JP2013187824A - Broadcasting system, transmitter and receiver used for the same, broadcasting method and program, and receiving/reproducing method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a broadcasting system in which a content to be reproduced does not lack even if a receiver moves to a different broadcasting area.SOLUTION: A transmitter 10 includes: a TS re-multiplexing section for multiplexing TS; a dummy frame generating section for inserting a dummy frame into TS; and an OFDM frame generating section for generating an OFDM transmission signal by performing a processing including time interleaving to the multiplexed TS. A dummy OFDM frame consisting only of the dummy frame is included in the OFDM transmission signal. A receiver 30 includes: a reception section 31 for receiving the OFDM transmission signal; and a channel search section 34 for determining a channel to be selected/received on the basis of field strength of a reception channel. When the dummy OFDM frame is detected in the receiver 30, the channel search section 34 measures the field strength of a candidate channel of an adjacent broadcasting area. When the candidate channel exceeding a receivable threshold is detected, the candidate channel is selected.

Description

  The present invention relates to a broadcasting system to which terrestrial digital broadcasting is applied, a transmitter and a receiver used therefor, a broadcasting method and a program, and a reception reproduction method and a program.

  Broadcasting contents such as news and regional information by multimedia broadcasting for mobile terminals and Area One Seg using Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) technology is being considered. For example, in a fixed broadcasting area centered on each station, broadcast unique content for each station (sightseeing information around the station, introduction of stores, etc.) and content common to all stations (for example, news) at regular time intervals. It is considered to broadcast on.

  In multimedia broadcasting for mobile terminals and Area One Seg, a large number of vacant channels are prepared, and the reception status does not depend on the number of receivers in the broadcasting area, which is suitable for distribution of news and regional information. On the other hand, in multimedia broadcasting for mobile terminals and area one seg, information is unilaterally distributed, and handover between areas with different broadcast frequencies (channels) is not assumed. For this reason, when moving across a plurality of broadcast areas, it is necessary to search for available channels in the destination broadcast area. While such a channel search is being performed, broadcast content cannot be received at the mobile station.

  In this regard, the receiving apparatus described in Patent Document 1 includes information on adjacent communities adjacent to the community corresponding to the current position of the receiver, and information on channels broadcast in each community, and is broadcast in adjacent communities. By selecting a channel and determining whether or not a broadcast signal can be received, it is possible to quickly determine a receivable channel.

Japanese Patent No. 4670953

  However, even with the technique described in Patent Document 1, broadcast content cannot be received during channel search. In particular, when broadcasting common content in multiple broadcast stations, users may miss the content being watched as they move to different broadcast areas. In multimedia broadcasting for mobile terminals and Area One Seg, Since information in response to a user request cannot be retransmitted, it becomes extremely difficult to view the missed content again.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a broadcasting system that does not cause missing content to be reproduced even when moving to a different broadcasting area.

  The broadcasting system of the present invention is a broadcasting system that includes a transmitter and a receiver, and broadcasts data including content from the transmitter to the receiver. The transmitter is provided for each broadcast area where the transmission signal of one channel or more can be received, and an input unit for inputting a transport stream of a data frame corresponding to the content, and a dummy unrelated to the content A dummy frame generation unit that generates a data frame, the transport stream is multiplexed, a remultiplexing unit that inserts the dummy data frame, and a transport stream multiplexed by the remultiplexing unit, A processing unit that performs processing including time interleaving and generates a transmission signal including a dummy broadcast frame including only the dummy data frame, and a transmission unit that transmits the transmission signal through a channel determined for each broadcast area. The receiver includes a receiving unit that receives the transmission signal of the selected channel, a decoding unit that decodes the transmission signal received by the receiving unit, and the data frame decoded by the decoding unit. Channel search for measuring the reception strength of transmission signals of channels corresponding to different broadcast areas at the timing when the playback unit and the dummy broadcast frame are received, and determining the channel to be selected based on the reception strength A part.

