JPH06101723B2 - Data transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In a transmission device that distributes data blocks to a plurality of transmission lines to perform data transmission, a signal requesting retransmission of a data block transmitted through an error-occurring transmission line and retransmission By transmitting the data block using a transmission line other than the error generation transmission line, the retransmission request signal is transmitted reliably, and the retransmission data block also avoids the occurrence of errors, and the recovery is surely and quickly performed. Complete.

[Industrial application field]

The present invention relates to a transmission device that uses a plurality of transmission lines to perform highly reliable and high-speed data transmission, and particularly when recovering data in which an error has occurred, a transmission line different from the transmission line in which the error has occurred is used. The present invention relates to a data transmission system that completes recovery at high speed and surely.

Recently, with the development of the information-oriented society, it has become popular to transmit data between devices provided at distant positions using a telephone line. For example, a plurality of terminal devices are connected to a computer system installed in the center via a telephone line, and data is transmitted between the computer system and each terminal device.

FIG. 4 is a diagram for explaining data transmission using a modem.

When data transmission is performed using a telephone line, usually modems 2 and 4 are installed at both ends of the telephone line 3 between the computer system 1 and the terminal device 5, as shown in FIG. Then, the modem 2 modulates the data sent from the computer system 1 and sends it to the telephone line 3, demodulates the modulated data received via the telephone line 3 and sends it to the computer system 1.

Further, the modem 4 modulates the data sent from the terminal device 5 and sends it to the telephone line 3, demodulates the modulated data received via the telephone line 3 and sends it to the terminal device 5, so that the computer system 1 and the terminal device Data transmission between 5 is performed.

What is important in such data transmission is data reliability and high-speed transmission. However, in a general telephone line, its electrical characteristics are limited, and a data transmission error occurs with a certain probability. The probability of this transmission error increases as the transmission rate increases.

Therefore, the transmission speed of the modem is limited, and when higher-quality transmission is required, the two opposing devices have a transmission control procedure negotiated with each other to check whether the transmitted data was correctly transmitted to the other party. However, data transmission is performed, and when the transmitted data is not correctly transmitted to the other party, recovery is performed by retransmitting the error data.

When higher speed data transmission is required, a means of increasing the amount of information per unit time by using a plurality of telephone lines has been considered. However, in this case, it takes time to retransmit the erroneous data, and the recovery is delayed, so that it is necessary that the actual data transmission rate does not decrease.

[Conventional technology]

FIG. 5 is a block diagram showing an example of conventional data transmission by a plurality of lines.

The transmission devices 6 and 7 send and receive data modulated by a modem via a plurality of telephone lines 8 and 9. Then, the data is divided into blocks of a certain size and transmitted alternately to the telephone lines 8 and 9 or by selecting an empty telephone line.

Here, each time the data block is received, the presence or absence of an error is checked, and the transmission device 6 retransmits the data block in which the error has occurred, so that the data block in which the error has occurred is eliminated and correct data is obtained in the computer system 1 and It is sent to the terminal device 5.

FIG. 6 is a sequence for explaining the operation of FIG.

For example, the data transmitted by the computer system 1 is transmitted by the transmission device 6
Is divided into data blocks 10, 11 and 12 by the transmission device 7
Sent to.

Sequence numbers indicating the transmission order are added to the data blocks 10 to 12, respectively. For example, when an error occurs in the data block 11 of the sequence, the transmission device 7 receives the data block 12, and Since the sequence number arrives after the number, the missing of the data block 11 is detected, and the retransmission request for the data block 11 is sent to the transmission device 6.

At this time, if the data block 11 is transmitted through the telephone line 8 at this time, the transmission device 7 requests the transmission of the data block of the sequence number via this telephone line 8.
13 is sent to the transmission device 6.

When the transmission device 6 receives this resend request 13, the telephone line 8
Data block 1 identical to data block 11 via
Retransmit 1 '.

[Problems to be solved by the invention]

As described above, when error recovery is conventionally performed, as in the case where only one telephone line is used, a retransmission request signal for a missing data block is transmitted via the telephone line in which an error has occurred, and a retransmission request is issued. The receiving transmission device also sends the retransmission data block via the telephone line in which the error occurred.

The telephone line in which an error has occurred may be deteriorated in a short time, but it usually continues for a long time.
In this case, there is a problem that the retransmission request signal does not arrive, the retransmitted data block may have an error again, and the recovery is not completed.

