponds to
signaling data (or signling bytes or signaling information), number
2 corresponds to dummy data bytes, number 3 corresponds to trellis
initialization bytes, number 4 corresponds to MPEG header, number 5
corresponds to known (training) data sequence, number 6 corresponds
to mobile service data (i.e., M/H Data), and number 9 corresponds
to RS parity bytes.
The size of the data groups, number of hierarchical regions within
the data group, the size of each region, the number of M/H blocks
included in each region, the size of each M/H block, and so on
described above are merely exemplary. Therefore, the present
invention will not be limited to the examples described above.
FIG. 9 illustrates an exemplary assignment order of data groups
being assigned to one of 5 sub-frames, wherein the 5 sub-frames
configure an M/H frame. For example, the method of assigning data
groups may be identically applied to all M/H frames or differently
applied to each M/H frame. Furthermore, the method of assigning
data groups may be identically applied to all sub-frames or
differently applied to each sub-frame. At this point, when it is
assumed that the data groups are assigned using the same method in
all sub-frames of the corresponding M/H frame, the total number of
data groups being assigned to an M/H frame is equal to a multiple
of `5`.
According to the embodiment of the present invention, a plurality
of consecutive data groups is assigned to be spaced as far apart
from one another as possible within the M/H frame. Thus, the system
can be capable of responding promptly and effectively to any burst
error that may occur within a sub-frame.
For example, when it is assumed that 3 data groups are assigned to
a sub-frame, the data groups are assigned to a 1.sup.st slot (Slot
#0), a 5.sup.th slot (Slot #4), and a 9.sup.th slot (Slot #8) in
the sub-frame, respectively. FIG. 9 illustrates an example of
assigning 16 data groups in one sub-frame using the above-described
pattern (or rule). In other words, each data group is serially
assigned to 16 slots corresponding to the following numbers: 0, 8,
4, 12, 1, 9, 5, 13, 2, 10, 6, 14, 3, 11, 7, and 15. Equation 1
below shows the above-described rule (or pattern) for assigning
data groups in a sub-frame. j=(4i+0) mod 16 Equation 1 Herein, 0=0
if i<4, 0=2 else if i<8, 0=1 else if i<12, 0=3 else.
Herein, j indicates the slot number within a sub-frame.
The value ofj may range from 0 to 15 (i.e., 0.ltoreq.j.ltoreq.15).
Also, value of i indicates the data group number. The value of i
may range from 0 to 15 (i.e., 0.ltoreq.j.ltoreq.15).
In the present invention, a collection of data groups included in
an M/H frame will be referred to as a "parade". Based upon the RS
frame mode, the parade transmits data of at least one specific RS
frame.
The mobile service data within one RS frame may be assigned either
to all of regions A/B/C/D within the corresponding data group, or
to at least one of regions A/B/C/D. In the embodiment of the
present invention, the mobile service data within one RS frame may
be assigned either to all of regions A/B/C/D, or to at least one of
regions A/B and regions C/D. If the mobile service data are
assigned to the latter case (i.e., one of regions A/B and regions
C/D), the RS frame being assigned to regions A/B and the RS frame
being assigned to regions C/D within the corresponding data group
are different from one another.
In the description of the present invention, the RS frame being
assigned to regions A/B within the corresponding data group will be
referred to as a "primary RS frame", and the RS frame being
assigned to regions C/D within the corresponding data group will be
referred to as a "secondary RS frame", for simplicity. Also, the
primary RS frame and the secondary RS frame form (or configure) one
parade. More specifically, when the mobile service data within one
RS frame are assigned either to all of regions A/B/C/D within the
corresponding data group, one parade transmits one RS frame. In
this case, also the RS frame will be referred to as a "primary RS
frame". Conversely, when the mobile service data within one RS
frame are assigned either to at least one of regions A/B and
regions C/D, one parade may transmit up to 2 RS frames.
More specifically, the RS frame mode indicates whether a parade
transmits one RS frame, or whether the parade transmits two RS
frames. Table 1 below shows an example of the RS frame mode.
TABLE-US-00001 TABLE 1 RS frame mode (2 bits) Description 00 There
is only one primary RS frame for all group regions 01 There are two
separate RS frames. Primary RS frame for group regions A and B
Secondary RS frame for group regions C and D 10 Reserved 11
Reserved
Table 1 illustrates an example of allocating 2 bits in order to
indicate the RS frame mode. For example, referring to Table 1, when
the RS frame mode value is equal to `00`, this indicates that one
parade transmits one RS frame. And, when the RS frame mode value is
equal to `01`, this indicates that one parade transmits two RS
frames, i.e., the primary RS frame and the secondary RS frame. More
specifically, when the RS frame mode value is equal to `01`, data
of the primary RS frame for regions A/B are assigned and
transmitted to regions A/B of the corresponding data group.
Similarly, data of the secondary RS frame for regions C/D are
assigned and transmitted to regions C/D of the corresponding data
group.
As described in the assignment of data groups, the parades are also
assigned to be spaced as far apart from one another as possible
within the sub-frame. Thus, the system can be capable of responding
promptly and effectively to any burst error that may occur within a
sub-frame.
Furthermore, the method of assigning parades may be identically
applied to all sub-frames or differently applied to each sub-frame.
According to the embodiment of the present invention, the parades
may be assigned differently for each M/H frame and identically for
all sub-frames within an M/H frame. More specifically, the M/H
frame structure may vary by M/H frame units. Thus, an ensemble rate
may be adjusted on a more frequent and flexible basis.
FIG. 10 illustrates an example of multiple data groups of a single
parade being assigned (or allocated) to an M/H frame. More
specifically, FIG. 10 illustrates an example of a plurality of data
groups included in a single parade, wherein the number of data
groups included in a sub-frame is equal to `3`, being allocated to
an M/H frame. Referring to FIG. 10, 3 data groups are sequentially
assigned to a sub-frame at a cycle period of 4 slots. Accordingly,
when this process is equally performed in the 5 sub-frames included
in the corresponding M/H frame, 15 data groups are assigned to a
single M/H frame. Herein, the 15 data groups correspond to data
groups included in a parade. Therefore, since one sub-frame is
configured of 4 VSB frame, and since 3 data groups are included in
a sub-frame, the data group of the corresponding parade is not
assigned to one of the 4 VSB frames within a sub-frame.
For example, when it is assumed that one parade transmits one RS
frame, and that a RS frame encoder located in a later block
performs RS-encoding on the corresponding RS frame, thereby adding
24 bytes of parity data to the corresponding RS frame and
transmitting the processed RS frame, the parity data occupy
approximately 11.37% (=24/(187+24).times.100) of the total code
word length. Meanwhile, when one sub-frame includes 3 data groups,
and when the data groups included in the parade are assigned, as
shown in FIG. 10, a total of 15 data groups form an RS frame.
Accordingly, even when an error occurs in an entire data group due
to a burst noise within a channel, the percentile is merely 6.67%
(=1/15.times.100). Therefore, the receiving system may correct all
errors by performing an erasure RS decoding process. More
specifically, when the erasure RS decoding is performed, a number
of channel errors corresponding to the number of RS parity bytes
may be corrected. By doing so, the receiving system may correct the
error of at least one data group within one parade. Thus, the
minimum burst noise length correctable by a RS frame is over 1 VSB
frame.
Meanwhile, when data groups of a parade are assigned as described
above, either main service data may be assigned between each data
group, or data groups corresponding to different parades may be
assigned between each data group. More specifically, data groups
corresponding to multiple parades may be assigned to one M/H
frame.
Basically, the method of assigning data groups corresponding to
multiple parades is very similar to the method of assigning data
groups corresponding to a single parade. In other words, data
groups included in other parades that are to be assigned to an M/H
frame are also respectively assigned according to a cycle period of
4 slots.
At this point, data groups of a different parade may be
sequentially assigned to the respective slots in a circular method.
Herein, the data groups are assigned to slots starting from the
ones to which data groups of the previous parade have not yet been
assigned.
For example, when it is assumed that data groups corresponding to a
parade are assigned as shown in FIG. 10, data groups corresponding
to the next parade may be assigned to a sub-frame starting either
from the 12.sup.th slot of a sub-frame. However, this is merely
exemplary. In another example, the data groups of the next parade
may also be sequentially assigned to a different slot within a
sub-frame at a cycle period of 4 slots starting from the 3.sup.rd
slot.
FIG. 11 illustrates an example of transmitting 3 parades (Parade
#0, Parade #1, and Parade #2) to an M/H frame. More specifically,
FIG. 11 illustrates an example of transmitting parades included in
one of 5 sub-frames, wherein the 5 sub-frames configure one M/H
frame.
When the 1.sup.st parade (Parade #0) includes 3 data groups for
each sub-frame, the positions of each data groups within the
sub-frames may be obtained by substituting values `0` to `2` for i
in Equation 1. More specifically, the data groups of the 1.sup.st
parade (Parade #0) are sequentially assigned to the 1.sup.st,
5.sup.th, and 9.sup.th slots (Slot #0, Slot #4, and Slot #8) within
the sub-frame. Also, when the 2.sup.nd parade includes 2 data
groups for each sub-frame, the positions of each data groups within
the sub-frames may be obtained by substituting values `3` and `4`
for i in Equation 1.
More specifically, the data groups of the 2.sup.nd parade (Parade
#1) are sequentially assigned to the 2.sup.nd and 12.sup.th slots
(Slot #3 and Slot #11) within the sub-frame.
Finally, when the 3.sup.rd parade includes 2 data groups for each
sub-frame, the positions of each data groups within the sub-frames
may be obtained by substituting values `5` and `6` for i in
Equation 1. More specifically, the data groups of the 3.sup.rd
parade (Parade #2) are sequentially assigned to the 7.sup.th and
11.sup.th slots (Slot #6 and Slot #10) within the sub-frame.
As described above, data groups of multiple parades may be assigned
to a single M/H frame, and, in each sub-frame, the data groups are
serially allocated to a group space having 4 slots from left to
right. Therefore, a number of groups of one parade per sub-frame
(NOG) may correspond to any one integer from `1` to `8`. Herein,
since one M/H frame includes 5 sub-frames, the total number of data
groups within a parade that can be allocated to an M/H frame may
correspond to any one multiple of `5` ranging from `5` to `40`.
FIG. 12 illustrates an example of expanding the assignment process
of 3 parades, shown in FIGS. 11, to 5 sub-frames within an M/H
frame.
FIG. 13 illustrates a data transmission structure according to an
embodiment of the present invention, wherein signaling data are
included in a data group so as to be transmitted.
As described above, an M/H frame is divided into 5 sub-frames. Data
groups corresponding to a plurality of parades co-exist in each
sub-frame. Herein, the data groups corresponding to each parade are
grouped by M/H frame units, thereby configuring a single
parade.
The data structure shown in FIG. 13 includes 3 parades (parade #0,
parade #1, parade #2). Also, a predetermined portion of each data
group (i.e., 37 bytes/data group) is used for delivering (or
sending) FIC information associated with mobile service data,
wherein the FIC information is separately encoded from the
RS-encoding process. The FIC region assigned to each data group
consists of one FIC segments.
Meanwhile, the concept of an M/H ensemble is applied in the
embodiment of the present invention, thereby defining a collection
(or group) of services. Each M/H ensemble carries the same QoS and
is coded with the same FEC code. Also, each M/H ensemble has the
same unique identifier (i.e., ensemble ID) and corresponds to
consecutive RS frames.
As shown in FIG. 13, the FIC segment corresponding to each data
group described service information of an M/H ensemble to which the
corresponding data group belongs.
General Description of the Transmitting System
FIG. 14 illustrates a block diagram showing a general structure of
a digital broadcast transmitting system according to an embodiment
of the present invention.
Herein, the digital broadcast transmitting includes a service
multiplexer 100 and a transmitter 200. Herein, the service
multiplexer 100 is located in the studio of each broadcast station,
and the transmitter 200 is located in a site placed at a
predetermined distance from the studio. The transmitter 200 may be
located in a plurality of different locations. Also, for example,
the plurality of transmitters may share the same frequency. And, in
this case, the plurality of transmitters receives the same signal.
This corresponds to data transmission using Single Frequency
Network (SFN). Accordingly, in the receiving system, a channel
equalizer may compensate signal distortion, which is caused by a
reflected wave, so as to recover the original signal. In another
example, the plurality of transmitters may have different
frequencies with respect to the same channel. This corresponds to
data transmission using Multi Frequency Network (MFN).
A variety of methods may be used for data communication each of the
transmitters, which are located in remote positions, and the
service multiplexer. For example, an interface standard such as a
synchronous serial interface for transport of MPEG-2 data
(SMPTE-310M). In the SMPTE-310M interface standard, a constant data
rate is decided as an output data rate of the service multiplexer.
For example, in case of the 8VSB mode, the output data rate is
19.39 Mbps, and, in case of the 16VSB mode, the output data rate is
38.78 Mbps. Furthermore, in the conventional 8VSB mode transmitting
system, a transport stream (TS) packet having a data rate of
approximately 19.39 Mbps may be transmitted through a single
physical channel. Also, in the transmitting system according to the
present invention provided with backward compatibility with the
conventional transmitting system, additional encoding is performed
on the mobile service data. Thereafter, the additionally encoded
mobile service data are multiplexed with the main service data to a
TS packet form, which is then transmitted. At this point, the data
rate of the multiplexed TS packet is approximately 19.39 Mbps.
At this point, the service multiplexer 100 receives at least one
type of main service data and table information (e.g., PSI/PSIP
table data) for each main service and encapsulates the received
data into a transport stream (TS) packet.
Also, according to an embodiment of the present invention, the
service multiplexer 100 receives at least one type of mobile
service data and table information (e.g., PSI/PSIP table data) for
each mobile service and encapsulates the received data into a
transport stream (TS) packet.
According to another embodiment of the present invention, the
service multiplexer 100 receives a RS frame, which is configured of
at least one type of mobile service data and table information for
each mobile service, and encapsulates the received RS frame data
into mobile service data packets of a transport stream (TS) packet
format.
And, the service multiplexer 100 multiplexes the encapsulated TS
packets for main service and the encapsulated TS packets for mobile
service based upon a predetermined multiplexing rule, thereby
outputting the multiplexed TS packets to the transmitter 200.
At this point, the RS frame has the size of N (row).times.187
(column), as shown in FIG. 15. Herein, N represents the length of a
row (i.e., number of columns), and 187 corresponds to the length of
a column (i.e., number of rows.
In the present invention, each row configured of N bytes will be
referred to as an M/H service data packet for simplicity. The M/H
service data packet may be configured of a 2-byte M/H header and a
(N-2)-byte M/H payload. Herein, the assigning 2 bytes to the M/H
header region is merely exemplary. The above-described
configuration may be altered by the system designer and will,
therefore, not be limited only to the example presented in the
description of the present invention.
The RS frame is generated by collecting (or gathering) table
information and/or mobiles service data collectively corresponding
to a size of (N-2) (row).times.187(column) bytes.
According to an embodiment of the present invention, the mobile
service data has the form of an IP datagram. Herein, the RS frame
may include table information and IP datagram corresponding to at
least one mobile service. Also, one RS frame may include table
information and IP datagram corresponding to one or more mobile
services. For example, IP datagram and table information of two
different types of mobile service data, such as news service (e.g.,
IP datagram for mobile service 1) and stock information service
(e.g., IP datagram for mobile service 2), may be included in a
single RS frame.
More specifically, either table information of a section structure
or an IP datagram of a mobile service data may be assigned to an
M/H payload within an M/H service data packet configuring the RS
frame. Alternatively, either an IP datagram of table information or
an IP datagram of a mobile service data may be assigned to an M/H
payload within an M/H service data packet configuring the RS
frame.
At this point, the size of the M/H service data packet including
the M/H header may not be equal to N bytes.
In this case, stuffing bytes may be assigned to the surplus (or
remaining) payload region within the corresponding M/H service data
packet. For example, after assigning program table information to
an M/H service data packet, when the length of the corresponding
M/H service data packet including the M/H header is equal to (N-20)
bytes, stuffing bytes may be assigned to the remaining 20-byte
region.
The RS frame may be assigned to at least one of regions A/B/C/D
within a data group by the transmitter. In the description of the
present invention, when the RS frame is assigned to regions A/B/C/D
within the data group, or when the RS frame is assigned to regions
A/B, the RS frame will be referred to as a primary RS frame.
Alternatively, when the RS frame is assigned to regions C/D, the RS
frame will be referred to as a secondary RS frame.
FIG. 16 is a diagram illustrating examples of fields allocated to
the M/H header region within the M/H service data packet according
to the present invention. Examples of the fields include
type_indicator field, error_indicator field, stuff_indicator field,
and pointer field.
The type_indicator field can allocate 3 bits, for example, and
represents a type of data allocated to payload within the
corresponding M/H service data packet. In other words, the
type_indicator field indicates whether data of the payload is IP
datagram or program table information. At this time, each data type
constitutes one logical channel. In the logical channel which
transmits the IP datagram, several mobile services are multiplexed
and then transmitted. Each mobile service undergoes demultiplexing
in the IP layer.
The error_indicator field can allocate 1 bit, for example, and
represents whether the corresponding M/H service data packet has an
error. For example, if the error_indicator field has a value of 0,
it means that there is no error in the corresponding M/H service
data packet. If the error_indicator field has a value of 1, it
means that there may be an error in the corresponding M/H service
data packet.
The stuff_indicator field can allocate 1 bit, for example, and
represents whether stuffing byte exists in payload of the
corresponding M/H service data packet. For example, if the stuff
indicator field has a value of 0, it means that there is no
stuffing byte in the corresponding M/H service data packet. If the
stuff_indicator field has a value of 1, it means that stuffing byte
exists in the corresponding M/H service data packet.
The pointer field can allocate 11 bits, for example, and represents
position information where new data (i.e., new signaling
information or new IP datagram) starts in the corresponding M/H
service data packet.
For example, if IP datagram for mobile service 1 and IP datagram
for mobile service 2 are allocated to the first M/H service data
packet within the RS frame as illustrated in FIG. 15, the pointer
field value represents the start position of the IP datagram for
mobile service 2 within the M/H service data packet.
Also, if there is no new data in the corresponding M/H service data
packet, the corresponding field value is expressed as a maximum
value exemplarily. According to the embodiment of the present
invention, since 11 bits are allocated to the pointer field, if
2047 is expressed as the pointer field value, it means that there
is no new data in the packet. The point where the pointer field
value is 0 can be varied depending on the type_indicator field
value and the stuff_indicator field value.
It is to be understood that the order, the position, and the
meaning of the fields allocated to the header within the M/H
service data packet illustrated in FIG. 16 are exemplarily
illustrated for understanding of the present invention. Since the
order, the position and the meaning of the fields allocated to the
header within the M/H service data packet and the number of
additionally allocated fields can easily be modified by those
skilled in the art, the present invention will not be limited to
the above example.
FIG. 17(a) and FIG. 17(b) illustrate another examples of RS frame
according to the present invention. FIG. 17(a) illustrates an
example of primary RS frame to be allocated to regions A/B within
the data group, and FIG. 17(b) illustrates an example of secondary
RS frame to be allocated to regions C/D within the data group.
In FIG. 17(a) and FIG. 17(b), a column length (i.e., the number of
rows) of the RS frame to be allocated to the regions A/B and a
column length (i.e., the number of rows) of the RS frame to be
allocated to the regions C/D are 187 equally. However, row lengths
(i.e, the number of columns) may be different from each other.
According to the embodiment of the present invention, when the row
length of the primary RS frame to be allocated 7to the regions A/B
within the data group is N1 bytes and the row length of the
secondary RS frame to be allocated to the regions C/D within the
data group is N2 bytes, a condition of N1>N2 is satisfied. In
this case, N1 and N2 can be varied depending on the transmission
parameter or a region of the data group, to which the corresponding
RS frame will be transmitted.
For convenience of the description, each row of the N1 and N2 bytes
will be referred to as the M/H service data packet. The M/H service
data packet within the RS frame to be allocated to the regions A/B
within the data group can be comprised of M/H header of 2 bytes and
payload of N1-2 bytes. Also, the M/H service data packet within the
RS frame to be allocated to the regions C/D within the data group
can be comprised of M/H header of 2 bytes and payload of N2-2
bytes.
In the present invention, the primary RS frame for the regions A/B
within the data group and the secondary RS frame for the regions
C/D within the data group can include at least one of program table
information and IP datagram. Also, one RS frame can include IP
datagram corresponding to one or more mobile services.
Corresponding parts of FIG. 15 can be applied to the other parts,
which are not described in FIG. 17(a) and FIG. 17(b).
Meanwhile, the value of N, which corresponds to the number of
columns within an RS frame, can be decided according to Equation
2.
.times..times..times..times. ##EQU00001##
Herein, NoG indicates the number of data groups assigned to a
sub-frame. PL represents the number of SCCC payload data bytes
assigned to a data group. And, P signifies the number of RS parity
data bytes added to each column of the RS frame. Finally, .left
brkt-bot.X.right brkt-bot. is the greatest integer that is equal to
or smaller than X.
More specifically, in Equation 2, PL corresponds to the length of
an RS frame portion. The value of PL is equivalent to the number of
SCCC payload data bytes that are assigned to the corresponding data
group. Herein, the value of PL may vary depending upon the RS frame
mode, SCCC block mode, and SCCC outer code mode. Table 2 to Table 5
below respectively show examples of PL values, which vary in
accordance with the RS frame mode, SCCC block mode, and SCCC outer
code mode. The SCCC block mode and the SCCC outer code mode will be
described in detail in a later process.
TABLE-US-00002 TABLE 2 SCCC outer code mode for Region A for Region
B for Region C for Region D PL 00 00 00 00 9624 00 00 00 01 9372 00
00 01 00 8886 00 00 01 01 8634 00 01 00 00 8403 00 01 00 01 8151 00
01 01 00 7665 00 01 01 01 7413 01 00 00 00 7023 01 00 00 01 6771 01
00 01 00 6285 01 00 01 01 6033 01 01 00 00 5802 01 01 00 01 5550 01
01 01 00 5064 01 01 01 01 4812 Others Reserved
Table 2 shows an example of the PL values for each data group
within an RS frame, wherein each PL value varies depending upon the
SCCC outer code mode, when the RS frame mode value is equal to
`00`, and when the SCCC block mode value is equal to `00`. For
example, when it is assumed that each SCCC outer code mode value of
regions A/B/C/D within the data group is equal to `00` (i.e., the
block processor 302 of a later block performs encoding at a coding
rate of 1/2), the PL value within each data group of the
corresponding RS frame may be equal to 9624 bytes. More
specifically, 9624 bytes of mobile service data within one RS frame
may be assigned to regions A/B/C/D of the corresponding data
group.
TABLE-US-00003 TABLE 3 SCCC outer code mode PL 00 9624 01 4812
Others Reserved
Table 3 shows an example of the PL values for each data group
within an RS frame, wherein each PL value varies depending upon the
SCCC outer code mode, when the RS frame mode value is equal to
`00`, and when the SCCC block mode value is equal to `01`.
TABLE-US-00004 TABLE 4 SCCC outer code mode for Region A for Region
B PL 00 00 7644 00 01 6423 01 00 5043 01 01 3822 Others
Reserved
Table 4 shows an example of the PL values for each data group
within a primary RS frame, wherein each PL value varies depending
upon the SCCC outer code mode, when the RS frame mode value is
equal to `01`, and when the SCCC block mode value is equal to `00`.
For example, when each SCCC outer code mode value of regions A/B is
equal to `00`, 7644 bytes of mobile service data within a primary
RS frame may be assigned to regions A/B of the corresponding data
group.
TABLE-US-00005 TABLE 5 SCCC outer code mode for Region C for Region
D PL 00 00 1980 00 01 1728 01 00 1242 01 01 990 Others Reserved
Table 5 shows an example of the PL values for each data group
within a secondary RS frame, wherein each PL value varies depending
upon the SCCC outer code mode, when the RS frame mode value is
equal to `01`, and when the SCCC block mode value is equal to `00`.
For example, when each SCCC outer code mode value of regions C/D is
equal to `00`, 1980 bytes of mobile service data within a secondary
RS frame may be assigned to regions C/D of the corresponding data
group.
Service Multiplexer
FIG. 18 illustrates a block diagram showing an example of the
service multiplexer. The service multiplexer includes a controller
110 for controlling the overall operations of the service
multiplexer, a table information generator 120 for the main
service, a null packet generator 130, an OM packet encapsulator
140, a mobile service multiplexer 150, and a transport multiplexer
160.
The transport multiplexer 160 may include a main service
multiplexer 161 and a transport stream (TS) packet multiplexer
162.
Referring to FIG. 18, at least one type of compression-encoded main
service data and table data generated from the table information
generator 120 for the main services are inputted to the main
service multiplexer 161 of the transport multiplexer 160. According
to the embodiment of the present invention, the table information
generator 120 generates PSI/PSIP table data, which is configured in
the form of an MPEG-2 private section.
The main service multiplexer 161 respectively encapsulates each of
the main service data and the PSI/PSIP table data, which are being
inputted, to MPEG-2 TS packet formats, thereby multiplexing the
encapsulated TS packets and outputting the multiplexed packets to
the TS packet multiplexer 162. Herein, the data packet being
outputted from the main service multiplexer 161 will hereinafter be
referred to as a main service data packet for simplicity.
The mobile service multiplexer 150 receives and respectively
encapsulates at least one type of compression-encoded mobile
service data and the table information (e.g., PSI/PSIP table data)
for mobile services to MPEG-2 TS packet formats. Then, the mobile
service multiplexer 150 multiplexes the encapsulated TS packets,
thereby outputting the multiplexed packets to the TS packet
multiplexer 162. Hereinafter, the data packet being outputted from
the mobile service multiplexer 150 will be referred to as a mobile
service data packet for simplicity.
Alternatively, the mobile service multiplexer 150 receives and
encapsulates an RS frame, which is generated by using at least one
type of compression-encoded mobile service data and the table
information for mobile services, to MPEG-2 TS packet formats. Then,
the mobile service multiplexer 150 multiplexes the encapsulated TS
packets, thereby outputting the multiplexed packets to the TS
packet multiplexer 162. Hereinafter, the data packet being
outputted from the mobile service multiplexer 150 will be referred
to as a mobile service data packet for simplicity.
According to an embodiment of the present invention, the mobile
service multiplexer 150 encapsulates an RS frame, which is inputted
in any one of the formats shown in FIG. 15, FIG. 17A, or FIG. 17B,
to a TS packet format.
At this point, the transmitter 200 requires identification
information in order to identify and process the main service data
packet and the mobile service data packet. Herein, the
identification information may use values pre-decided in accordance
with an agreement between the transmitting system and the receiving
system, or may be configured of a separate set of data, or may
modify predetermined location value with in the corresponding data
packet.