  With this configuration, when a dummy broadcast frame included in a transmission signal broadcast from a transmitter is received, a channel search can be performed to determine whether or not to receive in a channel in an adjacent broadcast area. Therefore, it is possible to prevent the possibility that the transport stream corresponding to the content cannot be received. Therefore, even when the receiver moves to a different broadcast area, content that is played back by the receiver is not lost, and smooth handover can be realized.

In the broadcast system, the transmitter of the transmitter further transmits a timing signal that is period information for inserting the dummy data frame, and the channel search unit of the receiver detects and selects the dummy broadcast frame. The channel to be tuned is determined, and then the channel to be tuned is determined at the timing at which the dummy broadcast frame is received based on the timing signal without detecting the dummy broadcast frame. With this configuration, once the dummy data frame is detected, the timing at which the dummy data frame is inserted is known thereafter, so that the channel search can be performed without detecting the dummy broadcast frame, thereby reducing the channel search time. be able to.

  In the above broadcasting system, the dummy data frame may be inserted into the transport stream while common content is being transmitted in the plurality of transmission areas. As a result, it is possible to switch the reception channel to a different broadcast area without causing the content being viewed to be missing.

  In the above broadcasting system, it is preferable that F ≧ I, where F is the number of dummy data frames to be inserted and I is the interleave length in the time interleaving. This makes it possible to reliably generate a dummy broadcast frame that includes only dummy data frames.

  In the broadcast system, the receiver stores a list of candidate channel information indicating channels that can be received in an adjacent broadcast area for each broadcast area, and the channel search unit detects the dummy broadcast frame. Then, the reception strength of the reception signal by the candidate channel is measured, and the channel to be tuned is determined based on the determination result of reception availability. With this configuration, the number of candidate channels necessary for channel search can be reduced, and the channel search time can be shortened.

  In the above broadcasting system, a reception unit that receives reception intensity information from the receiver, an intensity information collection unit that collects the reception intensity information for each broadcast area, and the dummy data according to fluctuations in the reception intensity information A transmitter control device further comprising: a dummy period determining unit for determining a frame insertion interval; and a transmitter for transmitting insertion interval information indicating the determined dummy data frame insertion interval to the transmitter, In the transmitter, the insertion interval of the dummy frame is updated when the insertion interval information is received.

With this configuration, even when the range of the broadcast area that can be received varies due to a change in the reception environment, by adjusting the insertion interval of the dummy frames according to the variation, it is ensured in the area where the broadcast areas overlap. A dummy broadcast frame can be received. Therefore, it is possible to eliminate the possibility of missing content played back by the receiver regardless of changes in the reception environment.

  Another aspect of the present invention is a transmitter in the above broadcasting system, and yet another aspect is a receiver in the above broadcasting system.

  Yet another aspect of the present invention is a broadcasting method for broadcasting data including content to a receiver from a transmitter provided for each broadcasting area in which the transmission signals of one channel or more can be received. An input step of inputting a transport stream of a data frame corresponding to the content, a dummy frame generation step of generating a dummy frame unrelated to the content, a multiplexing of the transport stream, and the dummy data A re-multiplexing step for inserting a frame and a process including time interleaving on the transport stream multiplexed in the re-multiplexing step to generate a transmission signal including a dummy broadcast frame composed only of the dummy data frame And a processing step for transmitting the transmission signal to a broadcast error. It has a configuration comprising a transmission step of transmitting the channel determined for each store. Even with such a configuration, as described above, even when the receiver moves to a different broadcast area, there is no loss of content played back by the receiver, and smooth handover can be realized. .

  According to still another aspect of the present invention, a transmitter is provided for each broadcast area in which the transmission signal of one channel or more can be received, and the transmission signal including the content broadcast from the transmitter is received and reproduced. A reception reproduction method for receiving the transmission signal of the selected channel, a decoding step for decoding the transmission signal received by the reception unit, and the decoding unit decoded by the decoding unit Measure the reception strength of the transmission signals of channels corresponding to different broadcast areas at the playback step of reproducing the data frame and the timing when the dummy broadcast frame unrelated to the content is received, and select a channel based on the reception strength A channel search step for determining a channel. Even with such a configuration, as described above, even when the receiver moves to a different broadcast area, there is no loss of content played back by the receiver, and smooth handover can be realized. .

