JPH04280132A - Information security method - Google Patents

Abstract

PURPOSE:To improve the reliability of communication information when information of a same content in a frame form transferred consecutively for plural number of times is received and communication information is extracted from a frame and to prevent number of times of consecutive transmission from the sender side from being increased. CONSTITUTION:An error consecutive detection signal outputted from a count processing circuit 13 when a pattern extracted from a reception frame is compared with a set pattern and a prescribed number of dissident result is consecutive for a prescribed number of times, and a coincidence signal outputted from a coincidence processing circuit when communication information extracted from the reception frame is compared with a preceding communication information for each time and the coincident result is consecutive for a prescribed number of times, are referenced to discriminate the correctness of the communication information.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a frame structure including at least a frame synchronization pattern and communication information, which is transmitted from a transmitting device to a receiving device multiple times with the same content. The present invention relates to an information protection method that extracts the communication information from the information received and prevents the communication information from being mistakenly recognized as the correct communication information even though the communication information is incorrect due to a code error. be. [0002] The line termination device in the optical fiber subscriber line transmission system operates by local power supply, and layer 1 is constantly supplied with power from the commercial power supply, and there is a method of transmitting alarm issuance prohibition information to the station side when the power supply is cut off. Although it has been proposed,
The present invention is applicable, for example, to a station that receives such alarm issuance prohibition information after being transferred. [0003] In a system that transfers information in the form of a frame structure between a transmitting device and a receiving device, there is a method for increasing the reliability of communication information contained in the information in the frame structure. It is necessary to prevent incorrect communication information from being mistakenly recognized as correct communication information due to code errors occurring in the system on the receiving side. Conventionally, in such cases, erroneous recognition has been prevented by using an error detection signal based on a frame synchronization pattern on the receiving side.This will be explained in detail below. [0004] Transfer information, which generally has a frame structure, includes a frame synchronization pattern for frame synchronization, communication information (information that users want to communicate between opposing devices), and whether or not errors occur in the entire transfer information. Consists of error monitoring information and other information for monitoring. A specific example of error monitoring information is CRC (Cyclic Redundancy).
There is a method called "dancy check" in which the entire transfer information is divided by a constant and the "remainder" is used as error monitoring information. FIG. 6 is an explanatory diagram showing the format of transfer information that is transferred in a frame. In the figure, F indicates a frame synchronization pattern, I indicates communication information, C indicates error monitoring information, and E indicates other information. As shown in this figure, the transfer information includes frame synchronization pattern, communication information,
The same frame format containing error monitoring information and other information is transferred multiple times. In the following explanation, the frame synchronization pattern, communication information, error monitoring information, and other information that are repeatedly transferred in each frame transfer are referred to as "frame synchronization pattern of each time,""communication information of each time,""error monitoring information of each time," and "frame synchronization pattern of each time." The information is explained under the names "Monitoring information" and "Other information for each episode." Further, in the conventional example and the embodiment of the present invention described below, only one-way information transfer is shown, but information transfer in the opposite direction can also be carried out by providing the same device and circuit. Furthermore, there are cases where the information whose reliability is to be increased is the entire communication information and cases where it is only a part of the communication information, but no distinction is made here. FIG. 2 is a block diagram showing a conventional example of an information protection method. The frame configuration transfer information transmitted from the transmitting device 1 is input to the input terminal 101 of the receiving device 2 and further input to the input terminal 102 of the synchronization separation circuit 3. The synchronization separation circuit 3 separates the transfer information having a frame structure into a frame synchronization pattern, communication information, error monitoring information, and other information. Communication information, output terminal 105 outputs error monitoring information, output terminal 10
Other information is output from 6. The frame synchronization pattern outputted from the output terminal 103 is inputted to the input terminal 107 of the pattern matching circuit 4, and is matched with a preset pattern. If the pattern differs, an error detection signal is outputted from the output terminal 108, and counting is performed. It is input to the input terminal 109 of the processing circuit 5. When the error detection signal inputted to the input terminal 109 of the counting processing circuit 5 continues a preset number of times depending on the transmission method, an out-of-synchronization signal is outputted from the output terminal 110, and the information recognition circuit 6 input terminal 11
1 is input. On the other hand, the communication information output from the output terminal 104 is input to the input terminal 112 of the coincidence processing circuit 7 and the input terminal 113 of the information recognition circuit 6. The correspondence processing circuit 7 compares the communication information input to the input terminal 112 of the coincidence processing circuit 7, and if the communication information matches the communication information a preset number of times consecutively, outputs a coincidence signal from the output terminal 114. output and input terminal 115 of the information recognition circuit 6
is input. The information recognition circuit 6 determines that the content of the communication information input to the input terminal 113 is correct when a coincidence signal is input to the input terminal 115 and no synchronization signal is input to the input terminal 111. to decide. The preset number of times in the matching processing circuit 7 of this conventional example is less than or equal to the number of times preset depending on the transmission method in the counting processing circuit 5. This conventional circuit configuration has a drawback that there is a high probability that the information recognition circuit 6 will erroneously recognize erroneous communication information as correct communication information due to a code error occurring in the system. Referring again to FIG. Another conventional example will be explained. In this conventional example, the preset number of times in the matching processing circuit 7 exceeds the number of times preset depending on the transmission method in the counting processing circuit 5, and this point differs from the conventional example described above. . At this time, although there is a low probability that the information recognition circuit 6 will erroneously recognize incorrect communication information as correct communication information due to a code error occurring in the system, the transmitting device 1
more than a preset number of times in
It is necessary to continuously transmit frames with the same content. Therefore, since the preset number of times depending on the transmission method in the counting processing circuit 5 is generally about 4 to 7 times, communication information of the same content is continuously sent to the transmitting device 1 a number of times exceeding this number. This has the disadvantage that the number of transmissions increases (the burden on the transmitter 1 becomes heavier). FIG. 3 is a block diagram showing yet another conventional example. The frame configuration transfer information transmitted from the transmitting device 1 is input to the input terminal 101 of the receiving device 2 and further input to the input terminal 102 of the synchronization separation circuit 3. The synchronization separation circuit 3 separates the frame configuration transfer information into a frame synchronization pattern, communication information, error monitoring information, and other information.The output terminal 103 of the synchronization separation circuit 3 separates the frame synchronization pattern, and the output terminal 104 outputs the communication Error monitoring information is output from the output terminal 105, and other information is output from the output terminal 106. The frame synchronization pattern outputted from the output terminal 103 is inputted to the input terminal 107 of the pattern matching circuit 4, and is matched with a preset pattern.
If they are different, an error detection signal is output from the output terminal 108 and input to the input terminal 109 of the counting processing circuit 5 and the input terminal 118 of the information recognition circuit 6. When the error detection signal inputted to the input terminal 109 of the counting processing circuit 5 continues for a preset number of times depending on the transmission method, an out-of-synchronization signal is outputted from the output terminal 110, and the error detection signal is inputted to the input terminal 109 of the information recognition circuit 6. It is input to terminal 119. The information recognition circuit 6 determines that the communication information input to the input terminal 120 is correct when no out-of-synchronization signal is input to the input terminal 119 and no error detection signal is input to the input terminal 118. [0012] With such a circuit configuration, the probability that erroneous communication information due to a code error occurring in the system is mistakenly recognized as correct communication information is low, and the transmission device 1 is made to continuously transmit the same requested communication information. The number of times may be small, but if the frame synchronization pattern in the transfer information is incorrect due to a code error that occurs in the system, the content of the communication information is determined to be incorrect even if the content of the communication information is not incorrect. There is a drawback that the contents of the communication information may not be recognized. FIG. 4 is a block diagram showing still another conventional example. Transfer information of the frame structure transmitted from the transmitting device 1 is input to the input terminal 101 of the receiving device 2, and is input to the input terminal 121 of the error detection circuit 10 and the input terminal 102 of the synchronization separation circuit 3. The synchronization separation circuit 3 separates the transfer information input to the input terminal 102 into a frame synchronization pattern, communication information, error monitoring information, and other information, and outputs the frame synchronization pattern and the output terminal from the output terminal 103 of the synchronization separation circuit 3. Communication information from 104, output terminal 105
Error monitoring information is output from the terminal 106, and other information is output from the output terminal 106. The frame synchronization pattern outputted from the output terminal 103 is inputted to the input terminal 107 of the pattern matching circuit 4, and is matched with a preset pattern.
If they are different, an error detection signal is output from the output terminal 108 and input to the input terminal 109 of the counting processing circuit 5. The error detection signal inputted to the input terminal 109 of the counting processing circuit 5 is outputted to the output terminal 110 as an out-of-synchronization signal when the error detection signal is inputted to the input terminal 109 of the counting processing circuit 5 consecutively a preset number of times depending on the transmission method.
and is input to the input terminal 122 of the information recognition circuit 6. On the other hand, the error monitoring information outputted from the output terminal 105 is inputted to the input terminal 123 of the error detection circuit 10. It performs the same calculation as when it was generated, compares the calculation result with the error monitoring information input to the input terminal 123, and outputs an error detection signal from the output terminal 124 if they do not match. The information recognition circuit 6 outputs an input terminal 126 when an out-of-synchronization signal is not input to the input terminal 122 and an error detection signal is not input to the input terminal 125.
determines that the communication information entered is correct. With such a circuit configuration, the information recognition circuit 6 determines that incorrect communication information due to a code error occurring in the system is correct communication information.
The probability of misrecognition is low, and the number of times the transmitter 1 is required to continuously transmit communication information with the same content is small. If the information is incorrect, there is a drawback that the content of the communication information is determined to be incorrect even if the communication information is not incorrect. FIG. 5 is a block diagram showing yet another conventional example. Transfer information of the frame structure transmitted from the transmitting device 1 is input to the input terminal 101 of the receiving device 2, and is input to the input terminal 102 of the synchronization separation circuit 3 and the input terminal 121 of the error detection circuit 10. The synchronization separation circuit 3 converts the transfer information input to the input terminal 102 into a frame synchronization pattern,
The output terminal 103 of the synchronization separation circuit 3 outputs the frame synchronization pattern, the output terminal 104 outputs the communication information, the output terminal 105 outputs the error monitoring information, and the output terminal 106 outputs the error monitoring information. Other information is output respectively. The frame synchronization pattern outputted from the output terminal 103 is inputted to the input terminal 107 of the pattern matching circuit 4, and is matched with a preset pattern.
If they are different, an error detection signal is output from the output terminal 108 and input to the input terminal 109 of the counting processing circuit 5 and the input terminal 127 of the information recognition circuit 6. When the error detection signal inputted to the input terminal 109 of the counting processing circuit 5 continues for a preset number of times depending on the transmission method, an out-of-synchronization signal is outputted from the output terminal 110, and the error detection signal is inputted to the input terminal 109 of the information recognition circuit 6. It is input to terminal 128. On the other hand, the error monitoring information outputted from the output terminal 105 is inputted to the input terminal 123 of the error detection circuit 10, and the error detection circuit generates error monitoring information on the transmission side based on the transfer information inputted to the input terminal 121. The same calculation as before is performed, the calculation result is compared with the error monitoring information input to the input terminal 123, and when there is a mismatch, an error detection signal is output from the output terminal 124, and the error detection signal is sent to the information recognition circuit 6. It is input to input terminal 129. The information recognition circuit 6 has no out-of-synchronization signal input to the input terminal 128, no error detection signal input to the input terminal 127, and no error detection signal input to the input terminal 129. When the input terminal 130
determines that the communication information entered is correct. With such a circuit configuration, the information recognition circuit 6 determines that incorrect communication information due to a code error occurring in the system is correct communication information.
The probability of misrecognition is low, and the number of times the transmitter 1 is requested to continuously transmit the same communication information may be small, but due to code errors that occur in the system, information other than the communication information in the transfer If the information is incorrect, or if the frame synchronization pattern in the transfer information is incorrect due to a code error that occurs in the system, there is a drawback that the communication information is determined to be incorrect even if the communication information is not incorrect. . [0019] The present invention improves the drawbacks of the above-mentioned prior art, increases the reliability of determining whether there is an error in transferred communication information, and reduces the burden on the transmitter side. It is an object of the present invention to provide an information protection method that does not require heavy transmission (no need to increase the number of consecutive transmissions of communication information with the same content). [Means for Solving the Problems] In order to achieve the above object, in the present invention, a frame structure including at least a frame synchronization pattern and communication information is transmitted from a transmitting device to a receiving device multiple times with the same content. From the information that has been
When implementing an information protection method that extracts the communication information and prevents the communication information from being mistakenly recognized as correct communication information even though it is incorrect communication information due to a coding error, it is necessary to A synchronization separation circuit extracts and outputs at least a frame synchronization pattern and communication information from the information, and a frame synchronization pattern output from the synchronization separation circuit is fetched and compared with a preset setting pattern, and when the result is a mismatch. a pattern matching circuit that outputs a mismatch signal; a counting processing circuit that receives the mismatch signal from the pattern matching circuit and outputs a continuous error detection signal when the mismatch signal continues a predetermined number of times; and an output from the synchronization separation circuit. It repeats the process of importing the received communication information and comparing it with the previously imported communication information that should have the same content, and outputs a match signal when a matching result is obtained consecutively for more than a preset number of times. I decided to prepare a matching processing circuit. [Operation] When determining whether the communication information outputted from the synchronization separation circuit is correct or incorrect, reference is made to the continuous error detection signal outputted from the counting processing circuit and the coincidence signal outputted from the coincidence processing circuit. I decided to do it. As a result, the reliability of the transferred communication information is increased, and the burden on the transmitting device side does not have to be heavy. [Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. Although this embodiment shows only one-way information transfer, it can also be implemented in the opposite direction by providing the same device and circuit. Furthermore, there are cases where the information whose reliability is to be increased is the entire communication information and cases where it is only a part of the communication information, but no distinction is made here. The present embodiment will be described in detail below with reference to FIG. 1, where 1 is a transmitting device, 2 is a receiving device, 3 is a synchronization separation circuit, 4 is a pattern matching circuit, 7 is a matching processing circuit, and 13 is a counting process. The circuit 6 is an information recognition circuit. Transfer information of the frame structure transmitted from the transmitting device 1 is input to the input terminal 101 of the receiving device 2,
Furthermore, it is input to the input terminal 102 of the synchronous separation circuit 3. The synchronization separation circuit 3 converts the transfer information into a frame synchronization pattern,
The output terminal 103 of the synchronization separation circuit 3 outputs the frame synchronization pattern, the output terminal 104 outputs the communication information, the output terminal 105 outputs the error monitoring information, and the output terminal 106 outputs the error monitoring information. Other information is output respectively. The frame synchronization pattern outputted from the output terminal 103 is inputted to the input terminal 107 of the pattern matching circuit 4, and is matched with a preset pattern. If the pattern differs, an error detection signal is outputted from the output terminal 108, and counting is performed. Input terminal 13 of processing circuit 13
It is input to 0. When the error detection signal inputted to the input terminal 130 of the counting processing circuit 13 continues a preset number of times, a continuous error detection signal is outputted from the output terminal 132, and the error detection signal is outputted from the input terminal 130 of the information recognition circuit 6. 133. On the other hand, the communication information output from the output terminal 104 is
The signal is input to the input terminal 112 of the matching processing circuit 7 and the input terminal 134 of the information recognition circuit 6. The communication information input to the input terminal 112 of the match processing circuit 7 is output from the output terminal 114 when the match processing circuit 7 compares the contents of the communication information each time and matches a preset number of times in succession. A coincidence signal is output and input to the input terminal 135 of the information recognition circuit 6. The information recognition circuit 6 determines that the communication information input to the input terminal 134 is correct when a coincidence signal is input to the input terminal 135 and a continuous error detection signal is not input to the input terminal 133. The reliability of communication information in this embodiment is expressed by the following equation. Q={1-(1-P)J }N ×[1-{1-(
1-P)F }M ]Q: Reliability of communication information P: Probability of code error occurrence J: Number of bits composing communication information F: Number of bits composing frame pattern N: Set by coincidence processing circuit 7 Number of times M: Number of times set in the counting processing circuit 13 In this embodiment, the matching processing times 7 and the counting processing circuit 13
The preset number of times can be arbitrarily set depending on the reliability of the required communication information and the probability of error occurrence during the transfer process in the system. Specifically, when the probability of code error occurrence is 10-4,
When the number of times the coincidence processing circuit 7 is set is 1 and the number of times the counting processing circuit 13 is set is 2, the reliability Q of communication information is
is (10-4)2 ×[1-{1-(1-10-4)
5 }] is 9.995×10 −9 . Further, when the number of times the matching processing circuit 7 is set is 3 times and the number of times the counting processing circuit 13 is set is 3 times, the reliability Q of the communication information is (10-4)3 × [1-{1-( 1-10
-4) 5 } 3 ] and obtain the value 10-11. [0027] As explained above, the information protection method according to the present invention protects the received transfer information when an error occurs in the process of transferring information in a frame structure between opposing devices. The reliability of the communication information contained therein can be increased, and the number of consecutive transmissions of the same communication information required of the transmitter can be reduced. Below, we will calculate the numerical values in specific cases and clarify the effects in detail. As an example, frame transfer information includes 5 bits of frame synchronization pattern, 1 bit of communication information, 5 bits of error monitoring information, and 77 bits of other information.
In the case of 8 bits, in the conventional example and the embodiment of the present invention, the effect of preventing incorrect communication information from being mistakenly recognized as correct communication information is achieved when the probability of code error occurrence (code error rate) is 0.5 (frame Let's compare the case of (out-of-synchronization state). In conventional example 1 shown in FIG. 2, if the preset number of times for the counting processing circuit 5 is 7 times and the preset number of times for the coincidence processing circuit 7 is 3 times depending on the transmission method, erroneous communication occurs. The probability of misrecognizing information as correct communication information (misrecognition rate) is the probability that one bit of communication information will be incorrect three times in a row, and is expressed as the cube of the code error rate, which is (0.5) 3
=0.125. Similarly, in the conventional example 2 shown in FIG.
If the set number of times is 7, and the preset number of matching processing circuits 7 is 8, the false recognition rate is the probability that one bit of communication information will be erroneous 8 times in a row and the frame synchronization pattern error will not be 7 times in a row. It is expressed by the following formula. (0.5)8 ×[1-{1-(1-0.5)5
}7]≒7.784×10−4 Similarly, in conventional example 3 in FIG. expressed. (0.5)×(1-0.5)5 ≈0.016 Similarly, in conventional example 4 shown in FIG. It is the product of the probability that an error will not be detected by the error monitoring code (miss rate). In the case of 5 bits of error monitoring information using CRC for error monitoring, the miss rate is generally 1/25, and the misrecognition rate is expressed by the following formula. (0.5)×(1/25)≒0.0160030
Similarly, in conventional example 5 in FIG. 5, the false recognition rate is the probability that one bit of communication information is erroneous once, the probability that an error in the entire transferred information including communication information is not detected by the error monitoring code (miss rate), and the frame synchronization pattern. It is the product of the probability of not making a mistake. Assuming that error monitoring is the same as in Conventional Example 4, the false recognition rate is expressed by the following formula. (0.5)×(1/25)×(1-0.5)5
≒4.883×10 −4 [0031] In the embodiment of the present invention shown in FIG.
Assuming that the preset number of times is 3, the misrecognition rate is the probability that one bit of communication information will be erroneous three times in a row and the frame synchronization pattern will not be erroneous three times in a row, and is calculated by the following formula. (0.5)3 × [1-{1-(1-0.5)5
}3]≈0.011 On the other hand, the probability of erroneously determining that the content of the communication information is incorrect when the content of the communication information is not incorrect in the conventional example and the embodiment of the present invention will be compared. As with the previous comparison, the transfer information of the frame is 5 bits of frame synchronization pattern, 1 bit of communication information,
A comparison will be made for the case where the error monitoring information is 5 bits and other information is 778 bits, and the code error occurrence rate is 10-4. In Conventional Example 1, if the content of the communication information is not incorrect, there is no possibility that the content of the communication information is incorrectly determined to be incorrect. In Conventional Example 2, the probability of incorrectly determining that the content of the communication information is incorrect when the content of the communication information is not incorrect is the probability that the frame synchronization pattern is incorrect seven times in a row, and {1-(1- 10-4)5 }7 =7.802×10
-24 In Conventional Example 3, the probability of incorrectly determining that the content of the communication information is incorrect when the content of the communication information is correct is the probability that the frame synchronization pattern is incorrect, and is 1-(1-10 -4) 5 = 4.999 x 10-4 In conventional example 4, when the content of the communication information is not incorrect, the probability of incorrectly determining that the content of the communication information is incorrect is that the transfer information other than the communication information is incorrect. , and the probability of being detected by the error monitoring code is {1-(1-10-4)788}×
1/25 = 2.368×10 −3 In Conventional Example 5, when the content of communication information is not erroneous, the probability that the content of the communication information is incorrect is determined as follows: Or the transfer information other than the communication information is incorrect,
And the probability of being detected by the error monitoring code is {1-(1-10-4)5}+[{1-(1-1
0-4)788 }×1/25] −{1-(1-
10-4)5 }×[{1-(1-10-4)788
}×1/25 ] =2.867×10 −3 In the embodiment of the present invention, the coincidence processing circuit 7 calculates the preset number of times depending on the transmission method, and the counting processing circuit 13 calculates the preset number of times, 3 times. times, the probability that the content of the communication information is incorrectly determined to be incorrect when the content of the communication information is not incorrect is the probability that the frame synchronization pattern is incorrect three times in a row, and is calculated by the following equation. {1-(1-10-4)5}3 =1.294×10
-10 As is clear from the above calculation of specific values, the information protection method according to the present invention:
In a system that transfers information in a frame structure between opposing devices, if an error occurs in the process, it increases the reliability of the received information and reduces the number of consecutive transmissions of the same communication information required of the transmitting device. There is an advantage.

[Brief explanation of the drawing]

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

FIG. 2 is a block diagram showing a conventional example of an information protection method.

FIG. 3 is a block diagram showing another conventional example of an information protection method.

FIG. 4 is a block diagram showing another conventional example of an information protection method.

FIG. 5 is a block diagram showing still another conventional example of an information protection method.

FIG. 6 is an explanatory diagram of a frame configuration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Transmitting device, 2... Receiving device, 3... Synchronization separation circuit, 4...
Pattern matching circuit, 5... Counting processing circuit, 6... Information recognition circuit, 7... Matching processing circuit, 10... Error detection circuit, 13... Counting processing circuit

Claims (1)

[Claims] 1. A frame structure that includes at least a frame synchronization pattern and communication information, and extracting the communication information from among information that has been transferred to a receiving device multiple times with the same content from a transmitting device; This is an information protection method that prevents erroneously recognizing that communication information is correct communication information even though it is incorrect communication information due to a coding error, and the method a synchronization separation circuit that extracts and outputs the frame synchronization pattern, and a pattern matching circuit that takes in the frame synchronization pattern output from the synchronization separation circuit and compares it with a preset setting pattern, and outputs a mismatch signal when the result does not match. A counting processing circuit that takes in the mismatch signal from the pattern matching circuit and outputs a continuous error detection signal when the mismatch signal continues a predetermined number of times, and a counting processing circuit that takes in the communication information output from the synchronization separation circuit, and takes in the communication information that was previously taken in. A matching processing circuit is prepared which repeatedly compares the communication information with the same content each time and outputs a matching signal when matching results are obtained consecutively exceeding a preset number of times. , Information protection characterized in that the correctness or incorrectness of the communication information outputted from the synchronization separation circuit is determined by referring to the consecutive error detection signal outputted from the counting processing circuit and the coincidence signal outputted from the coincidence processing circuit. Method.