As an example of the present invention, a different packet
identifier (PID) may be assigned to identify each of the main
service data packet and the mobile service data packet. More
specifically, by assigning a PID, which does not use for the main
service data packet, to the mobile service data packet, the
transmitter 200 refers to a PID of data packet inputted, thereby
can identify each of the main service data packet and the mobile
service data packet.
In another example, by modifying a synchronization data byte within
a header of the mobile service data, the service data packet may be
identified by using the synchronization data byte value of the
corresponding service data packet. For example, the synchronization
byte of the main service data packet directly outputs the value
decided by the ISO/IEC 13818-1 standard (i.e., 0.times.47) without
any modification. The synchronization byte of the mobile service
data packet modifies and outputs the value, thereby identifying the
main service data packet and the mobile service data packet.
Conversely, the synchronization byte of the main service data
packet is modified and outputted, whereas the synchronization byte
of the mobile service data packet is directly outputted without
being modified, thereby enabling the main service data packet and
the mobile service data packet to be identified.
A plurality of methods may be applied in the method of modifying
the synchronization byte. For example, each bit of the
synchronization byte may be inversed, or only a portion of the
synchronization byte may be inversed.
As described above, any type of identification information may be
used to identify the main service data packet and the mobile
service data packet. Therefore, the scope of the present invention
is not limited only to the example set forth in the description of
the present invention.
Meanwhile, a transport multiplexer used in the conventional digital
broadcasting system may be used as the transport multiplexer 160
according to the present invention. More specifically, in order to
multiplex the mobile service data and the main service data and to
transmit the multiplexed data, the data rate of the main service is
limited to a data rate of (19.39-K) Mbps. Then, K Mbps, which
corresponds to the remaining data rate, is assigned as the data
rate of the mobile service. Thus, the transport multiplexer which
is already being used may be used as it is without any
modification.
Herein, the transport multiplexer 160 multiplexes the main service
data packet being outputted from the main service multiplexer 161
and the mobile service data packet being outputted from the mobile
service multiplexer 150. Thereafter, the transport multiplexer 160
transmits the multiplexed data packets to the transmitter 200.
However, in some cases, the output data rate of the mobile service
multiplexer 150 may not be equal to K Mbps. For example, when the
service multiplexer 100 assigns K Mbps of the 19.39 Mbps to the
mobile service data, and when the remaining (19.39-K) Mbps is,
therefore, assigned to the main service data, the data rate of the
mobile service data that are multiplexed by the service multiplexer
100 actually becomes lower than K Mbps. This is because, in case of
the mobile service data, the pre-processor of the transmitting
system performs additional encoding, thereby increasing the amount
of data. Eventually, the data rate of the mobile service data,
which may be transmitted from the service multiplexer 100, becomes
smaller than K Mbps.
For example, since the pre-processor of the transmitter performs an
encoding process on the mobile service data at a coding rate of at
least 1/2, the amount of the data outputted from the pre-processor
is increased to more than twice the amount of the data initially
inputted to the pre-processor. Therefore, the sum of the data rate
of the main service data and the data rate of the mobile service
data, both being multiplexed by the service multiplexer 100,
becomes either equal to or smaller than 19.39 Mbps.
In order to set the final output data rate of the mobile service
multiplexer 150 to K Mbps, the service multiplexer 100 of the
present invention may perform various exemplary operations.
According to an embodiment of the present invention, the null
packet generator 130 may generate a null data packet, which is then
outputted to the mobile service multiplexer 150. Thereafter, the
mobile service multiplexer 150 may multiplex the null data packet
and the mobile service data packets, so as to set the output data
rate to K Mbps.
At this point, the null data packet is transmitted to the
transmitter 200, thereby being discarded. More specifically, the
null data packet is not transmitted to the receiving system. In
order to do so, identification information for identifying the null
data is also required. Herein, the identification information for
identifying the null data may also use a value pre-decided based
upon an agreement between the transmitting system and the receiving
system and may also be configured of a separate set of data. And,
the identification information for identifying the null data may
also change a predetermined position value within the null data
packet and use the changed value. For example, the null packet
generator 130 may modify (or change) a synchronization byte value
within the header of the null data packet, thereby using the
changed value as the identification information. Alternatively, the
transport_error_indicator flag may be set to `1`, thereby being
used as the identification information. According to the embodiment
of the present invention, the transport_error_indicator flag within
the header of the null data packet is used as the identification
information for identifying the null data packet. In this case, the
transport_error_indicator flag of the null data packet is set to
`1`, and the transport_error_indicator flag for each of the other
remaining data packets is reset to `0`, so that the null data
packet can be identified (or distinguished).
More specifically, when the null packet generator 130 generated a
null data packet, and if, among the fields included in the header
of the null data packet, the transport_error_indicator flag is set
to `1` and then transmitted, the transmitter 200 may identify and
discard the null data packet corresponding to the
transport_error_indicator flag.
Herein, any value that can identify the null data packet may be
used as the identification information for identifying the null
data packet. Therefore, the present invention will not be limited
only to the example proposed in the description of the present
invention.
As another example of setting (or matching) the final output data
rate of the mobile service multiplexer 150 to K Mbps, an operations
and maintenance (OM) packet (also referred to as OMP) may be used.
In this case, the mobile service multiplexer 150 may multiplex the
mobile service data packet, the null data packet, and the OM
packet, so as to set the output data rate to K Mbps.
Meanwhile, signaling data, such as transmission parameters, are
required for enabling the transmitter 200 to process the mobile
service data.
According to an embodiment of the present invention, the
transmission parameter is inserted in the payload region of the OM
packet, thereby being transmitted to the transmitter.
At this point, in order to enable the transmitter 200 to identify
the insertion of the transmission parameter in the OM packet,
identification information that can identify the insertion of the
transmission parameter in the type field of the corresponding OM
packet (i.e., OM_type field).
More specifically, an operations and maintenance packet (OMP) is
defined for the purpose of operating and managing the transmitting
system. For example, the OMP is configured in an MPEG-2 TS packet
format, and the value of its respective PID is equal to
`0.times.1FFA`. The OMP consists of a 4-byte header and a 184-byte
payload. Among the 184 bytes, the first byte corresponds to the
OM_type field indicating the type of the corresponding OM packet
(OMP). And, the remaining 183 bytes correspond to an OM payload
field, wherein actual data are inserted.
According to the present invention, among the reserved field values
of the OM_type field, a pre-arranged value is used, thereby being
capable of indicating that a transmission parameter has been
inserted in the corresponding OM packet. Thereafter, the
transmitter 200 may locate (or identify) the corresponding OMP by
referring to the respective PID. Subsequently, by parsing the
OM_type field within the OMP, the transmitter 200 may be able to
know (or recognize) whether or not a transmission parameter has
been inserted in the corresponding OM packet.
The transmission parameters that can be transmitted to the OM
packet include M/H frame information (e.g., M/H frame_index), FIC
information (e.g., next_FIC_version_number), parade information
(e.g., number_of_parades, parade_id, parade_repetition_cycle, and
ensemble_id), group information (e.g., number_of_group and
start_group_number), SCCC information (e.g., SCCC_block_mode and
SCCC_outer_code_mode), RS frame information (e.g., RS_Frame_mode
and RS_frame_continuity_counter), RS encoding information (e.g.,
RS_code_mode), and so on.
At this point, the OM packet in which the transmission parameter is
inserted may be periodically generated by a constant cycle, so as
to be multiplexed with the mobile service data packet.
The multiplexing rules and the generation of null data packets of
the mobile service multiplexer 150, the main service multiplexer
161, and the TS packet multiplexer 160 are controlled by the
controller 110.
The TS packet multiplexer 162 multiplexes a data packet being
outputted from the main service multiplexer 161 at (19.39-K) Mbps
with a data packet being outputted from the mobile service
multiplexer 150 at K Mbps. Thereafter, the TS packet multiplexer
162 transmits the multiplexed data packet to the transmitter 200 at
a data rate of 19.39 Mbps.
Transmitter
FIG. 19 illustrates a block diagram showing an example of the
transmitter 200 according to an embodiment of the present
invention. Herein, the transmitter 200 includes a controller 201, a
demultiplexer 210, a packet jitter mitigator 220, a pre-processor
230, a packet multiplexer 240, a post-processor 250, a
synchronization (sync) multiplexer 260, and a transmission unit
270.
Herein, when a data packet is received from the service multiplexer
100, the demultiplexer 210 should identify whether the received
data packet corresponds to a main service data packet, a mobile
service data packet, a null data packet, or an OM packet.
For example, the demultiplexer 210 uses the PID within the received
data packet so as to identify the main service data packet, the
mobile service data packet, and the null data packet. Then, the
demultiplexer 210 uses a transport_error_indicator field to
identify the null data packet.
If an OM packet is included in the received data packet, the OM
packet may identify using the PID within the received data packet.
And by using the OM_type field included in the identified OM
packet, the demultiplexer 210 may be able to know whether or not a
transmission parameter is included in the payload region of the
corresponding OM packet and, then, received.
The main service data packet identified by the demultiplexer 210 is
outputted to the packet jitter mitigator 220, the mobile service
data packet is outputted to the pre-processor 230, and the null
data packet is discarded. If the transmission parameter is included
in the OM packet, the corresponding transmission parameter is
extracted, so as to be outputted to the corresponding blocks.
Thereafter, the OM packet is discarded. According to an embodiment
of the present invention, the transmission parameter extracted from
the OM packet is outputted to the corresponding blocks through the
controller 201.
The pre-processor 230 performs an additional encoding process of
the mobile service data included in the service data packet, which
is demultiplexed and outputted from the demultiplexer 210. The
pre-processor 230 also performs a process of configuring a data
group so that the data group may be positioned at a specific place
in accordance with the purpose of the data, which are to be
transmitted on a transmission frame. This is to enable the mobile
service data to respond swiftly and strongly against noise and
channel changes. The pre-processor 230 may also refer to the
transmission parameter extracted in the OM packet when performing
the additional encoding process.
Also, the pre-processor 230 groups a plurality of mobile service
data packets to configure a data group. Thereafter, known data,
mobile service data, RS parity data, and MPEG header are allocated
to pre-determined regions within the data group.
Pre-Processor within Transmitter
FIG. 20 illustrates a block diagram showing the structure of a
pre-processor 230 according to the present invention. Herein, the
pre-processor 230 includes an M/H frame encoder 301, a block
processor 302, a group formatter 303, a signaling encoder 304, and
a packet formatter 305.
The M/H frame encoder 301, which is included in the pre-processor
230 having the above-described structure, data-randomizes the
mobile service data that are inputted to the demultiplexer 210,
thereby generating a RS frame corresponding an ensemble. Then, the
M/H frame encoder 301 performs an encoding process for error
correction in RS frame units.
The M/H frame encoder 301 may include at least one RS frame
encoder. More specifically, RS frame encoders may be provided in
parallel, wherein the number of RS frame encoders is equal to the
number of parades within the M/H frame. As described above, the M/H
frame is a basic time cycle period for transmitting at least one
parade. Also, each parade consists of one or two RS frames.
FIG. 21 illustrates a conceptual block diagram of the M/H frame
encoder 301 according to an embodiment of the present invention.
The M/H frame encoder 301 includes an input demultiplexer (DEMUX)
309, M number of RS frame encoders 310 to 31M-1, and an output
multiplexer (MUX) 320. Herein, M represent the number of parades
included in one M/H frame.
The input demultiplexer 309 output the inputted mobile service data
packet to a corresponding RS frame encoder among M number of RS
frame encoders in ensemble units.
At this point, the ensemble may be mapped to the RS frame encoder
or a parade. For example, when one parade is configured of one RS
frame, each ensemble, RS frame, and parade may be mapped to be in a
1:1:1 (or one-to-one-to-one) correspondence.
According to an embodiment of the present invention, each RS frame
encoder groups a plurality of mobile service data packets of the
ensemble inputted, so as to configure an RS frame corresponding to
the ensemble and, then, to perform an error correction encoding
process in RS frame units. Also, each RS frame encoder divides the
error-correction-encoded RS frame into a plurality of portions, in
order to assign the error-correction-encoded RS frame data to a
plurality of data groups. Based upon the RS frame mode of Table 1,
data within one RS frame may be assigned either to all of regions
A/B/C/D within multiple data groups, or to at least one of regions
A/B and regions C/D within multiple data groups.
When the RS frame mode value is equal to `01`, i.e., when the data
of the primary RS frame are assigned to regions A/B of the
corresponding data group and data of the secondary RS frame are
assigned to regions C/D of the corresponding data group, each RS
frame encoder generates a primary RS frame and a secondary RS frame
for each parade. Conversely, when the RS frame mode value is equal
to `00`, when the data of the primary RS frame are assigned to all
of regions A/B/C/D, each RS frame encoder generates a RS frame
(i.e., a primary RS frame) for each parade.
Also, each RS frame encoder divides each RS frame into several
portions. Each portion of the RS frame is equivalent to a data
amount that can be transmitted by a data group. The output
multiplexer (MUX) 320 multiplexes portions within M number of RS
frame encoders 310 to 310M-1 are multiplexed and then outputted to
the block processor 302.
For example, if one parade transmits two RS frames, portions of
primary RS frames within M number of RS frame encoders 310 to
310M-1 are multiplexed and outputted. Thereafter, portions of
secondary RS frames within M number of RS frame encoders 310 to
310M-1 are multiplexed and transmitted.
The input demultiplexer (DEMUX) 309 and the output multiplexer
(MUX) 320 operate based upon the control of the controller 201. The
controller 201 may provide necessary (or required) FEC modes to
each RS frame encoder. The FEC mode includes the RS code mode,
which will be described in detail in a later process.
FIG. 22 illustrates a detailed block diagram of an RS frame encoder
among a plurality of RS frame encoders within an M/H frame
encoder.
One RS frame encoder may include a primary encoder 410 and a
secondary encoder 420. Herein, the secondary encoder 420 may or may
not operate based upon the RS frame mode. For example, when the RS
frame mode value is equal to `00`, as shown in Table 1, the
secondary encoder 420 does not operate.
The primary encoder 410 may include a data randomizer 411, a
Reed-Solomon-cyclic redundancy check (RS-CRC) encoder (412), and a
RS frame divider 413. And, the secondary encoder 420 may also
include a data randomizer 421, a RS-CRC encoder (422), and a RS
frame divider 423.
More specifically, the data randomizer 411 of the primary encoder
410 receives mobile service data of a primary ensemble outputted
from the output demultiplexer (DE-MUX) 309. Then, after randomizing
the received mobile service data, the data randomizer 411 outputs
the randomized data to the RS-CRC encoder 412. At this point, since
the data randomizer 411 performs the randomizing process on the
mobile service data, the randomizing process that is to be
performed by the data randomizer 251 of the post-processor 250 on
the mobile service data may be omitted. The data randomizer 411 may
also discard the synchronization byte within the mobile service
data packet and perform the randomizing process. This is an option
that may be chosen by the system designer. In the example given in
the present invention, the randomizing process is performed without
discarding the synchronization byte within the corresponding mobile
service data packet.
The RS-CRC encoder 412 generates a RS frame corresponding to the
randomized primary ensemble, and performs forward error collection
(FEC)-encoding in the RS frame unit using at least one of a
Reed-Solomon (RS) code and a cyclic redundancy check (CRC) code.
The RS-CRC encoder 412 outputs the FEC-encoded RS frame to the RS
frame divider 413.
The RS-CRC encoder 412 groups a plurality of mobile service data
packets that is randomized and inputted, so as to generate a RS
frame. Then, the RS-CRC encoder 412 performs at least one of an
error correction encoding process and an error detection encoding
process in RS frame units. Accordingly, robustness may be provided
to the mobile service data, thereby scattering group error that may
occur during changes in a frequency environment, thereby enabling
the mobile service data to respond to the frequency environment,
which is extremely vulnerable and liable to frequent changes. Also,
the RS-CRC encoder 412 groups a plurality of RS frame so as to
generate a super frame, thereby performing a row permutation
process in super frame units. The row permutation process may also
be referred to as a "row interleaving process". Hereinafter, the
process will be referred to as "row permutation" for simplicity. In
the present invention, the row permutation process is optional.
More specifically, when the RS-CRC encoder 412 performs the process
of permuting each row of the super frame in accordance with a
pre-determined rule, the position of the rows within the super
frame before and after the row permutation process is changed. If
the row permutation process is performed by super frame units, and
even though the section having a plurality of errors occurring
therein becomes very long, and even though the number of errors
included in the RS frame, which is to be decoded, exceeds the
extent of being able to be corrected, the errors become dispersed
within the entire super frame. Thus, the decoding ability is even
more enhanced as compared to a single RS frame.
At this point, as an example of the present invention, RS-encoding
is applied for the error correction encoding process, and a cyclic
redundancy check (CRC) encoding is applied for the error detection
process in the RS-CRC encoder 412. When performing the RS-encoding,
parity data that are used for the error correction are generated.
And, when performing the CRC encoding, CRC data that are used for
the error detection are generated. The CRC data generated by CRC
encoding may be used for indicating whether or not the mobile
service data have been damaged by the errors while being
transmitted through the channel. In the present invention, a
variety of error detection coding methods other than the CRC
encoding method may be used, or the error correction coding method
may be used to enhance the overall error correction ability of the
receiving system.
Herein, the RS-CRC encoder 412 refers to a pre-determined
transmission parameter provided by the controller 201 so as to
perform operations including RS frame configuration, RS encoding,
CRC encoding, super frame configuration, and row permutation in
super frame units.
FIG. 23(a) and FIG. 23(b) illustrate a process of one or two RS
frame being divided into several portions, based upon an RS frame
mode value, and a process of each portion being assigned to a
corresponding region within the respective data group. According to
an embodiment of the present invention, the data assignment within
the data group is performed by the group formatter 303.
More specifically, FIG. 23(a) shows an example of the RS frame mode
value being equal to `00`. Herein, only the primary encoder 410 of
FIG. 22 operates, thereby forming one RS frame for one parade.
Then, the RS frame is divided into several portions, and the data
of each portion are assigned to regions A/B/C/D within the
respective data group. FIG. 23(b) shows an example of the RS frame
mode value being equal to `01`. Herein, both the primary encoder
410 and the secondary encoder 420 of FIG. 22 operate, thereby
forming two RS frames for one parade, i.e., one primary RS frame
and one secondary RS frame. Then, the primary RS frame is divided
into several portions, and the secondary RS frame is divided into
several portions. At this point, the data of each portion of the
primary RS frame are assigned to regions A/B within the respective
data group. And, the data of each portion of the secondary RS frame
are assigned to regions C/D within the respective data group.
Detailed Description of the RS Frame
FIG. 24(a) illustrates an example of an RS frame being generated
from the RS-CRC encoder 412 according to the present invention.
When the RS frame is generated, as shown in FIG. 24(a), the RS-CRC
encoder 412 performs a (Nc,Kc)-RS encoding process on each column,
so as to generate Nc-Kc(=P) number of parity bytes. Then, the
RS-CRC encoder 412 adds the newly generated P number of parity
bytes after the very last byte of the corresponding column, thereby
generating a column of (187+P) bytes. Herein, as shown in FIG.
24(a), Kc is equal to 187 (i.e., Kc=187), and Nc is equal to 187+P
(i.e., Nc=187+P). Herein, the value of P may vary depending upon
the RS code mode. Table 6 below shows an example of an RS code
mode, as one of the RS encoding information.
TABLE-US-00006 TABLE 6 RS code mode RS code Number of Parity Bytes
(P) 00 (211, 187) 24 01 (223, 187) 36 10 (235, 187) 48 11 Reserved
Reserved
Table 6 shows an example of 2 bits being assigned in order to
indicate the RS code mode. The RS code mode represents the number
of parity bytes corresponding to the RS frame.
For example, when the RS code mode value is equal to `10`,
(235,187)-RS-encoding is performed on the RS frame of FIG. 24(a),
so as to generate 48 parity data bytes. Thereafter, the 48 parity
bytes are added after the last data byte of the corresponding
column, thereby generating a column of 235 data bytes.
When the RS frame mode value is equal to `00` in Table 1 (i.e.,
when the RS frame mode indicates a single RS frame), only the RS
code mode of the corresponding RS frame is indicated. However, when
the RS frame mode value is equal to `01` in Table 1 (i.e., when the
RS frame mode indicates multiple RS frames), the RS code mode
corresponding to a primary RS frame and a secondary RS frame. More
specifically, it is preferable that the RS code mode is
independently applied to the primary RS frame and the secondary RS
frame.
When such RS encoding process is performed on all N number of
columns, a RS frame having the size of N(row).times.(187+P)
(column) bytes may be generated, as shown in FIG. 24(b).
Each row of the RS frame is configured of N bytes. However,
depending upon channel conditions between the transmitting system
and the receiving system, error may be included in the RS frame.
When errors occur as described above, CRC data (or CRC code or CRC
checksum) may be used on each row unit in order to verify whether
error exists in each row unit.
The RS-CRC encoder 412 may perform CRC encoding on the mobile
service data being RS encoded so as to create (or generate) the CRC
data. The CRC data being generated by CRC encoding may be used to
indicate whether the mobile service data have been damaged while
being transmitted through the channel.
The present invention may also use different error detection
encoding methods other than the CRC encoding method. Alternatively,
the present invention may use the error correction encoding method
to enhance the overall error correction ability of the receiving
system.
FIG. 24(c) illustrates an example of using a 2-byte (i.e., 16-bit)
CRC checksum as the CRC data. Herein, a 2-byte CRC checksum is
generated for N number of bytes of each row, thereby adding the
2-byte CRC checksum at the end of the N number of bytes. Thus, each
row is expanded to (N+2) number of bytes. Equation 3 below
corresponds to an exemplary equation for generating a 2-byte CRC
checksum for each row being configured of N number of bytes.
g(x)=x.sup.16+x.sup.12+x.sup.5+1 Equation 3
The process of adding a 2-byte checksum in each row is only
exemplary. Therefore, the present invention is not limited only to
the example proposed in the description set forth herein. As
described above, when the process of RS encoding and CRC encoding
are completed, the (N.times.187)-byte RS frame is expanded to a
(N+2).times.(187+P)-byte RS frame. Based upon an error correction
scenario of a RS frame expanded as described above, the data bytes
within the RS frame are transmitted through a channel in a row
direction. At this point, when a large number of errors occur
during a limited period of transmission time, errors also occur in
a row direction within the RS frame being processed with a decoding
process in the receiving system. However, in the perspective of RS
encoding performed in a column direction, the errors are shown as
being scattered. Therefore, error correction may be performed more
effectively. At this point, a method of increasing the number of
parity data bytes (P) may be used in order to perform a more
intense error correction process. However, using this method may
lead to a decrease in transmission efficiency. Therefore, a
mutually advantageous method is required. Furthermore, when
performing the decoding process, an erasure decoding process may be
used to enhance the error correction performance.
Additionally, the RS-CRC encoder 412 according to the present
invention also performs a row permutation (or interleaving) process
in super frame units in order to further enhance the error
correction performance when error correction the RS frame.
FIG. 25(a) to FIG. 25(d) illustrates an example of performing a row
permutation process in super frame units according to the present
invention. More specifically, G number of RS frames RS-CRC-encoded
is grouped to form a super frame, as shown in FIG. 25(a). At this
point, since each RS frame is formed of (N+2).times.(187+P) number
of bytes, one super frame is configured to have the size of
(N+2).times.(187+P).times.G bytes.
When a row permutation process permuting each row of the super
frame configured as described above is performed based upon a
pre-determined permutation rule, the positions of the rows prior to
and after being permuted (or interleaved) within the super frame
may be altered. More specifically, the i.sup.th row of the super
frame prior to the interleaving process, as shown in FIG. 25(b), is
positioned in the j.sup.th row of the same super frame after the
row permutation process, as shown in FIG. 25(c). The
above-described relation between i and j can be easily understood
with reference to a permutation rule as shown in Equation 4 below.
j=G(i mod (187+P))+.left brkt-bot.i/(187+P).right brkt-bot.
i=(187+P)(j mod G)+.left brkt-bot.j/G.right brkt-bot. Equation
4
where 0.ltoreq.i, j.ltoreq.(187+P)G-1; or
where 0.ltoreq.i, j<(187+P)G
Herein, each row of the super frame is configured of (N+2) number
of data bytes even after being row-permuted in super frame
units.
When all row permutation processes in super frame units are
completed, the super frame is once again divided into G number of
row-permuted RS frames, as shown in FIG. 25(d), and then provided
to the RS frame divider 413. Herein, the number of RS parity bytes
and the number of columns should be equally provided in each of the
RS frames, which configure a super frame. As described in the error
correction scenario of a RS frame, in case of the super frame, a
section having a large number of error occurring therein is so long
that, even when one RS frame that is to be decoded includes an
excessive number of errors (i.e., to an extent that the errors
cannot be corrected), such errors are scattered throughout the
entire super frame. Therefore, in comparison with a single RS
frame, the decoding performance of the super frame is more
enhanced.
The above description of the present invention corresponds to the
processes of forming (or creating) and encoding an RS frame, when a
data group is divided into regions A/B/C/D, and when data of an RS
frame are assigned to all of regions A/B/C/D within the
corresponding data group. More specifically, the above description
corresponds to an embodiment of the present invention, wherein one
RS frame is transmitted using one parade. In this embodiment, the
secondary encoder 420 does not operate (or is not active).
Meanwhile, 2 RS frames are transmitting using one parade, the data
of the primary RS frame may be assigned to regions A/B within the
data group and be transmitted, and the data of the secondary RS
frame may be assigned to regions C/D within the data group and be
transmitted. At this point, the primary encoder 410 receives the
mobile service data packets that are to be assigned to regions A/B
within the data group, so as to form the primary RS frame, thereby
performing RS-encoding and CRC-encoding. Similarly, the secondary
encoder 420 receives the mobile service data packets that are to be
assigned to regions C/D within the data group, so as to form the
secondary RS frame, thereby performing RS-encoding and
CRC-encoding. More specifically, the primary RS frame and the
secondary RS frame are generated independently.
FIG. 26 illustrates examples of receiving the mobile service data
packets that are to be assigned to regions A/B within the data
group, so as to form the primary RS frame, and receives the mobile
service data packets that are to be assigned to regions C/D within
the data group, so as to form the secondary RS frame, thereby
performing error correction encoding and error detection encoding
on each of the first and secondary RS frames.
More specifically, FIG. 26(a) illustrates an example of the RS-CRC
encoder 412 of the primary encoder 410 receiving mobile service
data packets of the primary ensemble that are to be assigned to
regions A/B within the corresponding data group, so as to generated
an RS frame having the size of N1(row).times.187(column). Then, in
this example, the primary encoder 410 performs RS-encoding on each
column of the RS frame generated as described above, thereby adding
P1 number of parity data bytes in each column. Finally, the primary
encoder 410 performs CRC-encoding on each row, thereby adding a
2-byte checksum in each row.
FIG. 26(b) illustrates an example of the RS-CRC encoder 422 of the
secondary encoder 420 receiving mobile service data packets of the
secondary ensemble that are to be assigned to regions C/D within
the corresponding data group, so as to generate an RS frame having
the size of N2(row).times.187(column). Then, in this example, the
secondary encoder 420 performs RS-encoding on each column of the RS
frame generated as described above, thereby adding P2 number of
parity data bytes in each column. Finally, the secondary encoder
420 performs CRC-encoding on each row, thereby adding a 2-byte
checksum in each row.
At this point, each of the RS-CRC encoders 412 and 422 may refer to
a pre-determined transmission parameter provided by the controller
201, the RS-CRC encoders 412 and 422 may be informed of M/H frame
information, FIC information, RS frame information (including RS
frame mode information), RS encoding information (including RS code
mode), SCCC information (including SCCC block mode information and
SCCC outer code mode information), data group information, and
region information within a data group. The RS-CRC encoders 412 and
422 may refer to the transmission parameters for the purpose of RS
frame configuration, error correction encoding, error detection
encoding. Furthermore, the transmission parameters should also be
transmitted to the receiving system so that the receiving system
can perform a normal decoding process. At this point, as an example
of the present invention, the transmission parameter is transmitted
through transmission parameter channel (TPC) to a receiving system.
The TPC will be described in detail in a later.
The data of the primary RS frame, which is encoded by RS frame
units and row-permuted by super frame units from the RS-CRC encoder
412 of the primary encoder 410, are outputted to the RS frame
divider 413. If the secondary encoder 420 also operates in the
embodiment of the present invention, the data of the secondary RS
frame, which is encoded by RS frame units and row-permuted by super
frame units from the RS-CRC encoder 422 of the secondary encoder
420, are outputted to the RS frame divider 423. The RS frame
divider 413 of the primary encoder 410 divides the primary RS frame
into several portions, which are then outputted to the output
multiplexer (MUX) 320. Each portion of the primary RS frame is
equivalent to a data amount that can be transmitted by one data
group. Similarly, the RS frame divider 423 of the secondary encoder
420 divides the secondary RS frame into several portions, which are
then outputted to the output multiplexer (MUX) 320.
Hereinafter, the RS frame divider 413 of the primary RS encoder 410
will now be described in detail. Also, in order to simplify the
description of the present invention, it is assumed that an RS
frame having the size of N(row).times.187(column), as shown in FIG.
24(a) to FIG. 24(c), that P number of parity data bytes are added
to each column by RS-encoding the RS frame, and that a 2-byte
checksum is added to each row by CRC-encoding the RS frame.
Accordingly, the RS frame divider 413 divides (or partitions) the
encoded RS frame having the size of (N+2)(row).times.187(column)
into several portions, each having the size of PL (wherein PL
corresponds to the length of the RS frame portion).
At this point, as shown in Table 2 to Table 5, the value of PL may
vary depending upon the RS frame mode, SCCC block mode, and SCCC
outer coder mode. Also, the total number of data bytes of the
RS-encoded and CRC-encoded RS frame is equal to or smaller than
5.times.NoG.times.PL. In this case, the RS frame is divided (or
partitioned) into ((5.times.NoG)-1) number of portions each having
the size of PL and one portion having a size equal to smaller than
PL. More specifically, with the exception of the last portion of
the RS frame, each of the remaining portions of the RS frame has an
equal size of PL. If the size of the last portion is smaller than
PL, a stuffing byte (or dummy byte) may be inserted in order to
fill (or replace) the lacking number of data bytes, thereby
enabling the last portion of the RS frame to also be equal to PL.
Each portion of an RS frame corresponds to the amount of data that
are to be SCCC-encoded and mapped into a single data group of a
parade.
FIG. 27(a) and FIG. 27(b) respectively illustrate examples of
adding S number of stuffing bytes, when an RS frame having the size
of (N+2)(row).times.(187+P) (column) is divided into 5.times.NoG
number of portions, each having the size of PL. More specifically,
the RS-encoded and CRC-encoded RS frame, shown in FIG. 27(a), is
divided into several portions, as shown in FIG. 27(b). The number
of divided portions at the RS frame is equal to (5.times.NoG).
Particularly, the first ((5.times.NoG)-1) number of portions each
has the size of PL, and the last portion of the RS frame may be
equal to or smaller than PL. If the size of the last portion is
smaller than PL, a stuffing byte (or dummy byte) may be inserted in
order to fill (or replace) the lacking number of data bytes, as
shown in Equation 5 below, thereby enabling the last portion of the
RS frame to also be equal to PL.
S=(5.times.NoG.times.PL)-((N+2).times.(187+P)) Equation 5
Herein, each portion including data having the size of PL passes
through the output multiplexer 320 of the M/H frame encoder 301,
which is then outputted to the block processor 302.
At this point, the mapping order of the RS frame portions to a
parade of data groups in not identical with the group assignment
order defined in Equation 1. When given the group positions of a
parade in an M/H frame, the SCCC-encoded RS frame portions will be
mapped in a time order (i.e., in a left-to-right direction).
For example, as shown in FIG. 11, data groups of the 2.sup.nd
parade (Parade #1) are first assigned (or allocated) to the
13.sup.th slot (Slot #12) and then assigned to the 3.sup.rd slot
(Slot #2). However, when the data are actually placed in the
assigned slots, the data are placed in a time sequence (or time
order, i.e., in a left-to-right direction). More specifically, the
1.sup.st data group of Parade #1 is placed in Slot #2, and the
2.sup.nd data group of Parade #1 is placed in Slot #12.
Block Processor
Meanwhile, the block processor 302 performs an SCCC outer encoding
process on the output of the M/H frame encoder 301. More
specifically, the block processor 302 receives the data of each
error correction encoded portion. Then, the block processor 302
encodes the data once again at a coding rate of 1/H (wherein H is
an integer equal to or greater than 2 (i.e., H.gtoreq.2)), thereby
outputting the 1/H-rate encoded data to the group formatter 303.
According to the embodiment of the present invention, the input
data are encoded either at a coding rate of 1/2 (also referred to
as "1/2-rate encoding") or at a coding rate of 1/4 (also referred
to as "1/4-rate encoding"). The data of each portion outputted from
the M/H frame encoder 301 may include at least one of pure mobile
service data, RS parity data, CRC data, and stuffing data. However,
in a broader meaning, the data included in each portion may
correspond to data for mobile services. Therefore, the data
included in each portion will all be considered as mobile service
data and described accordingly.
The group formatter 303 inserts the mobile service data
SCCC-outer-encoded and outputted from the block processor 302 in
the corresponding region within the data group, which is formed in
accordance with a pre-defined rule. Also, in association with the
data deinterleaving process, the group formatter 303 inserts
various place holders (or known data place holders) in the
corresponding region within the data group. Thereafter, the group
formatter 303 deinterleaves the data within the data group and the
place holders.
According to the present invention, with reference to data after
being data-interleaved, as shown in FIG. 5, a data groups is
configured of 10 M/H blocks (B1 to B10) and divided into 4 regions
(A, B, C, and D). Also, as shown in FIG. 5, when it is assumed that
the data group is divided into a plurality of hierarchical regions,
as described above, the block processor 302 may encode the mobile
service data, which are to be inserted to each region based upon
the characteristic of each hierarchical region, at different coding
rates. For example, the block processor 302 may encode the mobile
service data, which are to be inserted in region A/B within the
corresponding data group, at a coding rate of 1/2. Then, the group
formatter 303 may insert the 1/2-rate encoded mobile service data
to region A/B. Also, the block processor 302 may encode the mobile
service data, which are to be inserted in region C/D within the
corresponding data group, at a coding rate of 1/4 having higher (or
stronger) error correction ability than the 1/2-coding rate.
Thereafter, the group formatter 303 may insert the 1/2-rate encoded
mobile service data to region C/D. In another example, the block
processor 302 may encode the mobile service data, which are to be
inserted in region C/D, at a coding rate having higher error
correction ability than the 1/4-coding rate. Then, the group
formatter 303 may either insert the encoded mobile service data to
region C/D, as described above, or leave the data in a reserved
region for future usage.
According to another embodiment of the present invention, the block
processor 302 may perform a 1/H-rate encoding process in SCCC block
units. Herein, the SCCC block includes at least one M/H block. At
this point, when 1/H-rate encoding is performed in M/H block units,
the M/H blocks (B1 to B10) and the SCCC block (SCB1 to SCB10)
become identical to one another (i.e., SCB1=B1, SCB2=B2, SCB3=B3,
SCB4=B4, SCB5=B5, SCB6=B6, SCB7=B7, SCB8=B8, SCB9=B9, and
SCB10=B10). For example, the M/H block 1 (B1) may be encoded at the
coding rate of 1/2, the M/H block 2 (B2) may be encoded at the
coding rate of 1/4, and the M/H block 3 (B3) may be encoded at the
coding rate of 1/2. The coding rates are applied respectively to
the remaining M/H blocks.
Alternatively, a plurality of M/H blocks within regions A, B, C,
and D may be grouped into one SCCC block, thereby being encoded at
a coding rate of 1/H in SCCC block units. Accordingly, the
receiving performance of region C/D may be enhanced. For example,
M/H block 1 (B1) to M/H block 5 (B5) may be grouped into one SCCC
block and then encoded at a coding rate of 1/2. Thereafter, the
group formatter 303 may insert the 1/2-rate encoded mobile service
data to a section starting from M/H block 1 (B1) to M/H block 5
(B5). Furthermore, M/H block 6 (B6) to M/H block 10 (B10) may be
grouped into one SCCC block and then encoded at a coding rate of
1/4. Thereafter, the group formatter 303 may insert the 1/4-rate
encoded mobile service data to another section starting from M/H
block 6 (B6) to M/H block 10 (B10). In this case, one data group
may consist of two SCCC blocks.
According to another embodiment of the present invention, one SCCC
block may be formed by grouping two M/H blocks. For example, M/H
block 1 (B1) and M/H block 6 (B6) may be grouped into one SCCC
block (SCB1). Similarly, M/H block 2 (B2) and M/H block 7 (B7) may
be grouped into another SCCC block (SCB2). Also, M/H block 3 (B3)
and M/H block 8 (B8) may be grouped into another SCCC block (SCB3).
And, M/H block 4 (B4) and M/H block 9 (B9) may be grouped into
another SCCC block (SCB4). Furthermore, M/H block 5 (B5) and M/H
block 10 (B10) may be grouped into another SCCC block (SCB5). In
the above-described example, the data group may consist of 10 M/H
blocks and 5 SCCC blocks. Accordingly, in a data (or signal)
receiving environment undergoing frequent and severe channel
changes, the receiving performance of regions C and D, which is
relatively more deteriorated than the receiving performance of
region A, may be reinforced. Furthermore, since the number of
mobile service data symbols increases more and more from region A
to region D, the error correction encoding performance becomes more
and more deteriorated. Therefore, when grouping a plurality of M/H
block to form one SCCC block, such deterioration in the error
correction encoding performance may be reduced.
As described-above, when the block processor 302 performs encoding
at a 1/H-coding rate, information associated with SCCC should be
transmitted to the receiving system in order to accurately recover
the mobile service data. Table 7 below shows an example of a SCCC
block mode, which indicating the relation between an M/H block and
an SCCC block, among diverse SCCC block information.
TABLE-US-00007 TABLE 7 SCCC Block Mode 00 01 10 11 Description One
M/H Block Two M/H Blocks per SCCC Block per SCCC Block Reserved
Reserved SCB SCB input, SCB input, M/H Block M/H Blocks SCB1 B1 B1
+ B6 SCB2 B2 B2 + B7 SCB3 B3 B3 + B8 SCB4 B4 B4 + B9 SCB5 B5 B5 +
B10 SCB6 B6 -- SCB7 B7 -- SCB8 B8 -- SCB9 B9 -- SCB10 B10 --
More specifically, Table 4 shows an example of 2 bits being
allocated in order to indicate the SCCC block mode. For example,
when the SCCC block mode value is equal to `00`, this indicates
that the SCCC block and the M/H block are identical to one another.
Also, when the SCCC block mode value is equal to `01`, this
indicates that each SCCC block is configured of 2 M/H blocks.
As described above, if one data group is configured of 2 SCCC
blocks, although it is not indicated in Table 7, this information
may also be indicated as the SCCC block mode. For example, when the
SCCC block mode value is equal to `10`, this indicates that each
SCCC block is configured of 5 M/H blocks and that one data group is
configured of 2 SCCC blocks. Herein, the number of M/H blocks
included in an SCCC block and the position of each M/H block may
vary depending upon the settings made by the system designer.
Therefore, the present invention will not be limited to the
examples given herein. Accordingly, the SCCC mode information may
also be expanded.
An example of a coding rate information of the SCCC block, i.e.,
SCCC outer code mode, is shown in Table 8 below.
TABLE-US-00008 TABLE 8 SCCC outer code mode (2 bits) Description 00
Outer code rate of SCCC block is 1/2 rate 01 Outer code rate of
SCCC block is 1/4 rate 10 Reserved 11 Reserved
More specifically, Table 8 shows an example of 2 bits being
allocated in order to indicate the coding rate information of the
SCCC block. For example, when the SCCC outer code mode value is
equal to `00`, this indicates that the coding rate of the
corresponding SCCC block is 1/2. And, when the SCCC outer code mode
value is equal to `01`, this indicates that the coding rate of the
corresponding SCCC block is 1/4.
If the SCCC block mode value of Table 7 indicates `00`, the SCCC
outer code mode may indicate the coding rate of each M/H block with
respect to each M/H block. In this case, since it is assumed that
one data group includes 10 M/H blocks and that 2 bits are allocated
for each SCCC block mode, a total of 20 bits are required for
indicating the SCCC block modes of the 10 M/H modes. In another
example, when the SCCC block mode value of Table 7 indicates `00`,
the SCCC outer code mode may indicate the coding rate of each
region with respect to each region within the data group. In this
case, since it is assumed that one data group includes 4 regions
(i.e., regions A, B, C, and D) and that 2 bits are allocated for
each SCCC block mode, a total of 8 bits are required for indicating
the SCCC block modes of the 4 regions. In another example, when the
SCCC block mode value of Table 7 is equal to `01`, each of the
regions A, B, C, and D within the data group has the same SCCC
outer code mode.
Meanwhile, an example of an SCCC output block length (SOBL) for
each SCCC block, when the SCCC block mode value is equal to `00`,
is shown in Table 9 below.
TABLE-US-00009 TABLE 9 SIBL SCCC Block SOBL 1/2 rate 1/4 rate SCB1
(B1) 528 264 132 SCB2 (B2) 1536 768 384 SCB3 (B3) 2376 1188 594
SCB4 (B4) 2388 1194 597 SCB5 (B5) 2772 1386 693 SCB6 (B6) 2472 1236
618 SCB7 (B7) 2772 1386 693 SCB8 (B8) 2508 1254 627 SCB9 (B9) 1416
708 354 SCB10 (B10) 480 240 120
More specifically, when given the SCCC output block length (SOBL)
for each SCCC block, an SCCC input block length (SIBL) for each
corresponding SCCC block may be decided based upon the outer coding
rate of each SCCC block. The SOBL is equivalent to the number of
SCCC output (or outer-encoded) bytes for each SCCC block. And, the
SIBL is equivalent to the number of SCCC input (or payload) bytes
for each SCCC block. Table 10 below shows an example of the SOBL
and SIBL for each SCCC block, when the SCCC block mode value is
equal to `01`.
TABLE-US-00010 TABLE 10 SIBL SCCC Block SOBL 1/2 rate 1/4 rate SCB1
(B1 + B6) 528 264 132 SCB2 (B2 + B7) 1536 768 384 SCB3 (B3 + B8)
2376 1188 594 SCB4 (B4 + B9) 2388 1194 597 SCB5 (B5 + B10) 2772
1386 693
In order to do so, as shown in FIG. 28, the block processor 302
includes a RS frame portion-SCCC block converter 511, a byte-bit
converter 512, a convolution encoder 513, a symbol interleaver 514,
a symbol-byte converter 515, and an SCCC block-M/H block converter
516. The convolutional encoder 513 and the symbol interleaver 514
are virtually concatenated with the trellis encoding module in the
post-processor in order to configure an SCCC block. More
specifically, the RS frame portion-SCCC block converter 511 divides
the RS frame portions, which are being inputted, into multiple SCCC
blocks using the SIBL of Table 9 and Table 10 based upon the RS
code mode, SCCC block mode, and SCCC outer code mode. Herein, the
M/H frame encoder 301 may output only primary RS frame portions or
both primary RS frame portions and secondary RS frame portions in
accordance with the RS frame mode.
When the RS Frame mode is set to `00`, a portion of the primary RS
Frame equal to the amount of data, which are to be SCCC outer
encoded and mapped to 10 M/H blocks (B1 to B10) of a data group,
will be provided to the block processor 302. When the SCCC block
mode value is equal to `00`, then the primary RS frame portion will
be split into 10 SCCC Blocks according to Table 9. Alternatively,
when the SCCC block mode value is equal to `01`, then the primary
RS frame will be split into 5 SCCC blocks according to Table
10.
When the RS frame mode value is equal to `01`, then the block
processor 302 may receive two RS frame portions. The RS frame mode
value of `01` will not be used with the SCCC block mode value of
`01`. The first portion from the primary RS frame will be
SCCC-outer-encoded as SCCC Blocks SCB3, SCB4, SCB5, SCB6, SCB7, and
SCB8 by the block processor 302. The SCCC Blocks SCB3 and SCB8 will
be mapped to region B and the SCCC blocks SCB4, SCB5, SCB6, and
SCB7 shall be mapped to region A by the group formatter 303. The
second portion from the secondary RS frame will also be
SCCC-outer-encoded, as SCB1, SCB2, SCB9, and SCB10, by the block
processor 302. The group formatter 303 will map the SCCC blocks
SCB1 and SCB10 to region D as the M/H blocks B1 and B10,
respectively. Similarly, the SCCC blocks SCB2 and SCB9 will be
mapped to region C as the M/H blocks B2 and B9.
The byte-bit converter 512 identifies the mobile service data bytes
of each SCCC block outputted from the RS frame portion-SCCC block
converter 511 as data bits, which are then outputted to the
convolution encoder 513. The convolution encoder 513 performs one
of 1/2-rate encoding and 1/4-rate encoding on the inputted mobile
service data bits.
FIG. 29 illustrates a detailed block diagram of the convolution
encoder 513. The convolution encoder 513 includes two delay units
521 and 523 and three adders 522, 524, and 525. Herein, the
convolution encoder 513 encodes an input data bit U and outputs the
coded bit U to 5 bits (u0 to u4). At this point, the input data bit
U is directly outputted as uppermost bit u0 and simultaneously
encoded as lower bit u1u2u3u4 and then outputted. More
specifically, the input data bit U is directly outputted as the
uppermost bit u0 and simultaneously outputted to the first and
third adders 522 and 525.
The first adder 522 adds the input data bit U and the output bit of
the first delay unit 521 and, then, outputs the added bit to the
second delay unit 523. Then, the data bit delayed by a
pre-determined time (e.g., by 1 clock) in the second delay unit 523
is outputted as a lower bit u1 and simultaneously fedback to the
first delay unit 521. The first delay unit 521 delays the data bit
fed-back from the second delay unit 523 by a pre-determined time
(e.g., by 1 clock). Then, the first delay unit 521 outputs the
delayed data bit as a lower bit u2 and, at the same time, outputs
the fed-back data to the first adder 522 and the second adder 524.
The second adder 524 adds the data bits outputted from the first
and second delay units 521 and 523 and outputs the added data bits
as a lower bit u3. The third adder 525 adds the input data bit U
and the output of the second delay unit 523 and outputs the added
data bit as a lower bit u4.
At this point, the first and second delay units 521 and 523 are
reset to `0`, at the starting point of each SCCC block. The
convolution encoder 513 of FIG. 29 may be used as a 1/2-rate
encoder or a 1/4-rate encoder. More specifically, when a portion of
the output bit of the convolution encoder 513, shown in FIG. 29, is
selected and outputted, the convolution encoder 513 may be used as
one of a 1/2-rate encoder and a 1/4-rate encoder. Table 11 below
shown an example of output symbols of the convolution encoder
513.
TABLE-US-00011 TABLE 11 1/4 rate Region 1/2 rate SCCC block mode =
`00` SCCC block mode = `01` A, B (u0, u1) (u0, u2), (u1, u3) (u0,
u2), (u1, u4) C, D (u0, u1), (u3, u4)
For example, at the 1/2-coding rate, 1 output symbol (i.e., u0 and
u1 bits) may be selected and outputted. And, at the 1/4-coding
rate, depending upon the SCCC block mode, 2 output symbols (i.e., 4
bits) may be selected and outputted. For example, when the SCCC
block mode value is equal to `01`, and when an output symbol
configured of u0 and u2 and another output symbol configured of u1
and u4 are selected and outputted, a 1/4-rate coding result may be
obtained.
The mobile service data encoded at the coding rate of 1/2 or 1/4 by
the convolution encoder 513 are outputted to the symbol interleaver
514. The symbol interleaver 514 performs block interleaving, in
symbol units, on the output data symbol of the convolution encoder
513. More specifically, the symbol interleaver 514 is a type of
block interleaver. Any interleaver performing structural
rearrangement (or realignment) may be applied as the symbol
interleaver 514 of the block processor. However, in the present
invention, a variable length symbol interleaver that can be applied
even when a plurality of lengths is provided for the symbol, so
that its order may be rearranged, may also be used.
FIG. 30 illustrates a symbol interleaver according to an embodiment
of the present invention. Particularly, FIG. 30 illustrates an
example of the symbol interleaver when B=2112 and L=4096. Herein, B
indicates a block length in symbols that are outputted for symbol
interleaving from the convolution encoder 513. And, L represents a
block length in symbols that are actually interleaved by the symbol
interleaver 514. At this point, the block length in symbols B
inputted to the symbol interleaver 514 is equivalent to
4.times.SOBL. More specifically, since one symbol is configured of
2 bits, the value of B may be set to be equal to 4.times.SOBL.
In the present invention, when performing the symbol-intereleaving
process, the conditions of L=2.sup.m (wherein m is an integer) and
of L.gtoreq.B should be satisfied. If there is a difference in
value between B and L, (L-B) number of null (or dummy) symbols is
added, thereby generating an interleaving pattern, as shown in
P'(i) of FIG. 30. Therefore, B becomes a block size of the actual
symbols that are inputted to the symbol interleaver 514 in order to
be interleaved. L becomes an interleaving unit when the
interleaving process is performed by an interleaving pattern
generated from the symbol interleaver 514.
Equation 6 shown below describes the process of sequentially
receiving B number of symbols, the order of which is to be
rearranged, and obtaining an L value satisfying the conditions of
L=2.sup.m (wherein m is an integer) and of L.gtoreq.B, thereby
generating the interleaving so as to realign (or rearrange) the
symbol order.
In relation to all places, wherein 0.ltoreq.i.ltoreq.B-1,
P'(i)={89.times.i.times.(i+1)/2} mod L Equation 6
Herein, L.gtoreq.B, L=2.sup.m, wherein m is an integer.
As shown in P'(i) of FIG. 30, the order of B number of input
symbols and (L-B) number of null symbols is rearranged by using the
above-mentioned Equation 6. Then, as shown in P(i) of FIG. 30, the
null byte places are removed, so as to rearrange the order.
Starting with the lowest value of i, the P(i) are shifted to the
left in order to fill the empty entry locations. Thereafter, the
symbols of the aligned interleaving pattern P(i) are outputted to
the symbol-byte converter 515 in order. Herein, the symbol-byte
converter 515 converts to bytes the mobile service data symbols,
having the rearranging of the symbol order completed and then
outputted in accordance with the rearranged order, and thereafter
outputs the converted bytes to the SCCC block-M/H block converter
516. The SCCC block-M/H block converter 516 converts the
symbol-interleaved SCCC blocks to M/H blocks, which are then
outputted to the group formatter 303.
If the SCCC block mode value is equal to `00`, the SCCC block is
mapped at a one-to-one (1:1) correspondence with each M/H block
within the data group. In another example, if the SCCC block mode
value is equal to `01`, each SCCC block is mapped with two M/H
blocks within the data group. For example, the SCCC block SCB1 is
mapped with (B1, B6), the SCCC block SCB2 is mapped with (B2, B7),
the SCCC block SCB3 is mapped with (B3, B8), the SCCC block SCB4 is
mapped with (B4, B9), and the SCCC block SCB5 is mapped with (B5,
B10). The M/H block that is outputted from the SCCC block-M/H block
converter 516 is configured of mobile service data and FEC
redundancy. In the present invention, the mobile service data as
well as the FEC redundancy of the M/H block will be collectively
considered as mobile service data.
Group Formatter
The group formatter 303 inserts data of M/H blocks outputted from
the block processor 302 to the corresponding M/H blocks within the
data group, which is formed in accordance with a pre-defined rule.
Also, in association with the data-deinterleaving process, the
group formatter 303 inserts various place holders (or known data
place holders) in the corresponding region within the data group.
More specifically, apart from the encoded mobile service data
outputted from the block processor 302, the group formatter 303
also inserts MPEG header place holders, non-systematic RS parity
place holders, main service data place holders, which are
associated with the data deinterleaving in a later process, as
shown in FIG. 5.
Herein, the main service data place holders are inserted because
the mobile service data bytes and the main service data bytes are
alternately mixed with one another in regions B to D based upon the
input of the data deinterleaver, as shown in FIG. 5. For example,
based upon the data outputted after data deinterleaving, the place
holder for the MPEG header may be allocated at the very beginning
of each packet. Also, in order to configure an intended group
format, dummy bytes may also be inserted. Furthermore, the group
formatter 303 inserts initialization data (i.e., trellis
initialization byte) of the trellis encoding module 256 in the
corresponding regions. For example, the initialization data may be
inserted in the beginning of the known data sequence. The
initialization data is used for initializing memories within the
trellis encoding module 256, and is not transmitted to the
receiving system.
Additionally, the group formatter 303 may also insert signaling
information, which are encoded and outputted from the signaling
encoder 304, in corresponding regions within the data group. At
this point, reference may be made to the signaling information when
the group formatter 303 inserts each data type and respective place
holders in the data group. The process of encoding the signaling
information and inserting the encoded signaling information to the
data group will be described in detail in a later process.
After inserting each data type and respective place holders in the
data group, the group formatter 303 may deinterleave the data and
respective place holders, which have been inserted in the data
group, as an inverse process of the data interleaver, thereby
outputting the deinterleaved data and respective place holders to
the packet formatter 305. The group formatter 303 may include a
group format organizer 527, and a data deinterleaver 529, as shown
in FIG. 31. The group format organizer 527 inserts data and
respective place holders in the corresponding regions within the
data group, as described above. And, the data deinterleaver 529
deinterleaves the inserted data and respective place holders as an
inverse process of the data interleaver.