  According to the present invention, since channel search is performed during reception of dummy data, it is possible to eliminate the possibility of missing content being played even when the receiver moves across the broadcast area.

Explanatory drawing which shows the whole structure of the broadcasting system of this Embodiment Block diagram showing the configuration of each part of the broadcasting system Block diagram showing the configuration of the signal converter of the transmitter Explanatory drawing which shows the structure of the OFDM output frame in which the dummy frame was inserted Explanatory drawing showing list contents of representative channel information Flow chart showing the operation of the receiver Flow chart showing channel search operation Explanatory diagram showing the timing of channel search in the receiver Explanatory diagram showing how the coverage area changes Explanatory drawing which shows the structure of the broadcast system which concerns on another form of this Embodiment.

  Hereinafter, a broadcasting system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing the overall configuration of the broadcasting system of the present embodiment. The broadcasting system includes a plurality of transmitters 10 and a plurality of receivers 30, and the transmitters 10 and the receivers 30 communicate wirelessly. The transmitter 10 can be installed at an arbitrary place, and the receiver 30 can move while receiving a transmission wave from the transmitter 10.

  Reference numerals 51 to 53 denote ranges (broadcast areas A to C) that can be received by transmission waves (radio signals including content information) from the respective transmitters 10. In each broadcast area, one or a plurality of contents are simultaneously transmitted from the transmitter 10 via different channels (frequencies), and the user can view desired contents by selecting a channel with the receiver 30. it can. In order to prevent interference, different channels are used in adjacent broadcast areas.

  For this reason, when the receiver 30 passes the route indicated by the dotted line in the figure, for example, after receiving the content broadcast on the channel f1, it is switched to the channel f2 when moving to an adjacent area, and then the channel It is switched to f3. In this way, by switching the reception channel in each reception area, the content can be continuously viewed on the moving receiver.

  The transmitter 10 is provided with a distribution schedule according to a predetermined schedule, and the content is broadcast within the corresponding broadcast area according to the schedule. FIG. 1 shows an example of a content distribution schedule. In each broadcast area A to C, common content (for example, news) and individual content (for example, store introduction, facility introduction) are broadcast.

  Here, in all the broadcast areas A to C, the broadcast start time and end time of the common content do not necessarily coincide with each other, and it is only necessary that the time zones during which the common content is broadcast overlap. Note that the broadcast content is provided from a server (not shown), but the present invention is not limited to this, and a configuration in which each transmitter 10 generates broadcast content may be employed. In the embodiment shown in FIG. 1, only three broadcast areas A to C are shown, but it goes without saying that the number of broadcast areas may be four or more.

  The transmission of data from the transmitter 10 to the receiver 30 is based on the ISDB-T system conforming to the transmission system standard (ARIB STD-B31) for digital terrestrial television broadcasting. Therefore, in the following, the technical contents defined in this standard will be briefly described or omitted.

  As shown in FIG. 2, the transmitter 10 includes an input unit 11, a signal conversion unit 12, and a transmission unit 13. The input unit 11 receives content information to be broadcast and outputs a video signal, an audio signal, and a data signal to the signal conversion unit 12. The input unit 11 generates a video signal by shooting and generates an audio signal by recording. The input unit 11 includes an operation unit, and generates a data signal based on a user operation on the operation unit. Further, the input unit 11 may acquire part or all of the video signal, the audio signal, and the data signal from the outside of the transmitter 10.

  The signal conversion unit 12 is an OFDM (Orthogonal Frequency Division Multiplexing) transmission signal (hereinafter referred to as “OFDM”) for transmitting the video signal, audio signal, and data signal input from the input unit 11 from the transmission unit 13 to the receiver 30. Also referred to as “transmitted wave”). The transmission unit 13 wirelessly transmits the OFDM transmission signal generated by the signal conversion unit 12.

