WO2010032948A2

WO2010032948A2 - Apparatus and method for power saving in digital broadcasting system

Info

Publication number: WO2010032948A2
Application number: PCT/KR2009/005252
Authority: WO
Inventors: Seok-Min Hwang
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2008-09-18
Filing date: 2009-09-16
Publication date: 2010-03-25
Also published as: KR20100032509A; WO2010032948A3

Abstract

An apparatus and a method for power saving in digital broadcasting system are provided. A method for transmitting delta-T in a transmitter of the digital broadcasting system includes inserting the delta-T into Program Specific Information (PSI)/Service Information (SI), multiplexing a generated burst and the PSI/SI including the delta-T, and transmitting the multiplexed data.

Description

APPARATUS AND METHOD FOR POWER SAVING IN DIGITAL BROADCASTING SYSTEM

The present invention relates to an apparatus and method for power saving when data is transmitted and received by dividing several broadcasts in a time division manner by the use of time slicing used by Digital Video Broadcasting-Handheld (DVB-H) in a digital broadcasting service such as Satellite-Digital Multimedia Broadcasting (S-DMB), Terrestrial-DMB (T-DMB), Integrated Services Digital Broadcasting-Terrestrial (ISDB-T), Media Forward Link Only (Media FLO), DVB-Terrestrial (DVB-T), DVB-H, etc.

A Digital Video Broadcasting-Handheld (DVB-H) technique is derived from Digital Video Broadcasting-Terrestrial (DVB-T), and thus has a structure similar to the DVB-T in many aspects. Reliable data reception and power consumption are problems to be addressed in advance in the DVB-H in order to implement handheld techniques.

First, to increase reliability of received data, a Multi Protocol Encapsulation (MPE)-forward error correction function is added to a link layer of the Open System Interconnection (OSI)-7 layer. Thus, in addition to an error correction function used in the conventional system, a block de-interleaving function and a 4K mode and in-depth interleaving function are added to increase data reliability.

Second, to decrease power consumption, a time slicing technique is used so that several broadcast services are time-divided in one frequency. Thus, a Receive (Rx) modem operates only at the timing in which a desired broadcast reception function is transmitted, and does not operate during the rest of time, thereby decreasing power consumption.

FIG. 1 illustrates a data structure of DVB-H.

Referring to FIG. 1, when data is transmitted, an MPE process and a Forward Error Correction (FEC) coding process are performed on an Internal Protocol (IP) stream, and then a time division process based on time slicing is performed for each IP stream. Thereafter, a High Priority (HP) stream is generated and transmitted. In this case, in order to share the stream with a conventional DVB-T system, a packet consisting of an MPE section is generated into a transport packet stream when transmission is made on the air.

Data transmitted by a DVB-H transmitter and received by a receiver has a transport packet stream format of 188 bytes (i.e., 4 bytes + 184 bytes). Payload parts of the received transport packet stream may be combined to generate an MPE section stream with a size of 16 bytes to 4095 bytes.

One burst consists of a set of several MPE section streams as illustrated in FIG. 3. The MPE sections constituting one burst have much information in their header parts. In particular, information called ‘delta-T’ provides a function for managing a time-slicing function which is one of features of the DVB-H system.

FIG. 2 illustrates a burst duration and an off-time duration.

Referring to FIG. 2, one IP content is transmitted by being divided into bursts. In order for a receiver to receive a desired broadcast, the receiver is in a power-on state during the burst duration. During durations other than the burst duration, the receiver is in a power-off state.

That is, after the receiver receives one burst, no data is received until a subsequent burst is received, and thus the receiver can remain in the power-off state. This implies time slicing which is one of features of DVB-H. In addition, as described above, the time slicing uses delta-T information existing in a header part of an MPE section to confirm a position of a burst to be received next as illustrated in FIG. 4.

Therefore, the receiver can remain in the power-off state during a delta-T duration, and thus power consumption can be reduced.

FIG. 3 illustrates a burst structure.

