U.S. patent application number 12/868393 was filed with the patent office on 2011-02-24 for systems and methods of flexible power management applicable to digital broadcasting.
Invention is credited to Ching-Yung Chen, Fang-Chu Chen, Ce-Min Fang, Chih-Chun Feng.
Application Number | 20110044388 12/868393 |
Document ID | / |
Family ID | 34810892 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110044388 |
Kind Code |
A1 |
Chen; Ching-Yung ; et
al. |
February 24, 2011 |
SYSTEMS AND METHODS OF FLEXIBLE POWER MANAGEMENT APPLICABLE TO
DIGITAL BROADCASTING
Abstract
A system for receiving a digital broadcast includes an input
terminal that receives the digital broadcast containing scalable
data, and a controller for controlling an operation mode of the
system. In addition, the system may also include a processor that
decodes the data, and a power management device that varies the
amount of data to be decoded according to the operation mode.
Inventors: |
Chen; Ching-Yung; (Hsinchu,
TW) ; Chen; Fang-Chu; (Hsinchu, TW) ; Feng;
Chih-Chun; (Hsinchu, TW) ; Fang; Ce-Min;
(Hsinchu, TW) |
Correspondence
Address: |
ALSTON & BIRD LLP
BANK OF AMERICA PLAZA, 101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Family ID: |
34810892 |
Appl. No.: |
12/868393 |
Filed: |
August 25, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11140309 |
May 27, 2005 |
7809064 |
|
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12868393 |
|
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60627166 |
Nov 15, 2004 |
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Current U.S.
Class: |
375/240.25 ;
375/E7.026 |
Current CPC
Class: |
H04H 40/18 20130101 |
Class at
Publication: |
375/240.25 ;
375/E07.026 |
International
Class: |
H04N 11/02 20060101
H04N011/02 |
Claims
1. A system for receiving a digital broadcast, the system
comprising: an input terminal that receives the digital broadcast
containing scalable data; a controller for controlling an operation
mode of the system; a processor that decodes the data; and a power
management device that varies the amount of data to be decoded
according to the operation mode.
2. The system of claim 1, wherein the power management device is
that varies the amount of data to be received by the input
terminal.
3. The system of claim 1, wherein the system is a handheld device
operable with a battery power.
4. The system of claim 1, wherein the scalable data comprises data
coded with a fine grain scalability coding.
5. The system of claim 1, wherein the operation mode is selected
based on at least one of a total battery capacity, a remaining
battery capacity, a user's instructions, and a quality of service
selected.
6. The system of claim 1, wherein varying the amount of the data to
be decoded comprises activating the processor at least during the
intervals when the most significant portion of the scalable data is
to be processed.
7. The system of claim 1, wherein varying the amount of the data to
be decoded comprises deactivating the processor at least during the
intervals when the least significant portion of the scalable data
is present.
8. The system of claim 1, wherein the digital broadcast comprises
multiple bandwidth channels each having at least two services.
9. A power management method for a receiving system of a digital
broadcast, the method comprising: providing the digital broadcast
containing scalable data; selecting an operation mode of the
system; and varying the amount of data to be processed by the
receiving system according to the operation mode selected.
10. The method of claim 9, wherein the receiving system comprises a
handheld device operable with a battery power.
11. The method of claim 9, wherein the scalable data comprises data
coded with a fine grain scalability coding.
12. The method of claim 9, wherein the operation mode is selected
based on at least one of a battery capacity, a remaining battery
capacity, a user's instructions, and a quality of service
selected.
13. The method of claim 9, wherein varying the amount of data to be
processed comprises activating a processing at the receiving system
at least during the intervals corresponding to the most significant
portion of the scalable data.
14. The method of claim 9, wherein varying the amount of data to be
processed comprises deactivating a processing at the receiving
system at least during the intervals corresponding to the least
significant portion of the scalable data.
15. The method of claim 9, wherein the digital broadcast comprises
multiple bandwidth channels each having at least two services.
16. The method of claim 15, wherein varying the amount of data to
be processed comprises activating a processing at the receiving
system at least during the intervals corresponding to the most
significant portion of each frame belonging to a service
selected.
17. The method of claim 15, wherein the data of the at least two
services are placed at distinct time intervals.
18. The method of claim 15, wherein varying the amount of data to
be processed comprises deactivating a processing at the receiving
system at least during the intervals corresponding to a
non-selected service.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 11/140,309, filed May 27, 2005, which claims the benefit of
U.S. Provisional Patent Application No. 60/627,166, filed Nov. 15,
2004, both of which are hereby incorporated herein in their
entirety by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to systems and
methods of flexible power management, and more specifically, to
systems and methods of flexible power management applicable to
digital broadcasting.
[0003] The research, development, and promotion of digital
broadcasting, including digital TV (DTV) broadcasting, have made
digital broadcasting a much more popular and acceptable form of
broadcast. Replacing the conventional analog channels and programs
with their digital renditions is only one of many DTV's intrinsic
features. As many other industries, such as interne and mobile
communication one trend is to adequately integrate digital
broadcasting with other fields and applications of technologies and
services. One of those attempts includes using a handheld device to
receive and decode digital broadcasting signals, thereby allowing
consumers to enjoy digital broadcasting services anywhere and
anytime. Such application brings the applications of digital
broadcasting to a new level not reached by the conventional
devices. Among other efforts, a new Digital Video
Broadcasting-Handheld (DVB-H) standard has been proposed.
[0004] There are, of course, many differences between receiving a
DTV program from a home DTV set and from a personal handheld
device. For example, the display of the former is typically of
larger size than that of the latter, which also has limited power.
Among others, power consumption is an important consideration for
handheld devices, because a handheld device gets its power from an
energy-limited battery instead of a wall outlets. Therefore, an
energy efficient process is required for DTV broadcasting to
handheld devices.
[0005] Referring to FIG. 1A, in the case of Digital Video
Broadcasting-Terrestrial (DVB-T) system, all services (or programs)
within one channel are uniformly multiplexed based on capacity
division multiplexing (CDM) into a single transport stream (TS),
which is then modulated and transmitted. The receiver has to
demodulate the received signal all the time even though most
viewers usually need only one service at a time. Processing
information of all services, particularly the non-selected
services, unnecessarily consumes more power. Obviously, receivers
in the DVB-T system always suffer from a waste of power due to the
above arrangement for steaming.
[0006] Referring to FIG. 1B, to reduce the average receiver power
consumption, the DVB-H system introduces a scheme based on time
division multiplexing (TDM), known as "time-slicing", for
multimedia streaming. For example, DVB-H uses a time-slicing based
mechanism to put different services, which may be distinctive DTV
programs, at distinctive time slots. Accordingly, a receiver only
needs to process the information at and near the intervals where
the viewer-selected-service(s) are present. Indeed, the receiver
may deactivate most of the processing functions or enter into a
"sleeping" mode during most of the remaining intervals. For
example, referring to FIG. 1C, the burst duration indicates the
duration where a receiver is activated to process the information.
During the remaining duration, such as the off-time duration shown
in FIG. 1B, most of the signal processing functions may be
deactivated to reduce consumption of power. This mechanism has been
approved as part of DVB-H's standard. Nevertheless, it should be
noted that time-slicing provides the solution of only power saving
rather than power management. That is, the problem with DVB-H's
service-based time-slicing mechanism is a lack of flexibility for
power management. Under certain circumstances, the power
consumption of processing only one service may still be too much
for certain systems. Therefore, there remains a need for systems
and methods that provide flexibility in power management.
BRIEF SUMMARY OF THE INVENTION
[0007] A scheme of making use of scalable multimedia coding over a
service-based time-slicing scheme in a digital transmission system
may allow receivers to autonomously or flexibly manage their power
consumption.
[0008] A system for receiving a digital broadcast in one example
may include: an input terminal capable of receiving the digital
broadcast containing scalable data; a controller for controlling an
operation mode of the system; a processor capable of decoding the
data; and a power management device capable of varying the amount
of data to be decoded according to the operation mode.
[0009] A digital broadcasting system in one example may include: a
signal source capable of providing digital data containing at least
one of audio data and video data; and a data processing device
capable of partitioning the digital data into at least two sections
of partitioned data having different significance.
[0010] A power management method for a receiving system of a
digital broadcast in one example may include: providing the digital
broadcast containing scalable data; selecting an operation mode of
the system; and varying the amount of data to be processed by the
receiving system according to the operation mode selected.
[0011] A digital broadcasting method in one example may include:
providing data containing at least a first broadcast service and a
second broadcast service; encoding the first broadcast service and
the second broadcast service; placing a sequence of the encoded
first service and a sequence of the encoded second service at
distinct time intervals; and partitioning the sequence of the
encoded first service into at least two sections of partitioned
data according to the significance of the encoded data of the
encoded first service.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] The foregoing summary, as well as the following detailed
description of the invention, will be better understood when read
in conjunction with the appended drawings. For the purpose of
illustrating the invention, there are shown in the drawings
embodiments which are presently preferred. It should be understood,
however, that the invention is not limited to the precise
arrangements and instrumentalities shown.
[0013] In the drawings:
[0014] FIG. 1a illustrates a schematic diagram of exemplary DVB-T
broadcast signals in the prior art.
[0015] FIG. 1b illustrates a schematic diagram of exemplary DVB-H
broadcast signals in the prior art.
[0016] FIG. 1c illustrates an exemplary timing diagram to
illustrate the burst durations for decoding exemplary DVB-H
broadcast signals in the prior art.
[0017] FIG. 2 illustrates an exemplary block diagram of a
broadcasting or a receiving system in examples consistent with the
present invention.
[0018] FIG. 3 illustrates an example of dividing a bitstream frame
in examples consistent with the present invention.
[0019] FIG. 4 illustrates an example of dividing a service into
time-sliced portions in examples consistent with the present
invention.
[0020] FIG. 5 illustrates an example of a partition-stream
formation process in examples consistent with the present
invention.
[0021] FIG. 6a-6b illustrate an example of dividing each bitstream
frame into three sections and a timing diagram showing the possible
timing of processing only certain portions of orthogonal frequency
division multiplexing (OFDM) symbols in examples consistent with
the present invention.
[0022] FIG. 7 illustrates an example of adopting frame partition
and bitstream reordering in examples consistent with the present
invention.
[0023] FIG. 8 illustrates an example showing the differences of
system timing diagrams between one without OFDM reordering and one
with OFDM reordering in examples consistent with the present
invention.
[0024] FIGS. 9a-9d illustrate an exemplary approach for
partitioning bitstream frames in examples consistent with the
present invention.
[0025] FIG. 10 illustrates another exemplary approach of frame
partitioning and bitstream reordering in examples consistent with
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] According to the present invention, a scheme of malting use
of scalable multimedia coding over a service-based time-slicing
scheme in a digital transmission system may be provided to allow
receivers autonomously and flexibly managing their power
consumption. It is to be understood that the present invention may
be implemented in various forms of hardware, software, firmware,
special purpose processors, or a combination thereof.
[0027] It is to be further understood that, because some of the
constituent system components and method steps depicted in the
accompanying figures are preferably implemented in a combination of
hardware and software, the actual connections between the system
components (or the process steps) may differ depending upon the
manner in which the present invention is programmed. Given the
teachings herein, one of ordinary skill in the related art will be
able to contemplate these and similar implementations or
configurations of the present invention.
[0028] Examples illustrated below relate to systems and methods of
power management applicable to DTV systems. In one example, systems
such as systems for receiving digital broadcast may be operated
differently under two or more different modes to facilitate power
management. For example, a system may be operated under a
power-saving mode that requires less data processing resources or
less processor on-time, which in turn consumes less power. In some
examples, systems or methods having a coding mechanism based on
significance of digital data may be employed to facilitate flexible
power management. In particular, a system may process only a
portion of the data that has more significance to reduce power
consumption. In one example, scalable coding may be used.
[0029] Additionally, examples illustrated below may be applicable
to digital broadcasting, including DTV systems and handheld
devices. A power-limited or battery-operated device may employ the
examples of systems or methods illustrated below for processing
information of digital broadcasting. For example, when a device has
detected that the remaining power of the battery is limited, the
device may, with or without the instructions from the user, enter
into a power-saving mode to extend service time. The power
management may extend the service time for the user to watch video
program or listen to an audio program. In one example, a
power-saving mode may be achieved with reduced processing power or
reduced processing time. Such change may reduce video and/or audio
quality due to the reduction in the information processed and
presented. However, by adequately selecting operational modes and
decoding the data according to its significance, the reduction in
quality may become minimal or less apparent to viewers.
[0030] An analog video (or audio) generally consists of many motion
pictures (or waveforms) occurring consecutive in time. Take video
as an example for ease of presentation. After sampling, digitizing
and source encoding to the video, each picture's information will
be digitized and compressed into a (video) frame of information
bits. A bitstream is a stream of information bits consisting of
many frames juxtaposed in time. A scalable coding, such as fine
granular/grain scalability (FGS) coding proposed by Moving Picture
Expert Group (MPEG), place more significant or important
information of a compressed data closer to the beginning of each
bitstream frame. Therefore, even if some end portions of a
bitstream are truncated, the remaining part of a bitstream frame
can still be decoded to obtain most relevant or some video and/or
audio information. The decoded information, although incomplete,
may remain acceptable or intelligible to a viewer.
[0031] A scalable coding, such as scalable bitstream coding, may be
used in bandwidth management, e.g. to avoid over-occupying the
limited bandwidth with too much data. It may also be used for power
management, e.g. to reduce power consumption by processing only a
portion of the data. In one example, a power-limited device may
truncate or choose to receive only a part of the bitstream frame to
avoid processing the data in its entirety and to consume less
power.
[0032] An exemplary bitstream frame may be distributed over
multiple time slices, each carrying continuous portions of a
bitstream frame with different levels of significance. Therefore,
when a certain operation mode is selected to reduce power
consumption, a system may ignore less significant portions of data
or skip data processing during the intervals corresponding to those
data portions. For example, a system may skip data processing over
all layers, including from source decoding in the application layer
to channel decoding in the physical layer.
[0033] For example, referring to FIG. 3, a bitstream frame may be
divided into three continuous portions of different significance
levels, each occupying one time interval. FIG. 4 illustrates an
example of how a time-sliced service of a multiple-service
broadcast can be further divided into time-sliced portions.
Referring to both FIGS. 3 and 4, if the more significant data are
placed near the beginning, a system operating under a power-saving
mode may ignore the data in the time interval(s) corresponding to
the least significant portion(s) and may avoid some of the data
processing operations, such as demodulation, channel decoding, and
video decoding. For example, if one-third of the data is not
processed, the power consumption may be reduced by approximately
one-third. The reduced power consumption may extend the operating
time of a battery-operated device by approximately one-third.
[0034] Using the concept illustrated in FIGS. 3 and 4, a bitstream
frame may be divided into two, three, four, or any number of
continuous portions, each portion may have a distinct level of
significance and occupy a time interval. As a result, a system may
enter one of the multiple operation modes that may dictate how much
data of each frame is processed. Because some of the data in
certain time interval(s) corresponding to one or more less
significant portion(s) of a frame may be ignored, the system may
reduce power consumption by activating the system or its processing
only during certain time intervals and deactivating the system or
its processing during other time intervals, such as the off-time
interval illustrated in FIG. 4. Accordingly, a system, such as a
system for receiving digital broadcast, may provide multiple power
management or power-saving modes by varying the ratio or the
percentage of the data processed. Also, increasing the number of
the partitions associated with each bitstream frame may provide
more flexibility in system power management.
[0035] FIG. 5 illustrates an example of the partition stream
forming process. In one example, the known transmission methods
under the current standards, including the DVB-H standard, may be
used to transmit the symbols frame by frame.