  FIG. 3 is a diagram illustrating a configuration of the signal conversion unit 12 of the transmitter 10 according to the present embodiment. The signal conversion unit 12 includes an information source encoding unit 15, an MPEG-2 multiplexing unit 16, and a transmission path encoding unit 17. The information source encoding unit 15 includes a video encoding unit 18 that inputs and encodes a video signal, an audio encoding unit 19 that inputs and encodes an audio signal, and data that receives and encodes a data signal And an encoding unit 20. The video encoded data encoded by the video encoding unit 18, the audio encoded data encoded by the audio encoding unit 19, and the data encoded data encoded by the data encoding unit 20 are MPEG-2. Input to the multiplexing unit 16.

  The MPEG-2 multiplexing unit 16 multiplexes video encoded data, audio encoded data, and data encoded data, and as a transport stream (Transport Stream: hereinafter referred to as “TS”) defined by MPEG2 Systems. Output.

  The transmission line encoding unit 17 receives one or a plurality of TSs, performs re-multiplexing, performs a plurality of transmission line encodings as one TS according to the service intention, and outputs the result as an OFDM transmission wave . The transmission path encoding unit 17 includes a TS remultiplexing unit 21 and an OFDM frame generation unit 22.

  The TS remultiplexing unit 21 receives one or a plurality of TSs from the MPEG-2 multiplexing unit 16 and multiplexes and outputs data frames constituting the TS. The TS remultiplexing unit 21 includes a dummy frame generation unit 23 for inserting a dummy data frame for channel search.

  The dummy frame generation unit 23 generates a plurality of dummy data frames at regular time intervals. This dummy frame is inserted between data frames corresponding to common content (for example, news) in FIG. The number of dummy data frames inserted at a time is determined according to the time interleaving length in the interleaving unit 23 described later. The dummy data frame has a predetermined bit pattern so that the receiver 30 can identify it. Information on the interval at which dummy data frames are inserted and the number of dummy data frames to be inserted at a time are provided in the memory 26 in the TS remultiplexing unit 21 and can be changed as appropriate.

  The TS re-multiplexing unit 21 converts a plurality of TSs input from the MPEG-2 multiplexing unit 16 into a burst signal format in units of 188 bytes using a clock that is four times the IFFT (Inverse Fast Fourier Transform) sample clock. Convert, add outer code, and convert to single TS.

  The OFDM frame generation unit 22 includes a hierarchical parallel processing unit 25, an interleaving unit 26, and an IFFT unit 27. When performing hierarchical transmission, the hierarchical parallel processing unit 25 divides the TS input from the TS remultiplexing unit 21 into layers according to the designation of the hierarchical information, and performs processing for each layer. The hierarchical parallel processing unit 25 performs processing including error correction coding, byte interleaving, convolutional coding, and carrier modulation for each layer. In addition, the hierarchical parallel processing unit 22 synthesizes the signals that have undergone the above processing for each hierarchy.

  The interleaving unit 26 performs time interleaving and frequency interleaving on the synthesized signal in order to effectively exhibit error correction coding capability against electric field fluctuations and multipath interference in mobile reception. In the present embodiment, the time interleave length I is set to 4, for example, and convolutional interleaving is performed on the data for the previous and subsequent four frames.

  The IFFT unit 27 adds a synchronous pilot signal, a TMCC (Transmission and Multiplexing Configuration Control) signal, and an AC (Auxiliary Channel) signal to the interleaved signal to form and output an OFDM frame. The IFFT unit 27 performs an IFFT operation on the OFDM frame, generates an OFDM transmission signal, and outputs the OFDM transmission signal to the transmission unit 13.

