JP4730515B2 - Line alarm detection device, line alarm detection method and program - Google Patents

Description

  The present invention relates to a receiver of a communication system, and more particularly to a line alarm detection device that detects a line alarm.

  Conventionally, the configuration of the receiver of the digital microwave communication system is as shown in FIG. 2, and the line degradation detection circuit 15 counts errors for a certain period, and determines whether the alarm is activated or not according to the counted number. It was detected (for example, Patent Document 1).

  Here, the configuration of the prior art will be described.

  The transmitted signal is received by the antenna 11 and input to the demodulation unit 12.

  The transmitted signal is demodulated into a digital signal by the demodulator 12 and input to the frame synchronization circuit 13.

On the transmitter side, OH (Over
The frame synchronization of the frame pattern inserted in the (Head) portion is detected by the frame synchronization circuit 13 to detect the frame pattern. Then, a frame pulse representing the position of the frame is generated at the time of frame synchronization, and the data is synchronized with this frame pulse and output to the error correction decoder 14. In the case of digital microwave communication, the radio frame configuration is such that, for example, a wireless OH portion and a redundant portion of an error correction code are added to the input payload at the transmitter side (BCH code or RS as an error correction code). A block code such as a code is used).

  Based on the data from the frame synchronization circuit 13, the error correction decoder 14 generates a syndrome that is position information for identifying the location of the error. When an error occurs, a syndrome error is generated for each frame.

  The line deterioration detection circuit 15 has a function of counting frame pulse signals and syndrome errors sent from the error correction decoder 14. Based on the frame pulse transmitted every frame, the number of syndrome errors is counted for a certain period. The line deterioration detection circuit 15 activates an alarm when the syndrome error count value is equal to or greater than the threshold 2 (> threshold 1) when the alarm is canceled. When the threshold value is smaller than 2, the alarm release state is maintained. Further, even when the alarm is activated, the number of syndrome errors is counted for a certain period (same as the count period when the alarm is released). At this time, when the syndrome error count value is smaller than the threshold value 1 (<threshold value 2), the alarm is canceled. When the threshold value is 1 or more, the alarm activation state is maintained.

  The reason for providing a difference in threshold values such as threshold value 1 and threshold value 2 between alarm release and alarm activation is to avoid repeating the alarm activation state and the alarm release state in a certain line state. Even if there is a difference in threshold between alarm activation and alarm cancellation, if the period for counting syndrome errors is short, the probability of alarm activation (probability that the number of syndrome errors is greater than or equal to threshold 2) and the probability of alarm cancellation (the number of syndrome errors is the threshold) The probability less than 1) is as shown in FIG. In other words, when the BER (bit error rate) is point A in FIG. 3, the number of syndrome errors counted may be greater than or equal to the threshold 2 or smaller than the threshold 1 every count cycle, and the alarm state and the alarm release state are repeated. become. In order to prevent this, the cycle for counting syndrome errors is lengthened. As a result, even when the BER is the point A in FIG. 4, the count number of syndrome errors is prevented from being greater than or equal to the threshold 2 or smaller than the threshold 1 for each count period. That is, as shown in FIG. 4, the alarm activation probability and the alarm cancellation probability curve are not crossed. Therefore, in the BER state at point A in FIG. 4, the alarm activation state and the alarm release state are not repeated.

  However, if the cycle of the syndrome error count is lengthened so that the alarm activation state and the alarm release state are not repeated, it takes time to enter the alarm activation state when the line quality deteriorates rapidly due to fading or the like. . For example, in a device with line switching, if the line is switched based on alarm information, the line quality of one of the lines suddenly deteriorates due to fading and the communication is hindered, while the quality of the other line is good. Therefore, since the alarm is not activated, there is a problem that the line cannot be switched.

Moreover, in the above-described prior art, since the quality degradation is judged simply by counting the number of error corrections, it takes time to trigger an alarm even if the line is suddenly degraded. A problem occurs.
JP 2001-203673 A

  Therefore, the problem to be solved by the present invention has been made in view of the above-mentioned problems, and is to shorten the time until the alarm is activated when a sudden quality deterioration occurs in the line.

  Furthermore, the problem to be solved by the present invention is to improve the accuracy and speed of the line alarm.

The first invention for solving the above-described problems is
A line alarm detection device,
Error correction means for detecting an error in the input signal and correcting the error;
When the error is detected, the number of syndrome errors occurring in a predetermined time is counted and compared with a threshold value, and first deterioration information corresponding to a combination of the comparison result and the content of the current alarm information is generated. 1 deterioration information generating means;
When an error exceeding the correction capability of the error correction means occurs, the number of error correction failures that occur in a predetermined time shorter than the predetermined time used in the first degradation information generation means is counted and compared with a threshold value. Second deterioration information generating means for generating second deterioration information according to the result;
An alarm information generating unit that generates alarm information based on the first deterioration information and the second deterioration information.

