JPH0761061B2 - ARQ method - Google Patents

Description

The present invention relates to an automatic repeat request (ARQ) method for detecting the presence or absence of an error occurring in a data transmission process and automatically retransmitting data for error correction. In particular, the present invention relates to an ARQ system that can obtain high transmission efficiency in a data transmission system with a bad line environment and many errors.

(Prior Art) In a data transmission system that requires highly reliable communication, an automatic repeat request (ARQ) method is widely used as a method for controlling an error in transmitted data.

In the general ARQ system, in a two-way communication system, when certain information is not received via the forward channel, or when it is received by mistake, the backward channel is automatically used to notify the sender side. Is requested to retransmit the same information.

Specifically, an error-detectable parity bit is added to information bits such as characters and transmitted through the forward channel, and the receiving side performs error detection. If there is no error according to the result, an affirmative response is returned. If there is, a negative response is sent back from the backward channel to the transmitting side, and when the transmitting side receives the positive response, the following information,
When a negative response is received, the same information is retransmitted.

(Problems to be Solved by the Invention) However, in the above-described conventional ARQ method using only error detection, for example, when the communication circuit is wireless, when it comes to radio waves using the ionosphere in a spatial state, fading occurs. , The atmospheric noise, etc., or the circuit condition may be deteriorated due to the time zone, and then many errors will occur in the data transmission process. In such a case, the conventional ARQ method has an error. As long as data is sent, negative response will be sent back to the sending side as many times as necessary, and data will be sent again and again until error-free data is sent, resulting in significantly longer transmission time. There was a problem with.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ARQ method capable of reducing the required transmission time by improving the transmission efficiency in the ARQ method under the condition of poor line quality.

(Means for Solving the Problem) The present invention for solving the problems of the above-mentioned conventional example is, in the ARQ system, a character consisting of a plurality of bits is an information block in units of a plurality of characters, and the information block is provided with a horizontal and vertical system. Using the odd-even parity method for the vertical bit group, using the error correction code for the horizontal bit group, the error correction coded bit and parity bit The information block is added to the information block to form a transmission block, which is transmitted in the unit of the transmission block, and the reception side performs error correction of the information block and the parity bit by the received error correction code, and then the information block after the error correction. Error detection is performed by checking the parity bit relationship after error correction by odd-even parity, and the error characters are counted, and the value is less than or equal to a predetermined value. In the case of, a positive response is given to the transmitting side, and in the case of a predetermined value or more, a negative response is given.

(Function) According to the present invention, attention is paid to the fact that the general transmission data has redundancy that information itself has, and that the reception side can often understand the content even if a small amount of error remains in the transmission result. , The residual error rate after error correction on the receiving side is measured, and if this is less than a predetermined value, an affirmative response is made without making a negative response, and the information part (information block) with few residual errors is retransmitted. Since the ARQ method that does not allow it is used, even if the line environment is bad, a small amount of residual error within an allowable range can be ignored, so that the required transmission time can be shortened.

(Example) An example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a transmission code according to an embodiment of the present invention, in which this one block is transmitted as a transmission block in transmission block units.

The ARQ method of the present embodiment uses a BCH code, information is set to 8 bits per character, and 21 characters can be included in one transmission block, and the amount of information is set to 21 bits per line. Corrected coded parity is 10 bits per row,
The information amount + correction coded parity bit is used as 31 bits per row. Here, 21 characters are arranged in 8 bits in 1 column and 21 bits in 1 row, and represent one block of the information block.

Ii, j in FIG. 1 represents the j-th bit in the i-th character, Pi represents the parity bit for the i-th character,
Error correction codes C1, j to C1 for the j-th row in the information amount
The error correction code Ck, j is represented by using 0, j.
Represents the k-th column and the j-th row in the error correction code bit, and C
k, p is an error correction code of Pi expressed by using C1, p to C10, p, and represents the kth bit.

The order of transmission of each bit is such that, in the transmission block of FIG. 1, the first row is left to right and the second row is left to right. I2,1 beginning with
~ C10,1, I1,2 ~ C10,2, ..., I1,8 ~ C10,8, P1 ~ C10, p
The transmission is performed in this order.

Next, regarding each processing of the transmission side and the reception side of the forward system in the ARQ system, FIG. 2 showing a configuration block diagram of the transmission side and FIG. 3 showing a configuration block diagram of the reception side.
It will be explained using FIG.

As shown in FIG. 2, the processing on the transmission side is performed by an encoding circuit (CODER) 1 for transmitting information to be transmitted from I1,1 to I1,8, I2,1.
... I2,8, ... I21,1 to I21,8 are received in the order of bits, and P1 is set to the information of I1,1 to I1,8 and P1 is set to the information of I2,1 to I2,8.
P2 is set to the information of I21,1 to I21,8, and even or odd parity is added to 8 bits of one character. To add even or odd parity, add 1 parity bit to the 8 bits that make up one character to be transmitted, and make sure that the number of "1" states in the code of one character is odd (odd parity). The check bit is adjusted so that it is even or even (even parity). For example, even parity means that the parity bit is "1" when the total of 8 bits is odd and "0" when the total of 8 bits is even.

After adding even or odd parity to the information in the encoding circuit 1, the error correction code Ck, j is added to the j-th bit row of I, and the error correction code is also added to the P bit row. By adding Ck, p, I1,1 to Ck, 1, I1,2 to Ck, 2, ...
... Send in the order of P1 to Ck, p. This becomes a transmission block, which is transmitted in transmission block units.

This data is sequentially modulated by the modulator (MOD) 2 according to the determined modulation method, and output to the transmitter (XMIT) 3. Transmitter 3
Then, the modulated signal is transmitted to the space in a predetermined radio wave format.

As shown in Fig. 3, the processing on the receiving side is the receiver (RCV).
The radio wave is received at 4 and converted into a demodulated signal. Demodulator (CE
MO) 5 demodulates the demodulated signal in a predetermined demodulation format and outputs the demodulated data.

Then, the error correction circuit (FEC) 6 restores the demodulated data so as to have the arrangement of the transmission blocks shown in FIG. Then, from the decoding table (not shown), the error correction code line,
C1,1 to C10,1, C1,2 to C10,2, ..., C1,8 to C10,8, C1, p
.About.C10, p, one row of 21-bit information is extracted, and information bit rows I1,1 to I21,1, I1,2 to I21, transmitted based on the information from the decoding table are used. 2, ...
, I1,8 to I21,8 and parity bit rows P1 to P21 are rewritten to perform error correction, and the error-corrected information and parity are output.

In the decoding table, 1 corresponding to the error correction code row is stored in advance.
Information of 21 bits per row is stored, and the information corresponding to a specific error correction code row can be extracted in the error correction circuit 6.

Next, the error detection counter (ERROR COUNTER) 7 corrects the error-corrected information blocks from the first I to the 21st I to the parity P1 after the error correction.
~ P21 performs odd-even check on the relationship with the character bit of the corresponding information block, detects inconsistencies as errors, calculates the incorrect number of characters in 21 characters, and compares the calculated value with a predetermined value . If it is less than or equal to this predetermined value, an affirmative response is sent to the feedback circuit, one transmission block is sent out, and thereafter, processing for removing the error correction code and odd-even parity from the transmission block is performed.

If the value is equal to or more than the predetermined value, a negative response is made to the feedback circuit, one transmission block is not transmitted, the data of one transmission block is erased, and the retransmission based on the negative response is waited.

The above-mentioned predetermined value is set by experimentally obtaining the value that maximizes the transmission efficiency according to the state of the transmission circuit.
Further, the predetermined value is also determined by the redundancy of information, that is, the tolerance of how much error the information contains, and in the present embodiment, the predetermined value is 21.
If there is an error of 1 to 5 characters in the character, an affirmative response is made to the feedback circuit without making a negative response.

According to the ARQ method of the present embodiment, general transmission data such as character information has redundancy that information itself has, and even if a small amount of error remains in the transmission result, the contents can be understood by the receiving side. In many cases, the error correction of the information block and parity bit is performed on the receiving side based on the error correction code attached to the information block, and then the error corresponding to the character bit string of the error-corrected information block is corrected. Perform an odd-even check in relation to the corrected parity bit, and
ARQ method that measures the residual error rate of residual errors in the entire information block, and if it is less than a predetermined value, makes an affirmative response without giving a negative response so that information blocks with few residual errors are not retransmitted. Therefore, even if the line environment is bad, a small amount of residual error in an allowable range can be ignored, so that it is possible to shorten the required transmission time and increase the transmission efficiency.

Further, according to the present embodiment, after performing error correction by the error correction code, by performing error detection by vertical parity for those exceeding the correction range, it is suitable for the ARQ system in the state of poor line quality, and By varying the predetermined value of the number of errors according to the state of the line, it is possible to adjust the required transmission time.

(Effect of the Invention) According to the present invention, general transmission data has redundancy that information itself has, and even if a small amount of error remains in the transmission result, the reception side can often understand the content. Focusing attention, the residual error rate after error correction is performed on the receiving side is measured, and if this is less than or equal to a predetermined value, an affirmative response is made without making a negative response, and thus an information part (information block) with few residual errors. Since the ARQ method that does not retransmit data is used, even if the line environment is poor, a small amount of residual error can be ignored within an allowable range, which shortens the required transmission time and improves transmission efficiency. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a transmission code according to an embodiment of the present invention, FIG. 2 is a configuration block diagram of a transmission side, and FIG. 3 is a configuration block diagram of a reception side. 1 ... Encoding circuit 2 ... Modulator 3 ... ... Transmitter 4 ... ... Receiver 5 ... ... Demodulator 6 ... ... Error correction circuit 7 ... ... Error detection counter

Claims (1)

[Claims] 1. A character consisting of a plurality of bits is used as an information block in units of a plurality of characters, and a horizontal and vertical system is used for the information block to encode a bit group in the vertical direction by an odd-even parity system to obtain a horizontal direction. The bit group is encoded with an error correction code, and the error correction coded bits and parity bits are added to the information block to form a transmission block, which is transmitted in the transmission block unit and received by the receiving side. After the error correction of the information block and the parity bit by the error correction code, the error detection is performed by checking the odd-even parity of the relationship between the information block after the error correction and the parity bit after the error correction, and the error character is counted. However, if the value is less than or equal to the specified value, a positive response is sent to the sender, and if the value is greater than or equal to the specified value, a negative response is sent. ARQ system to be.