JP2002368707A - Data broadcast method, data relay method, data broadcast system, and data relay device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Even if the size of data to be transmitted is very large and the carousel period becomes very long, a receiving terminal acquires a data block that has failed to be received in a short time. A broadcasting station (1) divides one data module into a plurality of data blocks, and a plurality of receiving terminals (21, 22).
A plurality of data blocks are repeatedly broadcasted to 22 and 23. If there is a missing reception, the broadcasting station 1 receives a request to retransmit any of the data blocks from the receiving terminal 21 via the ground line 51. In response, the broadcasting station 1 transmits the data block to the receiving terminal 21 using the ground line 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data broadcast method, a data relay method, a data broadcast system, and a data relay device.

[0002]

2. Description of the Related Art A data transmission method using a data carousel is described in ARIB (Association of Radio Industries and Businesses) data broadcasting standard "ARIB STD-B24: Data broadcasting encoding method and transmission method in digital broadcasting". . According to data transmission by data carousel method,
By dividing a module that constitutes one program into a plurality of small data blocks and repeatedly broadcasting the data blocks for a plurality of programs, even if there is insufficient data block reception on the receiving side, the data block is lost. All the data blocks can be received by fetching the data blocks in the next round of the carousel. The data carousel method is adopted, for example, as a download method for BS digital broadcasting by the Japan Broadcasting Corporation.

Next, the operation will be described. FIG. 8 is referred to for the description of the operation. In the figure, 80, 81, and 82 indicate modules, 30 indicates DII, and 31 to 39 indicate DDB.

[0004] In order to perform data broadcasting by the data carousel broadcasting method, the components (modules) constituting each program are divided into a plurality of small data blocks as described above. For example, as shown in FIG. 8, the data of a program to be broadcast includes module 80, module 81, module 8
If there are three, module 80 is d-0.0, d
-0.1 and d-0.2 are divided into three data blocks. Similarly, the module 81 includes d-1.0, d-1.1,
The module 82 is divided into four data blocks d-1.2 and d-1.3, and the module 82 is divided into two data blocks d-2.0 and d-2.1. Next, DDB (download data bl) is performed based on each data block.
ock) having a broadcast data structure.

The individual modules 80, 81, 82
(Download info for identifying DII)
(ratio indication). All DII30s thus created
And DDBs 31 to 39 are repeatedly broadcast as shown in FIG. That is, DI related to a broadcast program
I30 is broadcasted, and immediately after that, the DDB that constitutes a certain module is broadcasted. For example, after the broadcast transmission of the DII 30 shown at the lower end of FIG. 8, the data blocks d-1.3, d-1.2, d-
DDB37,3 related to 1.1, d-1.0 respectively
6, 35 and 34 are broadcasted continuously. Immediately after that,
The DII 30 is broadcasted again, and thereafter, the data blocks d-0.2, d-
DDB33,3 related to 0.1, d-0.0 respectively
2, 31 are continuously broadcast.

By repeating the above-mentioned broadcast transmission,
It can be seen that after a certain time interval, the same DDB comes around. The broadcast receiver first receives one of the DIIs 30 and acquires information on all modules currently being broadcast on the data carousel. Next, necessary modules are received and processed according to the user's selection instruction. Rather, it receives and processes the DDBs needed to construct the indicated data module, and reconfigures the data module. For example, if the module 80 shown in FIG.
2, 33, and reconfigure module 80. If a certain DDB fails to be received due to a radio wave condition or the like, the failed DDB is received in the next carousel cycle. Therefore, the receiver can take in all necessary DDBs, and can reconfigure the module as desired by the user.

[0007]

Since the conventional data broadcasting method is configured as described above, data loss can be compensated for. However, when the amount of data is large, one cycle of the carousel is extremely difficult. It takes a lot of time, and there is a problem that the user has to wait for a long time to receive a data block that has been lost.

