JPH04111554A - Arq communication system - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency by fractionizing original data to transmit data again at the time of receiving a retransmission request continuously a prescribed number of times. CONSTITUTION:A terminal machine 1 is provided with a line control part 11, an ARQ control part 12, a data processing part 13, a data storage part 14, and a NACK frequency storage part 15. The ARQ control part 12 performs division of data to blocks, data error discrimination, fractionization of data blocks, and transmission and reception of a confirmation (ACK) signal and a retransmission request (NACK) signal. When the NACK signal is received continuously a prescribed number of times, the transmission state is judged to be bad, and the transmission side fractionizes original data to retransmit data, and the volume of this retransmission data is smaller than the original block data volume. Thus, a probability of normal transmission is raised to improve the transmission efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application This invention relates to an ARQ communication system that can improve transmission efficiency.

(b) Conventional technology In the field of handwritten communication, for example, to improve the transmission accuracy when transmitting data from one device to another using a line with relatively poor line conditions, such as a wireless communication line. A RQ (Automatic RepeatReq)
It has been proposed to adopt the UEST) communication method. In this ARQ communication method, data to be transmitted from one device (transmission side) is divided into blocks, transmitted with an ARQ code, and the other device (reception side) determines errors in the received data for each block. ACK if there is no error (confirmation)
If there is an error in the signal, a NACK (retransmission request) signal is sent to the transmitting side.

(c) Problems to be Solved by the Invention In the conventional ARQ communication system described above, when the receiving side determines that there is an error and sends a NACK signal to the transmitting side,
Upon receiving each NACK signal, the transmitting side retransmits the original data. However, if the line is a wireless transmission line or the like and the transmission conditions are extremely poor, it may be difficult to transmit one block perfectly if the block data is large, and the receiving side may send a NACK signal many times. The transmitting side has to retransmit the same block data many times, which can significantly deteriorate transmission efficiency.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide an ARQ communication system that can ensure relatively high transmission efficiency even in poor transmission conditions.

(d) Means and action for solving the problem A of this invention
In the RQ communication method, data is transmitted from one device to another via a transmission line, and errors in the data received by the other device are determined for each data block, and if there is an error in the data, a retransmission request is issued. In a communication method in which the data is sent to the one device and the other device that receives the retransmission request retransmits the data, if the one device receives the retransmission request a predetermined number of times in a row, the original data for which the retransmission request was made The data is divided into parts and retransmitted.

In this ARQ communication method, when a retransmission request (NACK signal) is received a predetermined number of times in a row, the transmission condition is determined to be poor, and the sending side divides the original data into smaller pieces and retransmits the data. The converted data is naturally a block with a smaller amount of data than the original block data, so
The probability of successful transmission is higher than before, and transmission efficiency is improved.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 2 is a block diagram of a terminal in a communication system in which the present invention is implemented. The terminal device 1 has a line control section 11 and an AR
Q control section 12, data processing section 13, data storage section 14,
and a NA, CK number storage unit 15. This terminal device 1 is connected to the other party's terminal device 3 via a communication line 2. The other party's terminal 3 also has the same configuration as the terminal 1. The communication line 2 may be a wired analog line or a digital line, or may be a wireless communication line.

The line control unit 11 is a connection (interface) unit to various communication lines 2. The ARQ control unit 12 performs data blocking, data error determination, data block segmentation, and sending and receiving of ACK signals and NACK signals. The data processing unit 13 performs processing other than communication control. For example, in the case of a handwritten communication terminal, encoding of facsimile data,
Processes computer data, etc. NACK count storage unit 1
5 stores the number of consecutively received NACKs. Transmission data is stored in the data storage unit 14, and at the time of transmission, it is divided into blocks by the ARQ control unit 12 as shown in FIG. Block data consists of subdivision bits (A), block numbers (B), information (I), and correction bits (F). The fragmentation bit distinguishes whether a block is a frame obtained by fragmenting original data or not. The block number is a serial number assigned to each block of transmission data. Information is pure data to be transmitted. The correction bit is an additional bit for checking whether there are any errors in the frame (block). For example, all data is divided by a polynomial and the remainder is added.

Next, the transmission operation of the embodiment terminal 1 will be explained with reference to the flowchart shown in FIG.

