JPH0410261B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] In a data transmission/reception system, when an error in received data is detected on the receiving side, reading of the receiving side buffer memory is prohibited, the contents of the receiving side buffer memory are cleared, and the sending side buffer memory is cleared. This retransmission data transmission/reception method aims to shorten the time it takes for the retransmission data to reach the receiving side by clearing and writing the retransmission data, storing the retransmission data in a receiving side buffer memory on the receiving side, and then releasing read prohibition.

[Industrial application field]

The present invention relates to a retransmission data transmission/reception method and apparatus in a data transmission/reception system, and more particularly to a buffer memory control method for reducing the time required for retransmission data sent in response to an image data transmission error to reach a receiving side.

[Conventional technology]

Generally, high-speed data such as image data is transmitted and received in predetermined units, for example, in units of frames.
For this purpose, buffer memories are provided on both the transmitting side and the receiving side, which store a predetermined unit of data and are of a type in which data is read out in the order in which they are written. Data is usually encoded as differential data such as DPCM from the transmitting side and sent to the receiving side. The receiving side receives this difference data in the predetermined units, combines it with the already received data, and reproduces the difference data into the original data.

In this way, the data received by the receiving side is differential data, so if even one bit of error occurs on the transmission path in the received data, the difference will be added to the error in the subsequent reproduced data, and the errors in the reproduced data will gradually disappear. It will spread.

To prevent this, when an error is detected in the received data, the receiving section issues a data retransmission instruction to the transmitting section, and the transmitting section receives this and resends the correct data, which is not based on the previous screen, via the transmitting side buffer memory. That's what I do.

In the conventional data transmission/reception system, when writing correct data to the transmitting side buffer memory in response to a data retransmission instruction, it was written in the same manner as normal transmission data. In other words, while writing transmission data to the sending buffer memory or reading transmission data from the sending buffer memory, writing of retransmitted data is on standby, and the retransmitted data is not written to the sending side until after writing or reading of the transmission data is completed. It was written to buffer memory. Then, on the receiving side, reading of the data received from the sending of the data retransmission instruction until the retransmission instruction data included in the retransmission data is detected is prohibited, and after the retransmission instruction data is detected, the data is received again, decoded, and reproduced. Was.

[Problems to be solved by the invention]

As mentioned above, conventionally, retransmission data is written to the transmitting side buffer memory only after a retransmission instruction is received from the receiving side and after the normal transmission data writing or reading that is being written or read is completed. Therefore, there is a problem that the time required from issuing a retransmission instruction until the retransmission data reaches the receiving side is too long. In particular, in a multi-buffer memory configuration in which multiple transmitting side buffer memories, each storing one frame of data, are arranged in parallel to eliminate waiting time in reading out transmitted data, multiple transmitting side buffer memories are arranged in parallel to eliminate waiting time in reading out transmitted data. Since the transmission data of the frame is sent out, the above problem becomes even more serious.

[Means for solving problems]

In order to solve the above problems, the present invention provides a data transmission/reception system in which, when an error is detected in received data on the receiving side, reading of the buffer memory on the receiving side from which data is read out in the order of writing is prohibited, and both the sending and receiving sides Clear the buffer memory in which the data is read in the order in which they were written, write retransmission data that is correct data to the sending buffer memory, and then store the retransmitted data in the receiving buffer memory on the receiving side, and release the read prohibition to read the retransmitted data. There is provided a retransmission data transmission/reception method characterized in that the retransmission data is read from the receiving side buffer memory.

[Effect]

By clearing the buffer memory on the sending and receiving sides in response to error detection in received data, retransmission data can be written immediately, and the written data can be read immediately, reducing data retransmission in a short time. It will be done.

〔Example〕

Embodiments of the present invention will be described below based on the accompanying drawings. The data transmission/reception system according to an embodiment of the present invention shown in the figure includes a sending side S and a receiving side R.
It is made up of Sender S is data generator DG
, a first switch SW1, three transmitting side buffer memories BM1, BM2 and BM3, and a second switch SW1.
switch SW2 and a transmission side control circuit SC. The receiving side R includes a third switch SW3,
The three receiving-side buffer memories BM4, BM5, and BM6, the fourth switch SW4, the data receiving section DR, and the receiving-side control circuit RC are all buffer memories on the transmitting and receiving sides in a format in which data is read out in the order in which they are written. It is a buffer memory. A second switch SW2 on the sending side S and a third switch SW3 on the receiving side are connected by a transmission line L. The data receiving section DR is equipped with an error detection circuit ED, and the data generating section DG is equipped with an initialization circuit INI.
It is equipped with

When the error detection circuit ED detects no error in the received data, the data generation unit DG transmits the difference data from the data of one screen that was reproduced last time in the data reception unit DR via the first switch SW1. Write to any one of the sending side buffer memories BM1, BM2, and BM3. The transmitting side control circuit SC includes transmitting side buffer memories BM1, BM2,
While controlling the write or read timing in BM3 and controlling the first and second switches SW1 and SW2 to write transmission data to any one of the transmitting side buffer memories BM1, BM2, and BM3, Transmission data that has already been written is read out onto the transmission path L from one of the remaining transmission buffer memories.

On the receiving side, under the control of the receiving side control circuit RC,
The data transmitted through the transmission line L is sent to the receiving side buffer memory BM4 via the third switch SW3.
While writing to either BM5 or BM6, BM4,
The data is sequentially read from BM5 and BM6 to the data receiving unit DR via switch SW4. The data receiving unit DR decodes the received data and reproduces screen data.