Japanese Patent Laid-Open Publication No. 2000-66690 discloses that a karaoke music data is broadcast from a center station to a large number of karaoke terminals by a broadcast wave, and a karaoke terminal receives a failed music data file from the center station via a ground line. However, if the size of one data file is very large, obtaining the entire data file on the terrestrial line will cause traffic congestion on the terrestrial line. Absent.

The present invention has been made to solve the above-mentioned problems, and is suitable for data broadcasting using a data carousel transmission method, the size of data to be transmitted is very large, and the period of the carousel is very large. It is an object of the present invention to provide a data broadcasting method, a data relay method, a data broadcasting system, and a data relay device that enable a receiving terminal to acquire a data block that has failed to be received in a short time even when the data block becomes longer.

[0010]

A data broadcasting method according to the present invention divides one data module into a plurality of data blocks and repeatedly broadcasts the plurality of data blocks to a plurality of receiving terminals. When a request to retransmit any of the data blocks is received from a receiving terminal via a terrestrial line, the data block is transmitted to the receiving terminal using the terrestrial line. .

According to the data relay method for complementing data broadcasting according to the present invention, a request to transmit any of the data blocks is received from a plurality of receiving terminals via a terrestrial line, and each of these receiving terminals receives the request. If there is a common data block among the data blocks, a request to transmit the data block is transmitted to the broadcasting station via a terrestrial line in a format for transmitting one request for the common data block to the broadcasting station. Received data block from the broadcast station via a terrestrial line, determine the destination of the data block according to the request from each receiving terminal,
The data block is transmitted to the receiving terminal via a ground line.

[0012] A data broadcasting system according to the present invention comprises a dividing unit for dividing one data module into a plurality of data blocks, and a broadcasting unit for repeatedly broadcasting a plurality of data blocks to a plurality of receiving terminals. A receiving unit connected to each receiving terminal via a ground line, a transmitting unit connected to each receiving terminal via a ground line, and a ground line from a receiving terminal which has a request to retransmit any of the above data blocks. And a control unit that instructs the transmission unit to transmit the data block to the reception terminal using a ground line when the reception unit receives the data block.

[0013] A data relay device according to the present invention comprises: a first receiving unit connected to each receiving terminal via a terrestrial line; a first transmitting unit connected to each receiving terminal via a terrestrial line; A second receiving unit connected by a line, a second transmitting unit connected to the broadcasting station by a terrestrial line, and a request to transmit any of the data blocks transmitted from the plurality of receiving terminals via the terrestrial line. When the first receiving unit receives the data block, if there is a data block common to the data blocks requested by each of these receiving terminals, one request for the common data block is transmitted to the broadcasting station, The second transmitting unit instructs the second transmitting unit to transmit a data block transmission request to the broadcasting station via the terrestrial line, and transmits the requested data block from the broadcasting station to the terrestrial line. Then, when the second receiving unit receives, the destination of the data block is determined according to a request from each of the receiving terminals, and the first transmitting unit transmits the data block to the receiving terminal via a terrestrial line. And a control unit for instructing the first transmission unit to transmit.

A data broadcasting system according to the present invention includes a dividing unit for dividing one data module into a plurality of data blocks, and a broadcast transmitting unit for repeatedly broadcasting a plurality of data blocks to a plurality of receiving terminals. A plurality of data relay devices described above, a receiving unit connected to each data relay device via a ground line, a transmitting unit connected to each data relay device via a ground line, and any one of the data blocks When the receiving unit receives a request for retransmission from a certain data relay device via a ground line, a control unit instructing the transmission unit to transmit the data block toward the data relay device using the ground line. It is provided with.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a diagram showing an overall configuration of a communication system according to Embodiment 1 of the present invention. In the figure, 1
Is a broadcasting station for performing data broadcasting, 21, 22, and 23 are receiving terminals for receiving data broadcasting, and 51, 52, and 53 are telephone lines and communication lines for performing communication between the broadcasting station 1 and the receiving terminals 21, 22, and 23, respectively. Terrestrial line.