  FIG. 4 is a diagram for explaining how the TS is multiplexed by the signal conversion unit 12. In the example of FIG. 4, the frame multiplexed by the TS remultiplexing unit 21 includes a data frame 51 input from the MPEG-2 multiplexing unit 16 and a dummy data frame 52 generated by the dummy frame generating unit 23. Combined and output. Thereafter, various processes are performed in the hierarchical parallel processing unit 25, convolutional interleaving with a cycle of 4 is performed in the interleaving unit 26, and the OFDM frame 53 is output to the transmission unit 13.

  Here, four dummy data frames 52 are inserted from the dummy frame generation unit 23, and convolutional interleaving with a period of 4 is performed in the interleaving unit 26 (ie, interleaving using four frames before and after is performed). Thus, an OFDM frame (dummy OFDM frame) 54 composed only of dummy data frames is generated. From the viewpoint of generating dummy OFDM frames, the number F of dummy data frames inserted from the dummy frame generation unit 23 may be equal to or greater than the time interleave length I in the interleave unit 26 (F ≧ I), and is not necessarily limited. It need not be the same as the interleave period.

  In FIG. 2, the receiver 30 is, for example, a mobile phone terminal, and includes a receiving unit 31, a decoding unit 32, a playback unit 33, a channel search unit 34, and a memory 35.

  The receiver 31 receives the OFDM transmission wave transmitted from the transmitter 13 of the transmitter 10. The receiving unit 31 measures the electric field strength of the OFDM transmission wave from the transmitter 10 and outputs the measurement result to the channel search unit 34.

  The decoding unit 32 decodes the OFDM transmission signal received by the reception unit 31 and detects a dummy OFDM frame. The decoding unit 32 restores the TS by performing processing such as FFT (Fast Fourier Transform), frequency deinterleaving, time deinterleaving, and error correction on the received OFDM transmission signal.

  The decoding unit 32 includes a dummy frame detection unit 36 that detects whether or not a dummy OFDM frame is included in the received OFDM transmission signal. As described above, the dummy data frame is composed of a predetermined bit pattern, and the dummy OFDM frame also has a predetermined bit pattern. When the dummy frame detection unit 36 detects a dummy OFDM frame, the dummy frame detection unit 36 outputs a signal for starting a channel search to the channel search unit 34.

  The reproduction unit 33 reproduces the video signal, the audio signal, and the data signal obtained by the decoding in the decoding unit 32. The reproduction unit 33 includes a display and a speaker. The video signal and the data signal are displayed on the display, and the audio signal is output from the speaker. The decoded data signal may be used for controlling the reproduction unit 33.

  When a dummy OFDM frame is detected, the channel search unit 34 performs a channel search for determining whether or not to select a channel in an adjacent broadcast area. The channel search unit 34 includes an adjacent area information storage unit 37 and a broadcast channel information storage unit 38. As shown in FIG. 5, the adjacent area information includes, for each broadcast area, information on transmitters corresponding to adjacent (or partially overlapping) broadcast areas and candidate channels (electric fields that can be received in the adjacent broadcast area). Information on channels used for intensity measurement is stored in association with each other.

  When the dummy OFDM frame is detected, the channel search unit 34 measures the electric field strength of the frequency indicated by the candidate channel in the adjacent broadcast area, and stores the obtained electric field strength information in the memory 35. The channel search unit 34 determines that the electric field strength obtained in this way is the strongest and has moved to an adjacent area when the threshold value is exceeded, and the content broadcast on the channel with the strongest electric field strength. Receive.

  The broadcast channel information storage unit 38 stores information on channels that can be received in each broadcast area, and switches the channels that can be received in each area by operating an operation unit (not shown) provided in the receiver 30. Playback output is possible. In addition, the memory 33 stores various information such as a measured value of the electric field strength of the candidate channel obtained in the past several channel searches, a broadcast area corresponding to the current position of the receiver, and a channel being selected.

  The broadcast area information corresponding to the currently selected channel may be extracted from the broadcast channel information storage unit 38 as the broadcast area information corresponding to the current position of the receiver 30. Alternatively, a GPS receiver (not shown) may be provided in the receiver 30, and a broadcast area corresponding to the current position may be specified based on position information obtained by the GPS receiver.