The packet formatter 305 removes the main service data place
holders and the RS parity place holders that were allocated for the
deinterleaving process from the deinterleaved data being inputted.
Then, the packet formatter 305 groups the remaining portion and
inserts the 3-byte MPEG header place holder in an MPEG header
having a null packet PID (or an unused PID from the main service
data packet). Furthermore, the packet formatter 305 adds a
synchronization data byte at the beginning of each 187-byte data
packet. Also, when the group formatter 303 inserts known data place
holders, the packet formatter 303 may insert actual known data in
the known data place holders, or may directly output the known data
place holders without any modification in order to make replacement
insertion in a later process. Thereafter, the packet formatter 305
identifies the data within the packet-formatted data group, as
described above, as a 188-byte unit mobile service data packet
(i.e., MPEG TS packet), which is then provided to the packet
multiplexer 240.
Based upon the control of the controller 201, the packet
multiplexer 240 multiplexes the data group packet-formatted and
outputted from the packet formatter 306 and the main service data
packet outputted from the packet jitter mitigator 220. Then, the
packet multiplexer 240 outputs the multiplexed data packets to the
data randomizer 251 of the post-processor 250. More specifically,
the controller 201 controls the time-multiplexing of the packet
multiplexer 240. If the packet multiplexer 240 receives 118 mobile
service data packets from the packet formatter 305, 37 mobile
service data packets are placed before a place for inserting VSB
field synchronization. Then, the remaining 81 mobile service data
packets are placed after the place for inserting VSB field
synchronization. The multiplexing method may be adjusted by diverse
variables of the system design. The multiplexing method and
multiplexing rule of the packet multiplexer 240 will be described
in more detail in a later process.
Also, since a data group including mobile service data in-between
the data bytes of the main service data is multiplexed (or
allocated) during the packet multiplexing process, the shifting of
the chronological position (or place) of the main service data
packet becomes relative. Also, a system object decoder (i.e., MPEG
decoder) for processing the main service data of the receiving
system, receives and decodes only the main service data and
recognizes the mobile service data packet as a null data
packet.
Therefore, when the system object decoder of the receiving system
receives a main service data packet that is multiplexed with the
data group, a packet jitter occurs.
At this point, since a multiple-level buffer for the video data
exists in the system object decoder and the size of the buffer is
relatively large, the packet jitter generated from the packet
multiplexer 240 does not cause any serious problem in case of the
video data. However, since the size of the buffer for the audio
data in the object decoder is relatively small, the packet jitter
may cause considerable problem. More specifically, due to the
packet jitter, an overflow or underflow may occur in the buffer for
the main service data of the receiving system (e.g., the buffer for
the audio data). Therefore, the packet jitter mitigator 220
re-adjusts the relative position of the main service data packet so
that the overflow or underflow does not occur in the system object
decoder.
In the present invention, examples of repositioning places for the
audio data packets within the main service data in order to
minimize the influence on the operations of the audio buffer will
be described in detail. The packet jitter mitigator 220 repositions
the audio data packets in the main service data section so that the
audio data packets of the main service data can be as equally and
uniformly aligned and positioned as possible. Additionally, when
the positions of the main service data packets are relatively
re-adjusted, associated program clock reference (PCR) values may
also be modified accordingly. The PCR value corresponds to a time
reference value for synchronizing the time of the MPEG decoder.
Herein, the PCR value is inserted in a specific region of a TS
packet and then transmitted.
In the example of the present invention, the packet jitter
mitigator 220 also performs the operation of modifying the PCR
value. The output of the packet jitter mitigator 220 is inputted to
the packet multiplexer 240. As described above, the packet
multiplexer 240 multiplexes the main service data packet outputted
from the packet jitter mitigator 220 with the mobile service data
packet outputted from the pre-processor 230 into a burst structure
in accordance with a pre-determined multiplexing rule. Then, the
packet multiplexer 240 outputs the multiplexed data packets to the
data randomizer 251 of the post-processor 250.
If the inputted data correspond to the main service data packet,
the data randomizer 251 performs the same randomizing process as
that of the conventional randomizer. More specifically, the
synchronization byte within the main service data packet is
deleted. Then, the remaining 187 data bytes are randomized by using
a pseudo random byte generated from the data randomizer 251.
Thereafter, the randomized data are outputted to the RS
encoder/non-systematic RS encoder 252.
On the other hand, if the inputted data correspond to the mobile
service data packet, the data randomizer 251 may randomize only a
portion of the data packet. For example, if it is assumed that a
randomizing process has already been performed in advance on the
mobile service data packet by the pre-processor 230, the data
randomizer 251 deletes the synchronization byte from the 4-byte
MPEG header included in the mobile service data packet and, then,
performs the randomizing process only on the remaining 3 data bytes
of the MPEG header. Thereafter, the randomized data bytes are
outputted to the RS encoder/non-systematic RS encoder 252. More
specifically, the randomizing process is not performed on the
remaining portion of the mobile service data excluding the MPEG
header. In other words, the remaining portion of the mobile service
data packet is directly outputted to the RS encoder/non-systematic
RS encoder 252 without being randomized. Also, the data randomizer
251 may or may not perform a randomizing process on the known data
(or known data place holders) and the initialization data included
in the mobile service data packet.
The RS encoder/non-systematic RS encoder 252 performs an RS
encoding process on the data being randomized by the data
randomizer 251 or on the data bypassing the data randomizer 251, so
as to add 20 bytes of RS parity data. Thereafter, the processed
data are outputted to the data interleaver 253. Herein, if the
inputted data correspond to the main service data packet, the RS
encoder/non-systematic RS encoder 252 performs the same systematic
RS encoding process as that of the conventional broadcasting
system, thereby adding the 20-byte RS parity data at the end of the
187-byte data. Alternatively, if the inputted data correspond to
the mobile service data packet, the RS encoder/non-systematic RS
encoder 252 performs a non-systematic RS encoding process. At this
point, the 20-byte RS parity data obtained from the non-systematic
RS encoding process are inserted in a pre-decided parity byte place
within the mobile service data packet.
The data interleaver 253 corresponds to a byte unit convolutional
interleaver. The output of the data interleaver 253 is inputted to
the parity replacer 254 and to the non-systematic RS encoder
255.
Meanwhile, a process of initializing a memory within the trellis
encoding module 256 is primarily required in order to decide the
output data of the trellis encoding module 256, which is located
after the parity replacer 254, as the known data pre-defined
according to an agreement between the receiving system and the
transmitting system. More specifically, the memory of the trellis
encoding module 256 should first be initialized before the received
known data sequence is trellis-encoded.
At this point, the beginning portion of the known data sequence
that is received corresponds to the initialization data and not to
the actual known data. Herein, the initialization data has been
included in the data by the group formatter within the
pre-processor 230 in an earlier process. Therefore, the process of
replacing the initialization data with memory values within the
trellis encoding module 256 are required to be performed
immediately before the inputted known data sequence is
trellis-encoded.
More specifically, the initialization data are replaced with the
memory value within the trellis encoding module 256, thereby being
inputted to the trellis encoding module 256. At this point, the
memory value replacing the initialization data are process with (or
calculated by) an exclusive OR (XOR) operation with the respective
memory value within the trellis encoding module 256, so as to be
inputted to the corresponding memory. Therefore, the corresponding
memory is initialized to `0`. Additionally, a process of using the
memory value replacing the initialization data to re-calculate the
RS parity, so that the re-calculated RS parity value can replace
the RS parity being outputted from the data interleaver 253, is
also required.
Therefore, the non-systematic RS encoder 255 receives the mobile
service data packet including the initialization data from the data
interleaver 253 and also receives the memory value from the trellis
encoding module 256.
Among the inputted mobile service data packet, the initialization
data are replaced with the memory value, and the RS parity data
that are added to the mobile service data packet are removed and
processed with non-systematic RS encoding. Thereafter, the new RS
parity obtained by performing the non-systematic RS encoding
process is outputted to the parity replacer 255. Accordingly, the
parity replacer 255 selects the output of the data interleaver 253
as the data within the mobile service data packet, and the parity
replacer 255 selects the output of the non-systematic RS encoder
255 as the RS parity. The selected data are then outputted to the
trellis encoding module 256.
Meanwhile, if the main service data packet is inputted or if the
mobile service data packet, which does not include any
initialization data that are to be replaced, is inputted, the
parity replacer 254 selects the data and RS parity that are
outputted from the data interleaver 253. Then, the parity replacer
254 directly outputs the selected data to the trellis encoding
module 256 without any modification. The trellis encoding module
256 converts the byte-unit data to symbol units and performs a
12-way interleaving process so as to trellis-encode the received
data. Thereafter, the processed data are outputted to the
synchronization multiplexer 260.
FIG. 32 illustrates a detailed diagram of one of 12 trellis
encoders included in the trellis encoding module 256. Herein, the
trellis encoder includes first and second multiplexers 531 and 541,
first and second exclusive OR (XOR) gates 532 and 542, and first to
third memories 533, 542, and 544.
More specifically, the first to third memories 533, 542, and 544
are initialized by the memory value instead of the initialization
data from the parity replacer 254. More specifically, when the
first symbol (i.e., two bits), which are converted from
initialization data (i.e., each trellis initialization data byte),
are inputted, the input bits of the trellis encoder will be
replaced by the memory values of the trellis encoder, as shown in
FIG. 32.
Since 2 symbols (i.e., 4 bits) are required for trellis
initialization, the last 2 symbols (i.e., 4 bits) from the trellis
initialization bytes are not used for trellis initialization and
are considered as a symbol from a known data byte and processed
accordingly.
When the trellis encoder is in the initialization mode, the input
comes from an internal trellis status (or state) and not from the
parity replacer 254. When the trellis encoder is in the normal
mode, the input symbol (X2X1) provided from the parity replacer 254
will be processed. The trellis encoder provides the converted (or
modified) input data for trellis initialization to the
non-systematic RS encoder 255.
More specifically, when a selection signal designates a normal
mode, the first multiplexer 531 selects an upper bit X2 of the
input symbol. And, when a selection signal designates an
initialization mode, the first multiplexer 531 selects the output
of the first memory 533 and outputs the selected output data to the
first XOR gate 532. The first XOR gate 532 performs XOR operation
on the output of the first multiplexer 531 and the output of the
first memory 533, thereby outputting the added result to the first
memory 533 and, at the same time, as a most significant (or
uppermost) bit Z2. The first memory 533 delays the output data of
the first XOR gate 532 by 1 clock, thereby outputting the delayed
data to the first multiplexer 531 and the first XOR gate 532.
Meanwhile, when a selection signal designates a normal mode, the
second multiplexer 541 selects a lower bit X1 of the input symbol.
And, when a selection signal designates an initialization mode, the
second multiplexer 541 selects the output of the second memory 542,
thereby outputting the selected result to the second XOR gate 543
and, at the same time, as a lower bit Z1. The second XOR gate 543
performs XOR operation on the output of the second multiplexer 541
and the output of the second memory 542, thereby outputting the
added result to the third memory 544. The third memory 544 delays
the output data of the second XOR gate 543 by 1 clock, thereby
outputting the delayed data to the second memory 542 and, at the
same time, as a least significant (or lowermost) bit Z0. The second
memory 542 delays the output data of the third memory 544 by 1
clock, thereby outputting the delayed data to the second XOR gate
543 and the second multiplexer 541.
The select signal designates an initialization mode during the
first two symbols that are converted from the initialization
data.
For example, when the select signal designates an initialization
mode, the first XOR gate 532 performs an XOR operation on the value
of the first memory 533, which is provided through the first
multiplexer 531, and on a memory value that is directly provided
from the first memory 533. That is, the first XOR gate 532 performs
an XOR operation on 2 bits having the same value. Generally, when
only one of the two bits belonging to the operand is `1`, the
result of the XOR gate is equal to `1`. Otherwise, the result of
the XOR gate becomes equal to `0`. Therefore, when the value of the
first memory 533 is processed with an XOR operation, the result is
always equal to `0`. Furthermore, since the output of the first XOR
gate 532, i.e., `0`, is inputted to the first memory 533, the first
memory 533 is initialized to `0`.
Similarly, when the select signal designates an initialization
mode, the second XOR gate 543 performs an XOR operation on the
value of the second memory 542, which is provided through the
second multiplexer 541, and on a memory value that is directly
provided from the second memory 542. Therefore, the output of the
second XOR gate 543 is also always equal to `0`. Since the output
of the second XOR gate 543, i.e., `0`, is inputted to the third
memory 544, the third memory 544 is also initialized to `0`. The
output of the third memory 544 is inputted to the second memory 542
in the next clock, thereby initializing the second memory 542 to
`0`. In this case also, the select signal designates the
initialization mode.
More specifically, when the first symbol being converted from the
initialization data byte replaces the values of the first memory
533 and the second memory 542, thereby being inputted to the
trellis encoder, each of the first and third memories 533 and 544
within the trellis encoder is initialized to `00`. Following the
process, when the second symbol being converted from the
initialization data byte replaces the values of the first memory
533 and the second memory 542, thereby being inputted to the
trellis encoder, each of the first, second, and third memories 533,
542, and 544 within the trellis encoder is initialized to
`000`.
As described above, 2 symbols are required to initialize the memory
of the trellis encoder. At this point, while the select signal
designates an initialization mode, the output bits (X2'X1') of the
first and second memories 533 and 542 are inputted to the
non-systematic RS encoder 255, so as to perform a new RS parity
calculation process.
The synchronization multiplexer 260 inserts a field synchronization
signal and a segment synchronization signal to the data outputted
from the trellis encoding module 256 and, then, outputs the
processed data to the pilot inserter 271 of the transmission unit
270. Herein, the data having a pilot inserted therein by the pilot
inserter 271 are modulated by the modulator 272 in accordance with
a pre-determined modulating method (e.g., a VSB method).
Thereafter, the modulated data are transmitted to each receiving
system though the radio frequency (RF) up-converter 273.
Multiplexing Method of Packet Multiplexer
Data of the error correction encoded and 1/H-rate encoded primary
RS frame (i.e., when the RS frame mode value is equal to `00`) or
primary/secondary RS frame (i.e., when the RS frame mode value is
equal to `01`), are divided into a plurality of data groups by the
group formatter 303. Then, the divided data portions are assigned
to at least one of regions A to D of each data group or to an M/H
block among the M/H blocks B1 to B10, thereby being deinterleaved.
Then, the deinterleaved data group passes through the packet
formatter 305, thereby being multiplexed with the main service data
by the packet multiplexer 240 based upon a de-decided multiplexing
rule. The packet multiplexer 240 multiplexes a plurality of
consecutive data groups, so that the data groups are assigned to be
spaced as far apart from one another as possible within the
sub-frame. For example, when it is assumed that 3 data groups are
assigned to a sub-frame, the data groups are assigned to a 1.sup.st
slot (Slot #0), a 5.sup.th slot (Slot #4), and a 9.sup.th slot
(Slot #8) in the sub-frame, respectively.
As described-above, in the assignment of the plurality of
consecutive data groups, a plurality of parades are multiplexed and
outputted so as to be spaced as far apart from one another as
possible within a sub-frame. For example, the method of assigning
data groups and the method of assigning parades may be identically
applied to all sub-frames for each M/H frame or differently applied
to each M/H frame.
FIG. 10 illustrates an example of a plurality of data groups
included in a single parade, wherein the number of data groups
included in a sub-frame is equal to `3`, and wherein the data
groups are assigned to an M/H frame by the packet multiplexer 240.
Referring to FIG. 10, 3 data groups are sequentially assigned to a
sub-frame at a cycle period of 4 slots. Accordingly, when this
process is equally performed in the 5 sub-frames included in the
corresponding M/H frame, 15 data groups are assigned to a single
M/H frame. Herein, the 15 data groups correspond to data groups
included in a parade.
When data groups of a parade are assigned as shown in FIG. 10, the
packet multiplexer 240 may either assign main service data to each
data group, or assign data groups corresponding to different
parades between each data group. More specifically, the packet
multiplexer 240 may assign data groups corresponding to multiple
parades to one M/H frame. Basically, the method of assigning data
groups corresponding to multiple parades is very similar to the
method of assigning data groups corresponding to a single parade.
In other words, the packet multiplexer 240 may assign data groups
included in other parades to an M/H frame according to a cycle
period of 4 slots. At this point, data groups of a different parade
may be sequentially assigned to the respective slots in a circular
method. Herein, the data groups are assigned to slots starting from
the ones to which data groups of the previous parade have not yet
been assigned. For example, when it is assumed that data groups
corresponding to a parade are assigned as shown in FIG. 10, data
groups corresponding to the next parade may be assigned to a
sub-frame starting either from the 12.sup.th slot of a
sub-frame.
FIG. 11 illustrates an example of assigning and transmitting 3
parades (Parade #0, Parade #1, and Parade #2) to an M/H frame. For
example, when the 1.sup.st parade (Parade #0) includes 3 data
groups for each sub-frame, the packet multiplexer 240 may obtain
the positions of each data groups within the sub-frames by
substituting values `0` to `2` for i in Equation 1. More
specifically, the data groups of the 1.sup.st parade (Parade #0)
are sequentially assigned to the 1.sup.st, 5.sup.th, and 9.sup.th
slots (Slot #0, Slot #4, and Slot #8) within the sub-frame. Also,
when the 2.sup.nd parade includes 2 data groups for each sub-frame,
the packet multiplexer 240 may obtain the positions of each data
groups within the sub-frames by substituting values `3` and `4` for
i in Equation 1. More specifically, the data groups of the 2.sup.nd
parade (Parade #1) are sequentially assigned to the 2.sup.nd and
12.sup.th slots (Slot #3 and Slot #11) within the sub-frame.
Finally, when the 3.sup.rd parade includes 2 data groups for each
sub-frame, the packet multiplexer 240 may obtain the positions of
each data groups within the sub-frames by substituting values `5`
and `6` for in Equation 1. More specifically, the data groups of
the 3rd parade (Parade #2) are sequentially assigned and outputted
to the 7.sup.th and 11.sup.th slots (Slot #6 and Slot #10) within
the sub-frame.
As described above, the packet multiplexer 240 may multiplex and
output data groups of multiple parades to a single M/H frame, and,
in each sub-frame, the multiplexing process of the data groups may
be performed serially with a group space of 4 slots from left to
right. Therefore, a number of groups of one parade per sub-frame
(NOG) may correspond to any one integer from `1` to `8`. Herein,
since one M/H frame includes 5 sub-frames, the total number of data
groups within a parade that can be allocated to an M/H frame may
correspond to any one multiple of `5` ranging from `5` to `40`.
Processing Signaling Information
The present invention assigns signaling information areas for
inserting signaling information to some areas within each data
group. FIG. 33 illustrates an example of assigning signaling
information areas for inserting signaling information starting from
the 1.sup.st segment of the 4.sup.th M/H block (B4) to a portion of
the 2.sup.nd segment. More specifically, 276(=207+69) bytes of the
4.sup.th M/H block (B4) in each data group are assigned as the
signaling information area. In other words, the signaling
information area consists of 207 bytes of the 1.sup.st segment and
the first 69 bytes of the 2.sup.nd segment of the 4.sup.th M/H
block (B4). For example, the 1.sup.st segment of the 4.sup.th M/H
block (B4) corresponds to the 17.sup.th or 173.sup.rd segment of a
VSB field.
The signaling information that is to be inserted in the signaling
information area is FEC-encoded by the signaling encoder 304,
thereby inputted to the group formatter 303. The signaling
information may include a transmission parameter which is included
in the payload region of an OM packet, and then received to the
demultiplexer 210.
The group formatter 303 inserts the signaling information, which is
FEC-encoded and outputted by the signaling encoder 304, in the
signaling information area within the data group. Herein, the
signaling information may be identified by two different types of
signaling channels: a transmission parameter channel (TPC) and a
fast information channel (FIC).
Herein, the TPC data corresponds to signaling information including
transmission parameters, such as RS frame information, RS encoding
information, FIC information, data group information, SCCC
information, and M/H frame information and so on. However, the TPC
data presented herein is merely exemplary. And, since the adding or
deleting of signaling information included in the TPC may be easily
adjusted and modified by one skilled in the art, the present
invention will, therefore, not be limited to the examples set forth
herein.
Furthermore, the FIC data is provided to enable a fast service
acquisition of data receivers, and the FIC data includes cross
layer information between the physical layer and the upper
layer(s).
FIG. 34 illustrates a detailed block diagram of the signaling
encoder 304 according to the present invention. Referring to FIG.
34, the signaling encoder 304 includes a TPC encoder 561, an FIC
encoder 562, a block interleaver 563, a multiplexer 564, a
signaling randomizer 565, and an iterative turbo encoder 566.
The TPC encoder 561 receives 10-bytes of TPC data and performs
(18,10)-RS encoding on the 10-bytes of TPC data, thereby adding 8
bytes of parity data to the 10 bytes of TPC data. The 18 bytes of
RS-encoded TPC data are outputted to the multiplexer 564.
The FIC encoder 562 receives 37-bytes of FIC data and performs
(51,37)-RS encoding on the 37-bytes of FIC data, thereby adding 14
bytes of parity data to the 37 bytes of FIC data. Thereafter, the
51 bytes of RS-encoded FIC data are inputted to the block
interleaver 563, thereby being interleaved in predetermined block
units. Herein, the block interleaver 563 corresponds to a variable
length block interleaver. The block interleaver 563 interleaves the
FIC data within each sub-frame in TNoG(column).times.51(row) block
units and then outputs the interleaved data to the multiplexer 564.
Herein, the TNoG corresponds to the total number of data groups
being assigned to a sub-frame. The block interleaver 563 is
synchronized with the first set of FIC data in each sub-frame.
The block interleaver 563 writes 51 bytes of incoming (or inputted)
RS codewords in a row direction (i.e., row-by-row) and
left-to-right and up-to-down directions and reads 51 bytes of RS
codewords in a column direction (i.e., column-by-column) and
left-to-right and up-to-down directions, thereby outputting the RS
codewords.
The multiplexer 564 multiplexes the RS-encoded TPC data from the
TPC encoder 561 and the block-interleaved FIC data from the block
interleaver 563 along a time axis. Then, the multiplexer 564
outputs 69 bytes of the multiplexed data to the signaling
randomizer 565. The signaling randomizer 565 randomizes the
multiplexed data and outputs the randomized data to the iterative
turbo encoder 566. The signaling randomizer 565 may use the same
generator polynomial of the randomizer used for mobile service
data. Also, initialization occurs in each data group.
The iterative turbo encoder 566 corresponds to an inner encoder
performing iterative turbo encoding in a PCCC method on the
randomized data (i.e., signaling information data). The iterative
turbo encoder 566 may include 6 even component encoders and 6 odd
component encoders.
FIG. 35 illustrates an example of a syntax structure of TPC data
being inputted to the TPC encoder 561. The TPC data are inserted in
the signaling information area of each data group and then
transmitted. The TPC data may include a sub-frame_number field, a
slot_number field, a parade_id field, a starting_group_number (SGN)
field, a number_of_groups (NoG) field, a parade_repetition_cycle
(PRC) field, an RS_frame_mode field, an RS_code_mode_primary field,
an RS_code_mode_secondary field, an SCCC_block_mode field, an
SCCC_outer_code_mode_A field, an SCCC_outer_code_mode_B field, an
SCCC_outer_code_mode_C field, an SCCC_outer_code_mode_D field, an
FIC_version field, a parade_continuity_counter field, and a TNoG
field.
The Sub-Frame_number field corresponds to the current Sub-Frame
number within the M/H frame, which is transmitted for M/H frame
synchronization. The value of the Sub-Frame_number field may range
from 0 to 4. The Slot_number field indicates the current slot
number within the sub-frame, which is transmitted for M/H frame
synchronization. Also, the value of the Sub-Frame number field may
range from 0 to 15. The Parade_id field identifies the parade to
which this group belongs. The value of this field may be any 7-bit
value. Each parade in a M/H transmission shall have a unique
Parade_id field.
Communication of the Parade_id between the physical layer and the
management layer may be performed by means of an Ensemble_id field
formed by adding one bit to the left of the Parade_id field. If the
Ensemble_id field is used for the primary Ensemble delivered
through this parade, the added MSB shall be equal to `0`.
Otherwise, if the Ensemble_id field is used for the secondary
ensemble, the added MSB shall be equal to `1`. Assignment of the
Parade_id field values may occur at a convenient level of the
system, usually in the management layer. The starting_group_number
(SGN) field shall be the first Slot_number for a parade to which
this group belongs, as determined by Equation 1 (i.e., after the
Slot numbers for all preceding parades have been calculated). The
SGN and NoG shall be used according to Equation 1 to obtain the
slot numbers to be allocated to a parade within the sub-frame.
The number_of_Groups (NoG) field shall be the number of groups in a
sub-frame assigned to the parade to which this group belongs, minus
1, e.g., NoG=0 implies that one group is allocated (or assigned) to
this parade in a sub-frame. The value of NoG may range from 0 to 7.
This limits the amount of data that a parade may take from the main
(legacy) service data, and consequently the maximum data that can
be carried by one parade. The slot numbers assigned to the
corresponding Parade can be calculated from SGN and NoG, using
Equation 1. By taking each parade in sequence, the specific slots
for each parade will be determined, and consequently the SGN for
each succeeding parade. For example, if for a specific parade SGN=3
and NoG=3 (010b for 3-bit field of NoG), substituting i=3, 4, and 5
in Equation 1 provides slot numbers 12, 2, and 6.
The Parade_repetition_cycle (PRC) field corresponds to the cycle
time over which the parade is transmitted, minus 1, specified in
units of M/H frames, as described in Table 12.
TABLE-US-00012 TABLE 12 PRC Description 000 This parade shall be
transmitted once every M/H frame. 001 This parade shall be
transmitted once every 2 M/H frames. 010 This parade shall be
transmitted once every 3 M/H frames. 011 This parade shall be
transmitted once every 4 M/H frames. 100 This parade shall be
transmitted once every 5 M/H frames. 101 This parade shall be
transmitted once every 6 M/H frames. 110 This parade shall be
transmitted once every 7 M/H frames. 111 Reserved
For example, if PRC field value is equal to `001`, this indicates
that the parade shall be transmitted once every 2 M/H frame.
The RS_Frame_mode field shall be as defined in Table 1. The
RS_Frame_mode field represents that one parade transmits one RS
frame or two RS frames.
The RS_code_mode_primary field shall be the RS code mode for the
primary RS frame. Herein, the RS_code_mode_primary field is defined
in Table 6.
The RS_code_mode_secondary field shall be the RS code mode for the
secondary RS frame. Herein, the RS_code_mode_secondary field is
defined in Table 6.