FIG. 2 is a diagram showing a data broadcasting system in the communication system according to the first embodiment of the present invention.
In the figure, 101 is a data broadcasting system, 102 is a database, 103 is a control unit, 104 is a division unit, 105
Is a wireless transmission unit (broadcast transmission unit), 106 is a broadcast satellite (broadcast transmission unit), 107 is a reception unit, 108 is a transmission unit, and 109 is a line interface. Data broadcasting system 101
Comprises a broadcasting station 1 and one or more broadcasting satellites 106. The broadcasting station 1 includes a database 102, a control unit 103, a division unit 104, a wireless transmission unit 105, a reception unit 107, and a transmission unit 10.
8. A line interface 109 is provided.

The database 102 stores data to be broadcast. The division unit 104 reads a data module from the database 102, divides the data module, generates a data block that matches the data broadcasting system, and passes the data block to the wireless transmission unit 105. Radio transmitting section 105 transmits a data stream including a data block to broadcast satellite 106, and broadcast satellite 106 transmits the data stream to receiving terminals 21, 22, 23 (FIG. 1).

The line interface 109 is connected to a terrestrial line.
8 is connected. In this embodiment, when receiving section 107 receives a request to retransmit any of the data blocks from a receiving terminal (one of receiving terminals 21, 22, 23) via a terrestrial line, control section 103 causes ,
The transmitting unit 108 is instructed to transmit the data block to the receiving terminal using the ground line.

Next, the operation will be described. FIG. 8 is referred to for the description of the operation. In the figure, reference numerals 80, 81, and 82 denote modules, and reference numeral 30 denotes a DII (download).
information indication), and 31 to 39 are DDB (download data).
block). In order for the broadcasting station 1 to perform data broadcasting by the data carousel broadcast transmission method, the dividing unit 1 of the broadcasting station 1
04 divides the components (modules) constituting each program into a plurality of small data blocks as described above. For example, as shown in FIG. 8, when there are three data of a program 80 to be broadcast, a module 80, a module 81, and a module 82, the module 80 has d-0.0, d-0.
1, and d-0.2, and the module 81 similarly includes d-1.0, d-1.1, d-
The module 82 is divided into four data blocks of 1.2 and d-1.3, and the module 82 is divided into two data blocks of d-2.0 and d-2.1. Next, the dividing unit 104
A block having a broadcast data structure called DDB is generated based on each data block.

The format of the DDB is as shown in FIG. In the figure, 40 indicates DII and 41 indicates DDB. The DDB 41 stores a module ID (ModuleId) as an identifier indicating a module before division.
And a descriptor such as a block number (BlockNum) indicating the number of the data block of the module, and the data of the divided data block is stored as a payload. For example, for a DDB created from the first data block d-0.0 generated by dividing a certain data content 0, the module ID = 0 and the block number = 0, and the data block d-0.0 0.0 data is stored. In this way, the same number of DBBs are created from the data blocks forming one module.

In order to broadcast data in the data carousel, the dividing unit 104 of the broadcasting station 1 uses DDB,
II information is generated. The format of DII is as shown in FIG. One DII 40 corresponds to one broadcast program, and includes information on all the modules of the program broadcasted by the data carousel. That is, the DII 40 transmits a transaction ID (Transacac) as a descriptor for identifying a broadcast program.
TionId) and the block size (Block Si
ze) and the number of modules (NumberModule)
s) and the like. The transaction ID is an identifier for identifying a corresponding broadcast program, and the block size indicates a length of a data block included as a payload of each DDB 41 of a module configuring the broadcast program.
The number of modules indicates the number of modules constituting a broadcast program.

