JP2001168872A - Communication system device and broadcast communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system device and a broadcast communication system, by which broadcast transmission is surely executed without causing any error, while securing sufficient confidentiality, only in a specified client group and a high reliability is secured. SOLUTION: First, in a server 1, the transmission of broadcast information is reported to the client group to which the information is desired to be transmitted, and then the information is divided into a plurality of blocks and successively transmitted. The client who receives the report fetches each block which is transmitted or retransmitted from the server 1 and detects an abnormality in each fetched block. The respective locks are connected, unless the abnormality exists and the broadcast information is reproduced. When an abnormality exists, the block is reported to the server 1. When the abnormality is reported from each client, the server 1 successively retransmits the lock with the abnormality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a communication system apparatus and a broadcast communication system provided with a server and a plurality of clients.

[0002]

2. Description of the Related Art FIG. 30 shows an example of a system having a server (computer) and a plurality of clients (personal computer or the like). Reference numeral 1 denotes a server to which a plurality of clients A, B, C,... Are connected via a communication line, for example, a LAN (local area network) 2. The server 1 has a broadcast communication function of simultaneously transmitting the same information to a specific group of clients A, B, C,. A broadcast code for indicating the broadcast information is added to the head of the broadcast information to be transmitted. Client A, B, C
.. Fetches broadcast information transmitted from the server 1 and detects from the broadcast code that the fetched information is broadcast information.

On the other hand, as shown in FIG. 31, there is an example in which a transmitting antenna 3 is provided in a server 1 and a receiving antenna 4 is provided in each client, and broadcast communication is performed via a satellite communication line using a communication satellite 5. .

In this case, the server 1 performs a scrambling process on the broadcast information to be transmitted, and adds a channel number to the head of the broadcast information. Clients A, B, C ... are LA
The scrambled broadcast information on N2 is fetched, and the broadcast information is restored based on the descrambling key corresponding to the channel number added to the scrambled broadcast information.

[0005]

In the case of the system shown in FIG. 30, the broadcast information transmitted from the server 1 is taken in not only by the original group of clients to be transmitted but also by other clients. There is a concern that secrets will be leaked.

In the case of the system shown in FIG. 31, since the broadcast information is subjected to a scrambling process, although there is a sense of security in terms of confidentiality as compared with the example shown in FIG. Is fixed, so that the broadcast information can be easily restored.

[0007] The present invention has been made in view of the above circumstances,
The communication system according to the first to third aspects of the present invention and the broadcast communication method according to the fourth aspect of the present invention provide a reliable broadcast without error while ensuring sufficient confidentiality only for a specific group of clients. An object of the present invention is to enable transmission and ensure high reliability.

[0008] A communication system according to the invention according to claim 5,
The broadcast communication system of the invention according to claim 6 is intended to be able to perform broadcast transmission while securing sufficient confidentiality only for a specific client group, and to secure high reliability.

A communication system according to the invention according to claim 7,
The broadcast communication system according to the invention according to claim 8 is capable of always performing reliable and reliable broadcast transmission to a client group, and has an object to ensure high reliability.

[0010]

According to a first aspect of the present invention, there is provided a communication system apparatus comprising: a notification unit for notifying a client group to which broadcast information is to be sent from a server to that effect; A first transmitting unit that divides the broadcast information into a plurality of blocks and sequentially transmits the divided information after the notification by the notifying unit, and is transmitted or retransmitted from the server when the notification is received from the server provided in each client. Capturing means for capturing each block to be detected, an abnormality detecting means provided in each client for detecting an abnormality of each block captured by the capturing means, and an abnormality detecting means provided for each client and detecting the abnormality of the abnormality detecting means. In the case of none, a reproducing unit that combines each block and reproduces the broadcast information, and provided in each client, and when the detection result of the abnormality detecting unit is abnormal, Notification means for notifying the server of a normal block; and second transmission means provided in the server and for sequentially retransmitting the block having the error when receiving notification of an error from each client. Prepare.