  FIG. 6 is a flowchart showing the reception / reproduction operation of the receiver 30. The receiver 30 receives the OFDM transmission signal from the transmitter 10 at the receiver 31 (S10). Next, the dummy frame detection unit 36 provided in the decoding unit 32 of the receiver 30 determines whether or not the OFDM frame included in the received OFDM transmission signal is a dummy OFDM frame (S11).

  When the received frame is a normal data frame (N in S11), the decoding unit 32 decodes the received data frame to generate a TS frame, and outputs the TS frame to the playback unit 33, which is broadcasted. The content is reproduced (S12). On the other hand, if the received frame is a dummy OFDM frame, the process proceeds to step S13 and a channel search described later is performed.

  FIG. 7 is a flowchart showing a channel search procedure. When the channel search is started, the channel search unit 34 reads out the broadcast area information corresponding to the current position of the receiver 30 from the memory 35, and selects the adjacent area candidate channels stored in the adjacent area information storage unit 37. Select (S20). Then, the receiver 30 measures the electric field strength at the frequency corresponding to the selected candidate channel, and the channel search unit 34 stores the measurement result in the memory 35 (S21). The selection of the main channel and the measurement of the electric field intensity are performed until the measurement of the electric field intensity of all candidate channels is completed (S22).

  When the measurement of the electric field strength by all candidate channels is completed (Y in S22), it is determined whether or not there is a channel having a higher electric field strength than the past several measurement results stored in the memory 35 (S23). If there is a channel whose electric field intensity is higher than the past measurement result, it means that the broadcast area corresponding to the channel is approaching. In such a case, the channel search unit 34 determines whether or not the electric field strength in the candidate channel exceeds a predetermined receivable threshold (receivable threshold) (S24).

  If the electric field strength exceeds the receivable threshold, it is determined that the receiver 30 has moved to the broadcast area corresponding to the candidate channel, the candidate channel is selected, and content reception is started (S25). On the other hand, when there is no high-intensity channel (N in S23 and 24), the receiving unit 31 selects the same channel as that before the channel search and continues receiving the same content as before (S26).

  FIG. 8 is an explanatory diagram showing a state in which a channel search is performed when the receiver 30 moves from a certain broadcast area 51 to an adjacent broadcast area 52. The receiver 30 continuously receives the OFDM frame 53 corresponding to the content broadcast in the broadcast area 52 in the broadcast area 51 before moving. When the dummy OFDM frame is detected, the receiver 30 performs the above-described channel search. In the channel search (channel search [1]) at the time point on the left side in the figure, the electric field strength from the adjacent broadcast area 52 is low, and the channel is not changed (the channel f1 corresponding to the broadcast area 51 before movement is selected). ) Next, when the channel search is performed when the receiver 30 enters the overlapping area of the broadcast areas 51 and 52 (channel search [2]), the receiver 30 selects the representative channel f2 in the broadcast area 52, and Reception of content broadcast in the broadcast area 52 is started.

  As described above, by performing a channel search for measuring the reception strength of the adjacent channel at the timing when the dummy OFDM frame is detected, even when moving to a different broadcast area, the content to be reproduced is lost. Nothing will happen. Therefore, in a broadcasting system for mobile stations such as multimedia broadcasting for mobile terminals and Area One Seg, handover can be realized efficiently.

  In the above embodiment, the description has been made on the assumption that the range in which content can be received in the broadcast area has not changed, but in reality, in each broadcast area due to factors such as building construction and tree growth. The receivable range varies. As shown in FIG. 9, when the receivable range in a certain broadcast area is reduced from the area 60a indicated by the dotted line to the area 60b indicated by the solid line, and the overlapping part 62 with the adjacent broadcast area 61 is reduced, the receiver When 30 passes through the overlapping portion 62, there is a possibility that a dummy OFDM frame is not received. In such a case, the content to be reproduced is lost.