The DII 40 stores information on modules constituting a corresponding broadcast program as module information. That is, module I of each module
D and the module size (Module
_Size). In the example shown in the figure, one broadcast program is composed of three modules having module IDs of 0, 1, and 2. The module with the module ID 0 has a length of 12 KB and the module with the module ID 1 has the length. Is 16 KB, and the module having a module ID of 2 has a length of 8 KB. Therefore, a device that receives a data stream according to the carousel method can know the outline of the components (modules) of the broadcast program from the DII 40, and uses the data in the order and processing conditions intended by the program creator from the DDB 41. (A moving image is displayed, a sound is generated, or a predetermined operation is performed when a user performs an operation).

The data broadcasting system 101 repeatedly broadcasts all the DIIs 40 and DDBs 41 (FIG. 3) created as described above, as shown in FIG. In other words, when broadcasting, DI
I30 is transmitted first, and immediately after that, the DDB that constitutes a certain module is transmitted. For example, after the broadcast transmission of the DII 30 shown at the lower end of FIG. 8, the data blocks d-1.3, d-1.2, d-1.
DDBs 37, 36, respectively associated with 1, d-1.0
35 and 34 are continuously broadcast. Immediately thereafter, the DII 30 is broadcast again, and thereafter, the data blocks d-0.2, d-0.
DDBs 33, 32 associated with 1, d-0.0, respectively.
31 is continuously broadcast.

The control unit 103 of the broadcasting station 1 manages these data to be transmitted and stores them in the database 102. For example, the DII 30 is stored in the database while being associated with TransactionId, which is a broadcast program identifier.

In the first embodiment, the broadcasting method is satellite broadcasting. That is, the wireless transmission unit 105 of the broadcast station 1
Transmits a data stream to one or more broadcasting satellites 106, and the broadcasting satellite 106 transmits the data stream to each receiving terminal by radio waves. However, the present invention is not intended to be limited to this mode, and the broadcasting station 1 transmits a data stream to one or more terrestrial relay stations by wire or wireless, and the terrestrial relay station transmits the data stream to each receiving terminal. A form of wireless transmission is also included in the scope of the present invention.

The receiving terminals 21, 22, 23 receive all the broadcasted data (DDB, DII). Take the receiving terminal 21 as an example. The receiving terminal 21 first receives and processes one of the DIIs 30, and acquires information on all the modules currently being broadcast in the data carousel from the DII 30. Next, the receiving terminal 21 receives and processes necessary modules according to the user's selection instruction. More precisely, receiving and processing the DDB needed to construct the indicated data module,
Reconfigure the data module.

For example, the number of modules of the DII 30 (N
It is understood from FIG. 3 that the number of modules constituting a certain broadcast program is 3 (see FIG. 3), and that the size of a data block included in one DDB 31 to 39 is 4 KB based on the block size (Block Size). Understand. Also, the module 80 in FIG. 8 (the module identifier (ModuleId) is 0)
Is necessary, attention is paid to the information relating to this, and it is found that the entire data size of the module 80 is 12 KB. The receiving terminal 21 captures the DDB related to the module 80 (the module identifier is 0), that is, the DDBs 31, 32, and 33, among the received DDBs,
Others are discarded.

If all the necessary DDBs 31, 32, and 33 can be received in the first round of the data carousel, the receiving terminal 21 transmits the module 80 from all the received DDBs.
Reconfigure. However, when the DDBs 31 and 32 can be obtained in the first round of the data carousel but the DDB 33 cannot be obtained due to radio wave conditions or the like, the receiving terminal 2
1 issues a data block transmission request message to the broadcasting station 1 via the ground line.

FIG. 4 shows an example of the format of a data block transmission request message and a data transmission message issued from the broadcasting station 1 in response thereto. In the figure, reference numeral 42 denotes an example of a data block transmission request message, and reference numeral 43 denotes an example of a data transmission message. As shown in the figure, the data block transmission request message 42 indicates a data block transmission request message (DATA_REQUEST) as a message type, a TransactionId indicating program information, and a ModuleId which is an identifier of a module having a required data block (for the module 80, 0), and a message format including a block number (BlockNum, 2 for DDB 33) of a required data block.
Further, the data block transmission request message 42 includes the identifier of the receiving terminal (the terminal 21 that has created the data block transmission request message 42) to be the destination of the retransmission.

In the broadcasting station 1, when the receiving unit 107 receives the data block transmission request message 42, the control unit 10 receives the data block transmission request message 42 from the database 102 managing the broadcast program.
3 extracts a necessary data block, generates a data transmission message 43 based on the data block, and instructs the transmission unit 108 to transmit the data transmission message 43 to the receiving terminal 21 that has requested transmission. As illustrated, the data transmission message 43 indicates a data transmission message (DATA_SEND) as a message type, and indicates a Tr indicating program information.
actionId, ModuleId (0 for module 80) which is the identifier of the module having the requested data block, and the block number of the requested data block (BlockNum, DDB33).
2), and a message format including the contents of the block data as a payload.

The destination receiving terminal 21 receives the data transmission message 43 sent from the broadcast station 1, extracts the payload therefrom, and receives the DDBs 31, 3 already received.
Module 80 is generated with the second payload.

As described above, according to the first embodiment, even if the entire amount of data broadcast by the data carousel is enormous and one cycle of the carousel is very long, the data blocks dropped in the next carousel cycle There is an advantage that data can be acquired in a short time without waiting for a long time to be broadcast.

Embodiment 2 FIG. In the first embodiment,
Although the broadcasting station 1 and the receiving terminals 21, 22, and 23 are directly connected via a terrestrial line, in this case, if the number of receiving terminals that failed in reception increases, communication traffic increases for the broadcasting station 1. The number of lines may be insufficient. Therefore, in the second embodiment of the present invention, a relay station is installed between a broadcasting station and a receiving terminal.

FIG. 5 is a diagram showing an overall configuration of a communication system according to the second embodiment. In the figure, 1 is a broadcasting station that performs data broadcasting, 211, 212, 213, 221, 22
2, 223, 231, 232, and 233 are receiving terminals for receiving data broadcasts, and 51, 52, and 53 are terrestrial lines for communicating between broadcast stations and relay stations.
3,521,522,523,531,532,533
Is a ground line for communication between the relay station and the receiving terminal.

Reference numerals 61, 62 and 63 are relay stations between the broadcasting station and the receiving terminal. The relay station 61 is connected to the broadcasting station 1 via a terrestrial line 51, and the receiving terminals 211 to 511 are connected via terrestrial lines 511 to 513.
213 respectively. The relay station 62 is connected to the broadcasting station 1 via a terrestrial line 52, and is connected to terrestrial lines 521 to 523.
Are connected to the receiving terminals 221 to 223, respectively.
The relay station 63 is connected to the broadcasting station 1 via a ground line 53, and connected to the receiving terminals 231 to 233 via ground lines 531 to 533, respectively.

The configuration of the broadcasting station 1 is the same as that shown in FIG. FIG. 6 is a diagram showing a configuration of the relay station 6 (any of 61, 62, 63). In the figure, 601 is a control unit, 602 is a receiving unit (first receiving unit, second receiving unit), 603 is a transmitting unit (first transmitting unit, second transmitting unit), and 604 is a line interface. . The line interface 604 is connected to the terrestrial line, so that the relay station 6 can communicate with the broadcasting station 1 in addition to the receiving terminals under the relay station 6.

Next, the operation will be described. The broadcast by the carousel from the broadcast station 1 is the same as in the first embodiment.

Next, retransmission when there is data loss will be described. Here, the receiving terminals 231, 232,
233 receives the module 80 as an example. 5, the receiving terminals 231, 232, 233 and the relay station 6
FIG. 7 is an extract of only 3.

In this figure, the receiving terminal 231 fails to receive the DDB corresponding to the data blocks d-0.0 and d-0.1 by carousel reception, and the receiving terminal 232 corresponds to the data block d-0.0. It is assumed that the receiving terminal 233 fails to receive the DDB corresponding to the data block d-0.0 and misses the DDB corresponding to the data block d-0.0. If there is no relay station, each of the receiving terminals 231 to 233 requests the broadcast station 1 to retransmit data directly. That is, the receiving terminal 231 issues two data block transmission request messages 42, the receiving terminal 232 issues one data block transmission request message 42, and the receiving terminal 233 also issues one data block transmission request message 42. , And a total of four data transmission requests are transmitted to the broadcasting station 1.

However, according to the second embodiment, as shown in FIG. 7, the terrestrial line relay station 63 is placed between the broadcasting station 1 and the receiving terminals 231, 232, and 233, and the data transmission request from each receiving terminal is transmitted. Is transmitted to the broadcasting station 1 in a lump, so that traffic congestion of a data transmission request to the broadcasting station 1 can be reduced.

In the example of FIG. 7, the relay station 63
1 receives two data block transmission request messages 42 designating the data blocks d-0.0 and d-0.1, and from the receiving terminal 232, the data blocks d-0.
0 is specified, and the data block d-
Data block transmission request message 4 specifying 0.0
Receive 2 As described above, a total of four data transmission requests are received, but since the transmission request specifying the data block d-0.0 is transmitted from all of the receiving terminals 231 to 233, the broadcasting station 1 must actually be read from the database. The block that must be used is the data block d-0.
0, d-0.1.

Therefore, in the second embodiment, relay station 63 transmits data block transmission request message 42 specifying two data blocks d-0.0 and d-0.1.
Is transmitted to the broadcasting station 1. That is, when the receiving unit 602 receives the data block transmission request message 42, if there is a data block common to the data blocks requested by each of the receiving terminals 231, 232, and 233, one The control unit 601 instructs the transmitting unit 603 to transmit a request to transmit a data block to the broadcasting station 1 via the ground line in a format for transmitting the request to the broadcasting station 1.

In the broadcasting station 1, when the receiving unit 107 (FIG. 2) receives the data block transmission request message 42, the two data block transmission request messages 4
The control unit 103 reads the data from the database 102 and sends the data block d-
The transmission unit 108 is instructed to transmit two data transmission messages 43 including 0.0 and d-0.1, respectively. In the relay station 63, when the receiving unit 602 receives two data transmission messages 43 respectively including the data blocks d-0.0 and d-0.1 transmitted from the broadcasting station 1, the control unit 601 transmits The destination of the data block is determined according to a request from the terminal. Then, the control unit 601 commands the transmission unit 603, and the transmission unit 603
31, two data transmission messages 43 each including two data blocks d-0.0 and d-0.1 are transmitted.
The data transmission message 43 including the data block d-0.0 is transmitted to the receiving terminal 233.

As described above, according to the second embodiment, even if the entire amount of data broadcast by the data carousel is enormous and one cycle of the carousel is very long, the data blocks dropped in the next carousel cycle There is an effect that data can be acquired in a short time without waiting for a long time to be broadcast. In addition, even when the number of receiving terminals is very large, effects such as a reduction in the amount of terrestrial communication on the broadcast station side can be obtained. In the first and second embodiments, the data block retransmission request is transmitted using the terrestrial line, and the data block is retransmitted in response to the retransmission request. However, a wireless line or a satellite line may be used. .

[0045]

As described above, according to the present invention, one data module is divided into a plurality of data blocks,
A plurality of data blocks are repeatedly broadcast to a plurality of receiving terminals, and when a request to retransmit any of the data blocks is received from a certain receiving terminal via a terrestrial line, the request is transmitted using the terrestrial line. Since the data block is configured to be transmitted to the receiving terminal, the total amount of data broadcast in the data carousel is enormous, and even if one cycle of the carousel is very long, the data block dropped in the next carousel cycle There is an effect that data can be acquired in a short time without waiting for a long time to be broadcast.