Referring to FIG. 3, one burst consists of several MPE sections, each of which has delta-T information in its header. Thus, as illustrated in FIG. 5, delta-T information of each MPE section has a slight difference.

However, since delta-T indicates a position of a next burst, the delta-T information of each MPE section indicates one position. Since the delta-T information exists in the header of the MPE section, a received stream has to be completely configured into an MPE section before confirming the position indicated by the delta-T information. This indicates that, as illustrated in FIG. 1, the receiver has to complete the MPE section by using a received transport packet stream.

Each MPE section has Cyclic Redundancy Check (CRC) information to evaluate reliability of data. Thus, the receiver configures an MPE section by using the received information and then performs a CRC operation to determine error occurrence in the configured section. If no error is detected as a result of the CRC operation, the receiver obtains the delta-T information from the MPE header.

Then, by using the delta-T information, the receiver can know a position of a burst to be received next. Therefore, the receiver may wait in a power-off state until a next burst is received after a current burst is completely received.

However, if an error is detected as a result of the CRC operation, an MPE section is erroneous in this state, and thus the receiver cannot obtain correct delta-information. Accordingly, the receiver has to remain in a power-on state until a correct MPE section can be received.

In general, a system for receiving a digital broadcast uses a Motion Picture Experts Group (MPEG)-2 Transport Stream (TS) as a transport protocol. A receiver of this broadcasting system can receive digital multimedia broadcasting data depending on a channel selected by a user only after receiving Program Specific Information (PSI) and Service Information (SI).

The PSI denotes information by which the receiver can de-multiplex and decode a specific stream in a multiplexed stream. The SI is information added to the PSI, and denotes guidance information on an individual program and a service provided to audiences.

Examples of the PSI include a Program Association Table (PAT), a Program Map Table (PMT), a Conditional Access Table (CAT), etc. Examples of the SI include a Service Description Table (SDT), a Network Information Table (NIT), an Event Information Table (EIT), a Time Offset Table (TOT), etc. The PSI and the SI are correctively referred hereinafter as PSI/SI.

The PAT includes an IDentification (ID) of a broadcasting channel currently being broadcast. Further, the PAT includes a Packet ID (PID) of the PMT having additional information of that broadcasting channel. That is, the PAT includes a PMT PID, i.e., a PID of the broadcasting channel. The PMT includes an individual broadcasting channel, i.e., a PID of an audio/video stream packet corresponding to the PMT PID.

Therefore, the PMT may have all portions of an audio/video stream packet for all broadcasts. Alternatively, there may be several PMTs, each of which includes an audio/video PID for one broadcast.

The CAT is used to transmit information required for an authentication function for determining whether a user is allowed to watch a broadcast. The NIT relates to information on a transport network of a current digital multimedia broadcast.

Each of pieces of PSI/SI information has specific repetition information, and is repetitively transmitted.

For reference, in most parts of the PSI/SI information, the NIT is transmitted with an interval of about 5 seconds. However, since the NIT has a large size, several TS streams (packets) constitute the NIT. The PAT and the PMT are transmitted with an interval of about 50 milliseconds (ms). Since the PAT and the PMT have a small size, they are constructed with one stream. The SDT is transmitted with an interval of about 1 second. Since the SDT has a smaller size than the NIT, the SDT is transmitted more frequently than the NIT.

In order for the user to watch the broadcast, the receiver has to receive the PSI/SI information, and thus data has to be transmitted continuously unlike in the case of using a burst. Therefore, data is persistently transmitted when using the PSI/SI information. In comparison thereto, when using the burst, a large amount of data is transmitted at one time and then the receiver enters a power-off duration.

In general, a burst duration of FIG. 2 for one burst is 100 ms or above, and one burst generally includes about 200 or more MPE sections. Therefore, even if several MPE sections are determined to be erroneous data after CRC determination, delta-T information can be received from the remaining MPE sections.

If one burst duration has a length of about 1 ms and one burst has an MPE section consisting of about 2 or 3 bursts, the MPE section may be incorrectly received when a reception condition of the receiver is not good. In this case, since a small number of MPE sections are included in one burst, a probability of receiving delta-T information may be significantly decreased.