In view of the above problems, the present invention has a plurality of telephone lines. Therefore, the retransmission request is transmitted also through another telephone line in which an error has not occurred and the retransmission request is also transmitted to the transmission device. The purpose is to ensure that recovery is completed by sending the retransmitted data block to the same telephone line.

[Means for solving problems]

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

The transmission device 16 is composed of a transmission unit 161 and a reception unit 162. The transmission unit 161 distributes the data transmitted by the higher-level device 15 such as a computer system by adding a sequence number to the data transmitted to the A line 19. Transmission number indicating transmission order and A line
The address indicating transmission to 19 is added.

Further, to the data to be transmitted to the B line 20, a transmission number indicating the transmission order and an address indicating transmission to the B line 20 are added. Then, the data is alternately transmitted to the A line 19 or the B line 20, or is transmitted to the vacant line.

The receiving unit 162 receives data from a lower device 18 such as a terminal device that enters through the A line 19 or the B line 20 and requests a retransmission by sending a missing number in the transmission order due to an error in a data block that has passed through the A line 19. , A data block that has passed through the B line 20 are connected by a sequence number, and the host device
Send to 15.

In addition, a resending request is made due to a missing number in the transmission order due to an error in the data block that has passed through the B line 20, and as described above, it is combined with the data block that has passed through the A line 19 by the sequence number and sent to the host device 15.

The transmission device 17 includes a reception unit 171 and a transmission unit 172. The transmission unit 172 is the transmission unit 161, and the reception unit 171 is the reception unit 162.
It has the same function as the above, and sends the data sent by the lower device 18 to the upper device 15 and sends the data sent by the upper device 15 to the lower device 18.

[Action]

 FIG. 2 is a sequence for explaining the operation of FIG.

The data transmitted from the host device 15 is transmitted to the transmission unit 161 of the transmission device 16, divided into blocks of a certain size, distributed to the A line 19 and the B line 20, modulated by a modem, and then transmitted. .

At this time, for example, if the data blocks are distributed alternately, the data blocks sent to the A line 19 are the data block 21 as shown in FIG. 'Is added with the sequence number.

The data block 22 has a sequence number and a code A and a transmission number 'for distinguishing the transmission line in the address field, and the data block 23 has a code A and a transmission number' in addition to the sequence number.

The data blocks demodulated by the modem of the transmission device 17 and received by the reception unit 171 are combined in sequence number order and sent to the lower device 18.

Here, for example, if an error occurs in the data block 22, the receiving unit 171 of the transmission device 17 detects the missing number of the data block 22 from the fact that the transmission number'followed by 'is obtained. The code A is read and the transmitter 17
The retransmission request 24 is sent to the receiving unit 162 of the transmission device 16 via the B line 20 in which no error has occurred so that the data block 'transmitted by the A line 19 is retransmitted by instructing the command.

The reception unit 162 of the transmission device 16 reads that the code B is added to the retransmission request, and instructs the transmission unit 161 to make the B line 20.
Then, the'data block 22 'for the A line requested to be retransmitted is retransmitted.

Therefore, error recovery is carried out using a telephone line in which no error has occurred, so that it is possible to recover quickly.

〔Example〕

FIG. 3 is a block diagram of a circuit showing an embodiment of the present invention.

The data that enters the data distribution unit 25 of the transmission unit 161 from the host device is divided into blocks of a predetermined size, and is distributed alternately to the A line procedure management unit 26 and the B line procedure management unit 27, for example.

In this case, as shown in data blocks 21 to 23 in FIG.
The line procedure management unit 26 is supplied with a sequence number and a data block added every other number.

The A line procedure management unit 26 indicates the address "0" and the transmission order at the A position in the address field of the data block, for example, when transmitting to the A line 19, as shown in data blocks 21 to 23 in FIG. Send the transmission numbers '~' to the B line 20
In the case of sending to the line A, the address "1" and the sending numbers 'to' are added to the position A, and the line interface unit 28 is instructed to send according to the transmission control procedure.

The B-line procedure management unit 27 sends the address field of the data block, for example, the address "2" and the transmission number "..." To the A line 19, and the address "3" to the B line 20. Numbers "to" are added respectively, and the line interface unit 28 is instructed to transmit according to the transmission control procedure.

The line interface unit 28 is the A line procedure management unit 26 and B
The data block sent out by the line procedure management unit 27 is temporarily stored in the buffer, this data block is modulated by the built-in modem, and the data block to which the addresses "0" and "2" are added passes through the A line 19. , The data blocks to which the addresses “1” and “3” are added are transmitted through the B line 20 and the transmission unit 17 respectively.
2 to the line interface unit 28 '.

