Note: Descriptions are shown in the official language in which they were submitted.
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Description
DIGITAL BROADCASTING SYSTEM AND DATA PROCESSING METHOD IN
THE DIGITAL BROADCASTING SYSTEM
Technical Field
[1] The present invention relates to a digital broadcasting system, and
more particularly, to a digital broadcasting system and a data processing
method.
Background Art
[2] 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.
Disclosure of Invention
[3] An object of some embodiments of the present invention is to
provide a digital broadcasting system and a data processing method that are
highly resistant to channel changes and noise.
[4] An object of some embodiments of the present invention is to
provide a digital broadcasting system and a method of processing data in a
digital
broadcasting system that can enhance the receiving performance of a receiving
system (or receiver) by having a transmitting system (or transmitter) perform
additional encoding on mobile service data.
[5] Another object of some embodiments of the present invention is to
provide a digital broadcasting system and a method of processing data in the
digital broadcasting system that can also enhance the receiving performance of
a
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digital broadcast 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.
[6] Another object of some embodiments of the present invention is
to provide a
digital broadcast system and a data processing method which can process
service data
discontinuously received on a time axis at a constant bit rate.
[6a] According to an aspect of the present invention, there is provided a
method of
transmitting a broadcast signal in a transmitter, the method comprising:
multiplexing mobile
data and main data; and transmitting a transmission frame including the
multiplexed mobile
data and main data, wherein a plurality of parades of data groups are
transmitted during slots
within the transmission frame, the slots being basic time periods for
multiplexing the mobile
data and the main data, wherein the data groups of one of the plurality of
parades are assigned
to be spaced apart from one another within the transmission frame, wherein
each of the data
groups includes the mobile data, signaling information and known data
sequences, wherein
the signaling information includes fast information channel (FIC) data,
wherein the FIC data
is divided into a plurality of FIC segments, and each of the plurality of FIC
segments includes
an FIC segment header and is transmitted in each of the data groups, wherein
the ensemble
includes the service and a signaling table describing the service, and wherein
the mobile data
belonging to the ensemble is RC-CRC (Reed Solomon ¨ cyclic redundancy check)
encoded
through a 2-dimensional Reed-Solomon (RS) frame, each row of a payload of the
RS frame
including a transport packet of the mobile data.
[6b] According to another aspect of the present invention, there is
provided a
method of receiving a broadcast signal in a receiver, the method comprising:
receiving the
broadcast signal including a transmission frame, wherein a plurality of
parades of data groups
in the broadcast signal is received during slots within the transmission
frame, the slots being
basic time periods for multiplexing mobile data and main data, wherein the
data groups of one
of the plurality of parades are spaced apart from one another within the
transmission frame,
and wherein each of the data groups includes the mobile data, signaling
information and
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known data sequences; demodulating the broadcast signal and obtaining, from
the signaling
information, fast information channel (FIC) data including binding information
between a
service of the mobile data and an ensemble and transmission parameter channel
(TPC) data
indicating a version of the FIC data, wherein the FIC data is divided into a
plurality of FIC
segments, and wherein each of the plurality of FIC segments includes an FIC
segment header
and is received in each of the data groups, and wherein the ensemble includes
the service and
a signaling table describing the service; building a Reed-Solomon (RS) frame
corresponding
to the ensemble by collecting a plurality of data portions which are mapped to
the data groups;
and decoding the RS frame, wherein the RS frame is a 2-dimensional data frame
through
which the mobile data belonging to the ensemble is RS-CRC (Reed Solomon -
cyclic
redundancy check) encoded, each row of a payload of the RS frame including a
transport
packet of the mobile data.
[6c] According to another aspect of the present invention, there is
provided an
apparatus for transmitting a broadcast signal, the apparatus comprising: a
multiplexer
configured to multiplex mobile data and main data; and a transmission unit
configured to
transmit a transmission frame including the multiplexed mobile data and main
data, wherein a
plurality of parades of data groups are transmitted during slots within the
transmission frame,
the slots being basic time periods for multiplexing the mobile data and the
main data, wherein
the data groups of one of the plurality of parades are assigned to be spaced
apart from one
another within the transmission frame, wherein each data group includes the
mobile data,
signaling information and known data sequences, wherein the signaling
information includes
fast information channel (FIC) data including binding information between a
service of the
mobile data and an ensemble and transmission parameter channel (TPC) data
indicating a
version of the FIC data, wherein the FIC data is divided to a plurality of FIC
segments, and
each of the plurality of FIC segments includes an FIC segment header and is
received in each
of the data groups, wherein the ensemble includes the service and a signaling
table describing
the service, and wherein the mobile data belonging to the ensemble is RS-CRC
(Reed
Solomon - cyclic redundancy check) encoded through a 2-dimensional Reed-
Solomon (RS)
frame, each row of a payload of the RS frame including a transport packet of
the mobile data.
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[6d] According to another aspect of the present invention, there is
provided an
apparatus for receiving a broadcast signal, the apparatus comprising: a tuner
configured to
receive a broadcast signal including a transmission frame, wherein a parade of
data groups is
received during slots within the transmission frame, the slots being basic
time periods for
multiplexing of mobile data and main data, and wherein each of the data groups
includes the
mobile data, signaling information and known data sequences, a demodulator
configured to
demodulate the received broadcast signal and obtain, from the signaling
information, fast
information channel (FIC) data including binding information between a service
of the mobile
data and an ensemble and transmission parameter channel (TPC) data indicating
a version of
the FIC data, wherein the FIC data is divided to a plurality of FIC segments,
and each of the
FIC segments includes an FIC segment header and is received in each of the
data groups, and
wherein the ensemble includes the service and a signaling table describing the
service; and an
RS frame decoder configured to build a Reed-Solomon (RS) frame corresponding
to the
ensemble by collecting a plurality of data portions which are mapped to the
data groups, and
decode the RS frame, wherein the RS frame is a 2-dimensional data frame
through which the
mobile data belonging to the ensemble is RS-CRC (Reed Solomon - cyclic
redundancy check)
encoded, and each row of a payload of the RS frame includes a transport packet
of the mobile
data.
[7] In one aspect, a data processing method
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includes receiving a broadcast signal in which main service data and mobile
service
data are multiplexed, demodulating the received broadcastsignal, outputting de-
modulation time information of a specific position of a broadcast signal
frame, and
acquiring reference time information contained in the mobile service data
frame,
setting the reference time information to a system time clock at a specific
time based
on the demodulation time information and decoding the mobile service data
according
to the system time clock.
[8] The reference time information may be a network time protocol (NTP)
timestamp.
The demodulation time information may include either one of the frame starting
point
and the frame end point of the broadcast signal. The manager set the reference
time in-
formation to the system time clock at interval of 968 milliseconds.
[9] The broadcast signal includes a data group in which the mobile service
data en-or-
correction-encoded by at least one of code rates, and the mobile service data
in the in-
terleaved data group includes periodically-inserted known data.
[101 In another aspect, a digital broadcast system includes a
receiver configured to receive a broadcast signal in which main service data
and
mobile service data are multiplexed, a demodulator configured to demodulate
the
received broadcastsignal, output demodulation time information of a specific
position
of a broadcast signal frame, and output a mobile service data frame from the
de-
modulated broadcast signal, a mobile service data frame decoder configured to
decoding the mobile service data frame and output a transport packet, a
transport
packet (TP) handler configured to output reference time information contained
in the
transport packet, a manager configured toset the outputted reference time
information
to a system time clock at a specific time based on the demodulation time
information, a
decoder configured to decode the mobile service data according to the system
time
clock and a display configured todisplay contents contained in the decoded
mobile
service data.
[11] The digital broadcast system may further include a buffer for
temporarily storing
mobile service data contained in the transport packet according to the system
time
clock. The manager may control the display for displaying contents contained
in the
mobile service data according to the system time clock.
1121 The demodulator outputs fast information channel (FTC) information
representing
binding information of a virtual channel in an ensemble and the ensemble of
the
mobile service data, and the mobile service data frame decoder decodes the
mobile
service data frame using the FTC information.
1131 The digital broadcast system and the data processing method according
to
some embodiments of the present
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invention have strong resistance to any errors encountered when mobile service
data is transmitted over the channel, and can be easily compatible with the
conventional receiver.
[14] The digital broadcast system according to some embodiments of
the
present invention can normally receive mobile service data without any errors
over
a poor channel which has lots of ghosts and noises. The digital broadcast
system
according to some embodiments of the present invention inserts known data at a
specific location of a data zone, and performs signal transmission, thereby
increasing the Rx performance under a high-variation channel environment.
[15] Also, some embodiments of the present invention can process
service data, which is discontinuously received with time, at a constant
bitrate.
Brief Description of the Drawings
[16] FIG. 1 illustrates a block diagram showing a general structure of a
digital broadcasting receiving system according to an embodiment of the
present
invention;
[17] FIG. 2 illustrates an exemplary structure of a data group according to
an embodiment of the present invention;
[18] FIG. 3 illustrates an RS frame according to an embodiment of the
present invention;
[19] FIG. 4 illustrates an example of an MH frame structure for
transmitting and receiving mobile service data according to an embodiment of
the
present invention;
[20] FIG. 5 illustrates an example of a general VSB frame structure;
[21] FIG. 6 illustrates an example of mapping positions of the first 4
slots
of a sub-frame in a spatial area with respect to a VSB frame;
[22] FIG. 7 illustrates an example of mapping positions of the first 4
slots
of a sub-frame in a chronological (or time) area with respect to a VSB frame;
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[23] FIG. 8 illustrates an exemplary order of data groups being assigned
to one of 5 sub-frames configuring an MH frame according to an embodiment of
the present invention;
[24] FIG. 9 illustrates an example of a single parade being assigned to an
MH frame according to an embodiment of the present invention;
[25] FIG. 10 illustrates an example of 3 parades being assigned to an MH
frame according to an embodiment of the present invention;
[26] FIG. 11 illustrates an example of the process of assigning 3 parades
shown in FIG. 10 being expanded to 5 sub-frames within an MH frame;
[27] FIG. 12 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;
[28] FIG. 13 illustrates a hierarchical signaling structure
according to an
embodiment of the present invention;
[29] FIG. 14 illustrates an exemplary FIC body format according to an
embodiment of the present invention;
[30] FIG. 15 illustrates an exemplary bit stream syntax structure with
respect to an FIC segment according to an embodiment of the present invention;
[31] FIG. 16 illustrates an exemplary bit stream syntax structure with
respect to a payload of an FIC segment according to an embodiment of the
present invention, when an FIC type field value is equal to '0';
[32] FIG. 17 illustrates an exemplary bit stream syntax structure of a
service map table according to an embodiment of the present invention;
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[33] FIG. 18 illustrates an exemplary bit stream syntax structure of an MH
audio descriptor according to an embodiment of the present invention;
[34] FIG. 19 illustrates an exemplary bit stream syntax structure of an
MH RTP payload type descriptor according to an embodiment of the present
invention;
[35] FIG. 20 illustrates an exemplary bit stream syntax structure of an
MH current event descriptor according to an embodiment of the present
invention;
[36] FIG. 21 illustrates an exemplary bit stream syntax structure of an
MH next event descriptor according to an embodiment of the present invention;
[37] FIG. 22 illustrates an exemplary bit stream syntax structure of an
MH system time descriptor according to an embodiment of the present invention;
[38] FIG. 23 illustrates segmentation and encapsulation processes of a
service map table according to an embodiment of the present invention;
[39] FIG. 24 illustrates a flow chart for accessing a virtual channel using
FIC and SMT according to an embodiment of the present invention;
[40] FIG. 25 shows a timing model;
[41] FIG. 26 shows a bit rate varying with time while signals are
transmitted and received according to a time slicing technique;
[42] FIG. 27 is a conceptual diagram illustrating a method for processing
a reception (Rx) signal at a constant data processing rate;
[43] FIG. 28 is a conceptual diagram illustrating a digital broadcast
reception system according to another embodiment of the present invention; and
[44] FIG. 29 is a flow chart illustrating a data processing method
according to an embodiment of the present invention.