When the operation starts, block data B with block number 1 is first transmitted (step 5T1). After sending,
It waits for a NACK signal or an ACK signal to be returned from the other party (step ST2.5T3). When the ACK signal is received, it means that the current transmission data has been successfully received by the other party, and the variable n indicating the block number is set to 1.
Increment to n=2 (step 5T4),
Returning to step STI, the next block of data B2 is transmitted.

On the other hand, the determination in step ST2 of receiving a NACK signal during data transmission is YES, and in the next step ST5, a variable N indicating the number of times the NACK signal is received is incremented by 1, and N=1, and in the initial state N= O), followed by N=3
(Step 5T6). At the beginning, N=1,
Since the determination is No, the original block data is retransmitted to the other party (step 5T7), and the process returns to step ST2. If the transmission condition is poor and the receiving side cannot receive data normally, retransmission and return of the NACK signal are repeated. N.A.C.
When the K signal is received three times in a row, N=3, and if the determination is YES in step ST6, the process moves to step ST8, and after clearing the variable N, the process moves to segmented data retransmission processing (step 5T9).

The fragmented data retransmission process transmits the information of the original block data,
The data is further divided into smaller pieces and retransmitted, and a specific example thereof will be described later. When the retransmission process of the fragmented data is completed, that is, when the transmission of the original block data is completed due to fragmentation, the variable n is incremented by 1 and the process proceeds to step 5.
T4) Return to step STI and move on to transmitting the next block data.

After the NACK signal is received once or twice, the ACK
When the signal is received, before proceeding to the fragmented data retransmission process, the determination is made in step ST2 and YES in step ST3.
Then, the variable n is incremented by 1 in step ST4, and the process returns to step STI to transmit the next block data.

Next, a specific example of retransmission processing of segmented data will be described. Assume that normal block data currently being transmitted is shown in a of FIG. Since it is normal block data, the subdivision focus is "0", the block number is 1, and the information to be transmitted is 1. ．． 1. , L, I4. If the NACA signal is received three times in a row while transmitting this block data,
Next, the process moves to fragmented data retransmission processing. First, as shown in Fig. 4b, the subdivision focus is set to "1", the block number is set to 1, the information of the original data is divided into four, and the I
Transmit only 1. When this subdivided data is received normally, the next subdivided data shown at C in FIG. 4 is transmitted. In this subdivision data, the subdivision bit is “1”
The block number remains the same, the block number is 2, and the information is divided I
Only 2 will be available. When this segmented data is also received normally, the segmented data shown in d and e of FIG. 4 is sequentially retransmitted in the same manner. For retransmission of segmented data, N
When the ACK signal is returned, the segmented data will be further retransmitted. To return from the fragmented data retransmission state to the normal block data transmission state, the fragmentation bit is returned to "0" as shown in f of Fig. 4, and the block number is changed to the state of a in Fig. 4. The block number 1 of the block data is followed by 2, and the information is also It', 1, +, l, ",
Assume that the amount of data is large at 14°.

In the above embodiment, the number of receptions of the NACK signal to proceed to the fragmented data retransmission process is set to N=3, but the present invention is of course not limited to this value, and depending on the system situation, N=1 or N= 2, or N may be 4 or more.

(F) Effects of the Invention According to this invention, when retransmission requests are received a predetermined number of times in succession, the original data is segmented and divided and retransmitted, so if the line condition becomes poor, Correspondingly, the amount of data can be transmitted in smaller amounts, reducing the probability that a retransmission request will be made for each piece of data, and as a result, transmission efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is a flow diagram for explaining the transmission operation of a terminal in a communication system according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the communication system according to an embodiment of the invention, and FIG. FIG. 4 is an explanatory diagram showing the format of block data and segmented data for explaining the segmented data retransmission process of the terminal. 1 and 3: terminal device, 2: communication line, 12: ARQ control section, 15: NACK number storage section. Patent applicant: Shimadzu Corporation Agent
Patent Attorney Shigeru Nakamura Diagram Diagram■

Claims (1)

[Claims] (1) Data is transmitted from one device to the other device via a transmission line, errors in the data received by the other device are determined for each data block, and if there is an error in the data, a retransmission request is sent to the one device. In an ARQ communication method in which one device receives a retransmission request and retransmits the data, if the one device receives a retransmission request a predetermined number of times in a row, the original data for which the retransmission request was made is An ARQ communication method characterized by subdividing and retransmitting the data.