According to a second aspect of the present invention, in the communication system according to the first aspect, the first and second transmitting means sequentially add a number to each block to be transmitted and a final code to the last block. Is added. The abnormality detecting means detects a data error of each block as an abnormality and detects a missing of each block based on a number and a final code added to each block. The notifying unit notifies the number of the abnormal block.

According to a third aspect of the present invention, there is provided a communication system according to the first aspect, wherein the notifying means includes a telephone provided in the server and a pager provided in each client, and transmits broadcast information. Notify all pagers simultaneously from the telephone via a wireless telephone line.

[0013] According to a fourth aspect of the present invention, in the broadcast communication method, first, a server notifies a client group that wants to send the broadcast information to that effect, and then divides the broadcast information into a plurality of blocks. Send in order. Upon receiving the notification, the client fetches each block transmitted or retransmitted from the server, detects an abnormality in each fetched block, and if there is no abnormality, combines the blocks to reproduce the broadcast information. If so, the server notifies the server of the block. When the server receives the notification of the abnormality from each client, the server sequentially retransmits the block having the abnormality.

According to a fifth aspect of the present invention, there is provided a communication system device provided in each client, a notifying means for notifying a server that the user wants to obtain broadcast information, and a notifying device provided in the server, wherein the client transmits the notification information. A first transmitting means for adding a specific ID to a descrambling key for descrambling the broadcast information when receiving the broadcast information, and transmitting the same to the client which issued the notification; Fetching means for taking in the descrambling key and ID transmitted from the server after the notification, and the broadcast information divided into a plurality of blocks after the first transmitting means transmits the descrambling key and ID. Then, each block is subjected to scramble processing and the same ID as transmitted by the first transmitting means is added, and it is sequentially transmitted. A second transmitting unit for transmitting, and an obtaining unit provided in each client and obtaining a block to which the same ID as the ID captured by the capturing unit is added among the blocks transmitted from the server; A restoring means for restoring each block acquired by the acquiring means by a scramble descrambling key taken in by the taking means, and a broadcast provided by combining each block provided in each client and restored by the restoring means. Reproducing means for reproducing information.

In the broadcast communication system according to the invention of claim 6, first, when each client wants to obtain the broadcast information, it notifies the server to that effect. When the server receives the notification from each client, the server adds a specific ID to a descrambling key for descrambling the broadcast information, and transmits it to the client that issued the notification. Each client captures the descrambling key and ID transmitted from the server after the notification. In the server, the descrambling key and ID
, The broadcast information is divided into a plurality of blocks, each block is scrambled, the same ID as that already transmitted is added, and the blocks are sequentially transmitted. In each client, of each block sent from the server,
A block to which the same ID as the ID captured by the capturing unit is added is obtained, and the obtained block is restored by the descrambling key captured by the capturing unit, and the restored blocks are combined. Play broadcast information.

According to a seventh aspect of the present invention, there is provided a communication system apparatus, wherein: a notifying means for notifying one of a group of clients that the broadcast information is to be transmitted from the server; First transmission means for dividing the broadcast information into a plurality of blocks and transmitting one of the blocks, fetching means provided in each client for capturing each block transmitted from the server, and fetching means provided in each client; When the notification is received, a notifying means for notifying the server whether or not the capturing by the capturing means is appropriate, and a notification means provided in the server and receiving notification from the client that the capturing is appropriate is performed each time. , A second transmitting means for transmitting one of the untransmitted blocks, provided in the server,
Every time the client receives a notification that the capture is inappropriate, the incorrect block is retransmitted.
A transmitting unit, a selecting unit provided in each client, for selecting a non-overlapping block among the blocks fetched by the fetching unit, and selecting a block fetched last for the duplicated block; And reproducing means for reproducing the broadcast information by combining the blocks selected by the selecting means.