According to a second invention for solving the above-mentioned problem, in the first invention,
The first deterioration information generating means changes a threshold value according to alarm information generated by the alarm information generating means.

A third invention for solving the above-mentioned problem is
A line alarm detection method,
A detection step for detecting an error in the input signal;
If an error is detected in the detection step, an error correction step for correcting the error; and
When an error is detected in the detection step, the number of syndrome errors occurring in a predetermined time is counted and compared with a threshold value, and first degradation information corresponding to a combination of the comparison result and the content of the current alarm information A first degradation information generation step for generating
When an error exceeding the correction capability occurs in the error correction step, the number of error correction impossible occurring in a predetermined time shorter than the predetermined time used in the first degradation information generation step is measured and compared with a threshold value. A second deterioration information generation step for generating second deterioration information according to the comparison result;
And an alarm information generation step of generating alarm information based on the first deterioration information and the second deterioration information.

According to a fourth invention for solving the above-mentioned problem, in the third invention,
The first deterioration information generation step includes a step of changing a threshold according to the alarm information generated in the alarm information generation step.

A fifth invention for solving the above-described problem is
A program used for a line alarm detection device, wherein the program includes the line alarm detection device,
Error correction means for detecting an error in the input signal and correcting the error;
When the error is detected, the number of syndrome errors occurring in a predetermined time is counted and compared with a threshold value, and first deterioration information corresponding to a combination of the comparison result and the content of the current alarm information is generated. 1 deterioration information generating means;
When an error exceeding the correction capability of the error correction means occurs, the number of error correction impossible occurring in a predetermined time shorter than the predetermined time used in the first deterioration information generating means is counted and compared with a threshold value, and the comparison result Second deterioration information generating means for generating second deterioration information according to
It is made to function as an alarm information generation means for generating alarm information based on the first deterioration information and the second deterioration information.

A sixth invention for solving the above-described problem is the above-mentioned fifth invention,
The first deterioration information generating means has means for changing a threshold according to alarm information generated by the alarm information generating means.

  According to the present invention, since it is configured to count the syndrome error of the error correction code and to detect the line quality deterioration by counting the error uncorrectable pulses, the alarm is activated when the line suddenly deteriorates. Time can be shortened.

  Further, according to the present invention, when an error exceeding the error correction capability occurs, the error correction impossible pulse generated for each frame is counted and the rapid deterioration of the line is monitored. The activation accuracy and the activation speed can be improved.

  First, the configuration of the present invention will be described.

  FIG. 1 is a block diagram of a receiver of a digital microwave communication system according to the present invention.

  The receiver includes an antenna 1, a demodulation unit 2, a frame synchronization unit 3, an error correction decoding unit 4, a line deterioration detection unit A 5, a line deterioration detection unit B 6, and an alarm information generation unit 7.

  The antenna 1 receives a transmitted signal (data).

  The demodulator 2 demodulates the received signal received by the antenna 1 into a digital signal.

  The frame synchronization unit 3 inputs the digital signal demodulated by the demodulation unit 2. Further, the frame synchronization unit 3 detects the coincidence / mismatch of the frame pattern redundant in the digital signal. If the frame patterns match, a frame pulse synchronized with the frame pattern is generated, and data is output in synchronization with the frame pulse.

  The correction decoding unit 4 receives the data and the frame pulse established by the frame synchronization unit 3 and generates a syndrome indicating a position for identifying the error location. When an error (syndrome error) occurs in the data, a syndrome error pulse indicating that there is an error for each frame is generated. Further, when an error exceeding its own error correction capability occurs, the correction decoding unit 4 generates an error uncorrectable pulse indicating that there is an error exceeding the correction capability for each frame.

  The line degradation detection unit A5 counts the number of syndrome error pulses output from the error correction decoding unit 4 for a certain period of time. By comparing the count value of this syndrome error with a threshold value, it is determined whether the line deterioration is activated (including the line deterioration activation hold) or the line deterioration is released (including the line deterioration release hold). Then, the line degradation information A indicating the determination result is generated and output to the alarm information generation unit 7. The fixed time is arbitrarily determined according to the number of frame pulses counted. Further, there are two types of threshold values, threshold value 1 (<threshold value 2) and threshold value 2, and the threshold value is changed instantaneously according to alarm information from the alarm information generation unit 7. That is, when the alarm information of the alarm information generation unit 7 is activated, the threshold value of the syndrome error counter is immediately changed to the threshold value 1. When the alarm of the alarm information generation unit 7 is canceled, the threshold value of the syndrome error counter is instantaneously changed to the threshold value 2.

