JP2001189714A - Data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the conventional data transmission system needs about twice transmission time of that in the case of a batch transmission because a data response arrives from a receiving side at every time when one data block is transmitted. SOLUTION: In this system, the data transmitted from a terminal 15a to a terminal 15b through a transmission control part 1 and a transmission control part 1b by half-duplex communication is divided into a plurality of blocks, all blocks are transmitted at once and only an error block by error checking is retransmitted, thereby reducing the transmission time, and also each block is provided with a block number and the complement of the block number, thereby reinforcing the error checking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system in half-duplex communication such as a satellite link, and more particularly to a protocol which can cope with a low link speed and poor link quality conditions.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing a data transmission system in a conventional half-duplex communication. In the figure, reference numeral 1 denotes a transmission control unit for controlling communication, which is arranged on each of a transmission side and a reception side. 2 is a transmission request from the transmission side, 3 is a transmission request 2
4 is a data block A, which is one data block obtained by dividing transmission data.
Is a data response to the data block A4, 6 is a data block B transmitted following the data block A, 7 is a data response to the data block B6, 8 is a data block C transmitted after the data block B, and 9 is a data response. This is a response when a transmission error occurs in the data block C in the data retransmission request for the block C8. 1
0 is a data block C to be retransmitted, and 11 is a data response to the data block C10. 12 is an end signal which is a signal indicating the end of the transmission data, and 13 is an end signal 12
Is a data response to

[0003]

In such a conventional data transmission system, a data response is received from the receiving side every time one data block is transmitted. Therefore, every time a data block is transmitted, the transmission time is about twice as long as when all data is transmitted without receiving a response.

[0004] In addition, conventionally used SUM, C
The error correction function such as RC does not check the arrangement of blocks when transmitting data in block divisions. In systems where the arrangement of blocks is important, there is a question about the reliability of the data. . Even if transmission between connected devices is guaranteed, it is considered that no guarantee is given between the transmitting side and the final receiving side terminal in consideration of the protocol of the entire system.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a data transmission system that performs data transmission in a short time even if a transmission error occurs and improves data quality. The purpose is to get.

[0006]

In a data transmission system according to the present invention, a first method for dividing data into a plurality of blocks, adding information about a block arrangement to each block, and transmitting data for each block is provided. A terminal device, a first transmission control unit to which the first terminal device is connected, a second transmission control unit connected to perform half-duplex communication with the first transmission control unit, The second transmission control unit is connected to the second transmission control unit, receives data transmitted from the first terminal device, and transmits a response signal to the first terminal device when all the blocks constituting the data are received. The terminal device, the second terminal device, for each block constituting the received data, performs an error check including a block array, if there is an error, retransmit the errored block of the first And forms a response signal to request the end device.

[0007] Further, information on a block arrangement given to each block of data transmitted by the first terminal device includes:
It is the block number of each block and the complement of this block number. A response signal for requesting the second terminal device to retransmit an error block is formed in response to a random error or a burst error.

Further, each block of data transmitted by the first terminal device contains information indicating the end or continuation of the data. Further, the first terminal device transmits a request signal including a transmission ID indicating the first terminal device and a reception ID indicating the second terminal device to the second terminal device prior to data transmission.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 According to the present invention, a data transmission system is configured to transmit data divided into a plurality of blocks at once using a half-duplex line, perform an error check on a receiving unit, and request retransmission of only an error block. It was done. In order to improve the transmission quality of data transmitted by this data transmission system, in addition to parity and CRC error correction, each block has its block number and its complement to ensure the assurance of each character unit and frame unit. As a result, it is possible to perform reception in a reliable block arrangement.

[0010] Also, in response to the possibility of burst or random errors in line quality, BER (Bi
When a random error having a t Error Rate of about 10 ⁻³ is detected on the receiving side, all error block numbers are enumerated, a retransmission request is performed, and when data cannot be received in a burst or in the middle, for example, Rather than listing all the block numbers, a request for retransmission is made, for example, after the m-th block.

FIG. 1 is a block diagram showing a data transmission system according to a first embodiment of the present invention. In FIG. 1, 1a is a transmission control unit for controlling communication, 1b is a transmission control unit for controlling communication, 15a is a terminal connected to the transmission control unit 1a, 15b is a terminal connected to the transmission control unit 1b, 1
6a and 16b are line controllers connected to the transmission controllers 1a and 1b by signal lines 17 and control lines 18, respectively. The signal line 17 is a line for performing half-duplex communication, and the line controllers 16a and 16b are connected by the signal line 17.

FIG. 2 is a sequence diagram showing a selective retransmission type block continuous transmission method of the data transmission system according to the first embodiment of the present invention. In FIG. 2, 1a, 1b, 15
a and 15b are the same as those in FIG.
The terminal 15a is a first terminal device on the transmitting side, the terminal 15b is a second terminal device on the receiving side, therefore the transmission control unit 1a is a first transmission control unit on the transmitting side, and the transmission control unit 1b is a This is a second transmission control unit. Reference numeral 20 denotes a transmission request transmitted from the terminal 15a, and reference numeral 21 denotes a transmission request response to the transmission request 20, which responds "reception possible" or "reception not possible" together with detailed contents shown in FIG. Reference numeral 22 denotes each data block to be transmitted, and reference numeral 23 denotes a data response to the transmission of each data block, which responds "normal" or "retransmission" together with detailed information shown in FIG. FIG.
Then, after all the data blocks 22 are received, an error check is performed.