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Detailed Description
[45]
Reference will now be made in detail to embodiments of the present invention.
Herein structures and operations of the invention illustrated in figures and
described by being
referred to the figures are examples of embodiments of the invention.
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[46]
[47] Definition of the terms used in the embodiments
[48] 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.
Fur-
thermore, 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.
[49] 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.
[50] Additionally, among the terms used in the present invention,
"MH"corresponds to the
initials of "mobile" and "handheld" and represents the opposite concept of a
fixed-type
system. Furthermore, the MH 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 correspondto MH 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 MH service data.
[51] 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 lowerdata rate as compared to the main
service
data. For example, if an A/V codec that is used for a conventional main
service cor-
responds 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.
[52] 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
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music, and filming sites of soap operas or series, services providing
information on
past match scores and player profiles and achievements, and services providing
in-
formation 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.
[53] 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.
[54] Furthermore, the digital broadcast 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.
[55] 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.
[56]
[57] Receiving System
[58] FIG. 1 illustrates a block diagram showing a general structure of a
digital
broadcasting receiving system according to an embodiment of the present
invention.
The digital broadcast receiving system according to the present invention
includes a
baseband processor 100, a management processor 200, and a presentation
processor
300.
[59] The baseband processor 100 includes an operation controller 110, a
tuner 120, a de-
modulator 130, an equalizer 140, a known sequence detector (or known data
detector)
150, a block decoder (or mobile handheld block decoder) 160, a promary Reed-
Solomon (RS) frame decoder 170, a secondary RS frame decoder 180, and a
signaling
decoder 190. The operation controller 110 controls the operation of each block
included in the baseband processor 100.
[60] By tuning the receiving system to a specific physical channel
frequency, the tuner
120 enables the receiving system to receive main service data, which
correspond to
broadcast signals for fixed-type broadcast receiving systems, and mobile
service data,
which correspond to broadcast signals for mobile broadcast receiving systems.
At this
point, the tuned frequency of the specific physical channel is down-converted
to an in-
termediate frequency (IF) signal, thereby being outputted to the demodulator
130 and
the known sequence detector 140. The passband digital IF signal being
outputted from
the tuner 120 may only include main service data, or only include mobile
service data,
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or include both main service data and mobile service data.
[61] The demodulator 130 performs self-gain control, carrier wave recovery,
and timing
recovery processes on the passband digital IF signal inputted from the tuner
120,
thereby modifying the IF signal to a baseband signal. Then, the demodulator
130
outputs the baseband signal to the equalizer 140 and the known sequence
detector 150.
The demodulator 130 uses the known data symbol sequence inputted from the
known
sequence detector 150 during the timing and/or carrier wave recovery, thereby
enhancing the demodulating performance.
[62] The equalizer 140 compensates channel-associated distortion included
in the signal
demodulated by the demodulator 130. Then, the equalizer 140 outputs the
distortion-
compensated signal to the blcok decoder 160. By using a known data symbol
sequence
inputted from the lnown sequence detector 150, the equalizer 140 may enhance
the
equalizing performance. Furthermore, the equalizer 140 may receive feed-back
on the
decoding result from the block decoder 160, thereby enhancing the equalizing
per-
formance.
[63] The known sequence detector 150 detects known data place (or position)
inserted by
the transmitting system from the input/output data (i.e., data prior to being
de-
modulated or data being processed with partial demodulation). Then, the known
sequence detector 150 outputs the detected known data position information and
known data sequence generated from the detected position information to the de-
modulator 130 and the equalizer 140. Additionally, in order to allow the block
decoder
160 to identify the mobile service data that have been processed with
additional
encoding by the transmitting system and the main service data that have not
been
processed with any additional encoding, the known sequence detector 150
outputs such
corresponding information to the block decoder 160.
[64] If the data channel-equalized by the equalizer 140 and inputted to the
block decoder
160 correspond to data processed with both block-encoding and trellis-encoding
by the
transmitting system (i.e., data within the RS frame, signaling data), the
block decoder
160 may perform trellis-decoding and block-decoding as inverse processes of
the
transmitting system. On the other hand, if the data channel-equalized by the
equalizer
140 and inputted to the block decoder 160 correspond to data processed only
with
trellis-encoding and not block-encoding by the transmitting system (i.e., main
service
data), the block decoder 160 may perform only trellis-decoding.
[65] The signaling decoder 190 decoded signaling data that have been
channel-equalized
and inputted from the equalizer 140. It is assumed that the signaling data
inputted to
the signaling decoder 190 correspond to data processed with both block-
encoding and
trellis-encoding by the transmitting system. Examples of such signaling data
may
include transmission parameter channel (TPC) data and fast information channel
(FIC)
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data. Each type of data will be described in more detail in a later process.
The FTC data
decoded by the signaling decoder 190 are outputted to the FTC handler 215.
And, the
TPC data decoded by the signlaing decoder 190 are outputted to the TPC handler
214.
[66] Meanwhile, according to the present invention, the transmitting system
uses RS
frames by encoding units. Herein, the RS frame may be divided into a primary
RS
frame and a secondary RS frame. However, according to the embodiment of the
present invention, the primary RS frame and the secodnary RS frame will be
divided
based upon the level of importance of the corresponding data.
[67] The primary RS frame decoder 170 receives the data outputted from the
block
decoder 160. At this point, according to the embodiment of the present
invention, the
primary RS frame decoder 170 receives only the mobile service data that have
been
Reed-Solomon (RS)-encoded and/or cyclic reduncancy check (CRC)-encoded from
the
block decoder 160.
[68] Herein, the primary RS frame decoder 170 receives only the mobile
service dataand
not the main service data. The primary RS frame decoder 170 performs inverse
processes of an RS frame encoder (not shown) included in the digital broadcast
transmitting system, thereby correcting errors existing within the primary RS
frame.
More specifically, the primary RS frame decoder 170 forms a primary RS frame
by
grouping a plurality of data groups and, then, correct errors in primary RS
frame units.
In other words, the primary RS frame decoder 170 decodes primary RS frames,
which
are being transmitted for actual broadcast services.
[69] Additionally, the secondary RS frame decoder 180 receives the data
outputted from
the block decoder 160. At this point, according to the embodiment of the
present
invention, the secondary RS frame decoder 180 receives only the mobile service
data
that have been RS-encoded and/or CRC-encoded from the block decoder 160.
Herein,
the secondary RS frame decoder 180 receives only the mobile service data and
not the
main service data. The secondary RS frame decoder 180 performs inverse
processes of
an RS frame encoder (not shown) included in the digital broadcast transmitting
system,
thereby correcting errors existing within the secondary RS frame. More
specifically,
the secondary RS frame decoder 180 forms a secondary RS frame by grouping a
plurality of data groups and, then, correct errors in secondary RS frame
units. In other
words, the secondary RS frame decoder 180 decodes secondary RS frames, which
are
being transmitted for mobile audio service data, mobile video service data,
guide data,
and so on.
[70] Meanwhile, the management processor 200according to an embodiment of
the
present invention includes an MH physical adaptation processor 210, an IP
network
stack 220, a streaming handler 230, a system information (SI) handler 240, a
file
handler 250, a multi-purpose internet main extensions (MIME) type handler 260,
and
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an electronic service guide (ESG) handler 270, and an ESG decoder 280, and a
storage
unit 290.
[71] The MH physical adaptation processor 210 includes a primary RS frame
handler 211,
a secondary RS frame handler 212, an MH transport packet (TP) handler 213, a
TPC
handler 214, an FTC handler 215, and a physical adpatation control signal
handler 216.
[72] The TPC handler 214 receives and processes baseband information
required by
modules corresponding to the MH physical adaptation processor 210. The
baseband in-
formation is inputted in the form of TPC data. Herein, the TPC handler 214
uses this
information to process the FTC data, which have been sent from the baseband
processor
100.
[73] The TPC data are transmitted from the transmitting system to the
receiving system
via a predetermined region of a data group. The TPC data may include at least
one of
an MH ensemble ID, an MH sub-frame number, a total number of MH groups (TNoG),
an RS frame continuity counter, a column size of RS frame (N), and an FTC
version
number.
[74] Herein, the MH ensemble ID indicates an identification number of each
MH
ensemble carried in the corresponding channel. The MH sub-frame number
signifies a
number identifying the MH sub-frame number in an MH frame, wherein each MH
group associated with the corresponding MH ensemble is transmitted. The TNoG
represents the total number of MH groups including all of the MH groups
belonging to
all MH parades included in an MH sub-frame.
[75] The RS frame continuity counter indicates a number that serves as a
continuity
counter of the RS frames carrying the corresponding MH ensemble. Herein, the
value
of the RS frame continuity counter shall be incrementedby 1 modulo 16 for each
successive RS frame.
[76] N represents the column size of an RS frame belonging to the
corresponding MH
ensemble. Herein, the value of N determines the size of each MH TP.
[77] Finally, the FTC version number signifies the version number of an FTC
body carried
on the corresponding physical channel.
[78] As described above, diverse TPC data are inputted to the TPC handler
214 via the
signaling decoedr 190 shown in FIG. 1. Then, the received TPC data are
processed by
the TPC handler 214. The received TPC data may also be used by the FTC handler
215
in order to process the FTC data.
[79] The FTC handler 215 processes the FTC data by associating the FTC data
received
from the baseband processor 100 with the TPC data.
[80] The physical adaptation controlsignal handler 216 collects FTC data
received through
the FTC handler 215 and ST data received through RS frames. Then, the physical
adaptation control signal handler 216 uses the collected FTC data and ST data
to
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configure and process IP datagrams and access information of mobile broadcast
services. Thereafter, the physical adaptation control signal handler 216
stores the
processed IP datagrams and access information to the storage unit 290.
[81] The primary RS frame handler 211 identifies primary RS frames received
from the
primary RS frame decoder 170 of the baseband processor 100 for each row unit,
so as
to configure an MH TP. Thereafter, the primary RS frame handler 211 outputs
the
configured MH TP to the MH TP handler 213.
[82] The secondary RS frame handler 212 identifies secondary RS frames
received from
the secondary RS frame decoder 180 of the baseband processor 100 for each row
unit,
so as to configure an MH TP. Thereafter, the secondary RS frame handler 212
outputs
the configured MH TP to the MH TP handler 213.
[83] The MH transport packet (TP) handler 213 extracts a header from each
MH TP
received from the primary RS frame handler 211 and the secondary RS frame
handler
212, thereby determining the data included in the corresponding MH TP. Then,
when
the determined data correspond to SI data (i.e., SI data that are not
encapsulated to IP
datagrams), the corresponding data are outputted to the physical adaptation
control
signal handler 216. Alterantively, when the determined data correspond to an
IP
datagram, the corresponding data are outputted to the IP network stack 220.
[84] The IP network stack 220 processes broadcast data that are being
transmitted in the
form of IP datagrams. More specifically, the IP network stack 220 processes
data that
are inputted via user datagram protocol (UDP), real-time transport protocol
(RTP),
real-time transport control protocol (RTCP), asynchronous layered
coding/layered
coding transport (ALC/LCT), file delivery over unidirectional transport
(FLUTE), and
so on. Herein, when the processed data correspond to streaming data, the corre-
sponding data are outputted to the streaming handler 230. And, when the
processed
data correspond to data in a file format, the corresponding data are outputted
to the file
handler 250. Finally, when the processed data correspond to SI-associated
data, the
corresponding data are outputted to the SI handler 240.
[85] The SI handler 240 receives and processes SI data having the form of
IP datagrams,
which are inputted to the IP network stack 220. When the inputted data
associated with
SI correspond to MIME-type data, the inputted data are outputted to the MIME-
type
handler 260. The MIME-type handler 260 receives the MIME-type SI data
outputted
from the SI handler 240 and processes the received MIME-type SI data.