In the broadcast communication system according to the invention of claim 8, first, the server notifies one of the clients that the broadcast information is to be transmitted, and after that, the broadcast information is divided into a plurality of blocks. Divide and send one of them. Each client fetches each block transmitted from the server, and when receiving the notification, notifies the server whether or not the fetching is appropriate. The server transmits one of the unsent blocks each time a notification that the capture is appropriate is received from the client, and the block that is incorrect each time that the notification that the capture is inappropriate is received from the client. Resubmit. Each client selects a non-overlapping block from among the fetched blocks, selects the last fetched block with respect to the duplicated block, combines these selected blocks, and reproduces the broadcast information.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Hereinafter, a first embodiment will be described with reference to the drawings. This first embodiment corresponds to the first, second and fourth aspects of the present invention. As shown in FIG. 1, a plurality of clients (personal computers, etc.) A, B, C... Are connected to a server (computer) 1 via a communication line, for example, a LAN (local area network) 2. The server 1 has the following means [1] to [3] as main functions. [1] Notification means for notifying a client group that wants to send broadcast information to that effect. [2] After the notification by the notification means, the broadcast information is divided into a plurality of blocks and sequentially transmitted, a number is sequentially added to each block to be transmitted, and a final code is added to the last block. 1 transmitting means. [3] When each client is notified of abnormalities,
A second method for sequentially retransmitting the abnormal blocks, adding the same number to the retransmitted blocks as in the first transmission, and adding the final code to the last block.
Transmission means.

The clients A, B, C,... Have the following means [11] to [14] as main functions. [11] A capturing unit that captures each block transmitted or retransmitted from the server 1 when receiving a notification from the server 1. [12] Abnormality detecting means for detecting an abnormality of each block fetched by the fetching means. Specifically, a data error of each block is detected, and a missing of each block is detected based on a number and a final code added to each block. [13] In the case where the detection result of the abnormality detection means is no abnormality,
Reproduction means for reproducing broadcast information by combining the blocks. [14] If the detection result of the abnormality detection means is abnormal,
Notifying means for notifying the server 1 of the number of the block in which an abnormality has occurred.

Next, the operation of the above configuration will be described with reference to the flowcharts of FIGS. FIG. 2 shows the control of the server 1 and FIG. 3 shows the control of each client.

The server 1 needs to transmit broadcast information to an arbitrary client group (step 10).
1), each of the clients to be broadcasted is sequentially notified of the fact (step 1).
02). For example, when the clients A and C are to be transmitted, first, a broadcast transmission notification is sent to the client A as shown in FIG.
To the broadcast transmission.

After completion of the notification, the server 1
, The broadcast information is divided into a plurality of blocks, and numbers "1", "2",...
In addition, a final code is added to the final block, and the final code is sequentially transmitted (step 103).

Among the clients, the clients A and C that have received the broadcast transmission notice (YE in step 201)
S), enter the reception mode, and fetch each block transmitted from the server 1 (step 20).
2), an abnormality is detected for each of the fetched blocks (step 203). That is, data error detection such as a CRC check is performed on each block, and missing of each block is detected based on the number and the final code added to each block.

Then, when there is an abnormality (YES in step 204), the clients A and C notify the server 1 of the number of the abnormal block (step 205).
For example, as shown in FIG. 7, if there is a data error in the block with the number “1” among the blocks fetched by the client A, the client A notifies the server 1 of the number “1”. If there is a data error in the block with the number “1” among the blocks captured by the client C and there is a missing block in the block with the number “2”, the client C stores the numbers “1” and “2” in the server 1 To inform.

The server 1 responds to the notification of the abnormality (YES in step 104) and, as shown in FIG. 8, sequentially retransmits the blocks having the abnormal numbers "1" and "2", and retransmits the blocks. The same numbers "1" and "2" as in the first transmission are added to each block to be transmitted, and the final code is added to the last block (step 105). Note that, in this case, the abnormality notification for the block with the number “1” has been received from both the clients A and C, but only one block with the number “1” is retransmitted.

As shown in FIG. 8, the clients A and C fetch each block retransmitted from the server 1 (step 202), and detect an abnormality again for each fetched block (step 203).

Here, as shown in FIG. 9, for example, among the blocks fetched by the client A, the number "1"
If there is a missing block, the client A notifies the server 1 of the number “1” again.

In response to the notification of the abnormality again (YES in step 104), the server 1 re-transmits the block of the number "1" as shown in FIG. The same number "1" and the last code as those at the time are added (step 105).

