JPH05235951A - Information distribution system - Google Patents

Abstract

PURPOSE:To relieve the load to a center and to receive information without error by repetitively transmitting information with error detection code from a center equipment and allowing a receiver side to receive succeeding repetitive transmission information when an error is detected. CONSTITUTION:When a center equipment 1 sets a transmission line in a form of 1:n to slave equipments 6 of plural contractors, a transmission control section 3 adds an error check code to transmission information and sends the information repetitively for a preset repetitive number of times. Upon the receipt of the transmission information, an error detection section 7 of the slave equipment 6 checks the information and stores it sequentially to a reception memory 9. When the result of error detection is fed to a reception control section 8, the result is stored in a table 10. When a first reception is finished, the reception control section 8 receives 2nd transmission information, and when the state of error check is stored in the table 10 even by the reception of the 2nd transmission information, 3rd information is received and when the error detection state is eliminated, the reception is finished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information distribution system in which a center device and a plurality of slave devices are connected in a one-to-n form via a network, and the same information is simultaneously distributed from the center device to a plurality of slave devices. ..

In recent years, wide-band ISDN has been actively researched, and it is expected that a large amount of data will be handled through a public network. One of the services via such a network is a service that distributes media such as newspapers through a public network. As a form of providing such a service, a center device as a distribution source is provided at one place or at several places, and from there, it is distributed to a large number of parties (contractors) through a public network. In this case, it becomes difficult to individually control the error with each partner who receives the information from the center.

[0003]

2. Description of the Related Art FIG. 5 is an explanatory diagram of an information distribution service via a public network. In this example, one center 50 is connected to a public network 51, and terminal devices 52 of a large number of contractors who have contracts to receive information from this center 50 are also connected to the public network 51. When providing information to the terminal device 52 of each contractor, the center 50 can establish a call with each contractor via the public network 51 and perform 1-to-n (point-to-multipoint) format transmission. Become. In this case, the information is transmitted from the center 50 and simultaneously received by the terminal devices 52 of a plurality of contractors.

This information distribution service has the advantage that it is efficient because it distributes information to the previous contractors at the same time, but when the number of contractors increases, the terminals 52 of all the contractors receive the information accordingly. It is highly possible that the information to be received cannot be received without error due to an abnormality in the state of the subscriber's terminal device 52 or the transmission line in the public network 51 or the like.

[0005]

As described above, when a large number of contractors simultaneously receive, if an error is detected in the device of each contractor, the device of the contractor who has detected each error by the conventional method is detected. Sends to the center a resend request for all information or a part (block) in which an error is detected. In response to this, the center will resend the individually requested information.

However, in such a conventional method, when the number of subscribers is large, the time for receiving a request for resending, processing for resending control of requested information, etc. and transmission time becomes enormous, resulting in a heavy load on the center side. was there.

It is an object of the present invention to provide an information distribution system which reduces the load on the center and allows the contractor side to receive information without error without exchanging information with the center.

[0008]

FIG. 1 is a block diagram showing the principle of the present invention. In FIG. 1, 1 is a center device, 2 is a transmission unit, 3 is a transmission control unit, 4 is a counter, 5 is a network, 6 is a slave device connected to the network 5 and provided on the side of many contractors, and 7 is an error. A detection unit, 8 is a reception control unit, 9 is a reception memory, and 10 is a table for storing error detection results.

According to the present invention, information to be simultaneously transmitted from the center to a plurality of contractor-side slave devices is continuously and repeatedly transmitted a predetermined number of times, and the contractor-side device performs error detection to determine whether or not there is an error detection. If it is not possible to receive without error, the receiving operation is performed again when the next repeated transmission information is received, and the receiving operation is ended when the information is normally received.

[0010]

When the center device 1 sets up a transmission path in a one-to-n format with a plurality of contractor-side slave devices 6 via a network 5 such as a public network, transmission is started. The transmission control unit 3 of the center apparatus 1 causes the transmission unit 2 to read the information stored therein and transmit the information, and an error detection code is added to the transmission information. The number of transmission repetitions is input in advance to the transmission control unit 3 according to the characteristics of the network 5, etc., and is internally set. When one information transmission is completed, the counter 4
Is incremented by 1 to cause the transmitter 2 to start transmitting again. When this operation is repeated and the counter 4 reaches the preset number of transmission repetitions, the transmission control unit 3 stops the transmission.