According to the present invention, a request to transmit any of the data blocks is received from a plurality of receiving terminals via the ground line, and a data block common to the data blocks requested by each of the receiving terminals is received. If there is, a request to transmit a data block is transmitted to the broadcasting station via a terrestrial line in a form of transmitting one request per common data block to the broadcasting station, and the requested data block is transmitted to the broadcasting station. From the receiving terminal, determine the destination of the data block according to a request from each of the receiving terminals, and complement the data broadcasting method so that the data block is transmitted to the receiving terminal via the ground line. Since the relay method is configured, even when the number of receiving terminals is very large, the traffic on the terrestrial line of the broadcasting station can be reduced. There is a result.

According to the present invention, a dividing section for dividing one data module into a plurality of data blocks, a broadcast transmitting section for repeatedly broadcasting a plurality of data blocks to a plurality of receiving terminals, A receiving unit connected to the receiving terminal via a ground line, a transmitting unit connected to each receiving terminal via a ground line, and a request to retransmit any of the data blocks from the receiving terminal via the ground line. When the receiving unit receives a signal, the data broadcasting system is configured to include a control unit that instructs the transmitting unit to transmit the data block to the receiving terminal using a terrestrial line. Even if the total amount of data to be processed is enormous and one cycle of the carousel is very long,
There is an effect that data can be acquired in a short time without waiting for a long time to broadcast a data block dropped in the next carousel cycle.

According to the present invention, the first receiving section connected to each receiving terminal via a ground line, the first transmitting section connected to each receiving terminal via a ground line, and the broadcast station connected via a ground line. A second receiving unit, a second transmitting unit connected to the broadcasting station via a terrestrial line, and a request to transmit one of the data blocks from a plurality of receiving terminals via the terrestrial line. When one receiving unit receives the data block, if there is a data block common to the data blocks requested by each of these receiving terminals, a data block transmission is performed in such a format that one request per common data block is transmitted to the broadcasting station. The second transmission unit instructs the second transmission unit to transmit the request to the broadcast station via the terrestrial line, and transmits the requested data block from the broadcast station to the broadcast station via the terrestrial line. 2 When the receiving unit receives, the destination of the data block is determined according to a request from each of the receiving terminals, and the first transmitting unit transmits the data block to the receiving terminal via a terrestrial line. Since the data relay device is configured to include a control unit that instructs one transmission unit, even if the number of receiving terminals is very large, it is possible to reduce the traffic on the terrestrial line on the broadcast station side. effective.

According to the present invention, a dividing unit for dividing one data module into a plurality of data blocks, a broadcast transmitting unit for repeatedly broadcasting a plurality of data blocks to a plurality of receiving terminals, A plurality of data relay devices, a receiving unit connected to each data relay device via a ground line, a transmitting unit connected to each data relay device via a ground line, and a request to retransmit any of the data blocks. When the receiving unit receives the data block from the data relay device via the ground line, the control unit instructs the transmission unit to transmit the data block to the data relay device using the ground line. Since the system is configured like a broadcasting system, the entire amount of data broadcast by the data carousel is enormous, and even if one cycle of the carousel is very long, the next carousel Without data block missed Le period long wait to come broadcast, there are effects such as will allow the acquisition of data in a short time.
Further, even when the number of receiving terminals is very large, there is an effect that the traffic on the terrestrial line on the broadcast station side can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a communication system according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a data broadcasting system in the communication system according to the first embodiment of the present invention.

FIG. 3 is a diagram showing formats of DII and DDB used in data broadcasting by a data carousel method.

FIG. 4 is a diagram showing an example of a format of a message transmitted via a terrestrial line used in the data broadcasting method according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an overall configuration of a communication system according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a relay station in a communication system according to Embodiment 2 of the present invention.

FIG. 7 is an enlarged view of a part of FIG. 5 for explaining a data broadcasting method according to a second embodiment of the present invention.

FIG. 8 is a conceptual diagram showing a general data broadcasting method using a data carousel method.