The block thus retransmitted is shown in FIG.
As in the case of "0", the information is captured by the client A that has performed the abnormality notification, and is also captured by the client C that has first received the broadcast notification (step 202).

The clients A and C respectively fetch blocks retransmitted from the server 1 (step 20).
2) Then, abnormality detection is performed again for each of the fetched blocks (step 203). And clients A and C
When there is no abnormality (NO in step 204), the fetched blocks are combined in numerical order and the broadcast information is reproduced (step 206). After transmitting the block in which the abnormality has occurred (including retransmission or re-retransmission), if a predetermined time has passed without an abnormality notification from each client (YES in step 106), the server 1 reports that the broadcast transmission has been completed. Based on the determination, a series of processing ends.

As described above, the server 1 is notified in advance to a client group that wants to send broadcast information, and the transmission information is fetched only to the client that has received the notification. Broadcast transmission while ensuring sufficient confidentiality.

Further, the broadcast information is divided into a plurality of blocks from the server 1 and transmitted in sequence, and the client to be transmitted fetches these blocks and detects the abnormality. 1 and retransmitted, the broadcast transmission without any errors can be completed, and the reliability can be improved.

In the above embodiment, the case where the information is transmitted between the server 1 and each client via the LAN 2 has been described as an example. However, as shown in FIG.
A transmission / reception antenna 6 is provided for each client, and a transmission / reception antenna 7 is provided for each client. Further, as shown in FIG. 12, a transmission antenna 3 is provided in the server 1 and a reception antenna 4 is provided in each client, and the same is applied to a system for performing broadcast communication via a satellite communication line using a communication satellite 5. It is possible.

(2) The second embodiment will be described. This second embodiment corresponds to the third aspect of the present invention. FIG.
As shown in the figure, a telephone 8 is installed on the server 1 and a pager 9 having the same called number is previously assigned to a specific group of clients A, B, C,. Set it up,
The broadcast transmission notification is simultaneously sent to each pager 9 via a wireless telephone line including a telephone 8, a telephone station 10, and a transmission antenna 11. Other configurations and operations are the same as those of the first embodiment.

(3) The third embodiment will be described. This third embodiment corresponds to the fifth and sixth aspects of the invention. The server 1 has the following [1] and [2] as main functions. [1] Upon receiving a notification from a client that the user wants to obtain broadcast information, a specific ID (hereinafter referred to as a specific ID) is used as a descrambling key for descrambling the broadcast information.
D), and transmits it to the client which has issued the notification of the acquisition. [2] After transmitting the descrambling key and the specific ID by the first transmitting means, the broadcast information is divided into a plurality of blocks, each of which is subjected to scramble processing, and
A second transmitting unit that adds the same specific ID as that transmitted by the transmitting unit and sequentially transmits the same.

The clients A, B, C... Have the following means [11] to [15] as main functions. [11] Notification means for notifying the server 1 when it is desired to obtain broadcast information. [12] A fetching means for fetching the descrambling key and the specific ID transmitted from the server 1 after the notification of the acquisition. [13] Acquisition means for acquiring a block to which the same specific ID as the specific ID fetched by the fetching means is added, among the blocks transmitted from the server 1. [14] Restoring means for restoring each block acquired by the acquiring means with the scramble release key acquired by the acquiring means. [15] Reproducing means for reproducing the broadcast information by combining the blocks reconstructed by the reconstructing means. Other configurations are the same as those of the first embodiment.

Next, the operation of the above configuration will be described with reference to the flowcharts of FIGS. FIG.
4 shows the control of the server 1, and FIG. 15 shows the control of each client. When each client wants to obtain broadcast information (YES in step 401), the client notifies the server 1 of a broadcast information acquisition request to that effect (step 402), as shown in FIG.

When receiving the above notification (YES in step 301), the server 1 adds a specific ID to a descrambling key for descrambling the broadcast information as shown in FIG. The credit ID is added and transmitted to the client which issued the notification of the broadcast information acquisition request (step 302). The specific ID is for distinguishing each block of the broadcast information from others and for causing the client to capture the block without error. The transmission ID is for designating only a client that has issued a broadcast information acquisition request notification as a transmission target.