When the slave device 6 on the contractor side receives the transmission information from the center device 1, the slave device 6 checks the error detection portion 7 and sequentially stores it in the reception memory 9 under the control of the reception control portion 8. When the error detection result of the error detection unit 7 is supplied to the reception control unit 8, the reception control unit 8 stores the result in the table 10. When one-time transmission information is sent by being divided into a plurality of blocks, the error detection result corresponding to the number of each block is sequentially stored in the table 10.

The reception control unit 8 receives the transmission information sent for the second time when the reception of the transmission information for the first time is completed. If the error is not detected in the first time by referring to the table 10, the reception control unit 8 The operation of storing the error detection result in the table 10 and the control of storing the reception information in the reception memory 9 are not performed for the transmission information of the second time. When the transmission information is composed of a plurality of blocks, if there is a block in which an error is detected at the first time, the information of the block number in which the error is detected at the time of receiving the second transmission information is stored in the reception memory 9. At the same time, the error detection result is stored in the table 10. If the error detection state is stored in the table 10 even after the second transmission information is received, the same process is performed when the third information is received, and the reception operation is performed when the error detection state is resolved. finish.

[0013]

FIG. 2 is a block diagram of a center device of the embodiment, FIG. 3 is a block diagram of a terminal device on the contractor side of the embodiment, and FIG. 4 is a diagram showing an operation example of the embodiment.

2 and 3 show an ATM as a network.
Wideband ISDN with Asynchronous Transfer Mode
It is an example when applied to. In the center device shown in FIG. 2, 20 is a transmission memory, 21 is a transmission control unit, and 22
Is a counter, 23 is an error code adding unit, 24 is an ATM cell assembling unit, and 25 is a transmitting unit.

To explain the operation, it is assumed that a 1-to-n call is set up via the broadband ISDN to all subscribers (not shown) who have contracts for transmitting information from the center device. The transmission information is stored in the transmission memory 20 of the center device in five blocks 0 to 4. The transmission control unit 21 is set with the number of times transmission is repeated (denoted as C). The number of times this transmission is repeated is determined based on the communication quality of the network and statistical data.

The information in the transmission memory 20 is sequentially read by the transmission controller 21. The block number is included in the information of each block, and the read information is added with an error detection code (parity, CRC code, etc.) by the error code addition unit 23 in each block unit, and is sent to the ATM cell assembly unit 24. Supplied. A header (5 octets) is added in the ATM cell assembling unit 24, assembled into cells of 53 octets in total, and transmitted from the transmitting unit 25 to the public broadband ISDN.

When the transmission control section 21 finishes transmitting the information of all the blocks of the transmission memory 20, the transmission control section 21 increments the counter 22 by +1.
Then, the second transmission operation is subsequently started. When this operation is repeated and the counter reaches C, the transmission is stopped.

The transmitted information is received by the contractor terminal shown in FIG. 3 (corresponding to the slave device 6 on the contractor side in FIG. 1) via the call transmission path set by the broadband ISDN.
In FIG. 3, 30 is an ATM cell disassembling unit, 31 is an error detecting unit, 32 is an information number detecting unit, 33 is a buffer, 34 is a receiving memory for storing information of each block of blocks 0 to 4, and 35 is a receiving control unit. , 36 is a table management unit, 37 is a table, and 38 is a memory access circuit.

The ATM cell received from the network is
The ATM cell disassembling unit 30 disassembles the header, removes the header, converts the original information, and inputs the information to the error detecting unit 31. Here, if error detection is performed and normal reception is performed, “0” indicating OK, and if an error is detected, “1” indicating NG is output to the reception control unit 35. The error detection result is supplied to the reception control unit 35. The information received by the error detector 31 is then subjected to block number detection by the information number detector 32, and the detected number is supplied to the reception controller 35. Further, the received information that has passed through the information number detecting section 32 is stored in the buffer 33.

The reception control unit 35 determines the reception completion flag of the corresponding information number to the table management unit 36 based on the detection result of the error detection unit 31 and the detection result of the information number from the information number detection unit 32. Then, it is controlled whether or not the information in the buffer 33 is written in the reception memory 34. That is, the table management unit 36 manages the table 37, the table 37 is provided with a reception completion flag corresponding to each information number, and the reception completion flag indicates the table management unit 36.
By this, writing and reading are performed, "1" is written in the case of normal reception, and "0" is set in the initial state and error detection.