[86] The file handler 250 receives data from the IP network stack 220 in an
object format
in accordance with the ALC/LCT and FLUTE structures. The file handler 250
groups
the received data to create a file format. Herein, when the correspondingfile
includes
ESG, the file is outputted to the ESG handler 270. On the other hand, when the
corre-
sponding file includes data for other file-based services, the file is
outputted to the pre-
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sentation controller 330 of the presentation processor 300.
[87] The ESG handler 270 processes the ESG data received from the file
handler 250 and
stores the processed ESG data to the storage unit 290. Alternatively, the ESG
handler
270 may output the processed ESG data to the ESG decoder 280, thereby allowing
the
ESG data to be used by the ESG decoder 280.
[88] The storage unit 290 stores the system information (SI) received from
the physical
adaptation control signal handler 210 and the ESG handler 270 therein.
Thereafter, the
storage unit 290 transmits the stored SI data to each block.
[89] The ESG decoder 280 either recovers the ESG data and SI data stored in
the storage
unit 290 or recovers the ESG data transmitted from the ESG handler 270. Then,
the
ESG decoder 280 outputs the recovered data to the presentation controller 330
in a
format that can be outputted to the user.
[90] The streaming handler 230 receives data from the IP network stack 220,
wherein the
format of the received data are in accordance with RTP and/or RTCP structures.
The
streaming handler 230extracts audio/video streams from the received data,
which are
then outputted to the audio/video (A/V) decoder 310 of the presentation
processor 300.
The audio/video decoder 310 then decodes each of the audio stream and video
stream
received from the streaming handler 230.
[91] The display module 320 of the presentation processor 300 receives
audio and video
signals respectively decoded by the A/V decoder 310. Then, the display module
320
provides the received audio and video signals to the user through a speaker
and/or a
screen.
[92] The presentation controller 330 corresponds to a controller managing
modules that
output data received by the receiving system to the user.
[93] The channel service manager 340 manages an interface with the user,
whichenables
the user to use channel-based broadcast services, such as channel map
management,
channel service connection, and so on.
[94] The application manager 350 manages an interface with a user using ESG
display or
other application services that do not correspond to channel-based services.
[95] Meanwhile, The streaming handler 230 may include a buffer temporarily
storing
audio/video data. The digital broadcasting reception system periodicallysets
reference
time information to a system time clock, and then the stored audio/video data
can be
transferred to A/V decoder 310 at a constant bitrate. Accordingly, the
audio/video data
can be processed at a bitrate and audio/video service can be provided.
[96]
[97] Data Format Structure
[98] Meanwhile, the data structure used in the mobile broadcasting
technology according
to the embodiment of the present invention may include a data group structure
and an
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RS frame structure, which will now be described in detail.
[99] FIG. 2 illustrates an exemplary structureof a data group according to
the present
invention.
[100] FIG. 2 shows an example of dividing a data group according to the
data structure of
the present invention into 10 MH blo In this example, each MH block has the
length of
16 segments. Referring to FIG. 2, only the RS parity data are allocated to
portions of
the first 5 segments of the MH block 1 (B1) and the last 5 segments of the MH
block
(B10). The RS parity data are excluded in regions A to D of the data group.
[101] More specifically, when it is assumed that one data group is divided
into regions A,
B, C, and D,each MH block may be included in any one of region A to region D
depending upon the characteristic of each MH block within the data group.
[102] 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. Addi-
tionally, 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
prede-
termined 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.
[103] Referring to FIG. 2, MH block 4 (B4) to MH block 7 (B7) correspond
toregions
without interference of the main service data. MH block 4 (B4) to MH block 7
(B7)
within the data group shown in FIG. 2correspond 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 MH block. In the description of
the
present invention, the region including MH block 4 (B4) to MH 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 MH 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.
[104] In the example of the data group shown in FIG. 2, MH block 3 (B3) and
MH block 8
(B8) correspond to a region having little interference from the main service
data.
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Herein, a long known data sequence is inserted in only one side of each MH
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 MH block 3 (B3), and another
long
known data sequence is inserted at the beginning of MH block 8 (B8). In the
present
invention, the region including MH block 3 (B3) and MH 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 MH 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).
[105] Referring to FIG. 2, MH block 2 (B2) and MH 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 MH block 2 (B2) and MH
block
9 (B9). Herein, the region including MH block 2 (B2) and MH block 9 (B9) will
be
referred to as "region C (=B2+B9)".
[106] Finally, in the example shown in FIG. 2, MH block 1 (B1) and MH 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 MH block 1 (B1) and MH block 10 (B10). Herein, the region including MH
block 1 (B1) and MH 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 per-
formance of region C/D may be deteriorated.
[107] Additionally, the data group includes a signaling information area
wherein signaling
information is assigned (or allocated).
[108] In the present invention, the signaling information area may start
from the 1st
segment of the 4th MH block (B4) to a portion of the 2nd segment.
[109] According to an embodiment of the present invention, the signaling
information area
for inserting signaling information may start from the 1st segment of the 4th
MH block
(B4) to a portion of the 2nd segment. More specifically, 276(=207+69) bytes of
the
4thMH 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
lstsegment and
the first 69 bytes of the 2nd segment of the 4th MH block (B4). The 1st
segment of the
4th MH block (B4) corresponds to the 17th or 173rd segment of a VSB field.
[110] 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).
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[111] Herein, the TPC data may include at least one of an MH ensemble ID,
an MH sub-
frame number, a total number of MH groups (TNoG), an RS frame continuity
counter,
a column size of RS frame (N), and an FTC version number.However, the TPC data
(or
information) presented herein are merely exemplary. And, since the adding or
deleting
of signaling information included in the TPC data 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 FTC is provided to enable a fast
service ac-
quisition of data receivers, and the FTC includes cross layer information
between the
physical layer and the upper layer(s). For example,when the data group
includes 6
known data sequences, as shown in FIG. 2, the signaling information area is
located
between the first known data sequence and the second known data sequence. More
specifically, the first known data sequence is inserted in the last 2 segments
of the 3rd
MH block (B3), and the second known data sequence in inserted in the 2nd and
3rdsegments of the 4th MH block (B4). Furthermore, the 3rd to 6thknown data
sequences are respectively inserted in the last 2 segments of each of the 4th,
5th, 6th,
and 7th MH blocks (B4, B5, B6, and B7). The lstand 3rd to 6th known data
sequences
are spaced apart by 16 segments.
[112]
[113] FIG. 3 illustrates an RS frame according to an embodiment of the
present invention.
[114] The RS frame shown in FIG. 3 corresponds to a collection of one or
more data
groups. The RS frame is received for each MH frame in a condition where the
receiving system receives the FTC and processes the received FTC and where the
receiving system is switched to a time-slicing mode so that the receiving
system can
receive MH ensembles including ESG entry points. Each RS frame includes TP
streams
of each service or ESG, and SMT section data may exist in all RS frames.
[115] The RS frame according to the embodiment of the present invention
consists of at
least one MH transport packet (TP). Herein, the MH TP includes an MH header
and an
MH payload.
[116] The MH payload may include mobile service data as wekk as signaling
data. More
specifically, an MH payload may include only mobile service data, or may
include
only signaling data, or may include both mobile service data and signaling
data.
[117] According to the embodiment of the present invention, the MH header
may identify
(or distinguish) the data types included in the MH payload.More specifically,
when the
MH TP includes a first MH header, this indicates that the MH payload includes
only
the signaling data. Also, when the MH TP includes a second MH header, this
indicates
that the MH payload includes both the signaling data and the mobile service
data.
Finally, when MH TP includes a third MH header, this indicates that the MH
payload
includes only the mobile service data.
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[118] In the example shown in FIG. 3, the RS frame is assigned with IP
datagrams (IP
datagram 1 and IP datagram 2) for two service types.
[119] The IP datagram in the MH-TP in the RS frame may include reference
time in-
formation (for example, network time stamp (NTP)), the detailed description
for the
reference time information will be disclosed by being referred to FIGs. 25 to
29.
[120]
[121] Data Transmission Structure
[122] FIG. 4illustrates a structure of a MH frame for transmitting and
receiving mobile
service data according to the present invention.
[123] In the example shown in FIG. 4, one MH frame consists of 5 sub-
frames, wherein
each sub-frame includes 16 slots. In this case, the MH frame according to the
present
invention includes 5 sub-frames and 80 slots.
[124] 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.
[125]
[126] FIG. 5 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 unit 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.
[127] If the first 118 data packets within the slot correspond to a data
group, 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.
[128] Meanwhile, when the slots are assigned to a VSB frame, an off-set
exists for each
assigned position.
[129]
[130] FIG. 6 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 spatial area. And,
FIG. 7 il-
lustrates 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 chronological (or time) area.
[131] Referring to FIG. 6 and FIG. 7, a 38th data packet (TS packet #37) of
a 1 stslot (Slot
#0) is mapped to the 1st data packet of an odd VSB field. A 38th data packet
(TS
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packet #37) of a 2nd slot (Slot #1) is mapped to the 157th data packet of an
odd VSB
field. Also, a 38th data packet (TS packet #37) of a 3rd slot (Slot #2) is
mapped to the
lstdata packet of an even VSB field. And, a 38th data packet (TS packet #37)
of a
4thslot (Slot #3) is mapped to the 157th 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.
[132]
[133] FIG. 8 illustrates an exemplary assignement order of data groups
being assigned to
one of 5 sub-frames, wherein the 5 sub-frames configure an MH frame. For
example,
the method of assigning data groups may be identically applied to all MH
frames or
differently applied to each MH frame. Furthermore, the method of assinging
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 MH frame, the total number
of
data groups being assigned to an MH frame is equal to a multiple of '5'.
[134] 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
MH frame. Thus, the system can be capable of responding promptly and
effectively to
any burst error that may occur within a sub-frame.
[135] For example, when it is assumed that 3 data groups are assigned to a
sub-frame, the
data groups are assigned to a 1st slot (Slot #0), a 5th slot (Slot #4), and a
9th slot (Slot
#8) in the sub-frame, respectively. FIG. 8 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.
[136] [Equation 11
[137] j = (4i + 0) mod 16
[138] herein, 0= 0 if i <4,
[139] 0 = 2 else if i < 8,
[140] 0 = 1 else if i< 12,
[141] 0 = 3 else.
[142] Herein, j indicates the slot number within a sub-frame. The value of
j may range from
0 to 15 (i.e.,
0 i 15
). Also, variable i indicates the data group number. The value of i may range
from 0
to 15 (i.e.,
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U< <15
).
[143] In the present invneiton, a collection of data groups included in a
MH 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.
[144] 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.
[145] According to the embodiment 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. 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 maytransmit
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. Such RS frame
mode is
transmitted as the above-described TPC data. Table 1 below shows an example of
the
RS frame mode.
[146] Table 1
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[Table 1]
[Table ]
RS frame mode Description
00 There is only a primary RS frame for all Group
Regions
01 There are two separate RS frames- Primary RS frame
for
Group Region A and B- Secondary RS frame for Group
Region C and D
Reserved
11 Reserved
[147] 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.
[148] 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
corre-
sponding 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.
[149] 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 MH frames or differently applied to each MH frame.
[150] According to the embodiment of the present invention, the parades may
be assigned
differently for each MH frame and identically for all sub-frames within an MH
frame.
More specifically, the MH frame structure may vary by MH frame units. Thus, an
ensemble rate may be adjusted on a more frequent and flexible basis.
[151] FIG. 9 illustrates an example of multiple data groups of a single
parade being
assigned (or allocated) to an MH frame. More specifically, FIG. 9 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
MH frame.
[152] Referring to FIG. 9, 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 MH frame, 15data groups are assigned to a
single
MH 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
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are included in a sub-frame, the data group of the corresponding parade is not
assigned
to one of the 4 VSB frames within asub-frame.
111531 For example,when it is assumed that one parade transmits one RS
frame, and that a
RS frame encoder (not shown) included in the transmitting system 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)x100) 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. 9, 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% (=1/15x100).
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.
111541 Meanwhile, when data groups of a parade are assigned as shown in
FIG. 9, either
main service data may be assigned between each data group, or data groups
corre-
sponding to different parades may be assigned between each data group. More
specifically, data groups corresponding to multiple parades may be assigned to
one
MH frame.
111551 Basically, the method of assigning data groups corresponding to
multiple paradesis
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 MH
frame are also respectively assigned according to a cycle period of 4 slots.
111561 At this point, data groups of a different parademay be sequentially
assigned to the re-
spective 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.
111571 For example, when it is assumed that data groups corresponding to a
parade are
assigned as shown in FIG. 9, data groups corresponding to the next parade may
be
assigned to a sub-frame starting either from the 12th 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 3rd slot.
111581 FIG. 10 illustrates an example of transmitting 3 parades (Parade #0,
Parade #1, and
Parade #2) to an MH frame. More specifically, FIG. 10 illustrates an example
of
transmitting parades included in one of 5 sub-frames, wherein the 5 sub-frames
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configure one MH frame.
[159] When the 1st 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 iin Equation 1. More specifically, the data groups of
the 1st parade
(Parade #0) are sequentially assigned to the 1st, 5th, and 9thslots (Slot #0,
Slot #4, and
Slot #8) within the sub-frame.
[160] Also, when the 2nd 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 iin Equation 1. More specifically, the data groups of the 2nd
parade (Parade
#1) are sequentially assigned to the 2nd and 12thslots (Slot #3 and Slot #11)
within the
sub-frame.
[161] Finally, when the 3rd 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 iin Equation 1. More specifically, the data groups of the 3rd
parade (Parade
#2) are sequentially assigned to the 7th and 1 lthslots (Slot #6 and Slot #10)
within the
sub-frame.
[162] As described above, data groups of multiple parades may be assigned
to a single MH
frame, and, in each sub-frame, the data groups are serially allocated to a
group space
having 4 slots from left to right.
[163] 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 MH frame includes 5 sub-
frames,
the total number of data groups within a paradethat can be allocated to an MH
frame
may correspond to any one multiple of '5' ranging from '5' to '40'.
[164] FIG. 11 illustrates an example of expanding the assignment process of
3 parades,
shown in FIG. 10, to 5 sub-frames within an MH frame.
[165] FIG. 12 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.
[166] As described above, an MH frame is divided into 5 sub-frames. Data
groups corre-
sponding to a plurality of parades co-exist in each sub-frame. Herein, the
data groups
corresponding to each parade are grouped by MH fram units, thereby configuring
a
single parade. The data structure shown in FIG. 12 includes 3 parades, one ESG
dedicated channel (EDC) parade (i.e., parade with NoG=1), and 2 service
parades (i.e.,
parade with NoG=4 and parade with NoG=3). Also, a predetermined portion of
each
data group (i.e., 37 bytes/data group) is used for delivering (or sending) FIC
in-
formation associated with mobile service data, wherein the FIC information is
separately encoded from the RS-encoding process. The FIC region assigned to
eachdata group consists of one FIC segments. Herein, each segment is
interleaved by
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MH sub-frame units, thereby configuring an FTC body, which corresponds to a
completed FTC transmission structure. However, whenever required, each segment
may be interleaved by MH frame units and not by MH sub-frame units, thereby
being
completed in MH frame units.
[167] Meanwhile, the concept of an MH ensemble is applied in the embodiment
of the
present invention, thereby defining a collection (or group) of services. Each
MH
ensemble carries the same QoS and is coded with the same FEC code. Also, each
MH
ensemble has the same unique identifier (i.e., ensemble ID) and corresponds to
con-
secutiveRS frames.
[168] As shown in FIG. 12, the FTC segment corresponding to each data group
described
service information of an MH ensemble to which the corresponding data group
belongs. When FTC segments within a sub-frame are grouped and deinterleved,
all
service information of a physical channel through which the corresponding FICs
are
transmitted may be obtained. Therefore, the receiving system may be able to
acquire
the channel information of the corresponding physical channel, after being
processed
with physical channel tuning, during a sub-frame period.
[169] Furthermore, FIG. 12 illustrates a structure further including a
separate EDC parade
apart from the service parade and wherein electronic service guide (ESG) data
are
transmitted in the 1st slot of each sub-frame.
[170] If the digital broadcasting reception system recognizes a frame start
point or a frame
end point of the MH frame (or the MH subframe), then the digital broadcasting
reception system can set the reference time information to the system time
clock at the
frame start point or the frame end point. The reference time information can
be the
network time protocol (NTP) timestamp. The detailed description for the
reference
time information will be disclosed by being referred to FIGs. 25 to 29.
[171]
[172] Hierarchical Signaling Structure
[173] FIG. 13 illustrates a hierarchical signaling structure according to
an embodiment of
the present invention. As shown in FIG. 13, the mobile broadcasting
techonology
according to the embodiment of the present invention adopts a signaling method
using
FTC and SMT. In the description of the present invention, the signaling
structure will
be referred to as a hierarchical signaling structure.
[174] Hereinafter, a detailed description on how the receiving system
accesses a virtual
channel via FTC and SMT will now be given with reference to FIG. 13.
[175] The FTC body defined in an MH transport (M1) identifies the physical
location of
each the data stream for each virtual channel and provides very high level
descriptions
of each virtual channel.
[176] Being MH ensemble level signaling information, the service map table
(SMT)
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provides MH ensemble level signaling information. The SMT provides the IP
access
information of each virtual channel belonging to the respective MH ensemble
within
which the SMT is carried. The SMT also provides all IP stream component level
in-
formation required for the virtual channel service acquisition.
[177] Referring to FIG. 13, each MH ensemble (i.e., Ensemble 0, Ensemble 1,
...,
Ensemble K) includes a stream information on each associated (or
corresponding)
virtual channel (e.g., virtual channel 0 IP stream, virtual channel 1 IP
stream, and
virtual channel 2 IP stream). For example, Ensemble 0 includes virtual channel
0 IP
stream and virtual channel 1 IP stream. And, each MH ensemble includes diverse
in-
formation on the associated virtual channel (i.e., Virtual Channel 0 Table
Entry,
Virtual Channel 0 Access Info, Virtual Channel 1 Table Entry, Virtual Channel
1
Access Info, Virtual Channel 2 Table Entry, Virtual Channel 2 Access Info,
Virtual
Channel N Table Entry, Virtual Channel N Access Info, and so on).
[178] The FIC body payload includes information on MH ensembles (e.g.,
ensemble id
field, and referred to as "ensemble location" in FIG. 13) and information on a
virtual
channel associated with the corresponding MH ensemble (e.g., when such
information
correspondsto a major channel num field and a minor channel num field, the in-
formation is expressed as Virtual Channel 0, Virtual Channel 1, ..., Virtual
Channel N
in FIG. 13).
[179] The application of the signaling structurein the receiving system
will now be
described in detail.
[180]
[181] When a user selects a channel he or she wishes to view (hereinafter,
the user-selected
channel will be referred to as "channel 0"for simplicity), the receiving
system first
parses the received FIC. Then, the receiving system acquires information on an
MH
ensemble (i.e., ensemble location), which is associated with the virtual
channel corre-
sponding to channel 0 (hereinafter, the corresponding MH ensemble will be
referred to
as "MH ensemble 0" for simplicity). By acquiring slots only correspondingto
the MH
ensemble 0 using the time-slicing method, the receiving system configures
ensemble
O. The ensemble 0 configured as described above, includes an SMT on the
associated
virtual channels (including channel 0) and IP streams on the corresponding
virtual
channels. Therefore, the receiving system uses the SMT included in the MH
ensemble
0 in order to acquire various information on channel 0 (e.g., Virtual Channel
0 Table
Entry) and stream access information on channel 0 (e.g., Virtual Channel 0
Access
Info). The receiving system uses the stream access information on channel 0 to
receive
only the associated IP streams, thereby providing channel 0 services to the
user.
[182]
[183] Fast Information Channel (FIC)
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[184] The digital broadcast receiving system according to the present
invention adopts the
fast information channel (FTC) for a faster access to a service that is
currently being
broadcasted.
[185] More specifically, the FTC handler215 of FIG. 1 parses the FTC body,
which cor-
responds to an FTC transmission structure, and outputs the parsed result to
the physical
adaptation control signal handler 216.
[186] FIG. 14 illustrates an exemplary FTC body format according to an
embodiment of the
present invention. According to the embodiment of the present invention, the
FTC
format consists of an FTC body header and an FTC body payload.
[187] Meanwhile, according to the embodiment of the present invention, data
are
transmitted through the FTC body header and the FTC body payload in FTC
segment
units. Each FTC segment has the size of 37 bytes, and each FTC segment
consists of a
2-byte FTC segment header and a 35-byte FTC segment payload. More
specifically, an
FTC body configured of an FTC body header and an FTC body payload, is
segmented in
units of 35 data bytes, which are then carried in at least one FTC segment
within the
FTC segment payload, so as to be transmitted.
[188] In the description of the present invention, an example of inserting
one FTC segment
in one data group, which is then transmitted, will be given. In this case, the
receiving
system receives a slot corresponding to each data group by using a time-
slicing
method.
[189] The signaling decoder 190 includedin the receiving system shown in
FIG. 1 collects
each FTC segment inserted in each data group. Then, the signaling decoder 190
uses
the collected FTC segments to created a single FTC body. Thereafter, the
signaling
decoder 190 performs a decoding process on the FTC body payload of the created
FTC
body, so that the decoded FTC body payload correspondsto an encoded result of
a
signaling encoder (not shown) included in the transmitting system.
Subsequently, the
decoded FTC body payload is outputted to theFIC handler 215. The FTC handler
215
parses the FTC data included in the FTC body payload, and then outputs the
parsed FTC
data to the physical adaptation control signal handler 216. The physical
adaptation
control signal handler 216 uses the inputted FTC data to perform processes
associated
with MH ensembles, virtual channels, SMTs, and so on.
[190] According to an embodiment of the present invention, when an FTC body
is
segmented, and when the size of the last segmented portion is smaller than 35
data
bytes, it is assumed that the lacking number of data bytes in the FTC segment
payload
is completed with by adding the same number of stuffing bytes therein, so that
the size
of the last FTC segment can be equal to 35 data bytes.
[191] However, it is apparent that the above-described data byte values
(i.e., 37 bytes for
the FTC segment, 2 bytes for the FTC segment header, and 35 bytes for the FTC
segment
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payload) are merely exemplary, and will, therefore, not limit the scope of the
present
invention.
[192]
[193] FIG. 15 illustrates an exemplary bit stream syntax structure with
respect to an FIC
segment according to an embodiment of the present invention.
[194] Herein, the FIC segment signifies a unit used for transmitting the
FIC data. The FIC
segment consists of an FIC segment header and an FIC segment payload.
Referring to
FIG. 15, the FIC segment payload corresponds to the portion starting from the
'for'loop
statement. Meanwhile, the FIC segment header may include a FIC type field, an
error indicator field, an FIC seg number field, and an FIC last seg
numberfield. A
detailed description of each field will now be given.
[195] The FIC type field is a 2-bit field indicating the type of the
corresponding FIC.
[196] The error indicator field is a 1-bit field, which indicates whether
or not an error has
occurred within the FIC segment during data transmission. If an error has
occurred, the
value of the error indicator field is set to '1'. More specifically, when an
error that has
failed to be recovered still remains during the configuration process of the
FIC
segment, the error indicator field value is set to '1'. The error indicator
field enables
the receiving system to recognize the presence of an error within the FIC
data.
[197] The FIC seg number field is a 4-bit field. Herein, when a single FIC
body is divided
into a plurality of FIC segments and transmitted, the FIC seg number field
indicates
the number of the corresponding FIC segment.
[198] Finally, the FIC last seg numberfield is also a 4-bit field. The
FIC last seg number field indicates the number of the last FIC segment within
the
corresponding FIC body.
[199] FIG. 16 illustrates an exemplary bit stream syntax structure with
respect to a payload
of an FIC segment according to the present invention, when an FIC type field
value is
equal to '0'.
[200] According to the embodiment of the present invention, the payload of
the FIC
segment is divided into 3 different regions. A first region of the FIC segment
payload
exists only when the FIC seg number field value is equal to '0'. Herein, the
first region
may include a current next indicator field, an ESG version field, and a
transport stream id field. However, depending upon the embodiment of the
present
invention, it may be assumed that each of the 3 fields exists regardless of
the
FIC seg number field.
[201] The current next indicator field is a 1-bit field. The current next
indicator field acts
as an indicator identifying whether the corresponding FIC data carry MH
ensemble
configuration information of an MH frame including the current FIC segment, or
whether the corresponding FIC data carry MH ensemble configuration information
of a
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next MH frame.
[202] The ESG version field is a 5-bit field indicating ESG version
information. Herein,
by providing version information on the service guide providing channel of the
corre-
sponding ESG, the ESG version field enables the receiving system to notify
whether
or not the corresponding ESG has been updated.
[203] Finally, the transport stream id field is a 16-bit field acting as a
unique identifier of
a broadcast stream through which the corresponding FTC segment is being
transmitted.
[204] A second region of the FTC segment payload corresponds to an ensemble
loop
region, which includes an ensemble id field, an ST _version field, and a num
channel
field.
[205] More specifically, the ensemble id field is an 8-bit field indicating
identifiers of an
MH ensemble through which MH services are transmitted. The MH services will be
described in more detail in a later process. Herein, the ensemble id field
binds the MH
services and the MH ensemble.
[206] The ST _version field is a 4-bit field indicating version information
of ST data
included in the corresponding ensemble, which is being transmitted within the
RS
frame.
[207] Finally, the num channel field is an 8-bit field indicating the
number of virtual
channel being transmitted via the corresponding ensemble.
[208] A third region of the FTC segment payload a channel loop region,
which includes a
channel type field, a channel activity field, a CA indicator field, a
stand alone service indicator field, a major channel num field, and a
minor channel num field.
[209] The channel type field is a 5-bit field indicating a service type of
the corresponding
virtual channel. For example, the channel type field may indicates an
audio/video
channel, an audio/video and data channel, an audio-only channel, a data-only
channel,
a file download channel, an ESG delivery channel, a notification channel, and
so on.
[210] The channel activity field is a 2-bit field indicating activity
information of the corre-
sponding virtual channel. More specifically, the channel activity field may
indicate
whether the current virtual channel is providing the current service.
[211] The CA indicator field is a 1-bit field indicating whether or not a
conditional access
(CA) is applied to the current virtual channel.
[212] The stand alone service indicator field is also a 1-bit field, which
indicates whether
the service of the corresponding virtual channel corresponds to a stand alone
service.
[213] The major channel num field is an 8-bit field indicating a major
channel number of
the corresponding virtual channel.
[214] Finally, the minor channel num field is also an 8-bit field
indicating a minor
channel number of the corresponding virtual channel.
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[215]
[216] Service Table Map
[2171 FIG. 17 illustrates an exemplary bit stream syntax structure of a
service map table
(hereinafter referred to as "SMT") according to the present invention.
[218] According to the embodiment of the present invention, the SMT is
configured in an
MPEG-2 private section format. However, this will not limit the scope of the
present invention. The SMT according to the embodiment of the present
invention
includes desription information for each virtual channel within a single MH
ensemble.
And, additional information may further be included in each descriptor area.
[219] Herein, the SMT according to the embodiment of the present invention
includes at
least one field and is transmitted from the transmitting system to the
receiving system.
[220] As described in FIG. 3, the SMT section may be transmitted by being
included in the
MH TP within the RS frame. In this case, each of the RS frame decoders 170 and
180,
shown in FIG. 1, decodes the inputted RS frame, respectively. Then, each of
the
decoded RS frames is outputted to the respective RS frame handler 211 and 212.
Thereafter, each RS frame handler 211 and 212 identifies the inputted RS frame
by
row units, so as to create an MH TP, thereby outputting the created MH TP to
the MH
TP handler 213. When it is determined that the corresponding MH TP includes an
SMT section based upon the header in each of the inputted MH TP, the MH TP
handler 213 parses the corresponding SMT section, so as to output the SI data
within
the parsed SMT section to the physical adaptation control signal handler 216.
However, this is limited to when the SMT is not encapsulated to IF datagrams.
[221] Meanwhile, when the SMT is not encapsulated to IP datagrams, and when
it is de-
termined that the corresponding MH TP includes an SMT section based upon the
header in each of the inputted MH TP, theMH TP handler 213 outputs the SMT
section
to the IP network stack 220. Accordingly, the IP network stack 220 performs IP
and
UDP processes on the inputted SMT section and, then, outputs the processed SMT
section to the SI handler 240. The SI handler 240 parses the inputted SMT
section and
controls the system so that the parsed SI data can be stroed in the storage
unit 290.
[222] The following corresponds to exampleof the fields that may be
transmitted through
the SMT.
[223] The table_id field corresponds to an 8-bit unsigned integer number,
which indicates
the type of table section. The table :id field allows the corresponding table
to be
defined as the service map table (SMT).
[224] The ensemble_id field is an 8-bit unsigned integer field, which
corresponds to an ID
value associated to the corresponding MH ensemble. Herein, the ensemble_id
field
may be assigned with a value ranging from range '0x00' to '0x3F'. It is
preferable that
the value of the ensemble_id field is derived from the parade_id of the TPC
data,
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WO 2009/038402 PCT/KR2008/005582
which is carried from the baseband processor of MH physical layer subsystem.
When
the corresponding MH ensemble is transmitted through (or carried over) the
primary
RS frame, a value of '0' may be used for the most significant bit (MSB), and
the
remaining 7 bits are used as the parade id value of the associated MH parade
(i.e., for
the least significant 7 bits). Alternatively, when the corresponding MH
ensemble is
transmitted through (or carried over) the secondary RS frame, a value of '1'
may be
used for the most significant bit (MSB).
[225] The num channels field is an 8-bit field, which specifies the number
of virtual
channels in the corresponding SMT section.
[226] Meanwhile, the SMT according to the embodimentof the present
invention provides
information on a plurality of virtual channels using the 'for' loop statement.
[227] The major channel num field corresponds to an 8-bit field, which
represents the
major channel number associated with the corresponding virtual channel.
Herein, the
major channel num field may be assigned with a value ranging from '0x00' to
'OxFF'.
[228] The minor channel num field corresponds to an 8-bit field, which
represents the
minor channel number associated with the corresponding virtual channel.
Herein, the
minor channel num field may beassigned with a value ranging from '0x00' to
'OxFF'.
[229] The short channel name field indicates the short name of the virtual
channel.
[230] The service id field is a 16-bit unsigned integer number (or value),
which identifies
the virtual channel service.
[231] The service type field is a 6-bit enumerated type field, which
designates the type of
service carried in the corresponding virtual channel as defined in Table 2
below.
[232] Table 2
[Table 2]
[Table ]
Ox00 [Reserved]
Ox01 MH digital television - The virtual channel carries
television
programming (audio, video and optional associated data)
conforming to ATSC standards.
0x02 MH audio - The virtual channel carries audio
programming
(audio service and optional associated data) conforming to
ATSC standards.
0x03 MH data only service - The virtual channel carries a
data
service conforming to ATSC standards, but no video or audio
component.
0x04- OxFF [Reserved for future ATSC use]
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[233] The virtual channel activity field is a 2-bit enumerated field
identifying the activity
status of the corresponding virtual channel. When the most significant bit
(MSB) of the
virtual channel activity field is '1', the virtual channel is active, and when
the most
significant bit (MSB) of the virtual channel activity field is '0', the
virtual channel is
inactive. Also, when the least significant bit (LSB) of the virtual channel
activity field
is '1', the virtual channel is hidden (when set to 1), and when the least
significant bit
(LSB) of the virtual channel activity field is '0', the virtual channel is not
hidden.
[234] The num components field is a 5-bit field, which specifies the number
of IP stream
components in the corresponding virtual channel.
[235] The IP version flag field corresponds to a 1-bit indicator. More
specifically, when
the value of the IP version flag field is set to '1', this indicates that a
source IP address field, a virtual channel target IP address field, and a
component target IP address field are IPv6 addresses. Alternatively, when the
value
of the IP version flag field is set to '0', this indicates that the source IP
address field,
the virtual channel target IP address field, and the component target IP
address
field are IPv4.
[236] The source IP address flag field is a 1-bit Boolean flag, which
indicates, when set,
that a source IP address of the corresponding virtual channel exist for a
specific
multicast source.
[237] The virtual channel target IP address flag field is a 1-bit Boolean
flag, which
indicates, when set, that the corresponding IP stream component is delivered
through
IP datagrams with target IP addresses different from the
virtual channel target IP address. Therefore, when the flag is set, the
receiving
system (or receiver) uses the component target IP address as the target IP
address in
order to access the corresponding IP stream component. Accordingly, the
receiving
system (or receiver) may ignore the virtual channel target IP address field
included
in the num channels loop.
[238] The source IP address field corresponds to a 32-bit or 128-bit field.
Herein,the
source IP address field will be significant (or present), when the value of
the
source IP address flag field is set to '1'. However, when the value of the
source IP address flag field is set to '0', the source IP address field will
become in-
significant (or absent). More specifically, when the source IP address flag
field value
is set to '1', and when the IP version flag field value is set to '0', the
source IP address field indicates a 32-bit IPv4 address, which shows the
source of the
corresponding virtual channel. Alternatively, when the IP version flag field
value is
set to '1', the source IP address field indicates a 128-bit IPv6 address,
which shows the
source of the corresponding virtual channel.
[239] The virtual channel target IP address field also corresponds to a 32-
bit or 128-bit
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field. Herein, the virtual channel target IP address field will be significant
(or
present), when the value of the virtual channel target IP address flag field
is set to
'1'. However, when the value of the virtual channel target IP address flag
field is set
to '0', the virtual channel target IP address field will become insignificant
(or
absent). More specifically, when the virtual channel target IP address flag
field
value is set to '1', and when the IP version flag field value is set to '0',
the
virtual channel target IP address field indicates a 32-bit target IPv4 address
as-
sociated to the corresponding virtual channel. Alternatively, when the
virtual channel target IP address flag field value is set to '1', and when the
IP version flag field value is set to '1', the virtual channel target IP
address field
indicates a 64-bit target IPv6 address associated to the correspondingvirtual
channel. If
the virtual channel target IP address field is insignificant (or absent), the
component target IP address field within the num channels loop should become
sig-
nificant (or present). And, in order to enable the receiving system to access
the IP
stream component, the component target IP address field should be used.
[240] Meanwhile, the SMT according to the embodiment of the present
invention uses a
'for'loop statement in order to provide information on a plurality of
components.
[241] Herein, the RTP payload type field, which is assigned with 7 bits,
identifies the
encoding format of the component based upon Table 3 shown below. When the IP
stream component is not encapsulated to RTP, the RTP payload type field shall
be
ignored (or deprecated).
[242] Table 3 below shows an example of an RTP payload type.
[243] Table 3
[Table 3]
[Table ]
RTP payload type Meaning
35 AVC video
36 MH audio
37 - 72 [Reserved for future ATSC use]
[244]
[245] The component target IP address flag field is a 1-bit Boolean flag,
which indicates,
when set, that the corresponding IP stream component is delivered through IP
datagrams with target IP addresses different from the
virtual channel target IP address. Furthermore, when the
component target IP address flag is set, the receivingsystem (or receiver)
uses the
component target IP address field as the target IP address for accessind the
cone-
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sponding IP stream component. Accordingly, the receiving system (or receiver)
will
ignore the virtual channel target IP address field included in the num
channels loop.
[246] The component target IP address field corresponds to a 32-bit or 128-
bit field.
Herein, when the value of the IP version flag field is set to '0', the
component target IP address field indicates a 32-bit target IPv4 address
associated to
the corresponding IP stream component. And, when the value of the IP version
flag
field is set to '1', the component target IP address field indicates a 128-bit
target IPv6
address associated to the correspondingIP stream component.
[247] The port num count field is a 6-bit field, which indicates the number
of UDP ports
associated with the corresponding IP stream component. A target UDP port
number
value starts from the target UDP port num field value and increases (or is in-
cremented) by 1. For the RTP stream, the target UDP port number should start
from
the target UDP port num field value and shall increase (or be incremented) by
2. This
is to incorporate RTCP streams associated with the RTP streams.
[248] The target UDP port num field is a 16-bit unsigned integer field,
which represents
the target UDP port number for the corresponding IP stream component. When
used
for RTP streams, the value of the target UDP port num field shall correspond
to an
even number. And, the next higher value shall represent the target UDP port
number of
the associated RTCP stream.
[249] The component level descriptor() represents zero or more descriptors
providing ad-
ditional information on the corresponding IP stream component.
[250] The virtual channel level descriptor() represents zero or more
descriptors providing
additional information for the corresponding virtual channel.
[251] Theensemble level descriptor() represents zero or more descriptors
providing ad-
ditional information for the MH ensemble, which is described by the
corresponding
SMT.
[252]
[253] FIG. 18 illustrates an exemplary bit stream syntax structure of an MH
audio de-
scriptor according to the present invention. When at least one audio service
is present
as a component of the current event, the MH audio descriptor() shall be used
as a
component level descriptor of the SMT. The MH audio descriptor() may be
capable
of informing the system of the audio languagetype and stereo mode status. If
there is
no audio service associated with the current event, then it is preferable that
the
MH audio descriptor() is considered to be insignificant (or absent) for the
current
event. Each field shown in the bit stream syntax of FIG. 18 will now be
described in
detail.
[254] The descriptor tag field is an 8-bit unsigned integer having a TBD
value, which
indicates that the corresponding descriptor is the MH audio descriptor(). The
de-
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scriptor length field is also an 8-bit unsigned integer, which indicates the
length (in
bytes) of the portion immediately following the descriptor length field up to
the end of
the MH audio descriptor(). The channel configuration field corresponds to an 8-
bit
field indicating the number and configuration of audio channels. The values
ranging
from '1' to '6' respectively indicate the the number and configuration of
audio channels
as given for "Default bit stream index number" in Table 42 of ISO/IEC 13818-
7:2006.
All other values indicate that the number and configuration of audio channels
are
undefined.
[255] The sample rate code field is a 3-bit field, which indicates the
sample rate of the
encoded audio data. Herein, the indication may correspondto one specific
sample rate,
or may correspond to a set of values that include the sample rate of the
encoded audio
data as defined in Table A3.3 of ATSC A/52B. The bit rate code field
corresponds to
a 6-bit field. Herein, among the 6 bits, the lower 5 bits indicate a nominal
bit rate.
More specifically, when the most significant bit (MSB) is '0', the
corresponding bit rate
is exact. On the other hand, when the most significant bit (MSB) is '0', the
bit rate cor-
responds to an upper limitas defined in Table A3.4 of ATSC A/53B. The
ISO 639 language code field is a 24-bit (i.e., 3-byte) field indicating the
language
used for the audio stream component, in conformance with ISO 639.2/B [x]. When
a
specific language is not present in the corresponding audio stream component,
the
value of each byte will be set to '0x00'.
[256] FIG. 19 illustrates an exemplary bit stream syntax structure of an MH
RTP payload
type descriptor according to the present invention.
[257] The MH RTP payload type descriptor() specifies the RTP payload type.
Yet, the
MH RTP payload type descriptor() exists only when the dynamic value of the
RTP payload type field within the num components loop of the SMT is in the
range
of '96' to '127'. The MH RTP payload type descriptor() is used as a
component level descriptor of the SMT.
[258] The MH RTP payload type descriptor translates (or matches) a dynamic
RTP payload type field value into (or with) a MIME type. Accordingly, the
receiving
system (or receiver) may collect (or gather) the encoding format of the IP
stream
component, which is encapsulated in RTP.
[259] The fields included in the MH RTP payload type descriptor() will now
be
described in detail.
[260] The descriptor tag field corresponds to an 8-bit unsigned integer
having the value
TBD, which identifies the current descriptor as the
MH RTP payload type descriptor().
[261] The descriptor length field also corresponds to an 8-bit unsigned
integer, which
indicates the length (in bytes) of the portion immediately following the de-
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scriptor length field up to the end of the MH RTP payload type descriptor().
[262] The RTP payload type field corresponds to a 7-bit field,
whichidentifies the
encoding format of the IP stream component. Herein, the dynamic value of the
RTP payload type field is in the range of '96' to '127'.
[263] The MIME type length field specifies the length (in bytes) of the
MIME type field.
[264] The MIME type field indicates the MIME type corresponding to the
encoding
format of the IP stream component, which is described by the
MH RTP payload type descriptor().
[265] FIG. 20 illustrates an exemplary bit stream syntax structure of an MH
current event
descriptor according to the present invention.
[266] The MH current event descriptor() shall be used as the
virtual channel level descriptor() within the SMT. Herein, the
MH current event descriptor() provides basic information on the current event
(e.g.,
the start time, duration, and title of the current event, etc.), which is
transmitted via the
respective virtual channel.
[267] The fields included in the MH current event descriptor() will now be
described in
detail.
[268] The descriptor tag field corresponds to an 8-bit unsigned integer
having the value
TBD, which identifies the current descriptor as the MH current event
descriptor().
[269] The descriptor length field also corresponds to an 8-bit unsigned
integer, which
indicates the length (in bytes) of the portion immediately following the de-
scriptor length field up to the end of the MH current event descriptor().
[270] The current event start time field corresponds to a 32-bit unsigned
integer quantity.
The current event start time field represents the start time of the current
event and,
more specifically, as the number of GPS seconds since 00:00:00UTC, January 6,
1980.
[271] The current event duration field corresponds to a 24-bit field.
Herein, the
current event duration field indicates the duration of the current event in
hours,
minutes, and seconds (wherein the format is in 6 digits, 4-bit BCD = 24 bits).
[272] The title length field specifies the length (in bytes) of the title
text field. Herein, the
value '0' indicates that there are no titles existing for the corresponding
event.
[273] The title text field indicates the title of the corresponding event
in event title in the
format of a multiple string structure as defined in ATSC A/65C [x].
[274]
[275] FIG. 21 illustrates an exemplary bit stream syntax structure of an MH
next event de-
scriptor according to the present invention.
[276] The optional MH next event descriptor() shall be used as the
virtual channel level descriptor() within the SMT. Herein, the
MH next event descriptor() provides basic information on the next event (e.g.,
the
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start time, duration, and title of the next event, etc.), which is transmitted
via the re-
spective virtual channel. The fields included in the
[277] MH next event descriptor() will now be described in detail.
[278] The descriptor tag field corresponds to an 8-bit unsigned integer
having the value
TBD, which identifies the current descriptor as the MH next event
descriptor().
[279] The descriptor length field also corresponds to an 8-bit unsigned
integer, which
indicates the length (in bytes) of the portion immediately following the de-
scriptor length field up to the end of the MH next event descriptor().
[280] The next event start time field corresponds to a 32-bit unsigned
integer quantity.
The next event start time field represents the start time of the next event
and, more
specifically, as the number of GPS seconds since 00:00:00 UTC, January 6,
1980.
[281] The next event duration field corresponds to a 24-bit field. Herein,
the
next event duration field indicates the duration of the next event in hours,
minutes,
and seconds (wherein the format is in 6 digits, 4-bit BCD = 24 bits).
[282] The title length field specifies the length (in bytes) of the title
text field. Herein, the
value '0' indicates that there are no titles existing for the corresponding
event.
[283] The title text field indicates the title of the corresponding event
in event title in the
format of a multiple string structure as defined in ATSC A/65C [x].
[284]
[285] FIG. 22 illustrates an exemplary bit stream syntax structure of an MH
system time
descriptor according to the present invention.
[286] The MH system time descriptor() shall be used as the ensemble level
descriptor()
within the SMT. Herein, the MH system time descriptor() provides information
on
current time and date.
[287] The MH system time descriptor() also provides information on the time
zone in
which the transmitting system (or transmitter) transmitting the corresponding
broadcast
stream is located, while taking into consideration the mobile/portable
characterstics of
the MH service data. The fields included in the MH system time descriptor()
will
now be described in detail.
[288] The descriptor tag field corresponds to an 8-bit unsigned integer
having the value
TBD, which identifies the current descriptor as the MH system time
descriptor().
[289] The descriptor length field also corresponds to an 8-bit unsigned
integer, which
indicates the length (in bytes) of the portion immediately following the de-
scriptor length field up to the end of the MH system time descriptor().
[290] The system time field corresponds to a 32-bit unsigned integer
quantity. The
system time field represents the current system time and, more specifically,
as the
number of GPS seconds since 00:00:00UTC, January 6, 1980.
[291] The GPS UTC offset field corresponds to an 8-bit unsigned integer,
which defines
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the current offset in whole seconds between GPS and UTC time standards. In
order to
convert GPS time to UTC time, the GPS UTC offset is subtracted from GPS time.
Whenever the International Bureau of Weights and Measures decides that the
current
offset is too far in error, an additional leap second may be added (or
subtracted). Ac-
cordingly, the GPS UTC offset field value will reflect the change.
[292] The time zone offset polarity field is a 1-bit field, which indicates
whether the time
of the time zone, in which the broadcast station is located, exceeds (or leads
or is
faster) or falls behind (or lags or is slower) than the UTC time. When the
value of the
time zone offset polarity field is equal to '0', this indicates that the time
on the current
time zone exceeds the UTC time. Therefore, the time zone offset polarity field
value
is added to the UTC time value. Conversely, when the value of the
time zone offset polarity field is equal to '1', this indicates thatthe time
on the current
time zone falls behind the UTC time. Therefore, the time zone offset polarity
field
value is subtracted from the UTC time value.
[293] The time zone offset field is a 31-bit unsigned integer quantity.
More specifically,
the time zone offset field represents, in GPS seconds, the time offset of the
time zone
in whichthe broadcast station is located, when compared to the UTC time.
[294] The daylight savings field corresponds to a 16-bit field providing
information on the
Summer Time (i.e., the Daylight Savings Time). The time zone field corresponds
to a
(5x8)-bit field indicating the time zone, in which the transmitting system (or
transmitter) transmitting the corresponding broadcast stream is located.
[295] FIG. 23 illustrates segmentation and encapsulationprocesses of a
service map table
(SMT) according to the present invention.
[296] According to the present invention, the SMT is encapsulated to UDP,
while including
a target IP address and a target UDP port number within the IP datagram.
[297] More specifically, the SMT is first segmented into a predetermined
number of
sections, then encapsulated to a UDP header, and finally encapsulated to an IP
header.
In addition, the SMT section provides signaling informationon all virtual
channel
included in the MH ensemble including the corresponding SMT section. At least
one
SMT section describing the MH ensemble is included in each RS frame included
in the
corresponding MH ensemble. Finally, each SMT section is identified by an
ensemble id included in each section. According to the embodiment of the
present
invention, by informing the receiving system of the target IP address and
target UDP
port number, the corresponding data (i.e., target IP address and target UDP
port
number) may be parsed without having the receiving system to request for other
ad-
ditional information.
[298]
[299] FIG. 24 illustrates a flow chart for accessing a virtual channel
using FIC and SMT
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according to the present invention.
[300] More specifically, a physical channel is tuned (S501). And, when itis
determined that
an MH signal exists in the tuned physical channel (S502), the corresponding MH
signal is demodulated (S503). Additionally, FTC segments are grouped from the
de-
modulated MH signal in sub-frame units (S504 and S505).