The SCCC_Block_mode field represents how M/H blocks within a data
group are assigned to SCCC block. The SCCC_Block_mode field shall
be as defined in Table 7.
The SCCC_outer_code_mode_A field corresponds to the SCCC outer code
mode for Region A within a data group. The SCCC outer code mode is
defined in Table 8.
The SCCC_outer_code_mode_B field corresponds to the SCCC outer code
mode for Region B within the data group. The SCCC_outer_code_mode_C
field corresponds be the SCCC outer code mode for Region C within
the data group. And, the SCCC_outer_code_mode_D field corresponds
to the SCCC outer code mode for Region D within the data group.
The FIC_version field represents a version of FIC data.
The Parade_continuity_counter field counter may increase from 0 to
15 and then repeat its cycle. This counter shall increment by 1
every (PRC+1) M/H frames. For example, as shown in Table 12,
PRC=011 (decimal 3) implies that Parade.sub.-- continuity_counter
increases every fourth M/H frame.
The TNoG field may be identical for all sub-frames in an M/H
Frame.
However, the information included in the TPC data presented herein
is merely exemplary. And, since the adding or deleting of
information included in the TPC may be easily adjusted and modified
by one skilled in the art, the present invention will, therefore,
not be limited to the examples set forth herein.
Since the TPC data (excluding the Sub-Frame_number field and the
Slot_number field) for each parade do not change their values
during an M/H frame, the same information is repeatedly transmitted
through all M/H groups belonging to the corresponding parade during
an M/H frame. This allows very robust and reliable reception of the
TPC data. Because the Sub-Frame_number and the Slot_number are
increasing counter values, they also are robust due to the
transmission of regularly expected values.
Furthermore, the FIC data is provided to enable a fast service
acquisition of data receivers, and the FIC information includes
cross layer information between the physical layer and the upper
layer(s).
FIG. 36 illustrates an example of a transmission scenario of the
TPC data and the FIC data. The values of the Sub-Frame_number
field, Slot_number field, Parade_id field, Parade_repetition_cycle
field, and Parade_continuity_counter field may corresponds to the
current M/H frame throughout the sub-frames within a specific M/H
frame. Some of TPC parameters and FIC data are signaled in
advance.
bThe SGN, NoG and all FEC modes may have values corresponding to
the current M/H frame in the first two sub-frames. The SGN, NoG and
all FEC modes may have values corresponding to the frame in which
the parade next appears throughout the 3.sup.rd, 4.sup.th and
5.sup.th sub-frames of the current M/H frame. This enables the M/H
receivers to receive (or acquire) the transmission parameters in
advance very reliably.
For example, when Parade_repetition_cycle=`000`, the values of the
3.sup.rd, 4.sup.th, and 5.sup.th sub-frames of the current M/H
frame correspond to the next M/H frame. Also, when
Parade_repetition_cycle=`011`, the values of the 3.sup.rd,
4.sup.th, and 5.sup.th sub-frames of the current M/H frame
correspond to the 4.sup.th M/H frame and beyond.
The FIC_version field and the FIC_data field may have values that
apply to the current M/H Frame during the 1.sup.st sub-frame and
the 2.sup.nd sub-frame, and they shall have values corresponding to
the M/H frame immediately following the current M/H frame during
the 3.sup.rd, 4.sup.th, and 5.sup.th sub-frames of the current M/H
frame.
Meanwhile, the receiving system may turn the power on only during a
slot to which the data group of the designated (or desired) parade
is assigned, and the receiving system may turn the power off during
the remaining slots, thereby reducing power consumption of the
receiving system. Such characteristic is particularly useful in
portable or mobile receivers, which require low power consumption.
For example, it is assumed that data groups of a 1.sup.st parade
with NOG=3, a 2.sup.nd parade with NOG=2, and a 3.sup.rd parade
with NOG=3 are assigned to one M/H frame, as shown in FIG. 37. It
is also assumed that the user has selected a mobile service
included in the 1.sup.st parade using the keypad provided on the
remote controller or terminal. In this case, the receiving system
turns the power on only during a slot that data groups of the
1.sup.st parade is assigned, as shown in FIG. 37, and turns the
power off during the remaining slots, thereby reducing power
consumption, as described above. At this point, the power is
required to be turned on briefly earlier than the slot to which the
actual designated data group is assigned (or allocated). This is to
enable the tuner or demodulator to converge in advance.
Assignment of Known Data (or Training Signal)
In addition to the payload data, the M/H transmission system
inserts long and regularly spaced training sequences into each
group. The regularity is an especially useful feature since it
provides the greatest possible benefit for a given number of
training symbols in high-Doppler rate conditions. The length of the
training sequences is also chosen to allow fast acquisition of the
channel during bursted power-saving operation of the demodulator.
Each group contains 6 training sequences. The training sequences
are specified before trellis-encoding. The training sequences are
then trellis-encoded and these trellis-encoded sequences also are
known sequences. This is because the trellis encoder memories are
initialized to pre-determined values at the beginning of each
sequence. The form of the 6 training sequences at the byte level
(before trellis-encoding) is shown in FIG. 38. This is the
arrangement of the training sequence at the group formatter 303.
FIG. 73 illustrates an example of a known data (training) sequence
represented using numbers at the byte level according to the
present invention. In FIG. 73, known data (training) bytes include
trellis initialization bytes.
The 1.sup.st training sequence is located at the last 2 segments of
the 3.sup.rd M/H block (B3). The 2.sup.nd training sequence may be
inserted at the 2.sup.nd and 3.sup.rd segments of the 4.sup.th M/H
block (B4). The 2.sup.nd training sequence is next to the signaling
area, as shown in FIG. 5. Then, the 3.sup.rd training sequence, the
4.sup.th training sequence, the 5.sup.th training sequence, and the
6.sup.th training sequence may be placed at the last 2 segments of
the 4.sup.th, 5.sup.th, 6.sup.th and 7.sup.th M/H blocks (B4, B5,
B6, and B7), respectively. As shown in FIG. 38, the 1.sup.st
training sequence, the 3.sup.rd training sequence, the 4.sup.th
training sequence, the 5.sup.th training sequence, and the 6.sup.th
training sequence are spaced 16 segments apart from one another.
Referring to FIG. 38, the dotted area indicates trellis
initialization data bytes, the lined area indicates training data
bytes, and the white area includes other bytes such as the
FEC-coded M/H service data bytes, FEC-coded signaling data, main
service data bytes, RS parity data bytes (for backwards
compatibility with legacy ATSC receivers) and/or dummy data
bytes.
FIG. 39 illustrates the training sequences (at the symbol level)
after trellis-encoding by the trellis encoder.
Referring to FIG. 39, the dotted area indicates data segment sync
symbols, the lined area indicates training data symbols, and the
white area includes other symbols, such as FEC-coded mobile service
data symbols, FEC-coded signaling data, main service data symbols,
RS parity data symbols (for backwards compatibility with legacy
ATSC receivers), dummy data symbols, trellis initialization data
symbols, and/or the first part of the training sequence data
symbols. Due to the intra-segment interleaving of the trellis
encoder, various types of data symbols will be mixed in the white
area.
After the trellis-encoding process, the last 1416 (=588+828)
symbols of the 1.sup.st training sequence, the 3.sup.rd training
sequence, the 4.sup.th training sequence, the 5.sup.th training
sequence, and the 6.sup.th training sequence commonly share the
same data pattern. Including the data segment synchronization
symbols in the middle of and after each sequence, the total length
of each common training pattern is 1424 symbols. The 2.sup.nd
training sequence has a first 528-symbol sequence and a second
528-symbol sequence that have the same data pattern. More
specifically, the 528-symbol sequence is repeated after the
4-symbol data segment synchronization signal. At the end of each
training sequence, the memory contents of the twelve modified
trellis encoders shall be set to zero (0).
FIG. 74 illustrates an example of a training sequence represented
using numbers at the symbol according to the present invention. In
FIG. 74, a VSB level value -7 is mapped to number 0, a VSB level
value -5 is mapped to number 1, a VSB level value -3 is mapped to
number 2, a VSB level value -1 is mapped to number 3, a VSB level
value 1 is mapped to number 4, a VSB level value 3 is mapped to
number 5, a VSB level value 5 is mapped to number 6, and a VSB
level value 7 is mapped to number 7.
Receiving System
FIG. 40 is a block diagram illustrating a receiving system
according to an embodiment of the present invention.
The receiving system of FIG. 40 includes a tuner 1301, a
demodulating unit 1302, a demultiplexer 1303, a program table
buffer 1304, a program table decoder 1305, a program table storage
unit 1306, a data handler 1307, a middleware engine 1308, an A/V
decoder 1309, an A/V post-processor 1310, an application manager
1311, and a user interface 1314. The application manager 1311 may
include a channel manager 1312 and a service manager 1313.
In FIG. 40, solid lines indicate data flows and dotted lines
indicate control flows.
The tuner 1301 tunes to a frequency of a specific channel through
any of an antenna, a cable, or a satellite and down-converts the
frequency to an Intermediate Frequency (IF) signal and outputs the
IF signal to the demodulating unit 1302. Here, the tuner 1301 is
controlled by the channel manager 1312 in the application manager
1311 and reports the result and strength of a broadcast signal of
the tuned channel to the channel manager 1312. Data received
through the frequency of the specific channel includes main service
data, mobile service data, a transmission parameter, and program
table information for decoding the main service data and the mobile
service data.
The demodulating unit 1302 performs VSB demodulation, channel
equalization, etc., on the signal output from the tuner 1301 and
identifies and separately outputs main service data and mobile
service data. The demodulating unit 1302 will be described in
detail in a later.
On the other hand, the transmitter can transmit signaling
information (or TPC information) including transmission parameters
by inserting the signaling information into at least one of a field
synchronization region, a known data region, and a mobile service
data region. Accordingly, the demodulating unit 1302 can extract
the transmission parameters from the field synchronization region,
the known data region, and the mobile service data region.
The transmission parameters may include M/H frame information,
sub-frame information, slot information, parade-related information
(for example, a parade_id, a parade repeat period, etc.),
information of data groups in a sub-frame, RS frame mode
information, RS code mode information, SCCC block mode information,
SCCC outer code mode information, FIC version information, etc.
The demodulating unit 1302 performs block decoding, RS frame
decoding, etc., using the extracted transmission parameters. For
example, the demodulating unit 1302 performs block decoding of each
region in a data group with reference to SCCC-related information
(for example, SCCC block mode information or an SCCC outer code
mode) included in the transmission parameters and performs RS frame
decoding of each region included in the data group with reference
to RS-related information (for example, an RS code mode).
In the embodiment of the present invention, an RS frame including
mobile service data demodulated by the demodulating unit 1302 is
input to the demultiplexer 1303.
That is, data inputted to the demultiplexer 1303 has an RS frame
data format as shown in FIG. 17(a) or FIG. 17(b). More
specifically, the RS frame decoder of the demodulating unit 1302
performs the reverse of the encoding process performed at the RS
frame encoder of the transmission system to correct errors in the
RS frame and then outputs the error-corrected RS frame to a data
derandomizer. The data derandomizer then performs derandomizing on
the error-corrected RS frame through the reverse of the randomizing
process performed at the transmission system to obtain an RS frame
as shown in FIG. 17(a) or FIG. 17(b).
The demultiplexer 1303 may receive RS frames of all parades and may
also receive only an RS frame of a parade including a mobile
service that the user desires to receive through power supply
control. For example, when RS frames of all parades are received,
the demultiplexer 1303 can demultiplex a parade including a mobile
service that the user desires to receive using a parade_id.
One parade carries one or two RS frames and one ensemble is mapped
to one RS frame. Therefore, when one parade carries two RS frames,
the demultiplexer 1303 needs to identify an RS frame carrying an
ensemble including mobile service data to be decoded from a parade
containing a mobile service that the user desires to receive. That
is, when a received single parade or a parade demultiplexed from a
plurality of parades carries a primary ensemble and a secondary
ensemble, the demultiplexer 1303 selects one of the primary and
secondary ensembles.
In an embodiment, the demultiplexer 1303 can demultiplex an RS
frame carrying an ensemble including mobile service data to be
decoded using an ensemble_id generated by adding one bit to a left
position of the parade_id.
The demultiplexer 1303 refers to the M/H header of the M/H service
data packet within the RS frame corresponding to the ensemble
including the mobile service data that are to be decoded, thereby
identifying when the corresponding M/H service data packet is the
program table information or the IP datagram of the mobile service
data. Alternatively, when the program table information and the
mobile service data are both configured in the form of IP
datagrams, the demultiplexer 1303 may use the IP address in order
to identify the IP datagram of the program table information and
the mobile service data.
Herein, the identified program table information is outputted to
the program table buffer 1304. And, audio/video/data streams are
separated from the IP datagram of mobile service data that are to
be selected among the IP datagrams of the identified mobile service
data, thereby being respectively outputted to the A/V decoder 1309
and/or the data handler 1307.
According to an embodiment of the present invention, when the
stuff_indicator field within the M/H header of the M/H service data
packet indicates that stuffing bytes are inserted in the payload of
the corresponding M/H service data packet, the demultiplexer 1303
removes the stuffing bytes from the payload of the corresponding
M/H service data packet. Then, the demultiplexer 1303 identifies
the program table information and the mobile service data.
Thereafter, the demultiplexer 1303 identifies A/V/D streams from
the identified mobile service data.
The program table buffer 1304 temporarily stores the section-type
program table information and then outputs the section-type program
table information to the program table decoder 1305.
The program table decoder 1305 identifies tables using a table_id
and a section_length in the program table information and parses
sections of the identified tables and produces and stores a
database of the parsed results in the program table storage unit
1306. For example, the program table decoder 1305 collects sections
having the same table identifier (table_id) to construct a table.
The program table decoder 1305 then parses the table and produces
and stores a database of the parsed results in the program table
storage unit 1306.
The A/V decoder 1309 decodes the audio and video streams outputted
from the demultiplexer 1303 using audio and video decoding
algorithms, respectively. The decoded audio and video data is
outputted to the A/V post-processor 1310.
Here, at least one of an AC-3 decoding algorithm, an MPEG 2 audio
decoding algorithm, an MPEG 4 audio decoding algorithm, an AAC
decoding algorithm, an AAC+ decoding algorithm, an HE AAC decoding
algorithm, an AAC SBR decoding algorithm, an MPEG surround decoding
algorithm, and a BSAC decoding algorithm can be used as the audio
decoding algorithm and at least one of an MPEG 2 video decoding
algorithm, an MPEG 4 video decoding algorithm, an H.264 decoding
algorithm, an SVC decoding algorithm, and a VC-1 decoding algorithm
can be used as the audio decoding algorithm.
The data handler 8507 processes data stream packets required for
data broadcasting among data stream packets separated (or
identified) by the demultiplexer 1303 and provides the processed
data stream packets to the middleware engine 1310 to allow the
middleware engine 1310 to be multiplexed them with A/V data. In an
embodiment, the middleware engine 1310 is a Java middleware
engine.
The application manager 1311 receives a key input from the TV
viewer and displays a Graphical User Interface (GUI) on the TV
screen in response to a viewer request through a User Interface
(UI). The application manager 1311 also writes and reads
information regarding overall GUI control of the TV, user requests,
and TV system states to and from a memory (for example, NVRAM or
flash memory). In addition, the application manager 1311 can
receive parade-related information (for example, a parade_id) from
the demodulating unit 1302 to control the demultiplexer 1303 to
select an RS frame of a parade including a required mobile service.
The application manager 1311 can also receive an ensemble_id to
control the demultiplexer 1303 to select an RS frame of an ensemble
including mobile service data to be decoded from the parade. The
application manager 1311 also controls the channel manager 1312 to
perform channel-related operations (for example, channel map
management and program table decoder operations).
The channel manager 1312 manages physical and logical channel maps
and controls the tuner 1301 and the program table decoder 1305 to
respond to a channel-related request of the viewer. The channel
manager also requests that the program table decoder 1305 parse a
channel-related table of a channel to be tuned and receives the
parsing results from the program table decoder 1305.
Demodulating Unit within Receiving System
FIG. 41 illustrates an example of a demodulating unit in a digital
broadcast receiving system according to the present invention. The
demodulating unit of FIG. 41 uses known data information, which is
inserted in the mobile service data section and, then, transmitted
by the transmitting system, so as to perform carrier
synchronization recovery, frame synchronization recovery, and
channel equalization, thereby enhancing the receiving performance.
Also the demodulating unit may turn the power on only during a slot
to which the data group of the designated (or desired) parade is
assigned, thereby reducing power consumption of the receiving
system.
Referring to FIG. 41, the demodulating unit includes an operation
controller 2000, a demodulator 2002, an equalizer 2003, a known
sequence detector 2004, a block decoder 2005, and a RS frame
decoder 2006. The demodulating unit may further include a main
service data processor 2008. The main service data processor 2008
may include a data deinterleaver, a RS decoder, and a data
derandomizer. The demodulating unit may further include a signaling
decoder 2013. The receiving system also may further include a power
controller 5000 for controlling power supply of the demodulating
unit.
More specifically, a frequency of a particular channel tuned by a
tuner down converts to an intermediate frequency (IF) signal. Then,
the down-converted data 2001 outputs the down-converted IF signal
to the demodulator 2002 and the known sequence detector 2004. At
this point, the down-converted data 2001 is inputted to the
demodulator 2002 and the known sequence detector 2004 via
analog/digital converter ADC (not shown). The ADC converts
pass-band analog IF signal into pass-band digital IF signal.
The demodulator 2002 performs self gain control, carrier recovery,
and timing recovery processes on the inputted pass-band digital IF
signal, thereby modifying the IF signal to a base-band signal.
Then, the demodulator 2002 outputs the newly generated base-band
signal to the equalizer 2003 and the known sequence detector
2004.
The equalizer 2003 compensates the distortion of the channel
included in the demodulated signal and then outputs the
error-compensated signal to the block decoder 2005.
At this point, the known sequence detector 2004 detects the known
sequence position information inserted by the transmitting end from
the input/output data of the demodulator 2002 (i.e., the data prior
to the demodulation process or the data after the demodulation
process). Thereafter, the position information along with the
symbol sequence of the known data, which are generated from the
detected position, is outputted to the operation controller 2000,
the demodulator 2002, the equalizer 2003, and the signaling decoder
2013. Also, the known sequence detector 2004 outputs a set of
information to the block decoder 2005. This set of information is
used to allow the block decoder 2005 of the receiving system to
identify the mobile service data that are processed with additional
encoding from the transmitting system and the main service data
that are not processed with additional encoding.
In addition, although the connection status is not shown in FIG.
41, the information detected from the known sequence detector 2004
may be used throughout the entire receiving system and may also be
used in the RS frame decoder 2006.
The data demodulated in the demodulator 2002 or the data equalized
in the channel equalizer 2003 is inputted to the signaling decoder
2013. The known data position information detected in the known
sequence detector 2004 is inputted to the signaling decoder
2013.
The signaling decoder 2013 extracts and decodes signaling
information (e.g., TPC information, and FIC information), which
inserted and transmitted by the transmitting end, from the inputted
data, the decoded signaling information provides to blocks
requiring the signaling information.
More specifically, the signaling decoder 2013 extracts and decodes
TPC data and FIC data, which inserted and transmitted by the
transmitting end, from the equalized data, and then the decoded TPC
data and FIC data outputs to the operation controller 2000, the
known sequence detector 2004, and the power controller 5000. For
example, the TPC data and FIC data is inserted in a signaling
information region of each data group, and then is transmitted to a
receiving system.
The signaling decoder 2013 performs signaling decoding as an
inverse process of the signaling encoder shown in FIG. 34, so as to
extract TPC data and FIC data. For example, the signaling decoder
2013 decodes the inputted data using the PCCC method and
derandomizes the decoded data, thereby dividing the derandomized
data into TPC data and FIC data. At this point, the signaling
decoder 2013 performs RS-decoding on the divided TPC data, so as to
correct the errors occurring in the TPC data. Subsequently, the
signaling decoder 2013 deinterleaves the divided FIC data and then
performs RS-decoding on the deinterleaved FIC data, so as to
correct the error occurring in the FIC data. The error-corrected
TPC data are then outputted to the operation controller 2000, the
known sequence detector 2004, and the power controller 5000.
The TPC data may also include a transmission parameter which is
inserted into the payload region of an OM packet by the service
multiplexer 100, and then is transmitted to transmitter 200.
Herein, the TPC data may include RS frame information, SCCC
information, M/H frame information, and so on, as shown in FIG. 35.
The RS frame information may include RS frame mode information and
RS code mode information. The SCCC information may include SCCC
block mode information and SCCC outer code mode information. The
M/H frame information may include M/H frame index information, and
the TPC data may include sub-frame count information, slot count
information, parade_id information, SGN information, NoG
information, and so on.
At this point, the signaling decoder 2013 can know the signaling
information region within a data group by using the known data
information being outputted from the known sequence detector 2004.
Namely, the 1.sup.st known sequence (or training sequence) is
located at the last 2 segments of the 3.sup.rd M/H block (B3)
within the data group. The 2.sup.nd training sequence may be
inserted at the 2.sup.nd and 3.sup.rd segments of the 4.sup.th M/H
block (B4). The 2.sup.nd known sequence is located at between
2.sup.nd and 3.sup.rd segments of the 4.sup.th M/H block (B4)
within the data group. Since the 2.sup.nd known sequence is
inserted and received next to the signaling information area, the
signaling decoder 2013 may extract and decode signaling information
included in the signaling information region from the data being
outputted in the demodulator 2002 or the channel equalizer
2003.
The power controller 5000 is inputted the M/H frame-associated
information from the signaling decoder 2013, and controls power of
the tuner and the demodulating unit. Alternatively, the power
controller 5000 is inputted a power control information from the
operation controller 2000, and controls power of the tuner and the
demodulating unit.
According to the embodiment of the present invention, the power
controller 5000 turns the power on only during a slot to which a
slot of the parade including user-selected mobile service is
assigned. The power controller 5000 then turns the power off during
the remaining slots.
For example, it is assumed that data groups of a 1.sup.st parade
with NOG-3, a 2.sup.nd parade with NOG-2, and a 3.sup.rd parade
with NOG=3 are assigned to one M/H frame, as shown in FIG. 37. It
is also assumed that the user has selected a mobile service
included in the 1.sup.st parade using the keypad provided on the
remote controller or terminal. In this case, the power controller
5000 turns the power on during a slot that data groups of the
1.sup.st parade is assigned, as shown in FIG. 37, and turns the
power off during the remaining slots, thereby reducing power
consumption.
The demodulator 2002 uses the known data symbol sequence during the
timing and/or carrier recovery, thereby enhancing the demodulating
performance. Similarly, the equalizer 2003 uses the known data so
as to enhance the equalizing performance. Moreover, the decoding
result of the block decoder 2005 may be fed-back to the equalizer
2003, thereby enhancing the equalizing performance.
Demodulator and Known Sequence Detector
At this point, the transmitting system may receive a data frame (or
VSB frame) including a data group which known data sequence (or
training sequence) is periodically inserted therein, as shown in
FIG. 5. Herein, the data group is divided into regions A to D, as
shown in FIG. 5. More specifically, in the example of the present
invention, each region A, B, C, and D are further divided into M/H
blocks B4 to B7, M/H blocks B3 and B8, M/H blocks B2 and B9, M/H
blocks B1 and B10, respectively.
Referring to FIG. 38 and FIG. 39, known data sequence having the
same pattern are included in each known data section that is being
periodically inserted. Herein, the length of the known data
sequence having identical data patterns may be either equal to or
different from the length of the entire (or total) known data
sequence of the corresponding known data section (or block). If the
two lengths are different from one another, the length of the
entire known data sequence should be longer than the length of the
known data sequence having identical data patterns. In this case,
the same known data sequences are included in the entire known data
sequence.
As described above, when the known data are periodically inserted
in-between the mobile service data, the channel equalizer of the
receiving system may use the known data as training sequences,
which may be used as accurate discriminant values. According to
another embodiment of the present invention, the channel equalizer
estimates a channel impulse response. Herein, the known data may be
used in the process. According to yet another embodiment of the
present invention, the channel equalizer may use the known data for
updating filter coefficients (i.e., equalization coefficients).
Meanwhile, when known data sequence having the same pattern is
periodically inserted, each known data sequence may be used as a
guard interval in a channel equalizer according to the present
invention. Herein, the guard interval prevents interference that
occurs between blocks due to a multiple path channel. This is
because the known data sequence located behind a mobile service
data section (i.e., data block) may be considered as being copied
in front of the mobile service data section.
The above-described structure is referred to as a cyclic prefix.
This structure provides circular convolution in a time domain
between a data block transmitted from the transmitting system and a
channel impulse response. Accordingly, this facilitates the channel
equalizer of the receiving system to perform channel equalization
in a frequency domain by using a fast fourier transform (FFT) and
an inverse fast fourier transform (IFFT).
More specifically, when viewed in the frequency domain, the data
block received by the receiving system is expressed as a
multiplication of the data block and the channel impulse response.
Therefore, when performing the channel equalization, by multiplying
the inverse of the channel in the frequency domain, the channel
equalization may be performed more easily.
The known sequence detector 2004 detects the position of the known
data being periodically inserted and transmitted as described
above. At the same time, the known sequence detector 2004 may also
estimate initial frequency offset during the process of detecting
known data. In this case, the demodulator 2002 may estimate with
more accuracy carrier frequency offset from the information on the
known data position information and initial frequency offset
estimation value, thereby compensating the estimated carrier
frequency offset.
Meanwhile, when known data is transmitted, as shown in FIG. 5, the
known sequence detector 2004 detects a position of second known
data region by using known data of the second known data region
that the same pattern is repeated twice.
At this point, since the known sequence detector 2004 is
well-informed of the data group structure, when the position of the
second known data region is detected, the known sequence detector
2004 can estimate positions of the first, third, fourth, fifth, and
sixth known data regions of a corresponding data group by counting
symbols or segments based upon the second known data region
position. If the corresponding data group is a data group including
field synchronization segment, the known sequence detector 2004 can
estimate the position of the field synchronization segment of the
corresponding data group, which is positioned chronologically
before the second known data region, by counting symbols or
segments based upon the second known data region position. Also,
the known sequence detector 2004 may estimate the known data
position information and the field synchronization position
information from the parade including mobile service selected by a
user based on the M/H frame-associated information outputted from
the signaling decoder 2013.
At least one of the estimated known data poison information and
field synchronization information is provided to the demodulator
2002, the channel equalizer 2003, the signaling decoder 2013, and
the operation controller 2000.
Also, the known sequence detector 2004 may estimate initial
frequency offset by using known data inserted in the second known
data region (i.e., ACQ known data region). In this case, the
demodulator 2002 may estimate with more accuracy carrier frequency
offset from the information on the known data position information
and initial frequency offset estimation value, thereby compensating
the estimated carrier frequency offset.