When receiving the normal reception, the reception control unit 35 reads the reception completion flag of the information number at that time through the table management unit 36. The reception completion flag is "0"
In this case, in order to write the information stored in the buffer 33 into the reception memory 34, a memory write instruction (read from the buffer 33) is issued to the buffer 33 and a write instruction is issued to the memory access circuit 38 together with an information number. To occur.

The memory access circuit 38 thereby writes the data in the buffer 33 into the corresponding block (information number). When the writing is completed, the reception controller 35 sets the reception completion flag corresponding to the corresponding information number in the table 37 to "1".

When error detection (NG) occurs, the information having the information number is instructed to be discarded in the buffer 33 and is not written in the reception memory 34. Further, nothing is written in the table 37.

Thus, at the time of the first (first) information transmission from the center device, the flag is set to "1" for normal reception of each information number and set to "0" for error detection. (Nothing is written).

When the second reception of information transmitted from the center device is received after the first reception of information is completed, the reception control unit 35 determines that the error detection unit 31 outputs a normal reception and outputs the information number. The information number from the detection unit 32 is used to determine the reception completion flag of the corresponding information number in the table 37, and a write instruction is issued to the memory access circuit 38 only when it is "0". That is, only the information of the information number (block) that cannot be normally received by the previous reception is stored in the reception memory 34, and the information of the information number (block) that was normally received previously and the error are detected. All information is discarded.

Next, an operation example of the embodiment will be described with reference to FIG. In this example, a center 40 having the configuration shown in the embodiment of FIG. 2 has two terminals, a contractor terminal 41 (# 1) and a contractor terminal 42 (# 2) having the configuration shown in FIG. It is connected. When information consisting of five blocks 0 to 4 is transmitted from the center 40, the contractor terminal 41
In (# 1), the three blocks 0 to 2 were OK (normal reception) at the first reception, but the reception of block 3 was OK at the second reception, and the block 4 was received at the third reception. The reception is OK, and the reception of all blocks has been completed in a total of three receptions.

On the other hand, in the case of the contractor terminal 42 (# 2), 1
The reception of blocks 1 to 4 is OK at the second reception, whereas the reception of block 0 is OK at the second reception, indicating that all the blocks have been normally received at the total of two receptions.

Although the above embodiment has been described with reference to the broadband ISDN example, it is obvious that other networks can be implemented by the same principle.

[0029]

According to the present invention, a service for distributing various kinds of information having a fixed amount of information in a one-to-n format through a network without using complicated control and a re-sending procedure that takes a lot of time. It can be realized, and the occurrence of errors can be easily dealt with. This makes it possible to reliably distribute error-free information to a large number of subscribers at a relatively high speed and improve the quality of distribution service.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of a center device according to an embodiment.

FIG. 3 is a configuration diagram of an embodiment of a contractor terminal.

FIG. 4 is a diagram showing an operation example of the embodiment.

FIG. 5 is an explanatory diagram of an information distribution service via a public network.

[Explanation of symbols]

 1 center device 2 transmission unit 3 transmission control unit 4 counter 5 network 6 contractor side slave device 7 error detection unit 8 reception control unit 9 reception memory 10 table for storing error detection results

Claims (2)

[Claims] 1. An information distribution method in which a center device and a large number of slave devices set a transmission path in a 1: n format via a network to distribute the same information from the center device to a plurality of slave devices at the same time. The device adds an error detection code to the transmission information, repeatedly transmits the same information repeatedly a predetermined number of times, and the receiving side performs error detection when the information is received, and when the information is normally received, the information is transmitted. An information distribution method characterized in that when reception is completed and an error is detected, the next repeated transmission information is received. 2. The transmission information from the center device according to claim 1, wherein the transmission information is composed of a plurality of blocks, an error detection code is added to each block, and the same information is continuously transmitted a predetermined number of times repeatedly. , The receiving side stores the reception status information indicating whether or not an error is detected for each block of the transmission information, and if a block in which the reception status information of the error detection is stored occurs at the previous reception of information, the corresponding block An information distribution method characterized in that only the information is received from the next repeatedly transmitted information.