Among the clients, the client that has issued the acquisition request receives the descrambling key and the specific ID transmitted from the server 1 according to the transmission ID (step 403). In the examples of FIGS. 16 and 17, only the client A issues a broadcast information acquisition request notification and responds to the request by transmitting the descrambling key and the specific ID only to the client A.

The server 1 has a descrambling key and
After transmitting the ID, as shown in FIG. 18, the broadcast information is divided into a plurality of blocks, each block is scrambled, the same specific ID as that already transmitted is added, and the blocks are sequentially transmitted. (Step 303). Among the clients, the client that has issued the broadcast information acquisition request obtains a block to which the same specific ID as the previously acquired specific ID is added among the blocks transmitted from the server 1 (step 404). Then, each client restores each of the acquired blocks by using the scramble descrambling key that has been previously acquired (step 40).
5) Then, the restored blocks are combined to reproduce the broadcast information (step 406).

As described above, the descrambling key and the specific ID are given in advance to the client requesting the acquisition of the broadcast information, and the client requesting the acquisition of the broadcast information receives the scramble descrambling key and the specific ID in advance. Each block of the broadcast information is fetched based on the specific ID, and the fetched block is restored and reproduced by the previously received descrambling key, so that sufficient confidentiality is secured only for a specific group of clients. Broadcast transmission can be performed. Even if each block of the broadcast information is taken in by another client, it is impossible to restore the broadcast information because the descrambling key is unknown at other clients. In the same manner as in the first embodiment, each client detects an abnormality in each block taken in, and if there is an abnormality, notifies the server 1 of the abnormality and retransmits the block. The information transmission can be completed, and the reliability can be further improved. Transmission of information between the server 1 and each client is performed over the LAN 2
However, the present invention can be similarly applied to the case of performing the broadcast communication by radio waves shown in FIG. 11 or the broadcast communication via the satellite communication line shown in FIG.

(4) The fourth embodiment will be described. This fourth embodiment corresponds to the seventh and eighth aspects of the invention. Server 1 has the following main functions [1] to [4]
Means. [1] Notification means for notifying one of a group of clients that broadcast information is to be sent. [2] A first transmission unit that, after the notification, divides the broadcast information into a plurality of blocks and transmits one of the blocks. [3] A second transmission of one of the untransmitted blocks each time a notification that the capture is appropriate is received from the client.
Transmission means. [4] A third transmission unit that retransmits the improper block each time a notification that the capture is improper is received from the client.

The clients A, B, C... Have the following means [11] to [14] as main functions. [11] Capture means for capturing each block transmitted from the server 1. [12] Notification means for notifying the server 1 of whether or not the capture by the capture means is appropriate, when receiving notification from the server 1 that the broadcast information is to be sent. [13] Selection means for selecting a non-overlapping block from among the blocks fetched by the fetching means, and selecting the last fetched block for the duplicated block. [14] A reproducing means for reproducing the broadcast information by combining the blocks selected by the selecting means. Other configurations are the same as those of the first embodiment.

Next, the operation of the above configuration will be described with reference to the flowcharts of FIGS. FIG.
0 indicates control of the server 1 and FIG. 21 indicates control of each client. If the server 1 needs to transmit broadcast information to the client group (Y in step 501)
ES), a so-called broadcast information reception request to transmit the broadcast information to an arbitrary one of the client groups is issued in FIG.
(Step 502). If the clients A, B, and C are to be transmitted, only the client A, for example, is notified of the broadcast information reception request.

After notifying the broadcast information reception request, the server 1 divides the broadcast information into a plurality of blocks, and adds numbers "1", "2",... One of the blocks having the smallest number (number "1") is transmitted as shown in FIG. 23 (step 50).
3). As shown in FIG. 23, the block transmitted in this manner is captured by the client A receiving the broadcast information reception request (YES in step 601; step 602), and is also captured by other clients.
(NO in step 601; step 610).

The client A, which has received the broadcast information reception request, determines that the reception has been completed (YES in step 603) if the block of the number “1” has been properly taken in (YES in step 603). As shown in FIG. 24, an "OK" response is issued to the server 1 (step 604).

When the server 1 receives the response of "OK" (YES in step 504), if the transmission of the last block is not completed yet (NO in step 505), the next number among the untransmitted blocks The block of "2" is transmitted (step 503). This transmitted block is shown in FIG.
As shown in FIG. 5, the data is captured by all clients (steps 602 and 610).

If the acquisition of the block with the number “2” is inappropriate, the client A determines that the reception is erroneous (NO in step 603, YE in step 605).
S) As shown in FIG. 26, a response of "NG" is issued to the server 1 (step 606).

When the server 1 receives the response of "NG" (NO in step 504, YES in step 505), the server 1 retransmits the improper number block "2" (step 506). This retransmitted block is taken in by all clients including the client A as shown in FIG. 27 (steps 602 and 610).

At the time of this retransmission, if the client A receiving the broadcast information reception request has properly taken in the retransmitted block of the number "2" (reception completed: YES in step 603), FIG. As shown in (1), a response of "OK" is issued to the server 1 (step 604).

When the server 1 receives the response of "OK" (YES in step 504), if the transmission of the last block has not been completed yet (NO in step 505), the server 1 The block of "3" is transmitted (step 503). The transmitted block is taken in by all clients as shown in FIG. 25 again (steps 602 and 610).

In this way, transmission or retransmission of each block from the server 1 is repeated. When the transmission of the last block is completed (YES in step 505), the broadcast transmission ends.

Each client sequentially fetches each block transmitted from the server 1 and determines whether or not each fetched block has an overlap, that is, one having the same number (step 607).

For example, when the block with the number “2” is retransmitted from the server 1, each client receives two blocks with the same number “2”.
In this way, when a plurality of the same blocks are fetched (YES in step 607), each client selects only the last block fetched from the two blocks (number "2") as shown in FIG. Then, the remaining one is discarded (step 608).

If there is no duplication in each of the fetched blocks (NO in step 607), each client selects all of the blocks (step 609). Then, each client combines the selected blocks and reproduces the broadcast information (step 610).

As described above, the broadcast information is divided into a plurality of blocks from the server 1 and one of them is transmitted. Each client fetches each block transmitted from the server 1 and receives the broadcast information. If the request has been received, the server notifies the server whether or not the capture is appropriate, and the server 1 transmits one of the untransmitted blocks every time the server 1 is notified that the capture is appropriate, In addition, each time a notification that the capture is inappropriate is received, the incorrect block is retransmitted, and each client selects a non-overlapping block among the captured blocks and For the selected block, select the last captured block, combine these selected blocks, and play back the broadcast information. It is possible to perform the always reliable broadcast transmission without a mistake for, can ensure high reliability.

It is to be noted that all the blocks of the broadcast information are taken in by all the clients. However, as in the third embodiment, only a specific client is given a descrambling key and a specific ID in advance. A specific client may capture each block of broadcast information based on a specific ID received in advance. By doing so, it is possible to perform broadcast transmission while ensuring sufficient confidentiality only for a specific client. Further, the case where the transmission of information between the server 1 and each client is performed via the LAN 2 has been described as an example, but the broadcast by radio waves shown in FIG. 11 or the satellite communication line shown in FIG. Broadcasting can be similarly performed.

[0058]

As described above, the communication system according to the first to third aspects of the present invention and the broadcast communication method according to the fourth aspect of the present invention provide sufficient confidentiality only for a specific group of clients. , And reliable and reliable broadcast transmission can be performed, and high reliability can be secured.

A communication system according to claim 5,
The broadcast communication system of the invention according to claim 6 can perform broadcast transmission while ensuring sufficient confidentiality only for a specific group of clients, and can secure high reliability.

A communication system according to the invention according to claim 7,
The broadcast communication system of the invention according to claim 8 can always perform reliable and reliable broadcast transmission to a client group, and can secure high reliability.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of each embodiment.

FIG. 2 is a flowchart illustrating control of a server according to the first embodiment.

FIG. 3 is a flowchart for explaining control of each client in the first embodiment.

FIG. 4 is a diagram showing a broadcast transmission notification from a server to a client in the first embodiment.

FIG. 5 is a diagram illustrating a broadcast transmission notification from a server to another client in the first embodiment.

FIG. 6 is a diagram illustrating transmission of broadcast information from a server to a client in the first embodiment.

FIG. 7 is a diagram showing notification of an abnormality from a client to a server in the first embodiment.

FIG. 8 is a diagram showing retransmission of broadcast information from a server to a client in the first embodiment.

FIG. 9 is a diagram showing notification of an abnormality from a client to a server in the first embodiment.

FIG. 10 is a diagram showing retransmission of broadcast information from a server to a client in the first embodiment.

FIG. 11 is a block diagram showing a configuration of a modification of the first embodiment.

FIG. 12 is a block diagram showing a configuration of another modification of the first embodiment.

FIG. 13 is a block diagram showing the configuration of the second embodiment.

FIG. 14 is a flowchart illustrating control of a server according to the third embodiment.

FIG. 15 is a flowchart illustrating control of each client according to the third embodiment.

FIG. 16 is a diagram showing a broadcast information acquisition request from a client to a server in the third embodiment.

FIG. 17 is a diagram showing transmission of a descrambling key and a specific ID from a server to a client in the third embodiment.

FIG. 18 is a diagram showing transmission of broadcast information from a server to a client in the third embodiment.

FIG. 19 is a diagram showing the capture of broadcast information of a client in the third embodiment.

FIG. 20 is a flowchart illustrating control of a server according to the fourth embodiment.

FIG. 21 is a flowchart illustrating control of each client according to the fourth embodiment.

FIG. 22 is a diagram showing a broadcast information reception request from a server to a client in the fourth embodiment.

FIG. 23 is a diagram showing transmission of first broadcast information from a server to a client in the fourth embodiment.

FIG. 24 is a diagram showing an “OK” response from a client to a server in the fourth embodiment.

FIG. 25 is a diagram showing transmission of next broadcast information from a server to a client in the fourth embodiment.

FIG. 26 is a diagram showing an “NG” response from a client to a server in the fourth embodiment.

FIG. 27 is a diagram showing retransmission of broadcast information of a client from a server in the fourth embodiment.

FIG. 28 is a diagram showing an “OK” response from the client to the server in the fourth embodiment.

FIG. 29 is an exemplary view for explaining a process of discarding and selecting broadcast information of a client according to the fourth embodiment;

FIG. 30 is a block diagram showing a configuration of a conventional system.

FIG. 31 is a block diagram showing the configuration of another conventional system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Server 2 ... LAN A, B, C ... Client 5 ... Communication satellite 6 ... Transmission / reception antenna 7 ... Transmission / reception antenna 9 ... Pager 10 ... Telephone office 11 ... Transmission antenna

Claims (8)

[Claims] 1. A device comprising a server and a plurality of clients, comprising: a notifying means for notifying a client group to which broadcast information is to be sent from the server to that effect; After the notification, the first is to divide the broadcast information into a plurality of blocks and sequentially transmit them.
Transmitting means, provided in each of the clients, and taking in each block to be transmitted or retransmitted from the server when receiving a notification from the server; and provided in each of the clients, An abnormality detecting means for detecting an abnormality of each block captured by the means; and a reproducing means provided in each of the clients, for combining the blocks and reproducing the broadcast information when the abnormality detecting means detects no abnormality. Means, provided in each of the clients, and, when the detection result of the abnormality detecting means indicates an abnormality, an informing means for informing the server of an abnormal block to the server; And a second transmitting means for sequentially retransmitting the blocks having an abnormality when receiving the notification of the communication system. Location. 2. The apparatus according to claim 1, wherein the first and second transmitting means sequentially add a number to each block to be transmitted and add a final code to a last block. Detecting an error and detecting missing of each block based on a number added to each block and a final code, wherein the notifying unit notifies a number of a block having an error. Item 2. The communication system according to item 1. 3. The notifying means includes a telephone set provided in the server and a pager provided in each of the clients, and simultaneously notifies the pager that broadcast information is to be transmitted from the telephone set to each pager via a wireless telephone line. The communication system according to claim 1, wherein 4. A server comprising a server and a plurality of clients, wherein the server notifies a client group that wants to send broadcast information to that effect, and thereafter divides the broadcast information into a plurality of blocks and sequentially The client that has received the notification fetches each block transmitted or retransmitted from the server, detects an abnormality of each fetched block, and if there is no abnormality, combines the blocks to broadcast information. Is reproduced, and if there is an abnormality, the block is notified to the server. When the server receives the notification of the abnormality from each client, the server sequentially retransmits the abnormal block. Broadcast method. 5. A device comprising a server and a plurality of clients, wherein said notifying means is provided in each of said clients and notifies said server when it wants to obtain broadcast information. When receiving the notification from each client, a specific ID is added to a descrambling key for descrambling the broadcast information, and the ID is transmitted to the client that issued the notification.
Sending means, provided in each of the clients, and taking-in means for taking in the descrambling key and ID transmitted from the server after the notification, and provided in the server and provided with the descrambling key and ID by the first transmitting means. After transmission, the broadcast information is divided into a plurality of blocks, each block is subjected to scramble processing, the same ID as transmitted by the first transmission means is added, and second transmission means for sequentially transmitting the same is provided; ID provided in each of the clients and among the blocks transmitted from the server, the ID captured by the capturing means
Acquisition means for acquiring a block to which the same ID is added, restoration means provided in each of the clients, and restoring each block acquired by the acquisition means with a scramble descrambling key taken in by the acquisition means; A communication unit which is provided in each client and reproduces broadcast information by combining the blocks restored by the restoration unit. 6. A device comprising a server and a plurality of clients, wherein each of the clients notifies the server when it wants to obtain broadcast information. The server receives the notification from each of the clients. In this case, a specific ID is added to the descrambling key for descrambling the broadcast information, and the ID is transmitted to the client that issued the notification. In each of the clients, the ID is transmitted from the server after the notification. After transmitting the descrambling key and the ID, the server transmits the descrambling key and the ID, divides the broadcast information into a plurality of blocks, performs scramble processing on each of the blocks, and performs the same ID as that already transmitted. , And sequentially transmits them. In each of the clients, the server Among the transmitted blocks, a block to which the same ID as the ID captured by the capturing unit is added is acquired, and each of the acquired blocks is restored by the descrambling key captured by the capturing unit. A broadcast communication method comprising combining the restored blocks to reproduce broadcast information. 7. A device comprising a server and a plurality of clients, wherein: a notifying means for notifying one of a group of clients of a desire to send broadcast information from the server; and A first transmission unit that divides the broadcast information into a plurality of blocks after the notification, and transmits one of the plurality of blocks; a capturing unit provided in each of the clients to capture each block transmitted from the server; A notification means provided in each client and notifying the server whether or not the capture by the capture means is appropriate when receiving the notification; and a notification means provided in the server and indicating that the capture is appropriate. A second transmitting means for transmitting one of the untransmitted blocks each time a notification is received from the client; and a second transmitting means provided in the server and indicating that the capture is inappropriate. A third transmitting unit that retransmits an improper block each time a notification is received from a client; and a block that is provided in each of the clients and that does not overlap among the blocks captured by the capturing unit. And selecting means for selecting the last captured block for the duplicated block; and reproducing means provided in each of the clients for combining the blocks selected by the selecting means and reproducing the broadcast information. A communication system device comprising: 8. A server comprising a server and a plurality of clients, wherein the server notifies one of a group of clients that the broadcast information is to be transmitted, and after the notification, divides the broadcast information into a plurality of blocks. Each of the clients fetches each block transmitted from the server, and when receiving the notification, notifies the server whether the fetching is appropriate or not. The server transmits one of the untransmitted blocks each time a notification that the capture is appropriate is received from the client, and determines that the block is incorrect each time the notification that the capture is inappropriate is received from the client. In each of the clients, a non-overlapping block is selected from the captured blocks, and Broadcast communication method for block selected last captured block, by coupling each to these selected blocks for reproducing broadcast information, and wherein the.