The line interface unit 28 'sends the data block demodulated by the built-in modem to the line interface unit 29 of the receiving unit 171. The line interface unit 29 has addresses "0" and "1"
The data block added with is the A line procedure management unit 30.
Then, the data blocks to which the addresses "2" and "3" are added are sent to the B line procedure management unit 31.

The A line procedure management unit 30 and the B line procedure management unit 31 monitor the procedure of the data block, delete the address and the transmission number, and send the data to the data multiplexing unit 32. The data multiplexing unit 3 combines the data blocks in the order of the sequence numbers of the data blocks, deletes the sequence numbers, and sends them to the lower device.

At this time, the A-line procedure management unit 30 and the B-line procedure management unit 31 perform error detection, and send a retransmission request for the data block in which the error has occurred to the transmission unit 172. That is, the A line procedure management unit 30 sends the A line procedure management unit 26 ', and the B line procedure management unit 31 sends the B line procedure management unit 27'. Therefore, it is possible to determine whether the data block in which an error has occurred in the A line 19 or the data block in which an error has occurred on the B line 20.

Here, for example, when an error occurs in the data block 22 as shown in FIG. 2, an error occurs in the A line 19, so that the address "0" or the address "2" is added to the data block 22. . If the address is "0", the A line procedure management unit 30 has detected an error, and if the address is "2", the B line procedure management unit 31 has detected an error.

When the A-line procedure management unit 30 detects an error, the A-line procedure management unit 26 'receives the resend request and knows that the error line is the A line 19 from the address "0". A resend request signal with 1 "and a transmission number 'is sent to the line interface unit 28'. The line interface unit 28 'modulates the resend request signal by the modem and sends it to the B line 20 because the address is "1".

The resend request signal that enters the line interface unit 28 via the B line 20 and is demodulated is the line interface unit 2 of the receiving unit 162.
Enter 9 ', and the address is "1", so the A line procedure management unit 3
It is sent to 0 '. The A line procedure management unit 30 'is the transmission unit 161.
The A-line procedure management unit 26 is notified of a resend request for the data block 22 of the transmission number ', and the A-line procedure management unit 26 sends the data block 22 via the B line 20. It is added to the block 22 and sent to the line interface unit 28.

When the B-line procedure management unit 31 detects an error, it can be inferred from the above. Further, the transmission unit 172 is the same as the transmission unit 161, and the reception unit 172 is the same as the reception unit 171, and other detailed description will be omitted. .

[Effects of the Invention] As described above, the present invention uses the telephone line in which no error has occurred to request and retransmit a data block in which an error has occurred, so error recovery can be performed easily and quickly. Can be completed.

[Brief description of drawings]

1 is a block diagram of the principle of the present invention, FIG. 2 is a sequence for explaining the operation of FIG. 1, FIG. 3 is a block diagram of a circuit showing an embodiment of the present invention, and FIG. 4 uses a modem. FIG. 5 is a block diagram showing an example of conventional data transmission by a plurality of lines, and FIG. 6 is a sequence explaining the operation of FIG. In the figure, 1 is a computer system, 2 and 4 are modems, 3 is a telephone line, 5 is a terminal device, 6,7,16 and 17 are transmission devices, 15 is an upper device, 18 is a lower device, and 25 and 25 'are Data distribution unit, 26,26 ', 30,30' are A line procedure management unit, 27,27 ', 31,31' are B line procedure management unit, 28,28 ', 29,29' are line interfaces 32, 32 'are data multiplexing units, 161, 172 are transmitting units, and 162, 171 are receiving units.

Claims (1)

[Claims] 1. A transmission device (16, 17) for performing data transmission by distributing and transmitting data blocks to a plurality of transmission lines, and detecting means for detecting a transmission line on which an error-occurring data block is transmitted. (162, 171) and selection means (161, 172) for sending a resend request for a data block in which an error has occurred to a transmission path other than the transmission path in which the error has occurred, based on the detection result of the detection means (162, 171) Provided to the transmission device (16, 17), the determination means (162, 171) for determining the transmission path selected by the selection means (161, 172) and the data block to be retransmitted to the transmission path determined by the determination means (162, 171) The transmission means (161, 172) for transmitting is provided in the transmission device (16, 17) on the transmission side, and a transmission line other than the transmission line in which the error has occurred is used, and the data block retransmission request in which the error has occurred and the data block based on this retransmission request. Data transmission method for characterized in that the transmission of the block.