In practice, there is a case where Entitlement Management Message (EMM) information is transmitted using a time slicing technique in a place where a current DVB-H service is commonly used. A burst duration of EMM is 1 ms, and consists of 2 or 3 MPE sections. Since the EMM information is used to determine whether the user is authenticated or not, it is not necessary to transmit a large amount of data.

In addition, in an environment where signal strength is weak, it is difficult to detect delta-T information since at least two TS streams are required for section configuration even if a burst consists of a plurality of sections.

Therefore, in a case where a reception condition of the receiver is not good, it may be difficult to receive the EMM information, and a probability of receiving correct delta-T information is decreased. In this case, the receiver may have to wait in a power-on state for a long period of time. Accordingly, there is a problem in that power consumption is rapidly increased.

An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide an apparatus and a method for power saving in a digital broadcasting system.

Another aspect of the present invention is to provide an apparatus and method for minimizing power consumption and for reliably receiving a next burst, wherein the power consumption is produced since a receiver remains in a power-on duration without entering a power-off duration when the receiver fails to receive delta-T information from a burst due to a poor reception condition in a digital broadcasting system.

In accordance with an aspect of the present invention, a method of transmitting delta-T in a transmitter of a digital broadcasting system is provided. The method includes inserting the delta-T into Program Specific Information (PSI)/Service Information (SI), multiplexing a generated burst and the PSI/SI including the delta-T, and transmitting the multiplexed data.

In accordance with another aspect of the present invention, a method for power saving in a receiver of a digital broadcasting system is provided. The method includes, if delta-T fails to be obtained from a received burst, obtaining the delta-T from PSI/SI, and turning off a communication modem at the timing in which a desired broadcast is not transmitted based on the delta-T.

In accordance with another aspect of the present invention, a transmitter apparatus for transmitting delta-T in a digital broadcasting system is provided. The apparatus includes a delta-T update unit for inserting a delta-T into PSI/SI, a multiplexer for multiplexing a generated burst and the PSI/SI including the delta-T, and a transmitter for transmitting the multiplexed data.

In accordance with another aspect of the present invention, an apparatus for performing a power saving function in a receiver of a digital broadcasting system is provided. The apparatus includes a burst configuration unit for configuring a burst from received information, a PSI/SI processor for obtaining PSI/SI and delta-T from the received information, and a controller for turning off a communication modem at the timing in which a desired broadcast is not transmitted based on the delta-T.

Other aspects, advantages and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention

The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a data structure of Digital Video Broadcasting-Handheld (DVB-H);

FIG. 2 illustrates a burst duration and an off-time duration;

FIG. 3 illustrates a burst structure;

FIG. 4 illustrates information indicated by delta-T;

FIG. 5 illustrates a relation between delta-T and a Multi Protocol Encapsulation (MPE) section;

FIG. 6 illustrates a Program Map Table (PMT) according to an exemplary embodiment of the present invention;

FIG. 7 is a block diagram illustrating a structure of a transmitter according to an exemplary embodiment of the present invention;

FIG. 8 illustrates an operation of a delta-T detection process of a receiver according to an exemplary embodiment of the present invention;

FIG. 9 illustrates a flowchart illustrating an operation of a transmitter according to an exemplary embodiment of the present invention;

FIG. 10 illustrates a flowchart illustrating an operation of a receiver according to an exemplary embodiment of the present invention; and

FIG. 11 illustrates a block diagram illustrating a structure of a receiver according to an exemplary embodiment of the present invention.

Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the exemplary embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.

By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

Hereinafter, an apparatus and method for power saving in a digital broadcasting system will be described.

The present invention relates to a technique capable of reducing power consumption in a state where a reception condition is not good by complementing a time slicing function of Digital Video Broadcasting-Handheld (DVB-H).