[301] According to the embodiment of the present invention, an FTC segment
is inserted in
a data group, so as to be transmitted. More specifically, the FTC segment
corresponding
to each data group described service information on the MH ensemble to which
the
corresponding data group belongs. When the FTC segments are grouped in sub-
frame
units and, then, deinterleaved, all service information on the physical
channel through
which the corresponding FTC segment is transmitted may be acquired. Therefore,
after
the tuning process, the receiving system may acquire channel information on
the corre-
sponding physical channel during a sub-frame period. Once the FTC segments are
grouped, in S504 and S505, a broadcast stream through which the corresponding
FTC
segment is being transmitted is identified (S506). For example, the broadcast
stream
may be identified by parsing the transport stream id field of the FTC body,
which is
configured by grouping the FTC segments.
[302] Furthermore, an ensemble identifier, a major channel number, a minor
channel
number, channel type information, and so on, are extracted from the FTC body
(S507).
And, by using the extracted ensemble information, only the slots corresponding
to the
designated ensemble are acquired by using the time-slicing method, so as to
configure
an ensemble (S508).
[303] Subsequently, the RS frame corresponding to the designated ensemble
is decoded
(S509), and an IP socket is opened for SMT reception (S510).
[304] According to the example given in the embodiment of the present
invention, the
SMT is encapsulated to UDP, while including a target IP address and a target
UDP
port number within the IP datagram. More specifically, the SMT is first
segmented into
a predetermined number of sections, then encapsulated to a UDP header, and
finally
encapsulated to an IP header. According to the embodiment of the present
invention,
by informing the receiving system of the target IP address and target UDP port
number, the receiving system parses the SMT sections and the descriptors of
each
SMT section without requesting for other additional information (S511).
[305] The SMT section provides signaling information on all virtual channel
included in
the MH ensemble including the corresponding SMT section. At least one SMT
section
describing the MH ensemble is included in each RS frame included in the corre-
sponding MH ensemble. Also, each SMT section is identified by an ensemble id
included in each section.
[306] Furthermore each SMT provides IP access information on each virtual
channel sub-
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ordinate to the corresponding MHensemble including each SMT. Finally, the SMT
provides IP stream component level information required for the servicing of
the corre-
sponding virtual channel.
[307] Therefore, by using the information parsed from the SMT, the IP
stream component
belonging to the virtual channel requested for reception may be accessed
(S513). Ac-
cordingly, the service associated with the corresponding virtual channel is
provided to
the user (S514).
[308]
[309] The relation of fast information channel data and other data
[310] As illustrated above, the MH broadcast signal, in which the main
service data and the
mobile service data are multiplexed, is transmitted. The transmission
parameter
channel signaling information is allocated in the TPC data, the fast
information
channel signaling information is allocated in the FTC data.
[311] The TPC data and the FTC data are multiplexed and the multiplexed TPC
data and
the FTC data are randomized. And the randomized data are error-correction-
encoded by
a 1/4 Parallel Concatenated Convolutional Code (PCCC) encoding scheme and the
encoded data transmitted in a data group.
[312] Meanwhile, the mobile service data in an ensemble is error-correction-
encoded by a
Serial Concatenated Convolutional Code (SCCC) outer encoding scheme and the
encoded data transmitted in the data group.
[313] The mobile service data includes content data for providing a service
and service
table information describing the service. The service table information
includes
channel information of an ensemble, which means a group of at least one
channel, and
service description information with respect to the channel information.
[314] Hereinafter, for convenience of description, when data units in the
same data group
are processed by different modulation/demodulation schemes, it is described
that the
respective data units are transmitted by way of different data channels, For
example,
both the TPC data and the FTC data are transmitted by way of a first channel
different
from a second channel in which the content data and the service description in-
formation in an ensemble are transmitted. Because the TPC data and the FTC
data are
processed by different modulation/demodulation schemes from those of the
content
data and the service description information.
[315] Under this assumption, a process by which the MH broadcast signal is
received is
described. First, the mobile service data and the main service data are
received in a
broadcast signal. A version of the FTC data is obtained from the TPC datain
the mobile
service data, and the binding information of an ensemble and a virtual channel
of the
ensemble is obtained from the FTC data. Accordingly, it is known that which
ensemble
has the channel a user selects.
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[316] And the ensemble transferring the corresponding channel is received
though a parade
of the broadcast signal. The data group can be obtained from the parade
received by
the receiver, a RS frame including the ensemble is obtainedafter gathering
data groups
from one MH frame. Then the RS frame is decoded and service table information
in
the decoded RS frame is parsed. The information describing the virtual channel
the
user wants to watch is obtained from the parsed service table information and
then a
service is provided from the virtual channel.
[317] The FTC data from a first data channel represents binding information
of anensemble
and a virtual channel, which are transmitted from a second data channel. Using
the
binding information, the service is provided more quickly by parsing the
service table
information.
[318] If the main service data and the multiplexed mobile service data are
received, an em-
bodiment for processing mobile service data at a constant bitrate and another
em-
bodiment will hereinafter be described. In this another embodiment, digital
broadcast
reception systems synchronize mobile services contained in the broadcast
signal are
synchronized and displayed, and components contained in the mobile service
contents
are synchronized and displayed.
[319] FIG. 25 shows a timing model. If video components and audio
components are
transmitted, an example for synchronizing two components is as follows.
[320] Each of the video component and the audio component is encoded, such
that the
encoded components can be stored in buffers of the data processing system and
the
transmission system.
[321] Audio/video components stored in buffers of the data processing
system or the
transmission system are encoded and multiplexed, such that the multiplexed
signals
may be stored or transmitted.
[322] A playback system or a reception system may decode or demultiplex
multiplexed
video/audio signals stored in the buffers. The demultiplexed video component
or the
demultiplexed audio component is stored in the buffer of the playback system
or the
reception system, such that the resulting video and audio components are
decoded by
individual decoders.
[323] The video and audio components to be synchronized in the above-
mentioned signal
processing flow undergo different time delays. For example, it is assumed that
this
timing model has a first constant time delay generated when data is stored in
or
transmitted to the storage apparatus. This time delay is represented by
"ConstantDelay
1" in FIG. 25
[324] A specific time, during which data is temporarily stored in the
buffer of a data
processing system, a transmission system, a playback system, or a reception
system,
may be differently decided according to system types, such that the
video/audio
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components are time-delayed in different ways. This time delay is represented
by
"Variable Delay" in FIG. 25
[325] However, in order to synchronize the video/audio components and
output the syn-
chronized components, it is assumed that another time delay is constant until
the video
and audio components enter the timing model and are then outputted from the
timing
model. This time delay is represented by "Constant Delay 2" in FIG. 25.
[326] Since the above-mentioned timing model is not operated, the
video/audio
components are not synchronized with each other, such that the user may feel
uncom-
fortable if he or she receives content data including video/audio components.
In order
to solve this problem, the MPEG-2 TS system defines a system time clock as the
value
of 27MHz, and the video/audio components are synchronized with each other.
[327] In accordance with contents prescribed in the MPEG-2 TS system, a
transmission
system, performs PCR(Program Clock Reference)-coding on a system time clock
frequency, and transmits the coded result to the reception system. This PCR
value
indicates a transmission system time as the value of 27MHz in a field
'program clock reference base field' of the MPEG-2 TS.
[328] The reception system sets a reception time of the last bit of the
field
'program clock reference base field' to a system time clock (STC). If the STC
value
corrected by the PCR is equal to a decoding time stamp (DTP) and a
presentation time
stamp (PTS) contained in a packetized elementary stream (PES), a correspondin-
gelementary stream is decoded, and the decoded elementary stream is output to
an
external part.
[329] It is assumed that a system time clock error range of 27MHz in the
MPEG-2 TS
system is set to +/- 810MHz, and successive PCR values are transmitted within
0.1
second.
[330] In the digital broadcast receptionsystem, input signals of the MPEG-2
system
decoder are used as output signal of a tuner or a channel decoder. In order to
maintain
a constant bitrate of a broadcast stream during the processing time of
broadcast signals,
all the constituent components of the digital broadcast receptionsystem are
operated. If
mobile service data such as MH broadcast signals is discontinuously received
on a
time axis, a digital broadcast reception system is able to reduce an amount of
power
consumption using the time slicing scheme.
[331] FIG. 26 shows time-variant bitrates provided when signals are
transmitted and
received by the time slicing scheme. For example, if a first service event
(service 1)
and a second service event (service 2) are received by a parade of MH
broadcast
signals (i.e., if the first and second service events are received in the
order of Parade
Index 1, Parade Index 2, and Parade Index 3), the amount of transmitted broad-
castsignals is not constant with time. It is assumed that the same data
quantity as that
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of the above case in which the digital broadcast receptionsystem receives
mobile
service data using the time slicing scheme is received at an average bitrate.
It is
assumed that a bandwidth of the mobile service data received by the time
slicing
scheme is larger than a bandwidth of the other case capable of receiving data
at the
average bitrate by N times. If data is received according to the two schemes,
it is
assumed that an amount of data for use in one scheme is equal to that of the
other
scheme.
[332] Thus, although an amount of data for use in one case in which the
digital broadcast
reception system receives broadcast signals using the time slicing scheme is
equal to
that of the other case in which the digital broadcast receptionsystem
continuously
receives broadcast signals, an amount of power consumption of the one case is
less
than that of the other case by 1/N + a.
[333] However, if broadcast signals are received in the form of a parade
according to the
time slicing scheme, the digital broadcast reception system is unable to
receive the
broadcast signals at a constant bitrate. So, if the broadcastsignals are
continuously
received, decoded and outputted, the digital broadcast receptionsystem may
have
difficulty in managing its own buffer. For example, if the time reference
value is
encoded at times ti and t2 (denoted by X) and data is transmitted by the MPEG-
2 TS
scheme, the encoded time reference field value may be different from an actual
system
time reference. For example, a time referencevalue encoded at the t2 time may
correspond to a time reference value obtained at a t3 time on the condition
that
broadcast signals are received at an average bitrate. If the time reference
value are
transmitted and received by the above scheme, an additional buffer may be
installed in
the digital broadcast reception system, broadcastsignals received in the form
of a
parade may be stored in this additional buffer, and the resulting broadcast
signals may
be outputted at an average bitrate.
[334] However, this scheme is very complicated, and serves as a recursive
process which
may continuously accumulate unexpectederrors in a process capable of
recovering an
original time reference time at an average bitrate, such that the broadcast
recep-
tionsystem becomes unstable.
[335] Although the time reference value may be recovered by the above
scheme, the
recovered time reference value may be changed with time at which a decoder of
the
digital broadcast reception system decodes broadcast signals. So, although the
same
digital broadcast receptionsystem is used, the recovered time reference value
may be
unexpectedly changed to another.For example, if the digital broadcast
reception system
may be powered on, or if a current channel is changed to anotherchannel, an un-
expected time difference may occur in a playback time of contents.
[336] FIG. 27 is a conceptual diagram illustrating an embodiment for
processing a
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reception signal at a constant data processing rate. In FIG. 27, a horizontal
axis is a
time axis, and each unit marked on the time axis is a unit for
transmitting/receiving the
MH broadcast signal.
[337] A time unit at the MH frame corresponding to 20 VSB frames is
0.968ms. The time
of 0.968ms is a time unit where a baseband processor of the digital broadcast
reception
system processes broadcast signals.
[338] As shown in FIG. 27, if the K-th MH frame (i.e., MH frame (H)) is
received, the
system can acquire the K-th RS frame (i.e., RS frame (K)) transmitted to the
MH frame
after thelapse of the time 0.968ms. The digital broadcast reception system
stores the
RS frame in a storage unit, and displays mobile service data provided as the
broadcast
signals.
[339] A baseband processor of the digital broadcast reception can
recognizethe beginning
part and the end part of each MH frame. The end part of any one of the MH
frames is
equal to the beginning part of the next MH frame following the above MH frame.