  Therefore, in another embodiment shown in FIG. 10, the transmitter control device 70 collects the electric field strength information, and controls the dummy frame insertion interval in the transmitter 10 based on the obtained electric field strength information. . The transmitter control device 70 includes a receiving unit 71, an intensity information collecting unit 72, a dummy cycle determining unit 73, and a transmitting unit 74.

  The receiving unit 71 is a wireless communication device compliant with, for example, the 3GPP standard, and receives the field strength data obtained by the channel search from the receiver 30 at regular time intervals. The intensity information collecting unit 72 collects the electric field intensity data received from the receiver 30 for each viewable area. The dummy period determining unit 73 obtains statistics of the electric field strength information of each viewing area obtained by the strength information collecting unit 72 and determines the dummy frame insertion interval. For example, when the statistical value of the electric field strength received in a certain viewing area becomes small, it is determined that the overlapping portion with the adjacent area has become small, and the dummy frame insertion interval is shortened. For such statistical processing, a known method such as calculating an average value of electric field strength or performing a known weighting operation can be used.

  The transmission unit 74 updates the dummy frame insertion interval by transmitting the dummy frame insertion interval information determined by the dummy cycle determination unit 73 to each transmitter 10. In this way, the statistics of the electric field strength information obtained at each receiver is taken, and the dummy frame insertion interval is determined according to the size of the statistics, so that the dummy OFDM frame can be reliably detected in the overlapping portion of adjacent viewing areas. Can be received.

  In the above embodiment, the receiver 30 is provided with a configuration for detecting a dummy OFDM frame. However, since the dummy OFDM frames are inserted at regular intervals, the number of detected OFDM frames is counted and a predetermined value (FIG. In the example of FIG. 8, when only m) is detected, it may be determined that the next received frame is a dummy OFDM frame, and a channel search may be performed. Thereby, the structure for detecting a dummy OFDM frame can be omitted.

  In the above embodiment, the channel search is performed every time the dummy OFDM frame is detected. However, the dummy OFDM frame insertion timing information may be notified from the transmitter 10 in advance by a broadcast wave or another line. In this case, the receiver 30 acquires dummy OFDM frame insertion timing information, and once the dummy OFDM frame can be detected, the dummy OFDM frame insertion timing is known thereafter, so that the channel search is performed at that timing. Is possible. This eliminates the need to detect a dummy OFDM frame every time, thereby reducing the channel search time.

  In the above embodiment, the common content and the local content are broadcast at regular intervals. However, these multiple types of content may be divided and broadcast by hierarchical division. Thereby, multiple types of content can be received simultaneously.

  The series of processes described above can be executed by hardware or can be executed by software. When executed by software, the program can be executed by installing the program in a computer from a program storage medium storing a program constituting the software.

  In the above embodiment, data transmission based on the ISDB-T system conforming to ARIB STD-B31 has been described as an example. However, the present invention is not limited to this and is equally applicable to various data transmission systems. can do.

  As described above, the broadcasting system of the present invention has an effect of preventing loss of content to be reproduced and realizing stabilization of video, a broadcasting system applying terrestrial digital broadcasting, a transmitter and a receiver used therefor It is useful as a broadcasting device, a broadcasting method and program, and a reception and reproduction method and program.

DESCRIPTION OF SYMBOLS 10 Transmitter 11 Input part 12 Signal converter 13 Transmitter 21 TS maximum multiplexing part 22 OFDM frame generation part 23 Dummy frame generation part 26 Interleaving part 30 Receiver 31 Reception part 32 Decoding part 33 Reproduction part 34 Channel search part 36 Dummy frame Detection unit 37 Adjacent area information storage unit 51 Data frame 52 Dummy data frame 53 OFDM frame 54 Dummy OFDM frame 70 Transmitter control device

Claims (13)

