JPH02166848A - Signal transmitting system - Google Patents

Abstract

PURPOSE:To send a correct code word even for a received word whose error can not be corrected by outputting the received word after adding a syndrome to the redundant bit of the received word when the error of the received word can not be corrected. CONSTITUTION:In a division circuit 1, by executing operation to obtain a remainder polynomial R(x) by dividing a received word polynomial A(x) by a generator polynomial G(x), the syndrome R of 16-bits, for instance, is obtained. In a ROM 2, in the case of the syndrome R is the one corresponding to one of a single error or a double error which are capable of being corrected, by accessing the address of the syndrome R, the erroneous place data of 16-bits is outputted. In a pulse generator 3, an error correction pulse P is generated at the timing of the bit to be corrected of the received word A according to the erroneous place data inputted from the ROM 2. In an erroneous bit correction circuit 4, the error is corrected by correcting the bit of the received word A at the timing at which the error correction pulse 2P is inputted from the generator 3. An addition circuit 7 adds the syndrome R supplied from a switch 6 to the part of the redundant bit of input from the circuit 4, and outputs them.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal transmission system, and particularly to a signal transmission system in a digital communication system that performs error correction using block codes.

[Conventional technology]

In digital communication systems, especially digital wireless communication systems, block codes are often used to correct transmission errors.

FIG. 2 is a block diagram of an example of such a digital communication system.

The data signal to be transmitted is divided into blocks at the terminal station II, redundant bits are added to the blocked information bits to form code words, and the codewords are sent to the transmission path. Intermediate relay station 12-1
In step 5, if there is an error in the received word that has been transmitted, it is corrected,
It is retransmitted with the correct code word. The terminal station 16 corrects any errors in the received word, removes redundant bits, and obtains a data signal.

For example, if the block code used is a code that can correct up to double errors, single errors and double errors in the received word can be corrected.
Severe errors are corrected to obtain the correct codeword. If three or more errors occur, the syndrome is classified as single error or double error.
When a syndrome of multiple errors is matched, the erroneous error is corrected, and the result of the error correction is a correct code word (although it contains an error). If the syndrome does not match either the single error syndrome or the double error syndrome, error correction cannot be performed. At this time, conventional signal transmission systems transmit received words that are not correct code words as they are.

[Problem to be solved by the invention]

Incidentally, the occurrence of an uncorrectable error in a certain relay section becomes particularly useful information for determining a failure in that relay section. However, in the conventional signal transmission system described above, since the received word that cannot be error corrected is sent out as is, for example, the line quality deteriorates in the relay section between relay stations 12 and 13, and the received word at relay station 13 is error-corrected. If an uncorrectable error occurs, the intermediate relay station 13 and its subordinate stations will determine that the received word contains an uncorrectable error.
Therefore, there is a drawback that information from a station that detects a received word whose error cannot be corrected cannot be used to determine in which relay section a failure has occurred.

An object of the present invention is to provide a signal transmission method that makes it possible to use detection information of uncorrectable received words for transmission path monitoring by transmitting correct code words even for uncorrectable received words. It's about doing.

[Means to solve the problem]

The signal transmission system of the present invention includes: a division circuit that obtains a syndrome from a block-encoded and transmitted received word; a speech correction pulse generation means that generates an error correction pulse based on the syndrome input from the division circuit; an error bit correction circuit that corrects errors in the received word based on the error correction pulse input from the error correction pulse generation means;
a detection circuit for detecting whether or not the error correction pulse is generated by the error correction pulse generation means; The circuit includes a switch that blocks the syndrome when the syndrome is generated, and an adder circuit that adds the passed output of this switch to the redundant bit of the output of the error bit correction circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The embodiment shown in FIG. It is configured with.

A is a received word that is a transmitted code word encoded into a block code capable of correcting single and double errors. Let A(x) be the polynomial whose coefficients are each bit of the received word A (hereinafter referred to as received word polynomial), and let G be the generating polynomial.
It is written as (x).

The division circuit 1 converts the received word polynomial A (x) into the generating polynomial G
By performing an operation to obtain a remainder polynomial R(x) by dividing by (x), a syndrome R of, for example, 16 bits is obtained from the received word A (which is a coefficient bit pattern of the remainder polynomial R(x)). This operation can be expressed as follows.