  The line deterioration detection unit B6 counts the number of uncorrectable pulses output from the error correction decoding unit 4 for a certain period of time. The error correction impossible pulse count value is compared with a threshold value, line degradation information B is generated according to the comparison result, and output to the alarm information generation unit 7. The fixed time is determined by the number of frame pulses, and is further shorter than one cycle of the frame pulse counter of the line deterioration detection unit A5. For example, the period is about 1/10. Further, the threshold value is any one type of value.

  The alarm information generation unit 7 detects an alarm using a logical sum of the line deterioration information A generated based on the syndrome error and the line deterioration information B generated based on the error correction impossible pulse. Then, alarm information indicating alarm activation or alarm cancellation is output based on the detection result.

  The probability of occurrence of a syndrome error and an error-correctable pulse for BER is as shown in FIG. Assuming that the alarm is activated when the BER is A in FIG. 5, the error correction impossible pulse is counted for a period (for example, 1/10) shorter than the period of the syndrome error count. If the count number is 20%, it can be determined that the BER is worse than the point A, the BER is deteriorated around the point B, and the line quality is rapidly deteriorated.

  If the syndrome error counter value starts counting at the same time as the error-correctable pulse counter value, an alarm is triggered when the syndrome error count value exceeds 90% of the total count (see point A in Fig. 4). Because the syndrome error occurrence probability is about 90%), even if a syndrome occurs in each frame, the syndrome error count value is about 11% of the threshold value, so the alarm is activated. do not do. In this way, by counting the number of pulses that cannot be corrected, it is possible to shorten the time until the alarm is activated when the line quality deteriorates rapidly.

  Next, operations of the frame synchronization unit 3, the error correction decoder 4, the line deterioration detection unit A5, the line deterioration detection unit B6, and the alarm information generation unit 7 of FIG. 1 will be described.

  First, the data demodulated into a digital signal by the demodulator 2 is input to the frame synchronizer 3.

  Here, a radio frame configuration in the case of digital microwave communication will be described. The radio frame configuration in the case of digital microwave communication includes, for example, a wireless OH portion and a redundant portion of an error correction code added to the payload input to the transmitter (BCH code, RS code, etc. as error correction code) The block code is used). Frame synchronization is performed by inserting a frame pattern into the OH unit on the transmitter side and detecting the frame pattern with the frame synchronization unit 3 on the reception side.

  The frame synchronization unit 3 detects a frame pattern from the data demodulated into a digital signal by the demodulation unit 2 and performs frame synchronization. At the time of frame synchronization, a frame pulse representing the position of the frame is generated and output to the error correction decoder 4 in synchronization with the data.

  The error correction decoder 4 generates a syndrome and corrects the error based on the syndrome when an error occurs. In addition, when an error occurs, a syndrome error pulse is generated for each frame. Furthermore, when an error exceeding the error correction capability occurs, an error uncorrectable pulse is generated for each frame.

  The line degradation detection unit A5 counts syndrome errors and frame pulses sent from the error correction decoder 4. Then, the counted syndrome error count value is compared with a threshold value.

  The line degradation detection unit A5 cancels the line degradation when the alarm information sent from the alarm information generation unit 7 is an alarm activation and the value of the syndrome error counter is smaller than the threshold value 1 (<threshold value 2). To do. When the value of the syndrome error counter is equal to or greater than the threshold value 1, the line degradation activation is held.

  On the other hand, if the alarm information sent from the alarm information generation unit 7 is alarm release, and the value of the syndrome error counter is greater than or equal to threshold value 2 (> threshold value 1), line degradation is activated. When the value of the syndrome error counter is smaller than the threshold value 2, the line degradation cancellation is held.

  The line deterioration detection unit B6 counts error correction impossible pulses and frame pulses sent from the error correction decoder 4. It is determined whether to activate or cancel the line degradation based on the count value of the error uncorrectable pulse.

  The alarm information generation unit 7 receives the line deterioration information A sent from the line deterioration detection unit A5 and the line deterioration information B sent from the line deterioration detection unit B6.

  When the line deterioration information A is a line deterioration activation and the line deterioration information B is a line deterioration activation, the alarm information generation unit 7 outputs alarm information indicating the alarm activation.

  When the line deterioration information A is the line deterioration activation and the line deterioration information B is the line deterioration cancellation, the alarm information indicating the alarm activation of the alarm information generation unit 7 is output.

  When the line deterioration information A is a line deterioration cancellation and the line deterioration information B is a line deterioration activation, the alarm information generation unit 7 outputs alarm information indicating the alarm activation.

  When the line deterioration information A is the line deterioration cancellation and the line deterioration information B is the line deterioration cancellation, the alarm information generation unit 7 outputs alarm information indicating the alarm cancellation.

  That is, when either the line deterioration information A or the line deterioration information B is in the line deterioration activation state in the alarm release state, the alarm is activated. Even if only the line degradation information B is released when the alarm is activated, the alarm activation remains maintained, and when both the line degradation information A and the line degradation information B are in the line degradation release state, the alarm is released for the first time. Is output.

  In the embodiment described above, the case of microwave communication has been described, but the present invention is not limited to this. That is, the present invention can be applied to a system having error correction means.

  Further, according to the present invention, when the alarm activation point is set to a place where the BER is worse than that in the example of FIG. 5 (around the point B in FIG. 5), the alarm is activated or the alarm is canceled by using only the error correction impossible pulse. It is also possible to do this.

  Further, the present invention can also be realized by using a parity bit error pulse instead of using an error uncorrectable pulse. In this case, it can be realized when a parity check bit is made redundant in the wireless OH part and a parity error is detected from the data after error correction.

  Further, in the above-described embodiment, as is apparent from the above description, it can be configured by hardware, but can also be realized by a program.

It is a block diagram for demonstrating the line | wire alarm detection apparatus of this invention. It is a block diagram for demonstrating the conventional line | wire alarm detection apparatus. It is a figure which shows the establishment at the time of shortening a count period. It is a figure which shows establishment when a count cycle is lengthened. It is a figure which shows the generation | occurrence | production probability of a syndrome error and an error correction impossible.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Demodulation part 3 Frame synchronization part 4 Error correction decoding part 5 Line degradation detection part A
6 Line degradation detector B
7 Alarm information generator

Claims (6)

A line alarm detection device,
Error correction means for detecting an error in the input signal and correcting the error;
When the error is detected, the number of syndrome errors occurring in a predetermined time is counted and compared with a threshold value, and first deterioration information corresponding to a combination of the comparison result and the content of the current alarm information is generated. 1 deterioration information generating means;
When an error exceeding the correction capability of the error correction means occurs, the number of error correction failures that occur in a predetermined time shorter than the predetermined time used in the first degradation information generation means is counted and compared with a threshold value. Second deterioration information generating means for generating second deterioration information according to the result;
A line alarm detection device comprising alarm information generation means for generating alarm information based on the first deterioration information and the second deterioration information.   The line alarm detection device according to claim 1, wherein the first deterioration information generation unit changes a threshold according to alarm information generated by the alarm information generation unit. A line alarm detection method,
A detection step for detecting an error in the input signal;
If an error is detected in the detection step, an error correction step for correcting the error; and
When an error is detected in the detection step, the number of syndrome errors occurring in a predetermined time is counted and compared with a threshold value, and first degradation information corresponding to a combination of the comparison result and the content of the current alarm information A first degradation information generation step for generating
When an error exceeding the correction capability occurs in the error correction step, count the number of uncorrectable errors that occur in a predetermined time shorter than the predetermined time used in the first degradation information generation step , and compare with a threshold value. A second deterioration information generation step for generating second deterioration information according to the comparison result;
A line alarm detection method comprising: an alarm information generation step of generating alarm information based on the first deterioration information and the second deterioration information. The line alarm detection method according to claim 3 , wherein the first deterioration information generation step includes a step of changing a threshold value according to the alarm information generated in the alarm information generation step. A program used for a line alarm detection device, wherein the program includes the line alarm detection device,
Error correction means for detecting an error in the input signal and correcting the error;
When the error is detected, the number of syndrome errors occurring in a predetermined time is counted and compared with a threshold value, and first deterioration information corresponding to a combination of the comparison result and the content of the current alarm information is generated. 1 deterioration information generating means;
When an error exceeding the correction capability of the error correction means occurs, the number of error correction failures that occur in a predetermined time shorter than the predetermined time used in the first degradation information generation means is counted and compared with a threshold value. Second deterioration information generating means for generating second deterioration information according to the result;
A program that functions as alarm information generation means for generating alarm information based on the first deterioration information and the second deterioration information. The program according to claim 5 , wherein the first deterioration information generation unit includes a unit that changes a threshold according to alarm information generated by the alarm information generation unit.

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