Operation Controller
The operation controller 2000 receives the known data position
information and the transmission parameter information and then
forwards M/H frame time information, a presence or non-presence of
a data group of a selected parade, position information of known
data within the data group, power control information and the like
to each block of the demodulating unit. The operation controller
2000, as shown in FIG. 41, controls operations of the demodulator
2002, the channel equalizer 2003, the block decoder 2005 and the RS
frame decoder 2006. And, the operation controller 2000 is able to
overall operations of the demodulating unit (not shown in the
drawing). Moreover, the operation controller 2000 can be
implemented with the separate block or can be included within a
prescribed one of the blocks of the demodulating unit shown in FIG.
41.
FIG. 42 is an overall block diagram of an operation controller
2000.
Referring to FIG. 42, the operation controller 2000 can include a
parade ID checker 3101, a frame synchronizer 3102, a parade mapper
3103, a group controller 3104 and a known sequence indication
controller 3105.
The operation controller 2000 receives known data position
information from the known sequence detector 2004 and receives
transmission parameter information from the signaling decoder 2013.
The operation controller 2000 then generates a control signal
necessary for a demodulating unit of a receiving system. For
instance, the known data position information detected by the known
sequence detector 2004 is inputted to the known sequence indication
controller 3105. And, the transmission parameter information (i.e.,
TPC data) decoded by the signaling decoder 2013 is inputted to the
parade ID checker 3101.
The parade ID checker 3101 compares a parade ID (parade ID selected
by a user) contained in the user control signal to a parade ID
inputted from the signaling decoder 2013. If the two parade IDs are
not identical to each other, the parade ID checker stands by until
a next transmission parameter is inputted from the signaling
decoder 2013.
If the two parade IDs are identical to each other, the parade ID
checker 3101 outputs the transmission parameter information to the
blocks within the operation controller 2000 and the overall
system.
If it is checked that the parade ID in the transmission parameter
information inputted to the parade ID checker 3101 is identical to
the parade ID selected by a user, the parade ID checker 3101
outputs starting_group_number (SGN) and number_of_groups (NOG) to
the parade mapper 3103, outputs sub_frame_number, slot_number and
parade_repetition_cycle PRC) to the frame synchronizer 3102,
outputs SCCC_block_mode, SCCC_outer_code_mode_A,
SCCC_outer_code_mode_B, SCCC_outer_code_mode_C and
SCCC_outer_code_mode_D to the block decoder 2005, and outputs
RS_frame_mode, RS_code_mode_primary and Rs_code_mode_secondary to
the RS frame decoder 2006.
The parade mapper 3103 receives the SGN and the NOG from the parade
ID checker as inputs, decides a data group is carried by which one
of sixteen slots within a Sub-frame, and then outputs the
corresponding information. Data group number transmitted every
sub-frame is set to an integer consecutive between SGN and
(SGN+NOG-1). For instance, if SGN=3 and NOG=4, four groups, of
which group numbers are 3, 4, 5 and 6, are transmitted for the
corresponding sub-frames, respectively. The parade mapper finds a
slot number j for transmitting a data group according to Equation 1
with a group number i obtained from SGN and NOG.
In the above example, in case of SGN=3 and NOG=4, if they are
inserted in Equation 1, slot numbers of groups transmitted
according to the above formula sequentially become 12, 2, 6 and
10.
The parade mapper 3103 then outputs the found slot number
information.
For example of outputting slot numbers, a method of using a bit
vector having 16 bits is available.
A bit vector SNi (i=0.about.15) can be set to 1 if there exists a
group transmitted for an i.sup.th slot. A bit vector SNi
(i=0.about.15) can be set to 0 if a group transmitted for an
i.sup.th slot does not exist. And, this bit vector can be outputted
as slot number information.
The frame synchronizer 3102 receives the sub_frame_number,
slot-number and PRC from the parade ID checker and then sends
slot_counter and frame_mask signals as outputs. The slot_counter is
the signal indicating a slot_number at a current timing point at
which a receiver is operating. And, the frame_mask is the signal
indicating whether a corresponding parade is transmitted for a
current frame. The frame synchronizer 3102 performs a process for
initializing slot_counter, sub_frame_number and frame.sub.--
counter in receiving signaling information initially. A counter
value of a current timing point is generated from adding a delayed
slot number L according to a time taken to decode signaling from
demodulation together with the signaling information inputted in
this process. After completion of the initialization process,
slot_counter is updated every single slot period, updates
sub_frame_counter every period of the slot_counter value, and
updates frame_counter every period of the sub_frame_counter. By
referring to the frame.sub.-- counter information and the PRC
information, a frame.sub.-- mask signal is generated. For example,
if a corresponding parade is being transmitted for a current frame,
`1` is outputted as the frame_mask. Otherwise, it is able to output
`0`.
The group controller 3104 receives the slot number information from
the parade mapper 3103. The group controller 3104 receives the
slot_counter and frame_mask information from the frame synchronizer
3102. The group controller 3104 then outputs
group_presence_indicator indicating whether an M/H group is being
transmitted. For instance, if the slot number information inputted
from the parade mapper 3103 corresponds to 12, 2, 6 and 10, when
the frame_mask information inputted from the frame synchronizer
3102 is 1 and the slot_counter inputted from the frame synchronizer
3102 includes 2, 6, 10 and 12, `1` is outputted as the
group_presence_indicator. Otherwise, it is able to output 0.
The known sequence indication controller 3105 outputs position
information of another known data, group start position information
and the like with position information of specific inputted known
data. In this case, since the known data are present at a
previously appointed position within the data group, if position
data of one of a plurality of known data sequences, it is able to
know data position information of another known sequence, data
group start position information and the like. The known sequence
indication controller 3105 can output known data and data group
position information necessary for the demodulating unit of the
receiving system using the group_presence_indicator information
only if the data group is transmitted. Alternatively, the known
sequence detector 2004 can perform operations of the known sequence
indication controller 3105.
Channel Equalizer
The data demodulated by the demodulator 2002 by using the known
data are inputted to the equalizer 2003. Additionally, the
demodulated data may also be inputted to the known sequence
detector 2004.
At this point, a data group that is inputted for the equalization
process may be divided into region A to region D, as shown in FIG.
5. More specifically, according to the embodiment of the present
invention, region A includes M/H block B4 to M/H block B7, region B
includes M/H block B3 and M/H block B8, region C includes M/H block
B2 and M/H block B9, and region D includes M/H block B1 and M/H
block B10. In other words, one data group is divided into M/H
blocks from B1 to B10, each M/H block having the length of 16
segments. Also, a long training sequence (i.e., known data
sequence) is inserted at the starting portion of the M/H blocks B4
to B8. Furthermore, two data groups may be allocated (or assigned)
to one VSB field. In this case, field synchronization data are
positioned in the 37.sup.th segment of one of the two data
groups.
Therefore, in a data group including field synchronization data,
when counting each segment starting from the first segment
including mobile service data, which is counted as segment number 0
(#0), field synchronization is located in a position corresponding
to segment number 37 (#37). Thereafter, 5 known data sequences are
respectively located in positions corresponding to each of segment
number (#53), segment number 69 (#69), segment number 85 (#85),
segment number 101 (#101), and segment number 117 (#117). More
specifically, a 1.sup.st known data sequence is located in segment
number 53 (#53), a 3.sup.rd known data sequence is located in
segment number 69 (#69), a 4.sup.th known data sequence is located
in segment number 85 (#85), a 5.sup.th known data sequence is
located in segment number 101 (#101), and a 6.sup.th known data
sequence is located in segment number 117 (#117).
The present invention may use known data and/or field
synchronization data for performing channel-equalization, wherein
the positions and contents of the known data and/or field
synchronization data are known based upon an agreement between the
transmitting system and the receiving system.
According to an embodiment of the present invention, the present
invention may enhance the receiving performance of the present
invention, by using the known data and/or field synchronization
data so as to estimate a channel impulse response (CIR), and by
compensating distortions, i.e., performing channel-equalization
using the estimated CIR.
In the description of the present invention, at least one of a
known data sequence and a field synchronization data sequence will
be referred to as a training sequence. More specifically, in a data
group including field synchronization data, a field synchronization
data sequence and a known data sequence correspond to the training
sequence. However, in a data group that does not include any field
synchronization data, only the known data sequence corresponds to
the training sequence. Furthermore, at least one of a known data
section and a field synchronization section will be referred to as
a training section.
In the training section, the present invention uses a training
sequence to estimate a CIR and, then, uses the estimated CIR to
channel-equalize the training sequence. Also, in a non-training
section, i.e., in a general data section, the present invention
interpolates or extrapolates using the CIRs estimated in the
training section and, then, uses the CIR generated by interpolation
or extrapolation, so as to channel-equalize the general data.
According to the embodiment of the present invention, the general
data correspond to mobile service data.
FIG. 44 illustrates the relation between a segment and a channel
impulse response (CIR) in a data group including field
synchronization data according to the present invention. And, FIG.
45 illustrates the relation between a segment and a channel impulse
response (CIR) in a data group not including any field
synchronization data according to the present invention.
Hereinafter, the CIR estimated in the field synchronization section
will be referred to as CIR(37), the CIR estimated in the 1.sup.st
known data sequence section will be referred to as CIR(53), the CIR
estimated in the 3.sup.rd known data sequence section will be
referred to as CIR(69), the CIR estimated in the 4.sup.th known
data sequence section will be referred to as CIR(85), the CIR
estimated in the 5.sup.th known data sequence section will be
referred to as CIR(101), and the CIR estimated in the 6.sup.th
known data sequence section will be referred to as CIR(117), for
simplicity.
More specifically, the present invention uses the CIR estimated in
the known data section and/or field synchronization section so as
to perform channel-equalization on the data within the respective
data group. At this point, depending upon the characteristics of
each region of the data group, any one of the estimated CIRs may be
directly used without modification, or a CIR generated by
interpolating or extrapolating at least 2 or more CIRs may be
used.
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.
In the description of the present invention, a linear interpolation
method will be described according to a first embodiment of the
present invention, and a cubic spline interpolation method will be
described according to a second embodiment of the present
invention.
First Embodiment
FIG. 43 illustrates an example of linear interpolation according to
the present invention. More specifically, in a random function
F(x), when given the values F(Q) and F(S) each from points x=Q and
x=S, respectively, the approximate value {circumflex over
(F)}.sup.(P) of the F(x) function at point x=P may be estimated by
using Equation 7 below. In other words, since the values of F(Q)
and F(S) respective to each point x=Q and x=S are known (or given),
a straight line passing through the two points may be calculated so
as to obtain the approximate value {circumflex over (F)}.sup.(P) of
the corresponding function value at point P. At this point, the
straight line passing through points (Q,F(Q)) and (S,F(S)) may be
obtained by using Equation 7 below.
.function..function..function..times..function..times..times.
##EQU00002##
Accordingly, Equation 8 below shows the process of substituting p
for x in Equation 7, so as to calculate the approximate value
{circumflex over (F)}.sup.(P) of the function value at point P.
.function..function..function..times..function..times..times..function..t-
imes..function..times..function..times..times. ##EQU00003##
In FIG. 44 and FIG. 45, when calculating the CIR of a general data
section, i.e., section [a] to section [e], and not of a training
section using linear interpolation, the CIR may be calculated by
using Equation 8 shown above.
For example, the CIR of section [a] may be obtained by respectively
substituting CIR(37) and CIR(53) for F(Q) and F(S) of Equation 8,
and the CIR of section [b] may be obtained by respectively
substituting CIR(53) and CIR(69) for F(Q) and F(S) of Equation 8.
Similarly, the CIR of section [c] may be obtained by respectively
substituting CIR(69) and CIR(85) for F(Q) and F(S) of Equation 8.
The CIR of section [d] may be obtained by respectively substituting
CIR(85) and CIR(101) for F(Q) and F(S) of Equation 8. And, finally,
the CIR of section [e] may be obtained by respectively substituting
CIR(101) and CIR(117) for F(Q) and F(S) of Equation 8. Thereafter,
the CIRs obtained in each section are used to channel-equalize the
data of the respective section. For example, the CIR obtained in
section [a] using linear interpolation is used for
channel-equalizing the mobile service data of section [a].
Second Embodiment
Meanwhile, in FIG. 44 and FIG. 45, the CIR of a general data
section, i.e., section [a] to section [e], and not of a training
section using linear interpolation, may be calculated by using
another interpolation method.
According to a second embodiment of the present invention, the CIR
of section [a] to section [e] may be calculated by using a cubic
spline interpolation method.
The cubic spline interpolation method uses a cubic equation, as
shown in Equation 9 below. fi(x)=ai*x.sup.3+bi*x.sup.2+ci*x+di
Equation 9
The cubic (polynomial) equation that can be in natural (or easy)
connection with other polynomial equations of earlier or later
sections is selected as the cubic equation. The functions selected
in each section will be referred to as a cubic spline interpolation
function, or a spline interpolation function, or a cubic function,
or a function. When selecting the spline interpolation function in
each section, the spline interpolation functions before and after
each point should be able to be processed with and each function
should have the same curvature.
More specifically, when generating a CIR of a particular section
using cubic spline interpolation, all possible CIRs are used,
instead of using only the two most approximate CIRs, as in the
linear interpolation method.
According to the embodiment of the present invention, in the data
group that does not include field synchronization data, the present
invention may use 5 CIRs, i.e., CIR(53), CIR(69), CIR(85),
CIR(101), and CIR(117), so as to generate cubic polynomial
equations of section [b] to section [e] (i.e., 4 sections). And, in
the data group that includes field synchronization data, the
present invention may use 6 CIRs, i.e., CIR(37), CIR(53), CIR(69),
CIR(85), CIR(101), and CIR(117), so as to generate cubic polynomial
equations of section [a] to section [e] (i.e., 5 sections). At this
point, the cubic equation, i.e., spline interpolation function,
applied to each section is different from one another. In other
words, the coefficient of the cubic equation applied to each
section is different from one another.
For example, the cubic equation, i.e., cubic interpolation
function, for calculating the CIR of section [a] using cubic spline
interpolation is shown in Equation 10 below.
f0(x)=a0*x.sup.3+b0*x.sup.2+c0*x+d0 Equation 10
The cubic equation for calculating the CIR of section [b] is shown
in Equation 11 below. f1(x)=a1*x.sup.3+b1*x.sup.2+c1*x+d1 Equation
11
The cubic equation for calculating the CIR of section [c] is shown
in Equation 12 below. f2(x)=a2*x.sup.3+b2*x.sup.2+c2*x+d2 Equation
12
The cubic equation for calculating the CIR of section [d] is shown
in Equation 13 below. f3(x)=a3*x.sup.3+b3*x.sup.2+c3*x+d3 Equation
13
The cubic equation for calculating the CIR of section [e] is shown
in Equation 14 below. f4(x)=a4*x.sup.3+b4*x.sup.2+c4*x+d4 Equation
14
Herein, the CIR calculated in the field synchronization section,
i.e., CIR(37), will be referred to as f(0), the CIR obtained in the
1.sup.st known data sequence, i.e., CIR(53), will be referred to as
f(1), the CIR obtained in the 3.sup.rd known data sequence, i.e.,
CIR(69), will be referred to as f(2), the CIR obtained in the
4.sup.th known data sequence, i.e., CIR(85), will be referred to as
f(3), the CIR obtained in the 5.sup.th known data sequence, i.e.,
CIR(101), will be referred to as f(4), and the CIR obtained in the
6.sup.th known data sequence, i.e., CIR(117), will be referred to
as f(5), for simplicity.
At this point, Equation 15 shown below corresponds to a matrix used
for calculating the coefficient of each cubic equation in the data
group that does not include field synchronization data. And,
Equation 16 shown below corresponds to a matrix used for
calculating the coefficient of each cubic equation in the data
group including field synchronization data.
##STR00001##
More specifically, Equation 15 corresponds to an equation used for
calculating coefficients (a1 to d4) of cubic equations (f1(x),
f2(x), f3(x), and f4(x)) corresponding to 4 different sections. The
constant matrix in Equation 15 has the size of [16.times.5], and
the CIR matrix has the size of [5.times.1].
Alternatively, Equation 16 corresponds to an equation used for
calculating coefficients (a0 to d4) of cubic equations (f0(x),
f1(x), f2(x), f3(x), and f4(x)) corresponding to 5 different
sections. The constant matrix in Equation 16 has the size of
[20.times.6], and the CIR matrix has the size of [6.times.1].
In Equation 15 and Equation 16, the constant matrix by which each
CIR is multiplied corresponds to a pre-decided value stored in the
memory. This value may be decided through experiments or may be
decided by calculation using calculating tools. Also, the constant
matrix may be stored in the memory in the form of a look-up table.
The value of the constant matrix is influenced by the number of
points that are to be referred to, i.e., by the number of CIRs.
Moreover, the value of the constant matrix is also influenced by
the x value. For example, the value of the constant matrix varies
when x=0, 1, 2, 3, . . . , as shown in FIG. 44 and FIG. 45 and when
x=16, 32, 48, . . . .
When calculating coefficients (a1 to d1) of the cubic equation in
section [b] corresponding to the data group that does not include
field synchronization data by applying Equation 15, the
coefficients may be calculated as shown in Equation 17 below.
a1=15/56*f(1)-34/56*f(2)+24/56*f(3)-6/56*f(4)+1/56
b1=-45/56*f(1)+102/56*f(2)-72/56*f(3)+18/56*f(4)-3/56
c1=-26/56*f(1)-12/56*f(2)+48/56*f(3)-12/56*f(4)+2/56
d1=112/56*f(1)-56/56*f(2) Equation 17
In Equation 17, f(1) to f(5) respectively correspond to CIR values
estimated by using the 1.sup.st known data sequence, and the
3.sup.rd to 6.sup.th known data sequences. Therefore, the
coefficients obtained in Equation 17 are applied to the cubic
equation shown in Equation 11. Then, when a specific point, i.e., x
value, within section [b] is substituted by the coefficients, the
CIR value of the point corresponding to the x value may be
calculated.
As described above, when generating a CIR for each section using
cubic spline interpolation, so as to channel-equalize data of the
corresponding section, the present invention may perform enhanced
channel-equalization, as compared to when using linear
interpolation. However, in order to enhance channel-equalizing
performance using cubic spline interpolation, the structure and
design of the present invention will become more complicated. For
example, when calculating the CIR using linear interpolation, a
memory capacity (or size) for storing the data of one section
(e.g., in the present invention, one section corresponds to the
size of 16 segments) is required. This is because the known data
sequence corresponding to the 53.sup.rd segment is required for
compensating channel distortion in the first data set of section
[a].
Conversely, when calculating the CIR using cubic spline
interpolation, data corresponding to up to the 117.sup.th segment
are required for compensating channel distortion in the first data
set of section [a]. Therefore, a memory size capable of storing all
data corresponding to the 5 sections is required. Arithmetically,
the cubic spline interpolation method requires a memory size 5
times the size of a memory used in the linear interpolation method.
Therefore, by considering the equalizing performance, price,
complexity, and so on, the present invention uses one of linear
interpolation and cubic spline interpolation, so as to generate a
CIR of a general data section located between training
sections.
Meanwhile, as described above, when using the cubic spline
interpolation method, in the data group that does not include field
synchronization data, 5 CIRs, i.e., CIR(53), CIR(69), CIR(85),
CIR(101), and CIR(117), are applied to the matrix shown in Equation
15, thereby obtaining coefficients of cubic equations corresponding
to 4 sections. Additionally, in the data group including field
synchronization data, 6 CIRs, i.e., CIR(37), CIR(53), CIR(69),
CIR(85), CIR(101), and CIR(117), are applied to the matrix shown in
Equation 16, thereby obtaining coefficients of cubic equations
corresponding to 5 sections.
However, as shown in FIG. 44 and FIG. 45, although each of section
[b], section [c], section [d], and section [e] corresponds to the
same section within the data group regardless of the field
synchronization data, the constants being multiplied by each CIR in
the actual polynomial equation are different from one another, as
shown in Equation 15 and Equation 16.
For example, in Equation 15, which is applied when using a data
group that does not include the field synchronization data, the
constant multiplied by each CIR in order to calculate coefficient
a1 of section [b] corresponds to 1/56[15-34 24-6 1]. On the other
hand, in Equation 16, which is applied when using a data group
including the field synchronization data, the constant multiplied
by each CIR in order to calculate coefficient a1 of section [b]
corresponds to 1/209[-71 217-241 120-30 6].
As described above, although each of section [b], section [c],
section [d], and section [e] corresponds to the same section within
the data group regardless of the field synchronization data, in the
above-described embodiment, since a different constant is applied
depending upon the presence or absence of the field synchronization
data, the complexity of the present invention may be increased.
More specifically, although section [b], section [c], section [d],
and section [e] are located in the same position within all data
groups, different cubic equations should be devised depending upon
the presence or absence of the field synchronization data.
Therefore, the complexity of the present invention is eventually
increased.
According to another embodiment of the present invention, the same
cubic equations are applied to the sections located in the same
position for each data group, so as to simplify the system
complexity. Then, by using the cubic spline interpolation method,
the increasing memory capacity may also be reduced. For this, the
present invention uses the same cubic equation to calculate the CIR
of a general data section located between training sections in all
data groups, regardless of the presence or absence of the field
synchronization data. More specifically, regardless of the presence
or absence of the field synchronization data, the coefficients of
each cubic equation of respective general data sections located
between training sections within each data group are calculated by
applying a single constant matrix. For example, the present
invention uses 5 CIRs to generate the cubic equation of the general
data section located between training sections in all data groups,
regardless of the presence or absence of the field synchronization
data. However, this is merely exemplary. Therefore, in other
examples, 4 CIRs may be used or 3 CIRs may be used to generate the
corresponding cubic equation. More specifically, the present
invention uses the same number of CIRs, i.e., the same number of
observation points, so as to configure the cubic equation of the
general data section located between training sections in all data
groups, regardless of the presence or absence of the field
synchronization data.
Furthermore, regardless of the presence or absence of the field
synchronization data, the present invention uses the constant
matrix of Equation 15 so as to calculate the coefficients of the
cubic equation.
More specifically, 5 points (i.e., 5 CIRs) are used to respectively
generate the cubic equations (f0(x) to f4(x)) for section [a] to
section [e] of the data group including the field synchronization
data. And, 5 points (i.e., 5 CIRs) are also used to respectively
generate the cubic equations (f1(x) to f4(x)) for section [b] to
section [e] of the data group that does not include any field
synchronization data. Moreover, regardless of the presence or
absence of the field synchronization data, the constant matrix of
Equation 15 is used as the constants, which are multiplied by the 5
CIRs so as to calculate the coefficients of the cubic equations
(f0(x) to f4(x)) for section [a] to section [e] or the cubic
equations (f1(x) to f4 (x)) for section [b] to section [e].
Accordingly, since the constant matrix of Equation 16 is no longer
required to be stored, the memory capacity can be reduced.
At this point, the 5 CIRs of the training sections that are used to
calculate the CIR of section [b] to section [e] of the data group
that does not include any field synchronization data respectively
correspond to CIR(53) (=f(1)), CIR(69) (=f(2)), CIR(85) (=f(3)),
CIR(101) (=f(4)), and CIR(117)(=f(5)). More specifically, the CIR
applied to the matrix of Equation 15 corresponds to f(1) to f(5),
the description of which is identical the above-described
method.
However, in the data group including the field synchronization
data, the 5 CIRs applied to each section vary.
For example, the 5 CIRs of the training section used for
calculating the CIR of section [a] in the data group including the
field synchronization data, respectively correspond to CIR(37)
(=f(0)), CIR(53) (=f(1)), CIR(69) (=f(2)), CIR(85) (=f(3)), and
CIR(101) (=f(4)). More specifically, the CIRs applied to the matrix
of Equation 15 correspond to f(0) to f(4). Also, the 5 CIRs of the
training section used for calculating the CIRs of section [b] to
section [d] in the data group including the field synchronization
data, may respectively correspond to CIR(37)(=f(0)), CIR(53)
(=f(1)), CIR(69) (=f(2)), CIR(85) (=f(3)), and CIR(101) (=f(4)), or
may respectively correspond to CIR(53) (=f(1)), CIR(69) (=f(2)),
CIR(85) (=f(3)), CIR(101) (=f(4)), and CIR(117) (=f(5)). More
specifically, the CIRs applied to the matrix of Equation 15 may
correspond to f(0) to f(4), or the CIRs applied to the matrix of
Equation 15 may correspond to f(1) to f(5).
Furthermore, the 5 CIRs of the training section used for
calculating the CIR of section [e] in the data group including the
field synchronization data, respectively correspond to CIR(53)
(=f(1)), CIR(69) (=f(2)), CIR(85) (=f(3)), CIR(101) (=f(4)), and
CIR(117) (=f(5)). More specifically, the CIRs applied to the matrix
of Equation 15 correspond to f(1) to f(5).
Equation 18 shown below corresponds to a matrix used for
calculating the coefficient of a cubic equation in each section by
applying f(0) to f(4) to the constant matrix of Equation 15 in the
data group including the field synchronization data.
##STR00002##
As shown in Equation 15, the constant matrix in Equation 18 also
has the size of [16.times.5], and the CIR matrix also has the size
of [5.times.1]. More specifically, the constant matrix of Equation
15 and that of Equation 18 are identical to one another.
However, one of the characteristics of the cubic spline
interpolation method is that, since there is no extending
information at the far-end side, the performance at the far-end
section may be deteriorated as compared to the inner sections.
More specifically, when comparing Equation 15 with Equation 18, in
Equation 15, the coefficients of section [b] and section [e], a1 to
d1 and a4 to d4 correspond to the information of the far-end
section. And, in Equation 18, the coefficients of section [a] and
section [d], a0 to d0 and a3 to d3 correspond to the information of
the far-end section.
At this point, since a0 to d0 and a4 to d4 do not overlap in
Equation 15 and Equation 18, the coefficients a0 to d0 of section
[a] are calculated by applying Equation 18, and the coefficients a4
to d4 of section [e] are calculated by applying Equation 15.
Furthermore, a1 to d1, a2 to d2, and a3 to d3 overlap in Equation
15 and Equation 18. At this point, in the cubic spline
interpolation method, since there is no extending information at
the far-end side, the performance at the far-end section may be
deteriorated as compared to the inner sections. Therefore,
according to the embodiment of the present invention, the
coefficients a1 to d1 of section [b] are calculated by applying
Equation 18, which corresponds to the inner section, and the
coefficients a3 to d3 of section [d] are calculated by applying
Equation 15, which corresponds to the inner section. And, since the
coefficients a2 to d2 of section [c] correspond to the inner
sections in both Equation 15 and Equation 18, either one of
Equation 15 and Equation 18 may be used to calculate the
coefficients a2 to d2. According to the embodiment of the present
invention, the coefficients a2 to d2 of section [c] are calculated
by applying Equation 15.