[Explanation of symbols]

1 broadcasting stations, 21-23, 211-213, 221-2
23, 231 to 233 receiving terminal, 6, 61 to 63 relay station, 30 DII, 31 to 39 DDB, 40 DI
I, 41 DDB, 42 data block transmission request message, 43 data transmission message, 51 to 53, 51
1 to 513, 521 to 523, 531 to 533 terrestrial line, 80, 81, 82 module, 101 data broadcasting system, 102 database, 103 control unit,
104 division unit, 105 radio transmission unit (broadcast transmission unit),
106 broadcast satellite (broadcast transmission unit), 107 reception unit, 1
08 transmission unit, 109 line interface, 601
Control unit, 602 receiving unit (first receiving unit, second receiving unit), 603 transmitting unit (first transmitting unit, second transmitting unit), 604 line interface.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/00 H04N 7/173 610Z 7/173 610 620A 620 H04B 7/15 Z F-term (Reference) 5C056 FA05 FA11 GA20 HA01 HA04 5C064 BA01 BB05 BB10 BC11 BC18 BC20 5D108 BG06 5K030 JA05 JL01 JL02 LD02 LD07 5K072 AA15 BB14 BB25 BB27 CC03 DD16 DD17 EE02 FF04 GG12 GG13

Claims (5)

[Claims] 1. A request for dividing one data module into a plurality of data blocks, repeatedly transmitting the plurality of data blocks to a plurality of receiving terminals, and retransmitting any of the data blocks. A data broadcast method comprising: receiving a data block from a receiving terminal via a ground line, and transmitting the data block to the receiving terminal using the ground line. 2. When a request to transmit any of the data blocks is received from a plurality of receiving terminals via a terrestrial line, and there is a data block common to the data blocks requested by each of the receiving terminals. Transmits a request to transmit a data block to a broadcasting station via a terrestrial line in the form of transmitting one request for a common data block to a broadcasting station, and transmits the requested data block from the broadcasting station to the terrestrial line. Receiving the data block according to a request from each of the receiving terminals, determining a destination of the data block, and transmitting the data block to the receiving terminal via a terrestrial line. Method. 3. A dividing unit for dividing one data module into a plurality of data blocks; a broadcasting unit for repeatedly broadcasting a plurality of data blocks to a plurality of receiving terminals; A receiving unit connected by a line, a transmitting unit connected to each receiving terminal by a ground line, and a receiving unit receiving a request to retransmit any of the data blocks from a receiving terminal via the ground line. Then, a control unit for instructing the transmission unit to transmit the data block to the reception terminal using a terrestrial line is provided. 4. A first terminal connected to each receiving terminal via a ground line.
A first transmitting unit connected to each receiving terminal via a ground line, a second receiving unit connected to a broadcasting station via a ground line, and a second transmitting unit connected to the broadcast station via a ground line. When the first receiving unit receives a request to transmit any of the data blocks from a plurality of receiving terminals via a terrestrial line, the first receiving unit receives a request for transmitting any one of the data blocks. If there is a data block to be
The second transmitter instructs the second transmitter to transmit a data block transmission request to the broadcast station via a terrestrial line in a format for transmitting one request for a common data block to the broadcast station. And when the second receiving unit receives the requested data block from the broadcasting station via a terrestrial line, determines the destination of the data block according to a request from each of the receiving terminals, and A data relay device comprising: a control unit that instructs the first transmission unit to transmit the first transmission unit to the reception terminal via a ground line. 5. A dividing unit for dividing one data module into a plurality of data blocks, and a broadcast transmitting unit for repeatedly broadcasting a plurality of data blocks to a plurality of receiving terminals. A plurality of data relay devices, a receiving unit connected to each data relay device via a ground line, a transmitting unit connected to each data relay device via a ground line, and a request to retransmit any of the data blocks. When the receiving unit receives the data block from the data relay device via the ground line, the control unit instructs the transmission unit to transmit the data block to the data relay device using the ground line. Broadcast system.