A(x)=Q(x) ・G(x)+R(x) (1
) If the received word A has no error and is a correct code word, the syndrome R is all "On."If the received word A is not a correct code word, the syndrome R is not all "0."

If the syndrome R is a syndrome corresponding to either a single error or a double error that can be corrected, the ROM 2 reads the address of the syndrome R.
Outputs 16-bit error location data. When syndrome R does not match an error syndrome that can be corrected (including when syndrome R is all '0')
, ROM2 does not output error location data. The pulse generator 3 generates an error correction pulse P at the timing of the bit to be corrected in the received word A based on the error location data input from the ROM 2. The error bit correction circuit 4 performs error correction by correcting the bits of the received word A at the timing when the error correction pulse 2P is input from the pulse generator 3. As a result, if the syndrome R matches the syndrome of an error that can be corrected, and if the syndrome R is all "0", the error bit correction circuit 4
The output of is the correct codeword, and in other cases it is not the correct codeword.

The detection circuit 5 detects whether the error correction pulse P is generated by detecting whether the ROM 2 outputs error location data. When the detection result is generated heat, the switch 6 is closed and the syndrome R output by the divider circuit 1 is
is supplied to the adder circuit 7. Also, when the detection result is a generator, the switch 6 is opened and the syndrome R is added to the adder circuit 7.
prevent it from being supplied to

The adder circuit 7 adds the syndrome R supplied from the switch 6 to the redundant bit portion of the input from the error bit correction circuit 4 and sends the result. Syndrome R from switch 6
is not supplied, the adder circuit 7 sends out the input from the error bit correction circuit 4 as is.

When the error correction pulse 2P is generated, the output of the error bit correction circuit 4 is a correct code word, and at this time, the adder circuit 7 sends out the output of the error bit correction circuit 4 as it is, so the sent signal is the correct codeword.

When the syndrome R does not match the syndrome of correctable errors, no error correction pulse P is generated, and as a result, the switch 6 is closed and the received word A output from the error bit correction circuit 4 without being corrected is Syndrome R
is added. If the polynomial of the addition result is written as B(x), then from equation (1), B(x) = A(x) + R(x) = Q
(x)·G(x) (2), and the signal sent from the adder circuit 7 at this time is also a code word.

Even when the received word A has no error and is a correct code word, the error correction pulse P is not generated, and the received word A is processed by the error correction circuit 4.
is passed through as it is, and the syndrome R is added in the adding circuit 7. At this time, since the syndrome R is all "0°', the addition result is the received word A itself, and the signal sent out at this time also has the correct code. It has become a word.

As explained above, the embodiment shown in FIG.
The signal sent from the source is the correct code word in any case.

In addition, in the present invention, when an error cannot be corrected, only the redundant bits are manipulated on the received word, and the equivalent operation is not applied to the information bits. No errors occur.

〔Effect of the invention〕

As explained above, the present invention adds a syndrome to the redundant bits of the received word and outputs the result when the received word is error-uncorrectable, thereby making it possible to send out a correct code word even for the received word whose error cannot be corrected. This has the advantage that information on stations that detect uncorrectable received words can be used to determine faulty relay sections in transmission path monitoring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of an example of a digital communication system. ■・・・Division circuit, 2・・・ROM, 3・
... Pulse generator, 4 ... Error bit correction circuit, 5 ... Detection circuit, 6 ... Switch, 7 ... Addition circuit. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] a division circuit that obtains a syndrome from a block-encoded and transmitted received word; an error correction pulse generation means that generates an error correction pulse based on the syndrome input from the division circuit; and an input from the error correction pulse generation means. an error bit correction circuit for error-correcting the received word based on the error correction pulse generated by the error correction pulse; a detection circuit for detecting whether or not the error correction pulse is generated by the error correction pulse generating means; and a detection result of the detection circuit is generated. a switch that passes the syndrome input from the divider circuit when the syndrome is not present and blocks the syndrome when the detection result indicates that the syndrome has been generated; A signal transmission method characterized by comprising an addition circuit that performs addition.