JPH03297236A - Data transmission system - Google Patents

Abstract

PURPOSE:To realize a high error check capability by providing an error check function employing an error check code, converting an m-bit data into an n-bit according to a coding rule of one to one correspondence and transferring the data as an mBnB block processing code so as to check an error. CONSTITUTION:An error check code generating circuit 11 receives signals 101,102 to obtain a 1st code employing exclusive-OR of all bits and a 2nd code employing exclusive-OR of optional two-bits, and outputs an error check signal 103. Flip-flop circuits 13-15 receive a clock signal 104 from a timing generating circuit 16 and output respectively error check signals 106,107,108 synchronously with signals 101-103. A frame data generating circuit 12 receives the signal 104 and outputs a frame data 105 synchronously with the signals 106-108. A time division multiplex circuit 17 receive the signals 105-108 and outputs a multiplex signal 111. An mBnB block code processing circuit 18 converts the 4-bit signal 111 into a 5-bit multiplex signal 112 and the signal 112 is transmitted as a transmission signal of this data transmission system.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a data transmission system that has a function of detecting errors that occur during transmission, and in particular, the present invention relates to a data transmission system that has a function of detecting errors that occur during transmission. The present invention relates to a data transmission system having a function of detecting errors by converting into n bits according to a one-to-one encoding rule and transmitting the data as an mBnB blocking code.

(Prior Art) Conventionally, various data transmission systems for binary signals have been considered for detecting errors occurring during transmission. In particular, in high-speed optical transmission, the mBnB blocking code total code n is 2.
There is a data transmission method that detects errors using the above integers, where m is smaller than n. In this data transmission system, each data consisting of m bits of the original signal is converted into n bits according to a one-to-one correspondence encoding rule, and the entire mBnB blocking code is transmitted. A data transmission method using the mBnB blocking code will be described below.

If all bit patterns of data consisting of m bits are associated with codes consisting of n bits on a one-to-one basis, a surplus bit pattern will be generated in the code consisting of n bits since m<n. Therefore, on the transmitting side, data consisting of m bits is
The received n bits are converted into a code made up of bits and transmitted, and the receiving side judges whether the bit pattern of the code made up of n bits corresponds to data made up of m bits that have not been associated with each other in advance. If the bit pattern corresponds to data consisting of m bits, it is considered normal transmission data with no transmission error, and if the received code consisting of n bits is a bit pattern corresponding to data consisting of m bits,
This is a data transmission method in which if a bit pattern does not correspond to data made up of bits, the transmission data is considered to have a transmission error. By appropriately selecting the total codes m and n of the mBnB blocking code, it is possible to provide high transmission efficiency characteristics suitable for the transmission data and the transmission device. Furthermore, since the transmission device is relatively simple, the cost required for the transmission circuit can be reduced. The data transmission system using all mBnB blocking codes is widely used because it has the above-mentioned advantages.

However, this data transmission system in which all mBnB block codes are encoded cannot sufficiently detect transmission errors, and when decoding a code consisting of n bits into data consisting of m bits, several 1-bit errors occur during transmission. This may expand to a bit error.

Therefore, in actual data transmission, after adding an error detection code to each data of the original signal to detect transmission errors, mB
All nB blocked codes are transmitted. Conventionally, as a simple error detection method, there is an error detection method in which a code obtained by the exclusive OR of all bits of data of an original signal is transmitted as an error detection code. Furthermore, there is a method of using a cyclic code or a convolutional code as an error detection code, which has higher error detection ability than the error detection using an exclusive OR code. Therefore, in conventional data transmission systems, after adding an error detection code consisting of an exclusive OR code of all bits of the data, a cyclic code, or a convolutional code to each data of the original signal, all codes of the mBnB blocking code are transmitted. was.

(Problem to be Solved by the Invention) However, it is necessary to add an error detection code consisting of an exclusive OR of all bits of the original signal, a cyclic code, or a convolutional code to each data of the original signal to completely block the mBnB blocking code. Data transmission systems that use code transmission have the following drawbacks.

Transmission error detection using a code based on the exclusive OR of all bits of the original signal does not detect all code errors in the mBnB blocking code, making it impossible to detect an even number of errors included in the decoded m-bit signal. There were drawbacks. In addition, transmission error detection using a cyclic code or acceptance code has higher error detection ability than transmission error detection using a code based on the exclusive OR of all bits of the original signal, but it requires a larger circuit scale and is less expensive. The drawback was that the device could not be realized. Furthermore, for transmission error detection using a cyclic code, the length of the cyclic code is a discrete value based on a mathematical formula, for example, 7
, 15, 31. . . , etc., resulting in poor suitability for the intended data transmission system.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a data transmission system that has high transmission error detection ability, can be realized at low cost, and has high adaptability.

(Means for Solving the Problems) The first data transmission method according to the present invention is characterized in that each piece of information data consists of m bits (m is an integer of 2 or more) (i is an integer of 1 or more). Generating an error detection code for each piece of information data of the signal, and combining the one error detection code into one piece of error detection data consisting of m bits,
Channel-based multiplexing is performed in which each information data of the i signals and the error detection data are time-division multiplexed for each data unit, and each data consisting of m bits of the time-division multiplexed signal is multiplexed one-to-one.
It is characterized in that it is converted into an mBnB blocking code of n bits (n is an integer greater than m) according to a corresponding encoding rule, and then transmitted.

Further, a second data transmission method according to the present invention is the first data transmission method described above, wherein the error detection code is a predetermined set of at least one set of information data each consisting of m bits of the i signals. The code is characterized by being an exclusive OR of p bits (11 is an integer greater than or equal to 2 and less than or equal to m).

Furthermore, a third data transmission method according to the present invention is the first data transmission method described above, in which the error detection code excludes all bits of information data consisting of m bits of each of the i signals. The first code is formed by an exclusive OR of at least one predetermined set of two bits of information data consisting of m bits, and the second code is formed by an exclusive OR of at least one set of m-bit information data.

(Operation) The data transmission system of the present invention uses an error detection code and data conversion based on a one-to-one encoding rule as means for detecting transmission errors. In error detection using an error detection code, a transmitting side generates an error detection code for original data, transmits the original data and the error detection code, and a receiving side detects errors in the original data based on the error detection code. Error detection in data conversion using one-to-one correspondence encoding rules is as follows:
On the transmitting side, the original data consisting of m bits is converted into n and t data (n>
Errors are detected by checking whether the bit pattern exists in a predetermined one-to-one correspondence encoding rule when decoding the received n and t data on the receiving side. do. Note that the number of bits of the error detection data consisting of i error detection codes must be the same as the number of bits m of the data of the original signal in order to carry out multiplex transmission for each channel.

As the error detection code, a code obtained by exclusive ORing of A bits (ρ is an integer of 2 or more and m or less) of the data of the original signal is used. Error detection using this exclusive OR code is performed by taking the exclusive OR of the predetermined ρ bits of the data of the original signal on the transmitting side, transmitting the data and the result of the exclusive OR, and receiving the The exclusive OR of a predetermined p bits of the received data is performed on the side, and the result is compared with the result performed on the transmitting side to detect errors.

Assuming that the error detection code is composed of a first code based on the exclusive OR of all bits of data and a second code based on the exclusive OR of two predetermined bits of data, this first code Since odd-numbered bit errors in decoded data can be detected by error detection using the code, the one-to-one correspondence encoding rule ensures that errors that cannot be detected become odd-numbered bit errors in decoded data as much as possible. is set to Further, as the second code, an exclusive OR of two bits of data is selected so that even-numbered bit errors in the decoded data can be detected to the maximum extent possible.

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

FIG. 1 is a block diagram showing an embodiment of a data transmitting device that implements the data transmission method of the present invention.

This data transmitting device 10 each transmits 4 pieces of data.
This is a device that time-division multiplexes and transmits two signals consisting of bits. Is this the data transmitter in Figure 2? It is a figure which shows the timing chart of IfIO. The operation of this data transmitting device 10 will be explained below using the timing chart shown in FIG.

The error detection code generation circuit 11 receives signals 101 and 102 each consisting of 4 bits, and generates signals 101 and 102.
Error detection is performed by calculating the first code by exclusive OR of all bits of data and the second code by exclusive OR of arbitrary two bits of data for each of It is output as a signal 103. FIG. 3 shows an example of the error detection signal 103. In this example,
The first code is the result of the exclusive OR of all bits of each data, and the second code is the result of the exclusive OR of the 2nd and 3rd bits of each data. . Flip-flops 13, 14, and 15 each receive a tarok signal 104 supplied from the timing generation circuit 16.
The signals 101, 102 and the error detection signal 103 are synchronized to generate the signals 106, 107 and the error detection signal 10.
Output as 8. The frame data generation circuit 12 inputs the clock signal 104 and outputs frame data 105 synchronized with the signals 106 and 107 and the error detection signal 108.The time division multiplexing circuit 17 converts the four input signals into four signals.
This circuit performs time-division multiplexing for each bit code length, and the frame data 105, signals 106 and 107, and error detection signal 1
08 are multiplexed for each channel using clock signals 109 and 110 supplied from the timing generation circuit 16 and output as a multiplexed signal 111. The mBnB encoding circuit 18 is a circuit that converts an input 4-bit signal into a 5-bit signal according to the one-to-one correspondence encoding rule shown in FIG. is converted into a multiplexed signal 112 and outputted, and the multiplexed signal 11
2 is transmitted as a transmission signal in the data transmission system of the present invention. This multiplex signal 112 is a frame synchronization signal synchronized with frame data 105.