As shown in FIG. 2, 20 to 23 are transmitted between the terminal 15a and the transmission control unit 1a, and then transmitted between the transmission control unit 1a and the transmission control unit 1b.
Next, the transmission is performed between the transmission control unit 1b and the terminal 15b.
24, after the terminal 15b receives all the data blocks 22 and transmits the data response 23 to the transmission control unit 1b,
In the transmission processing notification transmitted from the terminal 15b, "normal termination" or "transmission failure" is transmitted together with detailed information shown in FIG. Reference numeral 25 denotes a transmission process notification response indicating “OK” transmitted by the terminal 15a to the transmission process notification 24.

FIG. 3 is a diagram showing an arrangement of data blocks in the data transmission system according to the first embodiment of the present invention. FIG. 3A shows a data format.
FIG. 3B shows a status 1 format which is a request signal transmitted from the terminal on the transmission side, and FIG. 3C shows a status 2 format which is a response signal to the request signal. In FIG. 3, the numbers shown below each field indicate the field length in bits.

In FIG. 3, 27 is a SYNC character indicating the start of a frame, 28 is a block number of each block,
Reference numeral 29 denotes a block number and a complement number * block number, 30 denotes DATA forming a fixed-length data portion of 1017 bytes, and an additional code is required to set a transparent mode in a variable length. Therefore, by setting the length to a fixed length, the application can easily determine the data. 31 is a TERMINAL indicating the end or continuation of the data block, and 32 is a CRC for checking each block for errors.

Reference numeral 33 denotes a data block number indicating the number of blocks to be transmitted. By transmitting the data block number 33 in a transmission request, the data reception time can be predicted on the receiving side. Reference numeral 34 denotes a type 1 indicating the type of the request signal, and includes information whose details are shown in FIG. 35 is a transmission ID indicating a data transmission source, 36 is a reception ID indicating a data reception destination
Indicates the value of the transmission source device and the value of the reception destination device, respectively.

Reference numeral 37 denotes an error block number indicating an error block number, and reference numeral 38 denotes TYPE2 indicating a type of a response signal.
And as shown in FIG. Reference numeral 39 denotes TYPE3 indicating the response content of the response signal, and reference numeral 40 denotes TYPE4, which is a detailed description of TYPE3, and includes the information shown in FIG. The transmission timing conditions for the status 1 as the request signal and the status 2 as the response signal are as shown in FIG.

FIG. 4 is a diagram showing detailed contents of each data block of the data transmission system according to the first embodiment of the present invention. FIG. 5 is a diagram showing details of a request signal of a data block in the data transmission system according to the first embodiment of the present invention. FIG. 6 is a diagram showing details of a response signal of a data block in the data transmission system according to the first embodiment of the present invention. FIG. 7 is a diagram showing transmission timing conditions of a request signal and a response signal of the data transmission system according to the first embodiment of the present invention.

Next, the operation of the data transmission system configured as shown in FIG. 1 will be described. In the sequence shown in FIG. 2, first, the transmission request 20 is transmitted from the terminal 15a to the transmission control unit 1a.
Is performed, the transmission request response 21 is received from the transmission control unit 1a, and each data block 22 is transmitted at a stretch. Next, the transmission is transmitted from the transmission control unit 1a to the transmission control unit 1b, and is transmitted from the transmission control unit 1b to the terminal 15b. At this time, the transmission control unit 1a, the transmission control unit 1b, and the terminal 15b each perform an error check. On the receiving side, if an error occurs, determine how random errors, burst errors, etc. occur, and select a retransmission request method for only error blocks,
Request to sender.

Next, an error check method and data assurance will be described in detail. In the error correction, a block number 28 and a * block number 29 which is a complement of the block number are included in each block so as to ensure the arrangement of the block unit in addition to the parity and the CRC. Therefore, in a system in which the block arrangement is particularly important, for example, when the block number of the third block becomes erroneous 2, the block is conventionally determined to be the second block, but the block has its complement. Therefore, the certainty of the recognition of the block number is increased.

The processing of the retransmission request can be selected depending on how the burst or random error occurs. For example,
If it is a random error, you can request an error retransmission for the specified block.If all errors occur after a certain block, such as when all errors occur from a burst or in the middle, only the data after that block is retransmitted. Can be requested. How this error occurs is determined by the conditions of the line status and the line speed.

Further, the data transmission system of the present invention is devised as follows. TERMI shown in FIG.
By using the NAL 31, the data block can be continued arbitrarily, so that the data length can be made variable. Since the transmission mode is transparent, the type of data does not matter.