[0036] FIG. 6a illustrates an example of dividing each frame into
three sections. The OFDM symbols, carrying data corresponding to
different portions of the same or different frames, may be
transmitted consecutively over time. A receiving system may choose
to process the most significant portion of each frame and enter
into a "sleep mode" or "sleep period" during the time intervals
corresponding to less significant OFDM symbols. FIG. 6b illustrates
an example of a timing diagram showing the possible timing of
processing only the most significant portion of OFDM symbol of each
frame. Referring to FIG. 6b, a broadcast signal may carry multiple
services, each occupying different periods. In the example shown,
the "active" period of service may allow the transmission of OFDM
symbols corresponding to three frames, frames, n-1, n, and n+1.
[0037] Because the most significant OFDM symbol of each frame
resides at the beginning portion of each frame, a receiving system
in this particular example may have to repeat the
activating-deactivating operations for three times in order to
obtain the most significant data of the three frames. Therefore,
under this approach, there may be a concern in some examples that
both a broadcasting and a receiving system may need to keep track
of multiple group boundaries to accurately identify the timing of
each section and each frame. Additionally, the frequent on-off
operations of a receiving system may affect power consumption,
system design flexibility, and operational efficiency. To avoid
those restrictions, the OFDM symbols may be reordered, as
illustrated FIG. 7, to facilitate power management and system
design flexibility.
[0038] FIG. 7 illustrates an example adopting frame partition and
bitstream reordering, which in some examples may be done before the
physical layer. In one example, at the broadcasting front end, an
encoded bitstream may include several consecutive bitstream frames.
The frames may be partitioned into N equal portions, which may be
indexed by frame portion number p(m, n), where m indicates the
index of the bitstream frame, and n the index of the portion.
Secondly, all portions with the same second index number (n) will
be extracted out from their own bitstream frames and put together
in the order according to index m to form N partition streams. Each
partition stream is denoted by the common portion index.
[0039] In one example, a FGS bitstream may be partitioned and
reordered appropriately to fit the burst size defined by a
particular broadcast standard or specification, such as the DVB-H
standard for time-slicing of multiple services. Referring to FIG.
7, by reordering the OFDM symbols, portions of the same level of
significance from several frames, such as three frames in this
example, can be grouped together. As illustrated in FIG. 7, the
most significant portions (n=1) of frames 101, 102, and 103 are
reordered to form consecutive OFDM symbols, i.e. p(101, 1), p(102,
1), and p(103, 1). Accordingly, when a receiving system is under a
power-saving mode that processes only the most significant portion
of each frame, the system is activated only for one "on period",
rather than for three "on periods" illustrated in FIG. 6b.
[0040] FIG. 8 illustrates an example showing the differences of
system timing diagrams between one without OFDM symbol reordering
and one with OFDM symbol reordering. Compared to the approach
illustrated in FIG. 6a, the approach illustrated in FIG. 7 allows a
broadcasting and receiving system to keep track of fewer boundaries
(of OFDM symbols) that are needed to accurately identify the timing
of each section and each frame. However, depending on the broadcast
specification and system design, the broadcasting and receiving
systems may still need to keep track of many group boundaries and
to accurately synchronize with the timing of the broadcast
signals.
[0041] At a first glance, since the source is coded with FGS
coding, each frame and time interval should be divided into
arbitrarily smaller granularity than just one-third of the total.
However, taking the characteristics of OFDM technology into
account, the smallest possible granularity may be confined to the
amount of data carried in one OFDM symbol defined by the DVB-H
system, that is, one small time interval occupied by only one OFDM
symbol. In the case that one OFDM symbol carries only a small
portion of information bits in one frame, the above time-slicing
based power management concept can be directly realized without
much modification to the current DVB-H standard. However, this is
not always the case. Let us consider one typical operation mode,
defined in the DVB-H standard, of 8K sub-carriers, 16-QAM
modulation and 1/2 coding rate for convolutional code. In 8K mode,
the bitstream is carried by 6048 data sub-carriers (out of 8192
total sub-carriers). Therefore, with 16-QAM employed in each data
sub-carrier, each OFDM symbol carries 6048.times.4=24192 bits of
information of which only
24192.times.1/2.times.188/204.apprxeq.11147 bits are actual source
data, and the rest are redundant bits due to channel coding
(factors 1/2 for convolutional code and 188/204 for block code).
Considering a compressed video of a bit rate equal to 384 Kbps and
frame rate equal to 30 fps, each video frame is, on an average, of
the length 384000/30=12800 bits. Thus, every single OFDM symbol
covers a number of bits only slightly less than that within a frame
of the video on average. Recall that there are different picture
types such as P, B and I in video coding, with P and B pictures of
much less information than I pictures, indicating that there could
be frames whose lengths are too short to be segmented over multiple
OFDM symbols. This thus renders the "FGS over time-slicing
mechanism" based power management impossible. Next, let us
introduce the concept of partition streams, which may facilitate
FGS based power management.
[0042] The following paragraphs illustrate an exemplary mechanism
of forming frame partition streams for the purpose of
time-slice-based power management.
[0043] To obtain a finer granularity, each bitstream frame may go
through a preprocessor for partitioning and forming a new stream. A
preprocessed partition stream is a stream formed by segments
partitioned from different FGS coded video frames. In particular,
if a granularity of 1/N of a frame is desirable, then each
bitstream frame will be partitioned into N equal portions and each
one would be eventually put into one OFDM symbol. Since frames are
FGS coded each segment will have a significance level depending on
its original position in the frame. All the segments in one
partition stream have to be of the same significance level. If we
index each segment based on its position in a frame with a number,
say n.epsilon. {1, 2, . . . , N}, the same number will also be the
index of the partition stream it is in. The processes of partition
of each frame into multiple segments and formation of partition
streams from the resultant segments are briefly illustrated in
FIGS. 9a and 9b, respectively. The details of forming partition
streams from the video frames are given below.
[0044] First, let consecutive video frames of different lengths be
indicated as frame m-1, m, m+1, . . . as shown in FIG. 9a. If the
system decides on the smallest power managing granularity to be 1/N
of a frame, each frame will be partitioned into N equal segments,
with each segment indicated by frame index m and segment index n as
p(m,n). To form a partition stream all segments of the same segment
index n are extracted from their frames and orderly put together to
form a partition stream also indexed with the same index n, as
shown in FIG. 9b. Repeating the process for n=1, 2, . . . , N will
provide N partition streams. For example, partition stream 3 is
composed of all portions indexed by p(m, 3) from different video
frames. Since all frames are FGS coded and equally partitioned, the
index n of a partition stream may indicate its significance in this
specific video application, with higher number meaning less
significance. Note that, since frames are equally partitioned, all
partition streams will have the boundary of segments of the same
index coinciding in time.
[0045] FIG. 9c illustrates a matrix for illustrating an efficient
method of forming partition streams from the video frames.
Referring to FIG. 9c, each column represents the data in one frame,
which has multiple data sections or symbols (illustrated with
multiple rectangular sections) with decreasing significance levels
to the bottom. Each row represents data sections of the same level
of significance, but from different frames, with later frames to
the right. The consecutive data sections in one row hence form a
partition stream. For example, the p(1,1), p(2,1), p(3,1), p(4,1),
p(5,1), . . . in the first row constitute the first partition
stream and the p(1,2), p(2,2), p(3,2), p(4,2), p(5,2), . . . in the
second row constitute the second partition stream.
[0046] After the partition streams are formed, each partition
stream will undergo separate channel coding, interleaving, and QAM
modulation processes to keep significance levels assigned to each
stream distinctive. When forming the OFDM symbols, a system may
decide what information bits are to be included in one symbol.
Since OFDM symbols of less significance are used to enhance quality
to the corresponding OFDM symbols of higher significance of the
same frame, the numbers of OFDM symbols associated with different
significance within a burst duration should be the same in order to
ensure correct frame synchronization. Assume that the total number
of OFDM symbols to be sent in one burst duration is equal to Y. The
burst duration shall be first equally divided into N time
intervals, and then the nth time interval will be filled up with a
group of Y/N OFDM symbols resultant from the nth partition stream.
It is, of course, not difficult to manipulate the burst duration
and choose the value of N so that Y/N is an integer. OFDM symbols
of different significance will then fill up the burst duration
assigned for the service, with OFDM symbols of higher significance
placed closer to the beginning of the burst duration. Accordingly,
each OFDM symbol may carry a definite significance level as
assigned to the partition streams from which the symbol is formed.
In this manner, a system for receiving the broadcast may achieve
power saving by ignoring OFDM symbols with less significance.
[0047] FIG. 9d illustrates an example in which there are 21 OFDM
symbols taken from three partition streams to be sent in a burst.
(Of course, in a typical case of DVB-H applications, there could be
hundreds of OFDM symbols in one single burst.) Since there are only
three partition streams, the burst duration is divided into three
equal intervals. The first seven OFDM symbols, in this case, are
formed from partition stream 1 assigned with highest significance
level. Similarly, the next and the last seven OFDM symbols are
formed from partition stream 2 with middle significance level and
partition stream 3 with least significance level, respectively.
This simple example shows that receivers will have three options
for power management. More generally, with a preprocessing of
forming N partition streams, receivers will have N options for
power management.
[0048] The approach identified in FIGS. 9a-9d allows the data of
the same level significance to be grouped in one layer, such as one
FGS layer. However, some digital broadcast standards, such as the
DVB-H standard, do not process partition streams independently.
Therefore, depending on the standards used, the approach may not be
compatible with some of the broadcast standards that are currently
being used or proposed.
[0049] FIG. 10 illustrates an exemplary approach of frame
partitioning and bitstream reordering that may provide better
compatibility with known standards, such as the DVB-H standard. In
one example, the FGS frame partition may occur before the physical
layer processing of the data, and the bitstream reordering may also
occur before the physical layer processing of the data. Referring
to FIG. 10, the formed partition streams shown in FIG. 9c will be
first sliced to several portions each fitting the burst size
(number of bits to be transmitted in one burst duration) defined by
the DVB-H standard. Then, the data sections in one portion will be
transmitted in a certain order via the physical layer processing of
DVB-H without any modifications on the DVB-H standard. For example,
the data sections in the first portion will be transmitted in an
order of p(1,1), p(2,1), p(3,1), p(1,2), p(2,2), p(3,2), p(1,3),
p(2,3), p(1,5), p(2,5), p(3,5), p(1,6), p(2,6), p(3,6), and the
data sections in the second portion will be transmitted in an order
of p(4,1), p(5,1), p(6,1), p(4,2), p(5,2), p(6,2), p(4,3), p(5,3),
p(4,5), p(5,5), p(6,5), p(4,6), p(5,6), p(6,6).
[0050] The above description of one embodiment assumes that all
partition streams are formed with the same channel-coding rate. As
each partition stream has been assigned with a particular
significance level, it is possible (and also expected) that
different partition streams can be unequally protected by the
channel coding according to their significance levels. More
specifically, the partition stream with a higher significance level
could have a lower coding rate than those with lower significance
levels. Under a variable coding-rate approach, portions, identified
by indices p(m, n) in one example, of distinctive coding rates may
have distinctive lengths. If different coding rates are to be
employed, it is advised that the length of segments from each frame
shall be decided proportionally to the associated code rates. For
example, if each frame is to be partitioned into two segments
(N=2), with the first segment using coding rate 1/2 and the second
segment using coding rate 2/3, then ratio of the length of the two
segment may be: 1/2:2/3=3:4. This will ensure equal length of the
partition streams after channel coding and thus ensure proper
timing when it comes to placing OFDM symbols in a burst.
[0051] As illustrated above, examples consistent with the present
invention may provide systems and methods of flexible power
management that are applicable to digital broadcasting, such as the
digital broadcasting under the DTV and DVB-H standards. By applying
one or more the approaches illustrated above, a portable or
power-limited receiving system or device may achieve an adequate
balance between battery lifetime and viewing quality to users. The
examples of the systems and methods also allow a wide range or
flexible power management, such as flexible application and control
of different components, including from the RF components to
application layer components. Also, the fine granularity feature of
some examples allows a wide range of management schemes. Some
examples also provide compatibility with known standards, including
DVB-H, Digital Audio Broadcasting (DAB), or Digital Multimedia
Broadcasting (DMB) standards.
[0052] In summary, the examples above may provide a system for
receiving a digital broadcast. Depending on the design, the system
may include an input terminal, a controller, a processor, and a
power management device. The input terminal is capable of receiving
the digital broadcast containing scalable data; the controller may
control the operation modes of the system; the processor is capable
of decoding the digital broadcast; and the power management device
may vary the amount of data to be decoded according to the
operation mode. In particular, the system may be designed to allow
the power management device to vary the amount of data to be
received by the input terminal, thereby reducing the power
consumption of the system, which may be a handheld device operable
with a battery power. As noted above, the scalable data may be data
coded with FGS coding.
[0053] For the system in this example, the operation mode may be
selected based on various factors, such as the total battery
capacity of the system, the remaining battery capacity of the
system, user's instructions, the quality of service selected by the
system or a user, etc. The system may vary the amount of the data
to be decoded by activating the processor at least during the
intervals when the most significant portion of the scalable data is
to be processed. Depending on the operation mode, the processor may
be activated for longer intervals to decode additional portions of
the scalable data. Additionally, the system may vary the amount of
the data to be decoded by deactivating the processor at least
during the intervals when the least significant portion of the
scalable data is present. Depending on the operation mode, the
processor may be deactivated for longer intervals to reduce power
consumption.
[0054] In one example, the digital broadcast may include multiple
bandwidth-channels, and one or more of the channels may include two
or more services. In the context of digital broadcasting, each
"service" may represent one particular that a user may choose to
view. For example, one service may be a news program; another
service may be a football game; etc.
[0055] In addition to a system for receiving a digital broadcast,
the examples above may also provide a digital broadcasting system.
The digital broadcast system may include a signal source capable of
providing digital data containing at least one of audio data and
video data and a data processing device capable of partitioning the
digital data into at least two sections of partitioned data having
different significance. In some examples, the system may include a
channel coding device capable encoding at least a first broadcast
service and a second broadcast service and placing the encoded data
of the first and second broadcast services at distinct time
intervals. In one example, the digital data comprises the encoded
data.
[0056] In some examples, a data processing device may partition the
digital data by scalable coding or fine grain scalability coding.
Additionally, the data processing device may partition the digital
data at least via encoding the partitioned data with at least two
or more coding rates according to the significance of the encoded
data. In some examples, the digital data may include multiple
bitstreams for multiple frames and each bitstream is independently
modulated and partitioned to form the partitioned data.
[0057] The digital broadcast system may also include a reordering
device for reordering the partitioned data to consolidate symbols
of same or similar significance from different bitstream frames.
Furthermore, partitioning the digital data and reordering the
partitioned data may both occur at a physical layer processing of
the digital data or before the physical layer processing of the
digital data.
[0058] The examples illustrated also provide a power management
method for a receiving system of a digital broadcast. In
particular, the method may include providing the digital broadcast
containing scalable data; selecting an operation mode of the
system; and varying the amount of data to be processed by the
receiving system according to the operation mode selected. In some
examples, the digital broadcast may include multiple-bandwidth
channels, and one or more of the channels may include two or more
services.
[0059] Accordingly, varying the amount of data to be processed may
include activating a processing at the receiving system at least
during the intervals corresponding to the most significant portion
of each frame belonging to the service selected. To reduce power
consumption, varying the amount of data to be processed may also
include deactivating a processing at the receiving system at least
during the intervals of a non-selected service. As noted above, the
data of the two or more services in one channel may be placed at
distinct time intervals.
[0060] The examples illustrated also provide a digital broadcasting
method. The method may include providing data containing at least a
first broadcast service and a second broadcast service; encoding
the first broadcast service and the second broadcast service;
placing a sequence of the encoded first service and a sequence of
the encoded second service at distinct time intervals; and
partitioning the sequence of the encoded first service into at
least two sections of partitioned data according to the
significance of the encoded data of the encoded first service. The
various examples of coding techniques, including coding,
partitioning, reordering, and varying coding rates, have been
illustrated above.
[0061] The foregoing disclosure has been presented for purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise examples disclosed. As
noted above, many variations and modifications to the described
examples can be made. The scope of the invention is to be defined
only by the claims appended hereto and by their equivalents.
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