FIG. 5 is a block diagram showing an embodiment of a data receiving device that implements the data transmission system of the present invention.

As shown in FIG. 6, this data receiving device 50 receives a multiplexed signal 112, which is a 5-bit signal sent to the transmission path 60 from the data transmitting device 10 shown in FIG. This device extracts the components of the data signal and detects transmission errors in the data signal. nB
The mB decoding circuit 51 receives a multiplexed signal 11 which is a 5-bit signal.
2 is input and converted into a multiplexed signal 111 which is a 4-bit signal according to the one-to-one correspondence encoding rule shown in FIG.

Here, if the bit pattern of the received multiplexed signal 112 does not conform to the one-to-one correspondence encoding rule shown in FIG. 4, it is assumed that a transmission error has occurred and a decoding error signal 501 is output. The error detection circuit 52 receives the multiplexed signal 111, which is a 4-bit signal, and detects transmission errors in the signals 106 and 107 using the error detection signal 108 multiplexed with the multiplexed signal 111, as shown in FIG. Here, the first code and second code included in the error detection signal 108 are used to detect this transmission error. In the error detection circuit 52, the signal 106
When a transmission error is detected in at least one of the data error signal 50
Outputs 2. A decoding error signal 501 and a data error signal 502 are synchronized by flip-flops 53 and 54, respectively, input to an OR circuit 55, and output as an error signal 503. The frame data detection circuit 56 inputs the multiplexed signal 111, detects the frame data 105 included in the multiplexed signal 111, and outputs the time interval as a timing signal 504.

The timing generation circuit 57 inputs the timing signal 504 and outputs a clock signal 505 for time-division separation of the signals 101 and 102 from the multiplexed signal 111. The time division separation circuit 58 inputs the multiplexed signal 111 and the clock signal 505, and uses the clock signal 505 to time division separate the signals 101 and 102 from the multiplexed signal 111, and further time-expands the signals 101 and 102 to the flip-flop 13 of the data transmitting device 10.
The signals input to 14 are output as signals 101 and 102. At this time, the signal 101. which is output from the time division separation circuit 58.
Whether or not a transmission error in 102 has been detected can be determined by monitoring the error signal 503.

Next, the transmission error detection ability of the data transmission method described using the data transmitting device 10 and the data receiving device 50 will be described. Here, consider the data of a signal whose bit pattern is 0000''. When this data is converted to 5-bit data (485B encoding), it becomes ``00111'' according to the one-to-one correspondence encoding rule in Figure 4. , error detection for a 1-bit transmission path error in this data will be explained using FIG. 8. Bit pattern "00"
If a 1-bit transmission path error occurs in the transmission path 60 in data No. 111'', it will become one of the five types of data shown in Figure 8. The bit patterns of No. 111'' and No. 5 are shown in Figure 4. Since this is a bit pattern that does not follow the one-to-one correspondence encoding rule shown in Figure 4, it can be detected as a transmission error.The data of bit patterns N011, No. 2, and N004 are processed according to the one-to-one correspondence encoding rule shown in Figure 4. When decoding to 4bit data (<584B decoding), data with three bit patterns shown in Fig. 8 is obtained.Among the data with these three bit patterns,
For No. 1 data, transmission errors can be detected using the second code based on the exclusive OR of the 2nd and 3rd bits of the original data, and for No. 2 and No. 64 data, the exclusive OR of all bits of the original data is used to detect transmission errors. Transmission errors can be detected using the first code based on the logical sum. 1st and 2nd by exclusive OR
Detection of transmission errors with the codes No. 1, No. 2, and the exclusive OR result in the original data. No,
This can be detected by the fact that the result of the exclusive OR of the data in No. 4 is different. Therefore, all 1-bit transmission path errors can be detected. In the data transmission system of this embodiment using the one-to-one correspondence encoding rule shown in FIG. 4, all 1-bit transmission path errors can be detected.

Next, the ability to detect 2-bit transmission path errors will be explained using FIG. 9. When data with bit pattern “0000” is converted to 5-bit data (485B encoding),
"00111" from the one-to-one correspondence encoding rule shown in Figure 4
becomes. When a 2-bit transmission path error occurs in the transmission path 60, the data "00111" becomes 10 types of data as shown in FIG. In Figure 9, No, 1, N
o, 2, no.