The operation when the error detection circuit ED detects an error in received data will be described next.

When the error detection circuit ED detects an error in the received data, it gives a read inhibit signal (INH) to the reception side control circuit RC, which causes the reception side control circuit RC to turn off the fourth switch SW4 and close the reception side buffer memory. BM4, BM5, and BM6
Prohibits data reading from the data receiving unit DR. The error detection circuit ED also sends a data retransmission request signal (DREQ) to the initialization circuit INI in the data generation unit DG in response to error detection. When the receiving side control circuit RC also receives a read inhibit signal (INH) from the error detection circuit ED, it clears the contents of the receiving side buffer memories BM4, BM5, and BM6.

When the initialization circuit INI receives the data retransmission request signal (DREQ) from the error detection circuit ED,
In addition to creating retransmission data, the transmitter control circuit
Give the initialization instruction signal (INI2) to the SC. The retransmission data is correct data for one frame, not difference data from data that has already been transmitted, and includes a retransmission instruction bit indicating that it is retransmission data.

When the transmitting side control circuit SC receives the above initialization instruction signal (INIC2), the transmitting side buffer memory
After immediately clearing all BM1, BM2, and BM3, e.g.
The first switch SW1 is controlled to write retransmission data from the initialization circuit INI to BM1. The transmission side control circuit SC also controls the second switch SW2 to read the retransmission data from there immediately after writing it to the BM1 and send it to the transmission line L.

On the receiving side R, when the retransmission instruction detection circuit D detects the retransmission instruction bit in the retransmission data, it gives a retransmission instruction detection signal (D) to the receiving side control circuit RC, which causes the receiving side control circuit RC to switch the third switch SW3.
to immediately retransmit data from transmission line L.
For example, it is written to the buffer memory BM4 on the receiving side. After the receiving side control circuit RC finishes writing the retransmission data to BM4, the receiving side control circuit RC controls the data receiving section by a signal (INI1).
Notifies the DR that the retransmission data is ready, controls the fourth switch SW4 to cancel the read prohibition, and then sends the BM
4, the retransmission data is read out to the data receiving unit DR.

According to the above embodiment, as soon as the receiving section detects an error in the received data, both the transmitting side buffer memory and the receiving side buffer memory are cleared, so there is no need to wait for the completion of the buffer memory operation being read or written. , and retransmission data can be written and read immediately without having to wait for the completion of reading data already stored in the buffer memory.

Note that the present invention is not limited to the above embodiments; for example, the number of buffer memories may vary depending on the transmitting side,
Any number may be used on both receiving sides.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, when an error is detected in received data in a data transmission/reception system, retransmission data is sent after clearing the buffer memories on the transmitting side and the receiving side. The time from error detection to the time when retransmitted data reaches the receiving side is shortened, and in particular, the time during which a screen containing an error is displayed during image data transmission can be shortened.

[Brief explanation of drawings]

The accompanying drawing is a block diagram for explaining a retransmission data transmission/reception system according to an embodiment of the present invention. S...Sending side, R...Receiving side, DG...Data generation section, INI...Initialization circuit, BM1 to BM3...Sending side buffer memory, SC...Sending side control circuit, DR...Data receiving section, ED...Error detection circuit, BM4 ~BM
6... Receiving side buffer memory, RC... Receiving side control circuit, D... Retransmission instruction detection circuit.

Claims (1)

[Claims] 1. In a data transmission/reception system, when an error is detected in received data on the receiving side, reading of the buffer memory on the receiving side, where data is read out in the order of writing, is prohibited, and data is read out in the order of writing on the sending and receiving sides. After clearing the buffer memory and writing retransmission data, which is correct data, to the transmitting side buffer memory, and storing the retransmitted data in the receiving side buffer memory on the receiving side, read the retransmitted data from the receiving side buffer memory by canceling the read prohibition. A retransmission data transmission/reception method characterized by transmitting retransmission data. 2. The transmitting side is equipped with a data generating means, a transmitting side memory for storing transmission data from the data generating means, and a transmitting side control means for controlling writing/reading of data to and from the transmitting side memory, and the receiving side , a receiving side memory for storing data from the sending side memory, a data receiving means for receiving data from the receiving side memory, and a receiving side control means for controlling writing/reading of data to/from the receiving side memory. In a data transmission/reception system, wherein data is read from each of the transmitting side memory and the receiving side memory in the order in which they are written, the data receiving means comprises an error detection means,
When the error detecting means detects an error in the received data, the error detecting means inhibits reading of data from the receiving side memory to the data receiving means under the control of the receiving side control means and clears the receiving side memory, and A data retransmission request signal is sent to the data generation means, and the data generation means includes initialization means, and the initialization means responds to the data retransmission request signal to send a correct data retransmission request signal including retransmission instruction detection data. The retransmission data that is data is created, and the retransmission data is written into the transmission side memory after the transmission side memory is cleared under the control of the transmission side control means in response to the data retransmission request signal. Yes, the receiving side includes retransmission instruction detection means for detecting the retransmission instruction detection data from the retransmission data sent from the sending side memory, and the retransmission instruction detection means detects the retransmission instruction detection data. In response to the detection, under the control of the receiving side control means, the retransmission data is written in the receiving side memory and then the prohibition of reading data from the receiving side memory is canceled. retransmission data transmission/reception device.