A burst of the present invention is either a burst having a very short burst duration as in Entitlement Management Message (EMM) information or a burst consisting of 2 or 3 Multi Protocol Encapsulation (MPE) sections. However, the present invention also applies when a burst duration is sufficiently long and the number of MPE sections is great.

Delta-T information determines whether power consumption of a receiver can be decreased, and thus plays an important role for allowing a user to be able to receive a signal for a longer period of time.

If important information can be obtained only when it can be configured by receiving several Transport Stream (TS) packets, when a reception condition is not good, one MPE section preferably consists of one TS packet as in Program Specific Information (PSI)/Service Information (SI) rather than configuring a section by continuously receiving several TS packets.

In this case, it is not necessary to receive several TS packets to configure an MPE section, and thus it is easier to configure the MPE section by using PSI/SI information when signal strength is not good. Therefore, delta-T information can be easily detected.

As described above in FIG. 2, a receiver receives a burst during a specific time (i.e., a burst duration) to output a broadcast, and remains in a sleep state during a specific time (i.e., an off-time duration), thereby decreasing electrical current consumption. Herein, information indicating the specific time is a delta-T value of FIG. 4. The delta-T value exists in a header of an MPE section constituting the burst.

To extract the delta-T, an MPE section consisting of several TS packets are configured (or generated). Cyclic Redundancy Check (CRC) included in the configured MPE section has to coincide with CRC determined using a payload of the MPE section. If the two CRCs coincide with each other, it can be seen that there is no error in the configured MPE section. The delta-T value can be correctly extracted only from a header of the error-free MPE section.

However, if a reception condition of the receiver is not good and thus any one of the several TS packets constituting one MPE section cannot be received, it is difficult to configure the MPE section, and as a result, it is difficult to detect the delta-T.

Therefore, even if the receiver is in power-off duration, since a time of transmitting a next burst cannot be known, the receiver has to continuously receive data until a next section is detected.

In this case, the receiver can receive the delta-T information more frequently when the delta-T information is transmitted by being included in the PSI/SI.

The PSI/SI includes a variety of information, such as a Network Information Table (NIT), a Service Description Table (SDT), a Program Association Table (PAT), etc., which results in a large data size. Therefore, a section has to be configured using several TS packets similarly to a case of configuring an MPE section. However, in case of a Program Map Table (PMT), a section can be configured only using one TS packet. This is because the PMT has only an audio/video Packet IDentification (PID), which results in a small data size.

In addition, at present, DVB-Terrestrial (DVB-T) has an additional PMT for each broadcasting channel. This is because, as illustrated in FIG. 6, the PMT describes a PID of each broadcast or a characteristic (i.e., a stream type) of each broadcast, and several PS packets are required when information on all broadcasting channels is inserted to one PMT.

If one PMT has information on all broadcasting channels, a PMT value changes when a characteristic of one broadcast changes or when one broadcast is deleted or added. In this case, it takes a long time to receive a new PMT.

On the other hand, when information on one broadcast changes in a case where information on each broadcast is inserted to each PMT (e.g., 10 PMTs are present for 10 broadcasts), it is sufficient to change only a corresponding PMT. In addition, when one broadcast is deleted or added, it is sufficient to update only a newly added or deleted broadcast. Eventually, in case of the PMT, it is easier to update broadcasting information when each PMT is separately present for each broadcast.

Therefore, in addition to a conventional case where a delta-T value for reporting a position of a burst to be received next is inserted to each section, specific information is also included in the PSI/SI in the present invention.

An operation of a transmitter/receiver of the present invention is described below.

FIG. 7 illustrates a block diagram illustrating a structure of a transmitter according to an exemplary embodiment of the present invention.

Referring to FIG. 7, an Audio/Video (A/V) generator 710 generates A/V data. A burst generator 740 generates a burst by using contents generated by the A/V generator 710. In case of DVB-H, the contents are used to generate an MPE section (herein, an MPE header and a payload are separated).

A delta-T generator 730 generates a delta-T value on a real time basis by an operation of an internal timer, and inserts the delta-T value into each of MPE section generated by the burst generator 740.