The
baseband processor of the digital broadcast reception system is synchronized
with a
modulator of a digital broadcast transmission system, such that a modulator of
the
digital broadcast transmission system modulates each MH frame at intervals of
the
time 0.968ms and outputs the resulting MH frame. Therefore, the digital
broadcast
reception system and the digital broadcast transmission system processes
broadcast
signals at intervals of a constant time, the buffer of the digital broadcast
reception
system can process data at a constant data rate without any overflow or
underflow. In
order to allow each of the digital broadcast reception system and the digital
broadcast
transmission system to process data at the constant data processing rate, the
digital
broadcast transmission system can transmit referencetime information used as a
data
processing reference to the digital broadcast reception system. The digital
broadcast re-
ceptionsystem(s) can receive reference time information contained in broadcast
signals, and can process the received broadcast signals according to the
reference time
information. Accordingly, the digital broadcast reception system can process
data at
the same data processing rate as that of the digital broadcast transmission
system, and a
plurality of digital broadcast reception systems can simultaneouslydisplay the
same
contents. For the convenience of description and better understanding of the
present
invention, the reference time information at which the digital broadcast
reception
system is driven is called reference time information.
[340] Arrows marked at a lower part of FIG. 27 indicate time at which
reference time in-
formation is established at each MH frame. For example, the digital broadcast
recep-
tionsystem may set reference time information, which has been contained in a
frame
(e.g., RS frame) of the mobile service data on the basis of the MH frame, to a
system
time clock of the digital broadcastreception system. The digital broadcast
reception
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system may set reference time informationcontained in a frame of mobile
service data
acquired at intervals of the MH frame to the system time clock at intervals of
the MH
frame.
[341] The above-mentioned description shows the RS frame used as the mobile
service
dataframe. In case of the MH broadcast signal, the digital broadcast reception
system
receives one RS frame at intervals of 968msec, such that the reference time in-
formation may be established at intervals of 968msec. Therefore, if the recep-
tionsystem receives the (K+1)-th MH frame, it acquires the (K+1)-th RS frame
and sets
the reference time information in an IP datagram contained in the RS frame to
a system
time clock. If the reception system receives the (K+2)-th MH frame, it
acquires the
(K+2)-th RS frame and sets the reference time information in an IP datagram
contained
in the RS frame to a system time clock. The digital broadcast reception system
peri-
odically establishes this system time clock. In the example of FIG. 27, after
the RS
frame is received and reference time information contained in the received RS
frame is
acquired, the acquired reference time information is set to the system time
clock.
[342] For example, the reference time information acquired from an IP
datagram contained
in the K-th RS frame may be set to the system time clock at the beginning time
of the
(K+2)-th MH frame.
[343] For example, the digital broadcast reception system may establish the
referencetime
information at the beginning or end time of a specific MH subframe from among
MH
frames.
[344] For another example, in case of the MH broadcast system, the digital
broadcast
reception system may establish the system time clock at intervals of the MH
subframe.
In accordance with the exemplary MH broadcast signal frame, 5 MH subframes are
contained in the MH broadcast signal frame. If 5 MH reference times are
contained in
the RS frame, individual referencetimes may be sequentially set to the system
time
clock at the beginning time (or the end time) of the MH subframe.
[345] Reference time information contained in the mobile service data frame
can be peri-
odically established in association with the MH signal frame, and need not be
always
set to the beginning or end time of the MH frame or the MH subframe.
[346] The reference time information may indicate an absolute time such as
a network time
protocol (NTP) timestamp. If the service is transmitted and received using the
Internet
protocol shown in FIG. 3, service constituent components indicating
audio/video data
are configured in the form of real time transport protocol (RTP) packets, and
are
transmitted and received. The RTP packet header may be a timestamp used as a
time
unit at which an access unit (AU) such as a video frame is processed. As
reference
time informationof the timestamp, a network time protocol (NTP) timestamp,
which is
an absolute time in a sender report(SR) according to RTP control protocol
(RTCP),and
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a timestamp value of a reference clock of a system corresponding to the NTP
timestamp can be simultaneously transmitted.
[347] The digital broadcast reception system is able to set the NTP
timestamp in an IP
datagram contained in the mobile service data frame to the system time clock
at a
specific time of the frame. Herein, the NTP timestamp may be in the mobile
service
data frame, and it is not necessary that the NTP timestamp should be contained
in the
SR according to the RTCP
[348] The digital broadcast reception system may establish
synchronizationof audio/video
data received as the reference time information contained in the mobile
service data
frame. A plurality of receptionsystems establish the system time clock using
the same
reference time information, such that they are synchronized with each other
and
display contents transmitted as broadcast signals.
[349] For example, if the digital broadcast reception system receives the
MH broadcast
signal, a specific time for the MH signal processing (e.g., the beginning time
of the
MH signal frame or the beginning time of any one of MH signal frames) may be
used
as a time for establishing the reference time. In this example, the MH frame
start time
of the MH signal frame may be used as the reference time setup time. If the
start time
of the MH signal frame is used as the referencetime setup time and the Doppler
effect
is ignored, the digital broadcast reception system receiving the MH broadcast
signals
may establish the reference time at the same time as the above reference time
setup
time. Also, the actual referencetime value transmitted to the MH signal frame
may be
set to a system time clock at the same time as the above reference time setup
time.
[350] The digital broadcast reception system uses the NTP timestamp value
as refer-
encetime information, such that this reference time information can be used as
a
common wall clock which can be referred at a playback or decoding time of the
service. Also, this reference time information may be interoperable with the
other NTP
timestamp transmitted as sender report (SR) packets of the RTCP on the IP
layer.
[351]
[352] FIG. 28 is a block diagram illustrating a digital broadcast reception
system according
to another embodiment of the present invention.
[353] Referring to FIG. 28, a tuner 410 receives a broadcast signal(s). The
broadcast signal
may be a signal in which mobile service dataand main service data are
multiplexed.
Exemplary broadcast signals are shown in FIGS. 2 to 12.
[354] A demodulator 420 demodulates a reception signal(s). If the reception
signal is the
MH signal frame, the demodulator 420 can output the beginningtime (i.e., MH
frame
start) of the MH signal frame or the beginning time of each subframe of the MH
signal
frame. That is, the demodulator420 can output a demodulation time of a
specific
position of the received signal. The demodulator 420 extracts TPC or FIC data
from
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the MH signal frame, and outputs the extracted TPC or FTC data, and outputs
the RS
frame including ensemblesof mobile service data.
[355] The RS frame decoder 430 decodes the RS frame of FIG. 3, and outputs
MH
transport packets contained in the decoded RS frame to the transport packet
(TP)
handler 440. The TP contained in the MH broadcastsignal may have an TP
datagram,
which includes service table information of FIG. 17, mobile service data
acting as
content data, and referencetime information. In the above-mentioned example,
the
NTP timestamp is shown as reference time information. The TP handler 440 can
output each of mobile service data, service table information, and
referencetime in-
formation contained in the TP datagram.
[356] The outputted mobile service data is temporarily stored in a buffer
445, and the
service table information is outputted to the ST handler 450. The reference
time in-
formation is outputted to the system clock manager 475 contained in the
manager 470.
[357] The ST handler 450 decodes service table information generated from
the TP hanlder
440. In the above-mentioned example, the SMT is shown as service table
information.
The decoded service table information is stored in the service table
information storage
unit 460.
[358] For example, the manager 470 receives demodulation time information
of the output
signal frame of the demodulator. At this demodulation time according to the de-
modulation time information, the manager 470 determines reference time
information
to be a system time clock of the digital broadcast reception system. The
manager 470
can control the ST handler 450, the data handler 480, and the A/V decoder 490,
such
that data contained in the buffer 445 can be processed according to the
determined
system time clock at a constant bitrate.
[359] A channel manager 477 of the manager 470 can generate a channel map
using
service table information stored in the service table information storage unit
460. The
channel manager 477 forms the channel map according to binding information in-
dicating the relationshipbetween an ensemble for transmitting a user-selected
service
and a virtual channel contained in this ensemble. The channel manager 477
selects a
broadcastchannel to quickly output the virtual channel including the user-
selected
service, such that broadcast service of the selected channel is displayed.
[360] The data handler 480 processes data broadcast download data contained
in the buffer
445 according to a periodically-established system time clock. A middleware
engine
485 processes the output data of the data handler 480 according to a
periodically-
recovered system time clock, and provides a data broadcastapplication with the
resulting data. For example, the data broadcast data passes through the A/V
post-
processor 495 by On-Screen-Display (OSD), and the resulting broadcast data is
outputted to a user.
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[361] The A/V decoder 490 decodes mobile service data contained in the
buffer 445
according to the periodically-established system time clock, and outputs the
decoded
mobile service data. The A/V decoder 490 outputs the decoded video/audio data
to the
A/V post-processor 495. The interface unit 465 receives various control
signals (e.g., a
channel shifting signal, an application driving signal) for
managing/establishing the
digital broadcast system from the user, and outputs the received control
signals to the
manager 440 or the A/V post-processor 495.
[362] The A/Vpost-processor 495 allows the A/V data to be received in the
A/V decoder
490, and allows the received A/V data to be displayed. The AN post-processor
495
may output the A/V data to the interface unit 465 according to a control
signal. The A/
V data generated from the A/V post-processor 495 is provideto the user via the
display
(not shown). The display can provide the user with the audio/video data
according to a
system time clock recovered by the reference time decided by the above-
mentioned
scheme. The manager 470 controls the A/V post-processor 495 to synchronize
audio/
video data according to the NTP timestamp established at a specific position
of the
received signal frame. Upon receiving a control signal from the manager 470,
the
display outputs the synchronized audio/video data to the user. Thus, the
embodiment of
FIG. 28 may correspond to the embodiment of FIG. 1. The reference time used as
the
NTP timestamp value may be periodically restored and used as a system time
clock at
a specific time of the MH signal frame.
[363]
[364] FIG. 29 is a flow chart illustrating a data processing method.
[365] Referring to FIG. 29, the broadcast system receives a signal in which
main service
data and mobile service dataare multiplexed at step S801. As an example of the
mul-
tiplexed resultant signal, the MH broadcast signal can be used as an example
of the
multiplexed resultant signal. The mobile service data may be discontinuously
received
with time.
[366] The system demodulates the received broadcast signal, obtains
demodulation time in-
formationof a specific position, and obtains reference time information
contained in the
mobile service data frame at step S803. For example, demodulation time
information
of a specific position of the frame may be the beginning time of the MH signal
frame
or the beginning time of each subframe of the MH signal frame. The
demodulation
time information can be periodically repeated.
[367] The system determines the obtained reference time information to be a
system clock
at the above demodulation time at step S805.
[368] The system decodes the mobile service data according to the
determined system
clock at step S807.
[369] Thus, the received broadcast signal may be decoded or displayed
according to the
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reference time decided at a specific time. As a result, although mobile
service data is
discontinuously received, data can be processed at a constant bitrate.
[370] As apparent from the above description, the digital broadcast system
and the data
processing method according to the present invention have strong resistance to
any
errors encountered when mobile service data is transmitted over the channel,
and can
be easily compatible with the conventional receiver. The digital broadcast
system
according to the present invention can normally receive mobile service data
without
any errors over a poor channel which has lots of ghosts and noises. The
digital
broadcast system according to.the present invention inserts known data at a
specific
location of a data zone, and performs signal transmission, thereby increasing
the Rx
performance under a high-variation channel environment.
[371] Also, the present invention can process service data, which is
discontinuously
received with time, at a constant bitrate.
[372] It will be apparent to those skilled in the art that various
modifications and variations
can be made to the embodiments described above.
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.
Mode for the Invention
[373] The embodiments of the invention are described in the best mode of
the invention.
Industrial Applicability
[374] The digital broadcasting system and the data processing method
according to the
present invention can be used in broadcast and communication fields.