A broadcasting system that includes a transmitter and a receiver, and broadcasts data including content from the transmitter to the receiver,
The transmitter is provided for each broadcast area in which transmission signals of one channel or more can be received,
An input unit for inputting a transport stream of a data frame corresponding to the content;
A dummy frame generator for generating a dummy data frame irrelevant to the content;
A remultiplexing unit for multiplexing the transport stream and inserting the dummy data frame;
A processing unit that performs processing including time interleaving on the transport stream multiplexed by the remultiplexing unit, and generates a transmission signal including a dummy broadcast frame including only the dummy data frame;
A transmission unit for transmitting the transmission signal in a channel determined for each broadcast area,
The receiver
A receiver for receiving the transmission signal of the selected channel;
A decoding unit for decoding the transmission signal received by the reception unit;
A reproducing unit for reproducing the data frame decoded by the decoding unit;
A channel search unit that measures reception strength of transmission signals of channels corresponding to different broadcast areas at a timing at which the dummy broadcast frame is received, and determines a channel to be selected based on the reception strength. A broadcasting system characterized by that. The broadcast system according to claim 1,
The transmitter of the transmitter further transmits a timing signal that is period information for inserting the dummy data frame,
The channel search unit of the receiver detects the dummy broadcast frame to determine a channel to be selected, and then receives the dummy broadcast frame based on the timing signal without detecting the dummy broadcast frame. The broadcast system is characterized in that the channel to be selected is determined at a timing to be selected.   The broadcasting system according to claim 1 or 2, wherein the dummy data frame is inserted into the transport stream while common content is transmitted in a plurality of the transmission areas.   3. The broadcasting system according to claim 1, wherein F ≧ I, where F is the number of dummy data frames inserted and I is the interleaving length in the time interleaving. The receiver stores, for each broadcast area, a list of candidate channel information indicating channels that can be received in an adjacent broadcast area,
The channel search unit, when detecting the dummy broadcast frame, measures reception strength of a reception signal by the candidate channel and determines a channel to be selected based on a determination result of reception availability The broadcasting system according to claim 1 or 2. A receiving unit that receives reception intensity information from the receiver, an intensity information collecting unit that collects the reception intensity information for each broadcast area, and an insertion interval of the dummy data frame is determined according to fluctuations in the reception intensity information A transmitter control device further comprising: a dummy period determining unit, and a transmission unit for transmitting insertion interval information indicating the determined insertion interval of the dummy data frame to the transmitter,
The broadcasting system according to claim 1 or 2, wherein the transmitter updates the insertion interval of the dummy data frame when the insertion interval information is received.   The broadcasting system according to any one of claims 1 to 6, which performs multimedia broadcasting for mobile terminals or area one-segment broadcasting.   The transmitter in the broadcast system according to any one of claims 1 to 7.   The receiver in the broadcast system as described in any one of Claims 1 thru | or 7. A broadcasting method of broadcasting data including content to a receiver from a transmitter provided for each broadcast area in which the transmission signal of one channel or more is receivable,
An input step of inputting a transport stream of a data frame corresponding to the content;
A dummy frame generation step of generating a dummy data frame unrelated to the content;
Remultiplexing the transport stream and inserting the dummy data frame;
A process step of performing processing including time interleaving on the transport stream multiplexed in the remultiplexing step, and generating a transmission signal including a dummy broadcast frame including only the dummy data frame;
And a transmission step of transmitting the transmission signal through a channel determined for each broadcast area. A reception / reproduction method in which a transmitter is provided for each broadcast area in which the transmission signal of one or more channels can be received, and a transmission signal including content broadcast from the transmitter is received and reproduced
A receiving step of receiving the transmission signal of the selected channel;
A decoding step of decoding the transmission signal received by the receiving unit;
A reproduction step of reproducing the data frame decoded by the decoding unit;
A channel search step for measuring a reception strength of a transmission signal of a channel corresponding to a different broadcast area at a timing when a dummy broadcast frame unrelated to the content is received, and determining a channel to be selected based on the reception strength; Receiving and playing method including:   A broadcast program which, when executed by a transmitter, causes the transmitter to execute the broadcast method of claim 10.   A reception program that, when executed by a receiver, causes the receiver to execute the reception reproduction method according to claim 11.

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