A PSI/SI generator 720 generates PSI/SI information (e.g., NIT, PAT, SDT, PMT, etc.), and updates the PSI/SI information by considering TS packet header information.

A delta-T update unit 750 inserts delta-T information into the PSI/SI generated by the PSI/SI generator 720. The delta-T information is one of time information and changes always on a real time basis, and version information of a section does not change.

Since delta-T changes on a real time basis, version information of PSI/SI has to continuously change if the delta-T information is inserted into the PSI/SI. Therefore, the delta-T value is inserted after the PSI/SI information is generated. The delta-T is inserted into the PSI/SI by using the following methods.

First, information on all broadcasts exists in one PMT, and thus delta-T for all broadcasts can be inserted to one PMT.

Second, each PMT exists for each broadcast, and thus delta-T of a corresponding broadcast can be inserted to each PMT.

Third, it is possible to generate additional PSI/SI information (i.e., a Power On Table (POT)) that indicates delta-T.

As described above, the transmitter of the present invention inserts the delta-T information not only into the burst not also into the PSI/SI. Therefore, the receiver can receive the delta-T information with a higher probability, and thus power consumption can be prevented when the receiver waits in power-on duration since the receiver fails to configure an MPE section in a place where signal strength is weak and thus fails to obtain delta-T information

A multiplexer 760 performs multiplexing on an MPE section generated by the burst generator 740 and the PSI/SI including the delta-T information output by the delta-T update unit 750.

A transmission unit 770 represents a Transmit (Tx) modem, and transmits the information multiplexed by the multiplexer 760 on the air.

The receiver of the present invention may operate as described below.

The receiver receives PSI/SI information including delta-T while receiving one burst. The receiver may fail to configure a section by using burst data and thus may fail to obtain delta-T information.

That is, while receiving a burst, the receiver receives the PSI/SI information by which the delta-T information on a corresponding burst is transmitted. Thereafter, if the delta-T information cannot be obtained even after the receiving of the burst ends, as illustrated in FIG. 8, the burst ends in a Max Burst Duration (MBD). However, since the PSI/SI information can be continuously received, the delta-T information can be obtained.

FIG. 9 illustrates a flowchart illustrating an operation of a transmitter according to an exemplary embodiment of the present invention.

Referring to FIG. 9, an A/V generator generates A/V data (step 910). A burst generator generates an MPE section (or a burst) by using contents (i.e., A/V data) generated by the A/V generator (step 920).

A delta-T generator generates a delta-T value on a real time basis by an operation of an internal timer, and inserts the delta-T value to each of MPE section generated by the burst generator (step 930).

A delta-T update unit inserts delta-T information to generated PSI/SI (step 940). The delta-T information changes always on a real time basis, and version information of a section does not change. Since delta-T changes on a real time basis, version information of PSI/SI has to continuously change if the delta-T information is inserted into the PSI/SI. Therefore, the delta-T value is inserted after the PSI/SI information is generated.

A multiplexer performs multiplexing (or muxing) on an MPE section generated by the burst generator and the PSI/SI including the delta-T information output by the delta-T update unit (step 950).

A transmission unit represents a Tx modem, and transmits the information multiplexed by the multiplexer to a receiver on the air (step 960).

Thereafter, the procedure of FIG. 9 ends.

FIG. 10 illustrates a flowchart illustrating an operation of a receiver according to an exemplary embodiment of the present invention.

Referring to FIG. 10, upon receiving a TS packet through a communication modem, the receiver receives PSI/SI including delta-T information (step 1010).

The receiver performs burst configuration. If the burst configuration is unsuccessful (step 1020), the receiver obtains the delta-T information from the PSI/SI (step 1030).

If the burst configuration is successful (step 1020), the receiver obtains delta-T information from the configured burst data (step 1040).

Thereafter, the procedure of FIG. 10 ends.

Referring to FIG. 11, upon receiving a TS packet, a communication modem 1110 also receives PSI/SI including delta-T information.

A burst configuration unit 1120 configures a burst (i.e., an MPE section) from the received TS packet. A PSI/SI processor 1140 obtains PSI/SI information from the received TS packet. The PSI/SI processor 1140 also obtains the delta-T information included in the PSI/SI.

If the burst configuration unit 1120 successfully configures the burst, a controller 1130 controls on/off of the communication modem 1110 based on delta-T information included therein.

Otherwise, if the burst configuration unit 1120 fails to configure the burst, the controller 1130 controls on/off of the communication modem 1110 based on the delta-T information obtained by the PSI/SI processor 1140.

A higher layer 1150 performs a predetermined function (i.e., broadcast reproduction) based on information output by the burst configuration unit 1120 and information output by the PSI/SI processor 1140.

According to exemplary embodiments of the present invention, power consumption can be reduced, wherein the power consumption is produced since a receiver waits in a power-on state until a next MPE section is correctly received when a receiver fails to receive delta-T information due to a poor reception condition and thus fails to correctly receive an MPE section.

While the present invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims and their equivalents, and all differences within the scope will be construed as being included in the present invention.

Claims

A method of transmitting delta-T in a transmitter of a digital broadcasting system, the method comprising:

inserting the delta-T into Program Specific Information (PSI)/Service Information (SI);

multiplexing a generated burst and the PSI/SI including the delta-T; and

transmitting the multiplexed data.
The method of claim 1, wherein the inserting of the delta-T into the PSI/SI comprises, after generating the PSI/SI, inserting the delta-T into the generated PSI/SI.
The method of claim 1, wherein the inserting of the delta-T into the PSI/SI comprises, if all pieces of broadcast information exist in one Program Map Table (PMT), inserting delta-T for all broadcasts into one PMT.
The method of claim 1, wherein the inserting of the delta-T into the PSI/SI comprises, if PMTs exist for respective broadcasts, inserting delta-T of a corresponding broadcast into each PMT.
The method of claim 1, wherein the inserting of the delta-T into the PSI/SI comprises generating additional PSI/SI indicating the delta-T.
A method for power saving in a receiver of a digital broadcasting system, the method comprising:

if delta-T fails to be obtained from a received burst, obtaining the delta-T from Program Specific Information (PSI)/Service Information (SI); and

turning off a communication modem at the timing in which a desired broadcast is not transmitted based on the delta-T.
The method of claim 6, further comprising turning on the communication modem at the timing in which the desired broadcast is transmitted based on the delta-T.
A transmitter apparatus for transmitting delta-T in a digital broadcasting system, the apparatus comprising:

a delta-T update unit for inserting a delta-T into a Program Specific Information (PSI)/Service Information (SI);

a multiplexer for multiplexing a generated burst and the PSI/SI including the delta-T; and

a transmitter for transmitting the multiplexed data .
The apparatus of claim 8, wherein, after generating the PSI/SI, the delta-T update unit inserts the delta-T into the generated PSI/SI
The apparatus of claim 8, wherein, if all pieces of broadcast information exist in one Program Map Table (PMT), the delta-T update unit inserts the delta-T into the PSI/SI by inserting delta-T for all broadcasts into one PMT.
The apparatus of claim 8, wherein, if PMTs exist for respective broadcasts, the delta-T update unit inserts the delta-T into the PSI/SI by inserting delta-T of a corresponding broadcast into each PMT.
The apparatus of claim 8, wherein the delta-T update unit inserts the delta-T to the PSI/SI by generating additional PSI/SI indicating the delta-T.
An apparatus for performing a power saving function in a receiver of a digital broadcasting system, the apparatus comprising:

a burst configuration unit for configuring a burst from received information;

a Program Specific Information (PSI)/Service Information (SI) processor for obtaining PSI/SI and delta-T from the received information; and

a controller for turning off a communication modem at the timing in which a desired broadcast is not transmitted based on the delta-T.
The apparatus of claim 13, wherein the controller turns on the communication modem at the timing in which the desired broadcast is transmitted based on the delta-T.