In other words, in the data group including the field
synchronization data, the present invention calculates coefficients
a0 to d0 and a1 to d1 of section [a] and section [b] by applying
Equation 18, and the present invention calculates coefficients a2
to d2, a3 to d3, and a4 to d4 of section [c] to section [e] by
applying Equation 15. The coefficients calculated by using the
above-described method are substituted in the cubic equations of
section [a] to section [e] (i.e., in f0(x), f1(x), f2(x), f3(x),
and f4(x)), and when each of the coefficients is substituted for a
desired x value, CIRs of section [a] to section [e] may be
generated by cubic spline interpolation.
Meanwhile, the constant matrix values of Equation 15 and Equation
18 are influenced by the x value. However, since the x values
applied to Equation 15 (i.e., x=1 to 5) are different from the x
values applied to Equation 18 (i.e., x=0 to 4), the constant matrix
value of Equation 15 and the constant matrix value of Equation 18
may actually vary. In other words, the constant matrix values used
for calculating coefficients a0 to d0 of section [a] and
coefficients a1 to d1 of section [b] may differ from the constant
matrix values used for calculating coefficients a2 to d2 of section
[c], coefficients a3 to d3 of section [d], and coefficients a4 to
d4 of section [e].
In order to resolve this problem, the x values of the cubic
equation for section [a] and section [b] may be substituted with x'
values, so as to calculate the CIR of section [a] and the CIR of
section [b]. In other words, by substituting x' values for x values
of a cubic function in sections wherein i=0 and 1, the CIR of
sections wherein i=0 and 1 may be calculated. However, in sections
wherein i=2, 3, and 4 (i.e., in section [c] to section [e]), x
values are substituted for the cubic function, thereby calculating
the CIR.
Equation 19 below shows an example of a cubic equation (i.e., cubic
function), which applies x' values, so as to calculate CIRs of
section [a] and section [b].
f0(x')=a0*x'.sup.3+b0*x'.sup.2+c0*x'+d0
f1(x')=a1*x'.sup.3+b1*x'.sup.2+c1*x'+d1 Equation 19
FIG. 46 illustrates an example for calculating the CIR of each
section by substituting x' values for the cubic functions in the
sections wherein i=0 and 1 (i.e., in section [a] and section [b]),
and by substituting x values for the cubic functions in the
sections wherein i=2,3, and 4, within the data group including the
field synchronization data. Herein, the x' values may vary
depending upon the x values of each point. For example, when each
point value corresponds to x=0, 1, 2, . . . , as shown in FIG. 44
and FIG. 45, then, x'=x+1. In another example, when each point
value corresponds to x=16, 32, 48, . . . , then, x'=x+16. Such
calculation is possible because in the present invention, a
constant (or the same) interval between training sequences (e.g.,
16 segments) is maintained. More specifically, this is because the
field synchronization data sequence, the 1.sup.st known data
sequence, and the 3.sup.rd to 6.sup.th known data sequences are
spaced apart at intervals of 16 segments. Thus, the design (or
embodiment) of the receiving system using the cubic spline
interpolation method may be simplified.
Meanwhile, 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.
Herein, linear extrapolation is the simplest form among a wide
range of extrapolation operations.
FIG. 47 illustrates an example of linear extrapolation according to
the present invention. As shown in the above-described example of
linear interpolation, in the linear extrapolation also, when using
a random function F(x), and when the values of F(Q) and F(S)
respective to each point x=Q and x=S are known (or given), a
straight line passing through the two points may be calculated so
as to obtain the approximate value {circumflex over (F)}.sup.(P) of
the corresponding function value at point P. Herein, linear
extrapolation is one of the simplest examples among a wide range of
extrapolation methods. Accordingly, a variety of extrapolation
methods other than the above-described linear extrapolation method
may be used. Therefore, the present invention will not be limited
only to the example given herein.
More specifically, in the data group including the field
synchronization data, as shown in FIG. 44, the CIRs of section [f]
and section [g] may be calculated by extrapolating based upon 2
CIRs among CIR(37), CIR(53), CIR(69), CIR(85), CIR(101), and
CIR(117). Alternatively, in the data group that does not include
the field synchronization data, as shown in FIG. 45, the CIRs of
section [h] and section [g] may be calculated by extrapolating
based upon 2 CIRs among CIR(53), CIR(69), CIR(85), CIR(101), and
CIR(117).
However, when CIR information can only be obtained from one
direction, as in extrapolation, it is difficult to adequately
compensate channel distortion, as compared to the sections using
interpolation. This is because there is an absolute lack of
information on the respective channel at the point where the
corresponding data experience distortion.
For example, it is assumed that in order to calculate the CIR of
section [f], an equation for linear extrapolation is configured by
using CIR(37) and CIR(53), and that the configured equation is
extended and applied to section [f]. In this case, as the CIR of
the actual channel is spaced further apart from CIR(37), the
difference between CIR(37) and the CIR calculated in section [f]
may become greater. Also, when configuring an equation for linear
extrapolation by using CIR(37) and CIR(53), and when the configured
equation is extended and applied to section [f], the CIR is
extrapolated starting from the 37.sup.th segment to the 0.sup.th
segment, and, as described above, the CIRs are extrapolated so as
to compensate channel distortion. Accordingly, problems of having
the power of signals after compensation become higher or weaker may
occur. In this case, in the process for compensating channel
distortion, the signal power may be distorted, thereby becoming
unable to provide optimum performance.
FIG. 48 illustrates an example of a signal power being distorted in
a specific segment (e.g., segment number (#10)) of section [f],
which corresponds to one of the extrapolation sections of the data
group including the field synchronization data.
More specifically, although the signal power of the specific
segment is in direct proportion to the power of CIR, the signal
power in the 10.sup.th segment of the extrapolation section is
higher, whereas the CIR power is very weak (or low). In other
words, in case of FIG. 48, the two powers are not in direct
proportion to one another. Therefore, in the present invention
proposes a method for supplementing the problems of experiencing
unintended signal power distortion.
For this, according to an embodiment of the present invention, the
present invention compensates the power of the CIR estimated by
extrapolation in the specific segment, so that the proportional
relation between the power of the signal estimated from the
specific segment of the extrapolation section and the power of the
CIR generated by extrapolation can be identical to the proportional
relation between the power of the signal and the power of the CIR
measured in the training section. Accordingly, when adjusting the
power of the CIR in the extrapolation section, as described above,
the problems of unintended increase and/or decrease in signal power
may be reduced.
In the present invention, the signal power may be calculated from a
signal prior to being processed with channel-equalization, or from
a channel-equalized signal. For example, the signal power may be
calculated by squaring the input signal and accumulating the
squared value during a specific section (e.g., during the
corresponding segment section). Also, the signal power may be
measured via at least one of software and hardware.
Additionally, the method for compensating CIR power of an
extrapolation section may be applied section [f], section [g], and
section [h] of FIG. 44 and FIG. 45. According to an embodiment of
the present invention, among the extrapolation sections, segment
number 10 (#10) of section [f] will be described in detail.
More specifically, the CIR information acquired from field
synchronization data included in the 37.sup.th segment of FIG. 48
reflects the power of the signal of the 37.sup.th segment.
Similarly, the signal power of the 10.sup.th segment should be in a
constant relation with the power of the CIR of the 10.sup.th
segment (i.e., CIR(10)), which is generated by using CIR(37) and
CIR(53) in the extrapolation process. Therefore, the ratio between
the power of a receive signal on the 10.sup.th segment and the
power of the CIR(10) of the 10.sup.th segment in section [f], which
is generated by extrapolation, and the ratio between the power of a
receive signal of the 37.sup.th segment and the power of CIR(37)
including the field synchronization data, which is generated by
using the field synchronization data, should be maintained
identically (or equally). This is shown in Equation 20 below. CIR
PWR(10)/signal PWR(10)=CIR PWR(37)/signal PWR(37) Equation 20
Herein, CIR PWR(10) corresponds to the power of the CIR generated
in the 10.sup.th segment within the extrapolation section, section
[f], through extrapolation, and the signal PWR(10) corresponds to
the power of the receive signal of the 10.sup.th segment within the
extrapolation section, section [f]. Also, CIR PWR(37) corresponds
to the power of the CIR estimated in the training section (e.g.,
field synchronization section) using the field synchronization
data, and signal PWR(37) corresponds to the power of the receive
signal of the 37.sup.th segment including the field synchronization
data. However, as described above, the power of CIR(10), which is
generated by extrapolation using CIR(37) and CIR(53), may not
satisfy the relation shown in Equation 20, due to unintended
distortion. Therefore, the present invention calculates an .alpha.
value that can satisfy Equation 21 shown below, thereby
compensating the CIR power of a specific segment within the
extrapolation section (e.g., the 10.sup.th segment). .alpha.*CIR
PWR(10)/signal PWR(10)=CIR PWR(37)/signal PWR(37) Equation 21
More specifically, by obtaining the a value, and by multiplying the
power of the CIR generated in the specific segment within the
extrapolation section through extrapolation by the obtained .alpha.
value, the proportional relation between the power of the signal
measured in the specific segment and the power of the CIR estimated
through extrapolation in the specific segment within the
extrapolation section and the proportional relation between the
power of the signal measured in the training section and the power
of the CIR also measured in the training section become identical.
As described above, by adjusting the power of the CIR corresponding
to the extrapolation section, problems of unintended increase or
decrease in signal power may be reduced.
For example, as shown in FIG. 48, if the power of CIR(10) generated
in the 10.sup.th segment within the extrapolation section through
extrapolation is multiplied by an a value that can satisfy Equation
21, the proportional relation between the power of the signal
measured in the 10.sup.th segment and the power of the CIR
generated in the 10.sup.th segment through extrapolation and the
proportional relation between the power of the signal and the power
of the CIR both measured in the field synchronization section
become equal to one another.
FIG. 49 illustrates a channel equalizer according to an embodiment
of the present invention.
FIG. 49 illustrates a block diagram of a channel equalizer
according to an embodiment of the present invention. Referring to
FIG. 49, the channel equalizer includes a first frequency domain
converter 4100, a channel estimator 4110, a second frequency domain
converter 4121, a coefficient calculator 4122, a distortion
compensator 4130, and a time domain converter 4140. Herein, the
channel equalizer may further include a remaining carrier phase
error remover, a noise canceller (NC), and a decision unit.
The first frequency domain converter 4100 includes an overlap unit
4101 overlapping inputted data, and a fast fourier transform (FFT)
unit 4102 converting the data outputted from the overlap unit 4101
to frequency domain data.
The channel estimator 4110 includes a CIR estimator 4111, a first
cleaner 4113, a CIR calculator 4114, a second cleaner, and a
zero-padding unit. Herein, the channel estimator 4110 may further
include a phase compensator compensating a phase of the CIR which
estimated in the CIR estimator 4111.
The second frequency domain converter 4121 includes a fast fourier
transform (FFT) unit converting the CIR being outputted from the
channel estimator 4110 to frequency domain CIR.
The time domain converter 4140 includes an IFFT unit 4141
converting the data having the distortion compensated by the
distortion compensator 4130 to time domain data, and a save unit
4142 extracting only valid data from the data outputted from the
IFFT unit 4141. The output data from the save unit 4142 corresponds
to the channel-equalized data.
If the remaining carrier phase error remover is connected to an
output terminal of the time domain converter 4140, the remaining
carrier phase error remover estimates the remaining carrier phase
error included in the channel-equalized data, thereby removing the
estimated error. If the noise remover is connected to an output
terminal of the time domain converter 4140, the noise remover
estimates noise included in the channel-equalized data, thereby
removing the estimated noise.
More specifically, the receiving data demodulated in FIG. 49 are
overlapped by the overlap unit 4101 of the first frequency domain
converter 4100 at a pre-determined overlapping ratio, which are
then outputted to the FFT unit 4102. The FFT unit 4102 converts the
overlapped time domain data to overlapped frequency domain data
through by processing the data with FFT. Then, the converted data
are outputted to the distortion compensator 4130.
The distortion compensator 4130 performs a complex number
multiplication on the overlapped frequency domain data outputted
from the FFT unit 4102 included in the first frequency domain
converter 4100 and the equalization coefficient calculated from the
coefficient calculator 4122, thereby compensating the channel
distortion of the overlapped data outputted from the FFT unit 4102.
Thereafter, the compensated data are outputted to the IFFT unit
4141 of the time domain converter 4140. The IFFT unit 4141 performs
IFFT on the overlapped data having the channel distortion
compensated, thereby converting the overlapped data to time domain
data, which are then outputted to the save unit 4142. The save unit
4142 extracts valid data from the data of the channel-equalized and
overlapped in the time domain, and outputs the extracted valid
data.
Meanwhile, the received data are inputted to the overlap unit 4101
of the first frequency domain converter 4100 included in the
channel equalizer and, at the same time, inputted to the CIR
estimator 4111 of the channel estimator 4110.
The CIR estimator 4111 uses a training sequence, for example, data
being inputted during the known data section and the known data in
order to estimate the CIR. If the data to be channel-equalizing is
the data within the data group including field synchronization
data, the training sequence using in the CIR estimator 4111 may
become the field synchronization data and known data. Meanwhile, if
the data to be channel-equalizing is the data within the data group
not including field synchronization data, the training sequence
using in the CIR estimator 4111 may become only the known data.
For example, the CIR estimator 4111 estimates CIR using the known
data correspond to reference known data generated during the known
data section by the receiving system in accordance with an
agreement between the receiving system and the transmitting system.
For this, the CIR estimator 4111 is provided known data position
information from the known sequence detector 2004. Also the CIR
estimator 4111 may be provided field synchronization position
information from the known sequence detector 2004.
The estimated CIR passes through the first cleaner (or pre-CIR
cleaner) 4113 or bypasses the first cleaner 4113, thereby being
inputted to the CIR calculator (or CIR interpolator-extrapolator)
4114. The CIR calculator 4114 either interpolates or extrapolates
an estimated CIR, which is then outputted to the second cleaner (or
post-CIR cleaner) 4115.
The first cleaner 4113 may or may not operate depending upon
whether the CIR calculator 4114 interpolates or extrapolates the
estimated CIR. For example, if the CIR calculator 4114 interpolates
the estimated CIR, the first cleaner 4113 does not operate.
Conversely, if the CIR calculator 4114 extrapolates the estimated
CIR, the first cleaner 4113 operates.
More specifically, the CIR estimated from the known data includes a
channel element that is to be obtained as well as a jitter element
caused by noise. Since such jitter element deteriorates the
performance of the equalizer, it preferable that a coefficient
calculator 4122 removes the jitter element before using the
estimated CIR. Therefore, according to the embodiment of the
present invention, each of the first and second cleaners 4113 and
4115 removes a portion of the estimated CIR having a power level
lower than the predetermined threshold value (i.e., so that the
estimated CIR becomes equal to `0`). Herein, this removal process
will be referred to as a "CIR cleaning" process.
The CIR calculator 4114 performs CIR interpolation by multiplying
a1 least two or more CIRs estimated from the CIR estimator 4111 by
each of coefficients, thereby adding the multiplied values.
According to an embodiment of the present invention, by using two
CIRs estimated in the training section, the CIR of the general data
section located between training sections may be generated through
linear interpolation. According to another embodiment of the
present invention, by applying 5 CIRs estimated in the training
section to Equation 15 and Equation 18, the CIR of the general data
section located between training sections may be generated through
cubic spline interpolation. At this point, some of the noise
elements of the CIR may be added to one another, thereby being
cancelled. Therefore, when the CIR calculator 4114 performs CIR
interpolation, the original (or initial) CIR having noise elements
remaining therein. In other words, when the CIR calculator 4114
performs CIR interpolation, the estimated CIR bypasses the first
cleaner 4113 and is inputted to the CIR calculator 4114.
Subsequently, the second cleaner 4115 cleans the CIR interpolated
by the CIR interpolator-extrapolator 4114.
Conversely, in the CIR Interpolator/Extrapolator 4114, CIR
extrapolation is performed by using the difference between two CIRs
estimated by the CIR estimator 4112, so as to estimate the CIR
located outside of the two CIRs (i.e., the CIR of the extrapolation
section). At this point, according to an embodiment of the present
invention, the power of the CIR generated in the specific segment
through extrapolation is compensated so that the proportional
relation between the power of the signal measured in the specific
segment within the extrapolation section and the power of the CIR
estimated through extrapolation in the specific segment within the
extrapolation section can become identical to the proportional
relation between the power of the signal and the power of the CIR
both measured in the training section. However, when performing
extrapolation as described above, the noise element of the CIR may
rather be amplified. Accordingly, when the CIR calculator 4114
performs CIR extrapolation, the CIR cleaned by the first cleaner
4113 is used. More specifically, when the CIR calculator 4114
performs CIR extrapolation, the extrapolated CIR passes through the
second cleaner 4115, thereby being inputted to the zero-padding
unit 4116.
Meanwhile, when a second frequency domain converter (or fast
fourier transform (FFT2)) 4121 converts the CIR, which has been
cleaned and outputted from the second cleaner 4115, to a frequency
domain, the length and of the inputted CIR and the FFT size may not
match (or be identical to one another). In other words, the CIR
length may be smaller than the FFT size. In this case, the
zero-padding unit 4116 adds a number of zeros `0`s corresponding to
the difference between the FFT size and the CIR length to the
inputted CIR, thereby outputting the processed CIR to the second
frequency domain converter (FFT2) 4121. Herein, the zero-padded CIR
may correspond to one of the interpolated CIR, extrapolated CIR,
and the CIR estimated in the known data section.
The second frequency domain converter 4121 performs FFT on the CIR
being outputted from the zero padding unit 4116, thereby converting
the CIR to a frequency domain CIR. Then, the second frequency
domain converter 4121 outputs the converted CIR to the coefficient
calculator 4122.
The coefficient calculator 4122 uses the frequency domain CIR being
outputted from the second frequency domain converter 4121 to
calculate the equalization coefficient. Then, the coefficient
calculator 4122 outputs the calculated coefficient to the
distortion compensator 4130. Herein, for example, the coefficient
calculator 4122 calculates a channel equalization coefficient of
the frequency domain that can provide minimum mean square error
(MMSE) from the CIR of the frequency domain, which is outputted to
the distortion compensator 4130.
The distortion compensator 4130 performs a complex number
multiplication on the overlapped data of the frequency domain being
outputted from the FFT unit 4102 of the first frequency domain
converter 4100 and the equalization coefficient calculated by the
coefficient calculator 4122, thereby compensating the channel
distortion of the overlapped data being outputted from the FFT unit
4102.
Block Decoder
Meanwhile, if the data being inputted to the block decoder 2005,
after being channel-equalized by the equalizer 2003, correspond to
the data having both block encoding and trellis encoding performed
thereon (i.e., the data within the RS frame, the signaling
information data, etc.) by the transmitting system, trellis
decoding and block decoding processes are performed on the inputted
data as inverse processes of the transmitting system.
Alternatively, if the data being inputted to the block decoder 2005
correspond to the data having only trellis encoding performed
thereon (i.e., the main service data), and not the block encoding,
only the trellis decoding process is performed on the inputted data
as the inverse process of the transmitting system.
The trellis decoded and block decoded data by the block decoder
2005 are then outputted to the RS frame decoder 2006. More
specifically, the block decoder 2005 removes the known data, data
used for trellis initialization, and signaling information data,
MPEG header, which have been inserted in the data group, and the RS
parity data, which have been added by the RS encoder/non-systematic
RS encoder or non-systematic RS encoder of the transmitting system.
Then, the block decoder 2005 outputs the processed data to the RS
frame decoder 2006. Herein, the removal of the data may be
performed before the block decoding process, or may be performed
during or after the block decoding process.
Meanwhile, the data trellis-decoded by the block decoder 2005 are
outputted to the data deinterleaver of the main service data
processor 2008. At this point, the data being trellis-decoded by
the block decoder 2005 and outputted to the data deinterleaver may
not only include the main service data but may also include the
data within the RS frame and the signaling information.
Furthermore, the RS parity data that are added by the transmitting
system after the pre-processor 230 may also be included in the data
being outputted to the data deinterleaver.
According to another embodiment of the present invention, data that
are not processed with block decoding and only processed with
trellis encoding by the transmitting system may directly bypass the
block decoder 2005 so as to be outputted to the data deinterleaver.
In this case, a trellis decoder should be provided before the data
deinterleaver. More specifically, if the inputted data correspond
to the data having only trellis encoding performed thereon and not
block encoding, the block decoder 2005 performs Viterbi (or
trellis) decoding on the inputted data so as to output a hard
decision value or to perform a hard-decision on a soft decision
value, thereby outputting the result.
Meanwhile, if the inputted data correspond to the data having both
block encoding process and trellis encoding process performed
thereon, the block decoder 2005 outputs a soft decision value with
respect to the inputted data.
In other words, if the inputted data correspond to data being
processed with block encoding by the block processor 302 and being
processed with trellis encoding by the trellis encoding module 256,
in the transmitting system, the block decoder 2005 performs a
decoding process and a trellis decoding process on the inputted
data as inverse processes of the transmitting system. At this
point, the RS frame encoder of the pre-processor included in the
transmitting system may be viewed as an outer (or external)
encoder. And, the trellis encoder may be viewed as an inner (or
internal) encoder. When decoding such concatenated codes, in order
to allow the block decoder 2005 to maximize its performance of
decoding externally encoded data, the decoder of the internal code
should output a soft decision value.
FIG. 50 illustrates a detailed block diagram of the block decoder
2005 according to an embodiment of the present invention. Referring
to FIG. 50, the block decoder 2005 includes a feedback controller
4010, an input buffer 4011, a trellis decoding unit (or 12-way
trellis coded modulation (TCM) decoder or inner decoder) 4012, a
symbol-byte converter 4013, an outer block extractor 4014, a
feedback deformatter 4015, a symbol deinterleaver 4016, an outer
symbol mapper 4017, a symbol decoder 4018, an inner symbol mapper
4019, a symbol interleaver 4020, a feedback formatter 4021, and an
output buffer 4022. Herein, just as in the transmitting system, the
trellis decoding unit 4012 may be viewed as an inner (or internal)
decoder. And, the symbol decoder 4018 may be viewed as an outer (or
external) decoder.
The input buffer 4011 temporarily stores the mobile service data
symbols being channel-equalized and outputted from the equalizer
2003. (Herein, the mobile service data symbols may include symbols
corresponding to the signaling information, RS parity data symbols
and CRC data symbols added during the encoding process of the RS
frame.) Thereafter, the input buffer 4011 repeatedly outputs the
stored symbols for M number of times to the trellis decoding unit
4012 in a turbo block (TDL) size required for the turbo decoding
process.
The turbo decoding length (TDL) may also be referred to as a turbo
block. Herein, a TDL should include at least one SCCC block size.
Therefore, as defined in FIG. 5, when it is assumed that one M/H
block is a 16-segment unit, and that a combination of 10 M/H blocks
form one SCCC block, a TDL should be equal to or larger than the
maximum possible combination size. For example, when it is assumed
that 2 M/H blocks form one SCCC block, the TDL may be equal to or
larger than 32 segments (i.e., 828.times.32=26496 symbols). Herein,
M indicates a number of repetitions for turbo-decoding pre-decided
by the feed-back controller 4010.
Also, M represents a number of repetitions of the turbo decoding
process, the number being predetermined by the feedback controller
4010.
Additionally, among the values of symbols being channel-equalized
and outputted from the equalizer 2003, the input symbol values
corresponding to a section having no mobile service data symbols
(including RS parity data symbols during RS frame encoding and CRC
data symbols) included therein, bypass the input buffer 4011
without being stored. More specifically, since trellis-encoding is
performed on input symbol values of a section wherein SCCC
block-encoding has not been performed, the input buffer 4011 inputs
the inputted symbol values of the corresponding section directly to
the trellis encoding module 4012 without performing any storage,
repetition, and output processes. The storage, repetition, and
output processes of the input buffer 4011 are controlled by the
feedback controller 4010. Herein, the feedback controller 4010
refers to SCCC-associated information (e.g., SCCC block mode and
SCCC outer code mode), which are outputted from the signaling
decoder 2013 or the operation controller 2000, in order to control
the storage and output processes of the input buffer 4011.
The trellis decoding unit 4012 includes a 12-way TCM decoder.
Herein, the trellis decoding unit 4012 performs 12-way trellis
decoding as inverse processes of the 12-way trellis encoder.
More specifically, the trellis decoding unit 4012 receives a number
of output symbols of the input buffer 4011 and soft-decision values
of the feedback formatter 4021 equivalent to each TDL, so as to
perform the TCM decoding process.
At this point, based upon the control of the feedback controller
4010, the soft-decision values outputted from the feedback
formatter 4021 are matched with a number of mobile service data
symbol places so as to be in a one-to-one (1:1) correspondence.
Herein, the number of mobile service data symbol places is
equivalent to the TDL being outputted from the input buffer
4011.
More specifically, the mobile service data being outputted from the
input buffer 4011 are matched with the turbo decoded data being
inputted, so that each respective data place can correspond with
one another. Thereafter, the matched data are outputted to the
trellis decoding unit 4012. For example, if the turbo decoded data
correspond to the third symbol within the turbo block, the
corresponding symbol (or data) is matched with the third symbol
included in the turbo block, which is outputted from the input
buffer 4011. Subsequently, the matched symbol (or data) is
outputted to the trellis decoding unit 4012.
In order to do so, while the regressive turbo decoding is in
process, the feedback controller 4010 controls the input buffer
4011 so that the input buffer 4011 stores the corresponding turbo
block data. Also, by delaying data (or symbols), the soft decision
value (e.g., LLR) of the symbol outputted from the symbol
interleaver 4020 and the symbol of the input buffer 4011
corresponding to the same place (or position) within the block of
the output symbol are matched with one another to be in a
one-to-one correspondence. Thereafter, the matched symbols are
controlled so that they can be inputted to the TCM decoder through
the respective path. This process is repeated for a predetermined
number of turbo decoding cycle periods. Then, the data of the next
turbo block are outputted from the input buffer 4011, thereby
repeating the turbo decoding process.
The output of the trellis decoding unit 4012 signifies a degree of
reliability of the transmission bits configuring each symbol. For
example, in the transmitting system, since the input data of the
trellis encoding module correspond to two bits as one symbol, a log
likelihood ratio (LLR) between the likelihood of a bit having the
value of `1` and the likelihood of the bit having the value of `0`
may be respectively outputted (in bit units) to the upper bit and
the lower bit. Herein, the log likelihood ratio corresponds to a
log value for the ratio between the likelihood of a bit having the
value of `1` and the likelihood of the bit having the value of `0`.
Alternatively, a LLR for the likelihood of 2 bits (i.e., one
symbol) being equal to "00", "01", "10", and "11" may be
respectively outputted (in symbol units) to all 4 combinations of
bits (i.e., 00, 01, 10, 11). Consequently, this becomes the soft
decision value that indicates the degree of reliability of the
transmission bits configuring each symbol. A maximum a posteriori
probability (MAP) or a soft-out Viterbi algorithm (SOYA) may be
used as a decoding algorithm of each TCM decoder within the trellis
decoding unit 4012.
The output of the trellis decoding unit 4012 is inputted to the
symbol-byte converter 4013 and the outer block extractor 4014.
The symbol-byte converter 4013 performs a hard-decision process of
the soft decision value that is trellis decoded and outputted from
the trellis decoding unit 4012. Thereafter, the symbol-byte
converter 4013 groups 4 symbols into byte units, which are then
outputted to the data deinterleaver of the main service data
processor 2008 of FIG. 41. More specifically, the symbol-byte
converter 4013 performs hard-decision in bit units on the soft
decision value of the symbol outputted from the trellis decoding
unit 4012. Therefore, the data processed with hard-decision and
outputted in bit units from the symbol-byte converter 4013 not only
include main service data, but may also include mobile service
data, known data, RS parity data, and MPEG headers.
Among the soft decision values of TDL size of the trellis decoding
unit 4012, the outer block extractor 4014 identifies the soft
decision values of B size of corresponding to the mobile service
data symbols (wherein symbols corresponding to signaling
information, RS parity data symbols that are added during the
encoding of the RS frame, and CRC data symbols are included) and
outputs the identified soft decision values to the feedback
deformatter 4015.
The feedback deformatter 4015 changes the processing order of the
soft decision values corresponding to the mobile service data
symbols. This is an inverse process of an initial change in the
processing order of the mobile service data symbols, which are
generated during an intermediate step, wherein the output symbols
outputted from the block processor 302 of the transmitting system
are being inputted to the trellis encoding module 256 (e.g., when
the symbols pass through the group formatter, the data
deinterleaver, the packet formatter, and the data interleaver).
Thereafter, the feedback deformatter 2015 performs reordering of
the process order of soft decision values corresponding to the
mobile service data symbols and, then, outputs the processed mobile
service data symbols to the symbol deinterleaver 4016.
This is because a plurality of blocks exist between the block
processor 302 and the trellis encoding module 256, and because, due
to these blocks, the order of the mobile service data symbols being
outputted from the block processor 302 and the order of the mobile
service data symbols being inputted to the trellis encoding module
256 are not identical to one another. Therefore, the feedback
deformatter 4015 reorders (or rearranges) the order of the mobile
service data symbols being outputted from the outer block extractor
4014, so that the order of the mobile service data symbols being
inputted to the symbol deinterleaver 4016 matches the order of the
mobile service data symbols outputted from the block processor 302
of the transmitting system. The reordering process may be embodied
as one of software, middleware, and hardware.
The symbol deinterleaver 4016 performs deinterleaving on the mobile
service data symbols having their processing orders changed and
outputted from the feedback deformatter 4015, as an inverse process
of the symbol interleaving process of the symbol interleaver 514
included in the transmitting system. The size of the block used by
the symbol deinterleaver 4016 during the deinterleaving process is
identical to interleaving size of an actual symbol (i.e., B) of the
symbol interleaver 514, which is included in the transmitting
system. This is because the turbo decoding process is performed
between the trellis decoding unit 4012 and the symbol decoder 4018.
Both the input and output of the symbol deinterleaver 4016
correspond to soft decision values, and the deinterleaved soft
decision values are outputted to the outer symbol mapper 4017.
The operations of the outer symbol mapper 4017 may vary depending
upon the structure and coding rate of the convolution encoder 513
included in the transmitting system. For example, when data are
1/2-rate encoded by the convolution encoder 513 and then
transmitted, the outer symbol mapper 4017 directly outputs the
input data without modification. In another example, when data are
1/4-rate encoded by the convolution encoder 513 and then
transmitted, the outer symbol mapper 4017 converts the input data
so that it can match the input data format of the symbol decoder
4018. For this, the outer symbol mapper 4017 may be inputted
SCCC-associated information (i.e., SCCC block mode and SCCC outer
code mode) from the signaling decoder 2013. Then, the outer symbol
mapper 4017 outputs the converted data to the symbol decoder
4018.
The symbol decoder 4018 (i.e., the outer decoder) receives the data
outputted from the outer symbol mapper 4017 and performs symbol
decoding as an inverse process of the convolution encoder 513
included in the transmitting system. At this point, two different
soft decision values are outputted from the symbol decoder 4018.
One of the outputted soft decision values corresponds to a soft
decision value matching the output symbol of the convolution
encoder 513 (hereinafter referred to as a "first decision value").
The other one of the outputted soft decision values corresponds to
a soft decision value matching the input bit of the convolution
encoder 513 (hereinafter referred to as a "second decision
value").
More specifically, the first decision value represents a degree of
reliability the output symbol (i.e., 2 bits) of the convolution
encoder 513. Herein, the first soft decision value may output (in
bit units) a LLR between the likelihood of 1 bit being equal to `1`
and the likelihood of 1 bit being equal to `0` with respect to each
of the upper bit and lower bit, which configures a symbol.
Alternatively, the first soft decision value may also output (in
symbol units) a LLR for the likelihood of 2 bits being equal to
"00", "01", "10", and "11" with respect to all possible
combinations. The first soft decision value is fed-back to the
trellis decoding unit 4012 through the inner symbol mapper 4019,
the symbol interleaver 4020, and the feedback formatter 4021. On
the other hand, the second soft decision value indicates a degree
of reliability the input bit of the convolution encoder 513
included in the transmitting system. Herein, the second soft
decision value is represented as the LLR between the likelihood of
1 bit being equal to `1` and the likelihood of bit being equal to
`0`. Thereafter, the second soft decision value is outputted to the
outer buffer 4022. In this case, a maximum a posteriori probability
(MAP) or a soft-out Viterbi algorithm (SOYA) may be used as the
decoding algorithm of the symbol decoder 4018.
The first soft decision value that is outputted from the symbol
decoder 4018 is inputted to the inner symbol mapper 4019. The inner
symbol mapper 4019 converts the first soft decision value to a data
format corresponding the input data of the trellis decoding unit
4012. Thereafter, the inner symbol mapper 4019 outputs the
converted soft decision value to the symbol interleaver 4020. The
operations of the inner symbol mapper 4019 may also vary depending
upon the structure and coding rate of the convolution encoder 513
included in the transmitting system.
The symbol interleaver 4020 performs symbol interleaving, as shown
in FIG. 30, on the first soft decision value that is outputted from
the inner symbol mapper 4019. Then, the symbol interleaver 4020
outputs the symbol-interleaved first soft decision value to the
feedback formatter 4021. Herein, the output of the symbol
interleaver 4020 also corresponds to a soft decision value.
With respect to the changed processing order of the soft decision
values corresponding to the symbols that are generated during an
intermediate step, wherein the output symbols outputted from the
block processor 302 of the transmitting system are being inputted
to the trellis encoding module (e.g., when the symbols pass through
the group formatter, the data deinterleaver, the packet formatter,
the RS encoder, and the data interleaver), the feedback formatter
4021 alters (or changes) the order of the output values outputted
from the symbol interleaver 4020. Subsequently, the feedback
formatter 4020 outputs values to the trellis decoding unit 4012 in
the changed order. The reordering process of the feedback formatter
4021 may configure at least one of software, hardware, and
middleware.
The soft decision values outputted from the symbol interleaver 4020
are matched with the positions of mobile service data symbols each
having the size of TDL, which are outputted from the input buffer
4011, so as to be in a one-to-one correspondence. Thereafter, the
soft decision values matched with the respective symbol position
are inputted to the trellis decoding unit 4012. At this point,
since the main service data symbols or the RS parity data symbols
and known data symbols of the main service data do not correspond
to the mobile service data symbols, the feedback formatter 4021
inserts null data in the corresponding positions, thereby
outputting the processed data to the trellis decoding unit 4012.
Additionally, each time the symbols having the size of TDL are
turbo decoded, no value is fed-back by the symbol interleaver 4020
starting from the beginning of the first decoding process.
Therefore, the feedback formatter 4021 is controlled by the
feedback controller 4010, thereby inserting null data into all
symbol positions including a mobile service data symbol. Then, the
processed data are outputted to the trellis decoding unit 4012.
The output buffer 4022 receives the second soft decision value from
the symbol decoder 4018 based upon the control of the feedback
controller 4010. Then, the output buffer 4022 temporarily stores
the received second soft decision value. Thereafter, the output
buffer 4022 outputs the second soft decision value to the RS frame
decoder 2006. For example, the output buffer 4022 overwrites the
second soft decision value of the symbol decoder 4018 until the
turbo decoding process is performed for M number of times. Then,
once all M number of turbo decoding processes is performed for a
single TDL, the corresponding second soft decision value is
outputted to the RS frame decoder 2006.
The feedback controller 4010 controls the number of turbo decoding
and turbo decoding repetition processes of the overall block
decoder, shown in FIG. 50. More specifically, once the turbo
decoding process has been repeated for a predetermined number of
times, the second soft decision value of the symbol decoder 4018 is
outputted to the RS frame decoder 2006 through the output buffer
4022. Thus, the block decoding process of a turbo block is
completed. In the description of the present invention, this
process is referred to as a regressive turbo decoding process for
simplicity.
At this point, the number of regressive turbo decoding rounds
between the trellis decoding unit 4012 and the symbol decoder 4018
may be defined while taking into account hardware complexity and
error correction performance. Accordingly, if the number of rounds
increases, the error correction performance may be enhanced.
However, this may lead to a disadvantageous of the hardware
becoming more complicated (or complex).
Meanwhile, the main service data processor 2008 corresponds to
block required for receiving the main service data. Therefore, the
above-mentioned blocks may not be necessary (or required) in the
structure of a digital broadcast receiving system for receiving
mobile service data only.
The data deinterleaver of the main service data processor 2008
performs an inverse process of the data interleaver included in the
transmitting system. In other words, the data deinterleaver
deinterleaves the main service data outputted from the block
decoder 2005 and outputs the deinterleaved main service data to the
RS decoder. The data being inputted to the data deinterleaver
include main service data, as well as mobile service data, known
data, RS parity data, and an MPEG header. At this point, among the
inputted data, only the main service data and the RS parity data
added to the main service data packet may be outputted to the RS
decoder. Also, all data outputted after the data derandomizer may
all be removed with the exception for the main service data. In the
embodiment of the present invention, only the main service data and
the RS parity data added to the main service data packet are
inputted to the RS decoder.
The RS decoder performs a systematic RS decoding process on the
deinterleaved data and outputs the processed data to the data
derandomizer.
The data derandomizer receives the output of the RS decoder and
generates a pseudo random data byte identical to that of the
randomizer included in the digital broadcast transmitting system.
Thereafter, the data derandomizer performs a bitwise exclusive OR
(XOR) operation on the generated pseudo random data byte, thereby
inserting the MPEG synchronization bytes to the beginning of each
packet so as to output the data in 188-byte main service data
packet units.
RS Frame Decoder
The data outputted from the block decoder 2005 are in portion
units. More specifically, in the transmitting system, the RS frame
is divided into several portions, and the mobile service data of
each portion are assigned either to regions A/B/C/D within the data
group or to any one of regions A/B and regions C/D, thereby being
transmitted to the receiving system. Therefore, the RS frame
decoder 2006 groups several portions included in a parade so as to
form an RS frame. Alternatively, the RS frame decoder 2006 may also
group several portions included in a parade so as to form two RS
frames. Thereafter, error correction decoding is performed in RS
frame units.
For example, when the RS frame mode value is equal to `00`, then
one parade transmits one RS frame. At this point, one RS frame is
divided into several portions, and the mobile service data of each
portion are assigned to regions A/B/C/D of the corresponding data
group, thereby being transmitted. In this case, the RS frame
decoder 2006 extracts mobile service data from regions A/B/C/D of
the corresponding data group, as shown in FIG. 51(a). Subsequently,
the RS frame decoder 2006 may perform the process of forming (or
creating) a portion on a plurality of data group within a parade,
thereby forming several portions. Then, the several portions of
mobile service data may be grouped to form an RS frame. Herein, if
stuffing bytes are added to the last portion, the RS frame may be
formed after removing the stuffing byte.
In another example, when the RS frame mode value is equal to `01`,
then one parade transmits two RS frames (i.e., a primary RS frame
and a secondary RS frame). At this point, a primary RS frame is
divided into several primary portions, and the mobile service data
of each primary portion are assigned to regions A/B of the
corresponding data group, thereby being transmitted. Also, a
secondary RS frame is divided into several secondary portions, and
the mobile service data of each secondary portion are assigned to
regions C/D of the corresponding data group, thereby being
transmitted.
In this case, the RS frame decoder 2006 extracts mobile service
data from regions A/B of the corresponding data group, as shown in
FIG. 51(b). Subsequently, the RS frame decoder 2006 may perform the
process of forming (or creating) a primary portion on a plurality
of data group within a parade, thereby forming several primary
portions. Then, the several primary portions of mobile service data
may be grouped to form a primary RS frame. Herein, if stuffing
bytes are added to the last primary portion, the primary RS frame
may be formed after removing the stuffing byte. Also, the RS frame
decoder 2006 extracts mobile service data from regions C/D of the
corresponding data group. Subsequently, the RS frame decoder 2006
may perform the process of forming (or creating) a secondary
portion on a plurality of data group within a parade, thereby
forming several secondary portions. Then, the several secondary
portions of mobile service data may be grouped to form a secondary
RS frame. Herein, if stuffing bytes are added to the last secondary
portion, the secondary RS frame may be formed after removing the
stuffing byte.
More specifically, the RS frame decoder 2006 receives the
RS-encoded and/or CRC-encoded mobile service data of each portion
from the block decoder 2005. Then, the RS frame decoder 2006 groups
several portions, which are inputted based upon RS frame-associated
information outputted from the signaling decoder 2013 or the
operation controller 2000, thereby performing error correction. By
referring to the RS frame mode value included in the RS
frame-associated information, the RS frame decoder 2006 may form an
RS frame and may also be informed of the number of RS code parity
data bytes and the code size. Herein, the RS code is used to
configure (or form) the RS frame. The RS frame decoder 2006 also
refers to the RS frame-associated information in order to perform
an inverse process of the RS frame encoder, which is included in
the transmitting system, thereby correcting the errors within the
RS frame. Thereafter, the RS frame decoder 2006 adds 1 MPEG
synchronization data byte to the error-correction mobile service
data packet. In an earlier process, the 1 MPEG synchronization data
byte was removed from the mobile service data packet during the RS
frame encoding process. Finally, the RS frame decoder 2006 performs
a derandomizing process on the processed mobile service data
packet.
FIG. 52 illustrates, when the RS frame mode value is equal to `00`,
an exemplary process of grouping several portion being transmitted
to a parade, thereby forming an RS frame and an RS frame
reliability map.
More specifically, the RS frame decoder 2006 receives and groups a
plurality of mobile service data bytes, so as to form an RS frame.
According to the present invention, in transmitting system, the
mobile service data correspond to data RS-encoded in RS frame
units. At this point, the mobile service data may already be error
correction encoded (e.g., CRC-encoded). Alternatively, the error
correction encoding process may be omitted.
It is assumed that, in the transmitting system, an RS frame having
the size of (N+2).times.(187+P) bytes is divided into M number of
portions, and that the M number of mobile service data portions are
assigned and transmitted to regions A/B/C/D in M number of data
groups, respectively. In this case, in the receiving system, each
mobile service data portion is grouped, as shown in FIG. 52(a),
thereby forming an RS frame having the size of (N+2).times.(187+P)
bytes. At this point, when stuffing bytes (S) are added to at least
one portion included in the corresponding RS frame and then
transmitted, the stuffing bytes are removed, thereby configuring an
RS frame and an RS frame reliability map. For example, as shown in
FIG. 27, when S number of stuffing bytes are added to the
corresponding portion, the S number of stuffing bytes are removed,
thereby configuring the RS frame and the RS frame reliability
map.
Herein, when it is assumed that the block decoder 2005 outputs a
soft decision value for the decoding result, the RS frame decoder
2006 may decide the `0` and `1` of the corresponding bit by using
the codes of the soft decision value. 8 bits that are each decided
as described above are grouped to generate 1 data byte. If the
above-described process is performed on all soft decision values of
several portions (or data groups) included in a parade, the RS
frame having the size of (N+2).times.(187+P) bytes may be
configured.
Additionally, the present invention uses the soft decision value
not only to configure the RS frame but also to configure a
reliability map.
Herein, the reliability map indicates the reliability of the
corresponding data byte, which is configured by grouping 8 bits,
the 8 bits being decided by the codes of the soft decision
value.
For example, when the absolute value of the soft decision value
exceeds a pre-determined threshold value, the value of the
corresponding bit, which is decided by the code of the
corresponding soft decision value, is determined to be reliable.
Conversely, when the absolute value of the soft decision value does
not exceed the pre-determined threshold value, the value of the
corresponding bit is determined to be unreliable. Thereafter, if
even a single bit among the 8 bits, which are decided by the codes
of the soft decision value and group to configure one data byte, is
determined to be unreliable, the corresponding data byte is marked
on the reliability map as an unreliable data byte.
Herein, determining the reliability of one data byte is only
exemplary. More specifically, when a plurality of data bytes (e.g.,
at least 4 data bytes) are determined to be unreliable, the
corresponding data bytes may also be marked as unreliable data
bytes within the reliability map. Conversely, when all of the data
bits within the one data byte are determined to be reliable (i.e.,
when the absolute value of the soft decision values of all 8 bits
included in the one data byte exceed the predetermined threshold
value), the corresponding data byte is marked to be a reliable data
byte on the reliability map. Similarly, when a plurality of data
bytes (e.g., at least 4 data bytes) are determined to be reliable,
the corresponding data bytes may also be marked as reliable data
bytes within the reliability map. The numbers proposed in the
above-described example are merely exemplary and, therefore, do not
limit the scope or spirit of the present invention.
The process of configuring the RS frame and the process of
configuring the reliability map both using the soft decision value
may be performed at the same time. Herein, the reliability
information within the reliability map is in a one-to-one
correspondence with each byte within the RS frame. For example, if
a RS frame has the size of (N+2).times.(187+P) bytes, the
reliability map is also configured to have the size of
(N+2).times.(187+P) bytes. FIG. 52(a') and FIG. 52(b') respectively
illustrate the process steps of configuring the reliability map
according to the present invention.
Subsequently, the RS frame reliability map is used on the RS frames
so as to perform error correction.
FIG. 53 illustrates example of the error correction processed
according to embodiments of the present invention. FIG. 53
illustrates an example of performing an error correction process
when the transmitting system has performed both RS encoding and CRC
encoding processes on the RS frame.
As shown in FIG. 53 (a) and FIG. 53(a'), when the RS frame having
the size of (N+2).times.(187+P) bytes and the RS frame reliability
map having the size of (N+2).times.(187+P) bytes are generated, a
CRC syndrome checking process is performed on the generated RS
frame, thereby verifying whether any error has occurred in each
row. Subsequently, as shown in FIG. 53(b), a 2-byte checksum is
removed to configure an RS frame having the size of N.times.(187+P)
bytes. Herein, the presence (or existence) of an error is indicated
on an error flag corresponding to each row. Similarly, since the
portion of the reliability map corresponding to the CRC checksum
has hardly any applicability, this portion is removed so that only
N.times.(187+P) number of the reliability information bytes remain,
as shown in FIG. 53(b').
After performing the CRC syndrome checking process, as described
above, a RS decoding process is performed in a column direction.
Herein, a RS erasure correction process may be performed in
accordance with the number of CRC error flags. More specifically,
as shown in FIG. 53(c), the CRC error flag corresponding to each
row within the RS frame is verified. Thereafter, the RS frame
decoder 2006 determines whether the number of rows having a CRC
error occurring therein is equal to or smaller than the maximum
number of errors on which the RS erasure correction may be
performed, when performing the RS decoding process in a column
direction. The maximum number of errors corresponds to P number of
parity bytes inserted when performing the RS encoding process. In
the embodiment of the present invention, it is assumed that 48
parity bytes have been added to each column (i.e., P=48).
If the number of rows having the CRC errors occurring therein is
smaller than or equal to the maximum number of errors (i.e., 48
errors according to this embodiment) that can be corrected by the
RS erasure decoding process, a (235,187)-RS erasure decoding
process is performed in a column direction on the RS frame having
(187+P) number of N-byte rows (i.e., 235 N-byte rows), as shown in
FIG. 53(d). Thereafter, as shown in FIG. 53(e), the 48-byte parity
data that have been added at the end of each column are removed.
Conversely, however, if the number of rows having the CRC errors
occurring therein is greater than the maximum number of errors
(i.e., 48 errors) that can be corrected by the RS erasure decoding
process, the RS erasure decoding process cannot be performed. In
this case, the error may be corrected by performing a general RS
decoding process. In addition, the reliability map, which has been
generated based upon the soft decision value along with the RS
frame, may be used to further enhance the error correction ability
(or performance) of the present invention.
More specifically, the RS frame decoder 2006 compares the absolute
value of the soft decision value of the block decoder 2005 with the
pre-determined threshold value, so as to determine the reliability
of the bit value decided by the code of the corresponding soft
decision value. Also, 8 bits, each being determined by the code of
the soft decision value, are grouped to form one data byte.
Accordingly, the reliability information on this one data byte is
indicated on the reliability map. Therefore, as shown in FIG.
53(c), even though a particular row is determined to have an error
occurring therein based upon a CRC syndrome checking process on the
particular row, the present invention does not assume that all
bytes included in the row have errors occurring therein. The
present invention refers to the reliability information of the
reliability map and sets only the bytes that have been determined
to be unreliable as erroneous bytes. In other words, with disregard
to whether or not a CRC error exists within the corresponding row,
only the bytes that are determined to be unreliable based upon the
reliability map are set as erasure points.
According to another method, when it is determined that CRC errors
are included in the corresponding row, based upon the result of the
CRC syndrome checking result, only the bytes that are determined by
the reliability map to be unreliable are set as errors. More
specifically, only the bytes corresponding to the row that is
determined to have errors included therein and being determined to
be unreliable based upon the reliability information, are set as
the erasure points. Thereafter, if the number of error points for
each column is smaller than or equal to the maximum number of
errors (i.e., 48 errors) that can be corrected by the RS erasure
decoding process, an RS erasure decoding process is performed on
the corresponding column. Conversely, if the number of error points
for each column is greater than the maximum number of errors (i.e.,
48 errors) that can be corrected by the RS erasure decoding
process, a general decoding process is performed on the
corresponding column.
More specifically, if the number of rows having CRC errors included
therein is greater than the maximum number of errors (i.e., 48
errors) that can be corrected by the RS erasure decoding process,
either an RS erasure decoding process or a general RS decoding
process is performed on a column that is decided based upon the
reliability information of the reliability map, in accordance with
the number of erasure points within the corresponding column. For
example, it is assumed that the number of rows having CRC errors
included therein within the RS frame is greater than 48. And, it is
also assumed that the number of erasure points decided based upon
the reliability information of the reliability map is indicated as
40 erasure points in the first column and as erasure points in the
second column. In this case, a (235,187)-RS erasure decoding
process is performed on the first column. Alternatively, a
(235,187)-RS decoding process is performed on the second column.
When error correction decoding is performed on all column
directions within the RS frame by using the above-described
process, the 48-byte parity data which were added at the end of
each column are removed, as shown in FIG. 53(e).
As described above, even though the total number of CRC errors
corresponding to each row within the RS frame is greater than the
maximum number of errors that can be corrected by the RS erasure
decoding process, when the number of bytes determined to have a low
reliability level, based upon the reliability information on the
reliability map within a particular column, while performing error
correction decoding on the particular column. Herein, the
difference between the general RS decoding process and the RS
erasure decoding process is the number of errors that can be
corrected. More specifically, when performing the general RS
decoding process, the number of errors corresponding to half of the
number of parity bytes (i.e., (number of parity bytes)/2) that are
inserted during the RS encoding process may be error corrected
(e.g., 24 errors may be corrected). Alternatively, when performing
the RS erasure decoding process, the number of errors corresponding
to the number of parity bytes that are inserted during the RS
encoding process may be error corrected (e.g., 48 errors may be
corrected).
After performing the error correction decoding process, as
described above, a RS frame configured of 187 N-byte rows (or
packet) may be obtained as shown in FIG. 53(e). The RS frame having
the size of N.times.187 bytes is outputted by the order of N number
of 187-byte units. At this point, 1 MPEG synchronization byte,
which had been removed by the transmitting system, is added to each
187-byte packet, as shown in FIG. 53(f). Therefore, a 188-byte unit
mobile service data packet is outputted.
At this point, the RS frame decoded mobile service data is
performed a derandomizing process, which corresponds to the inverse
process of the randomizer included in the transmitting system and
then the derandomized data are outputted, thereby obtaining the
mobile service data transmitted from the transmitting system. In
the present invention, the RS frame decoder 2006 may perform the
data derandomizing function.
An RS frame decoder may be configured of M number of RS frame
decoders provided in parallel, wherein the number of RS frame
encoders is equal to the number of parades (=M) within an M/H
frame, a multiplexer for multiplexing each portion and being
provided to each input end of the M number of RS frame decoders,
and a demultiplexer for demultiplexing each portion and being
provided to each output end of the M number of RS frame
decoders.
As described above, the present invention has the following
advantages. Herein, the present invention is robust (or strong)
against any error that may occur when transmitting mobile broadcast
service data through a channel. And, the present invention is also
highly compatible to the conventional system.
Additionally, the present invention may also receive the mobile
broadcast service data without any error occurring, even in
channels having severe ghost effect and noise.
Furthermore, by inserting known data in a specific position within
a data region and by transmitting the processed data, the receiving
performance of a receiving system may be enhanced even in channel
environments (or conditions) undergoing frequent channel
changes.
Additionally, by estimating the CIR of the general data section
located between training sections through cubic spline
interpolation, so as to channel-equalize the data of the
corresponding section, the channel-equalizing performance of the
present invention may be enhanced even in an environment undergoing
frequent channel changes. Furthermore, by compensating the power of
the CIR estimated in the specific segment within the extrapolation
section through extrapolation, so that the proportional relation
between the power of the signal measured in the specific segment
and the power of the CIR generated in the specific segment through
extrapolation can become identical to the proportional relation
between the power of the signal and the power of the CIR both
measured in the training section, problems of unintended increase
or decrease in signal power, which is estimated in the
extrapolation section through extrapolation, may be reduced.
The present invention is even more effective when applied to mobile
and portable receivers, which are also liable to frequent change in
channels, and which require strength (or robustness) 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.
* * * * *