4. No. 8. No, 9. Since No. 10 is not included in the one-to-one correspondence encoding rule in FIG. 4, a transmission error can be detected. No, 3. No, 5. No
, 6. When the four 5-bit data No. 7 is converted into 4-bit data according to the table in FIG. 4 (584B decoding), the four bit patterns shown in FIG. 9 are obtained. Transmission errors in decoded bit data No. 4 and No. 5 can be detected by a parity check using the first code based on the exclusive OR of all bits of the original data. 4 and data N
0.6 can detect transmission errors using the second code obtained by exclusive ORing of the second and third bits of the original data. This is the result of exclusive OR in the original data and No.
This is because the results of exclusive OR on data No. 5, No. 6, and No. 6 are different. No.

In the two data, No. 3 and N097, no transmission error can be detected and they are received as normal data. Therefore, approximately 80% of 2-bit transmission path errors can be detected.

As explained above, in the data transmission system using the data transmitting device f10 and the data receiving device 50 shown in FIGS. 1 and 5, all 1-bit transmission path errors in the 4-bit data transmission path are detected. Approximately 80% of 2-bit transmission line errors can be detected.

In the data transmission method of this embodiment, the number of original signals to be multiplexed and transmitted is 2, and the data of the original signals is 4 bits, but the number of original signals to be transmitted and the number of bits of the data of the original signals are different. In that case, it is necessary to make the number of bits of one data of the error detection signal formed by the error detection code of each original signal equal to the number of bits of data of the original signal. In addition, data on the transmission path is m
The values of m and n used in the BnB blocking code are also m=4. A number other than n = 5 may be used. In this case, if the value of n is larger than the value of m, the ability to detect transmission errors will increase, but the data transmission efficiency will decrease. Therefore, m and n The value of must be determined by fully considering the ability to detect transmission errors and the data transmission efficiency.Furthermore, the one-to-one correspondence encoding rule is based on the exclusive OR of all bits of data. and a second code based on the exclusive OR of 2 bits in at least one set of data, and the ability to detect transmission errors by the mBnB blocking code. It must be determined to maximize the ability to detect transmission errors.

(Effects of the Invention) As explained in detail above, the data transmission method of the present invention is based on the first code based on the exclusive OR of all bits of the data and the exclusive OR of a set of 2 bits in the data. High error detection capability can be obtained by combining error detection using an error detection code formed with the second code and error detection using an mBnB blocking code.

Furthermore, since the error detection capability is a code based on exclusive OR, the detection circuit has a simple configuration and can be realized at low cost. Furthermore, since the number m of data bits of the original signal to be transmitted can be freely set, it is possible to realize a highly compatible data transmission method that is not limited by the number of bits of data of the signal to be transmitted.

The present invention has the above effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a data transmitting device that implements the data transmission method of the present invention, and FIG. 2 is a diagram showing a timing chart of the data transmitting device 10 shown in FIG.
FIG. 3 is a diagram explaining the generation of the error detection signal 103, and FIG.
The figure shows a one-to-one correspondence encoding rule, FIG. 5 is a block diagram showing an embodiment of a data receiving device that implements the data transmission method of the present invention, and FIG. 6 shows the configuration of the data transmission method of the present invention. 7 is a diagram illustrating detection of transmission errors using the error detection signal 108, and FIGS. 8 and 9 are diagrams showing 2-bit transmission in the data transmission system realized by the data transmitting device 10 and the data receiving device 50. FIG. 2 is a diagram illustrating the ability to detect path errors. 11...Error detection code generation circuit, 12...Frame data generation circuit, 13, 14, 15.53.54...
Flip-flop, 16.57... Timing generation circuit, 17... Time division multiplexing circuit, 18... mBnB encoding circuit, 51... nBmB decoding circuit, 52...
Error detection circuit, 55...OR circuit, 56...frame data detection circuit, 58...time division separation circuit.

Claims (3)

[Claims] (1) Generating an error detection code for each piece of information data of i (i is an integer of 1 or more) signals each of which has m bits (m is an integer of 2 or more);
channel-based multiplexing in which the i error detection codes are combined into one m-bit error detection data, and each information data of the i signals and the error detection data are time-division multiplexed for each data unit; The method is characterized in that each data consisting of m bits of the time division multiplexed signal is converted into an mBnB blocking code consisting of n bits (n is an integer larger than m) according to a one-to-one correspondence encoding rule, and then transmitted. Data transmission method. (2) The error detection code is m for each of the i signals.
2. The data transmission method according to claim 1, wherein the code is an exclusive OR of at least one set of predetermined l bits (l is an integer of 2 or more and m or less) of information data consisting of bits. . (3) The error detection code is a predetermined set of at least one set of a first code obtained by exclusive OR of all bits of information data consisting of m bits of each of the i signals and information data consisting of m bits. 2. The data transmission system according to claim 1, wherein the second code is an exclusive OR of two bits.