Further, since the transmission ID 35 and the reception ID 36 are included in the request signal, the terminal of the transmission partner can be selected according to the type of data. Furthermore, in order to ensure transmission guarantees throughout the system, as well as guarantees between the transmitting and receiving devices, if transmission is performed via another device, a response from the receiving terminal is received, so that the transmitting side can reliably send to the receiving side. It becomes possible to recognize that the data has been transmitted. In addition, by allowing the host to select the line monitor information in a certain cycle, data can be transmitted efficiently even when there are n terminals. According to the first embodiment, data transmission can be performed in a short time, data reliability can be improved, and furthermore, transmission guarantee can be improved in the entire system.

[0024]

Since the present invention is configured as described above, it has the following effects. A first terminal device that divides data into a plurality of blocks, adds information about a block arrangement to each block, and transmits data for each block, and a first transmission control to which the first terminal device is connected A second transmission control unit connected to perform half-duplex communication with the first transmission control unit,
The second transmission control unit is connected to receive data transmitted from the first terminal device, and to transmit a response signal to the first terminal device when all blocks constituting the data are received. The second terminal device performs an error check including a block arrangement for each block constituting the received data, and when there is an error, retransmits the block with the error to the first terminal device. Since the response signal is formed to request the device, transmission can be performed in a short time even if a transmission error occurs, and data transmission in a reliable block arrangement can be performed.

Further, the information on the block arrangement given to each block of the data transmitted by the first terminal device is as follows:
Since the block number of each block and the complement of the block number are used, the block arrangement can be surely confirmed. In addition, since the response signal for requesting retransmission of the error block by the second terminal device is formed according to a random error or a burst error, an optimal response signal can be formed.

Furthermore, since each block of data transmitted by the first terminal device includes information indicating the end or continuation of the data, the block can be continued as appropriate, and the data length can be varied. can do. The first terminal device has a transmission ID indicating the first terminal device.
And a request signal including a reception ID indicating the second terminal device,
Before sending data, it sends to the second terminal device,
Depending on the type of data, the terminal device of the transmission partner can be selected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a data transmission system according to a first embodiment of the present invention.

FIG. 2 is a sequence diagram showing a selective retransmission block continuous transmission method of the data transmission system according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an arrangement of data blocks in the data transmission system according to the first embodiment of the present invention.

FIG. 4 is a diagram showing details of each data block of the data transmission system according to the first embodiment of the present invention.

FIG. 5 is a diagram showing details of a request signal of a data block in the data transmission system according to the first embodiment of the present invention.

FIG. 6 is a diagram showing details of a response signal of a data block in the data transmission system according to the first embodiment of the present invention.

FIG. 7 is a diagram showing transmission timing conditions of a request signal and a response signal of the data transmission system according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a data transmission method in conventional half-duplex communication.

[Explanation of symbols]

1 transmission controller, 15 terminal, 16 line controller, 17 signal line, 18 control line, 20 transmission request, 21 transmission request response, 22 each data block,
23 data response, 24 transmission processing notification, 25 transmission processing notification response, 27 SYNC character, 28 block number, 29 * block number, 30 DAT
A, 31 TERMINAL, 32 CRC, 33
Number of data blocks, 34 TYPE1, 35 transmission ID, 36 reception ID, 37 error block number, 38 TYPE2, 39 TYPE3, 40
TYPE4.

Continuation of the front page (72) Inventor Takahito Noda 2-4-1, Hamamatsucho, Minato-ku, Tokyo Mitsubishi Space Software Co., Ltd. F-term (reference) 5K014 AA03 DA02 FA05 HA09 5K034 AA02 AA09 DD03 GG04 HH11 MM03

Claims (5)

[Claims] In a data transmission system configured to perform half-duplex data communication between a first terminal device and a second terminal device, data is divided into a plurality of blocks and each block has a block arrangement. A first terminal device that adds information and transmits the data for each block, a first transmission control unit to which the first terminal device is connected, and a half-duplex communication with the first transmission control unit. A second transmission control unit connected to perform, connected to the second transmission control unit, receives data transmitted from the first terminal device, all the blocks constituting the data are received A second terminal device that transmits a response signal to the first terminal device when the second terminal device performs an error check including a block arrangement for each block configuring the received data. A data transmission system, wherein the response signal is formed so as to request the first terminal device to retransmit the erroneous block when there is an error. 2. The information according to claim 1, wherein the information relating to the block arrangement given to each block of the data transmitted by the first terminal device is a block number of each block and a complement of the block number. Data transmission system. 3. The data transmission system according to claim 1, wherein a response signal for requesting retransmission of the error block by the second terminal device is formed in response to a random error or a burst error. . 4. The data terminal according to claim 1, wherein each block of data transmitted by the first terminal device includes information indicating the end or continuation of the data.
The data transmission system according to claim 1. 5. The first terminal device transmits a request signal including a transmission ID indicating the first terminal device and a reception ID indicating the second terminal device to the second terminal device prior to data transmission. The data transmission system according to any one of claims 1 to 4, wherein: