JPH0771075B2 - Code error quality monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used for quality control of digital lines. In particular,
The present invention relates to a code error quality monitoring device that measures the code error quality of a digital line.

The present invention makes it possible to monitor the code error quality in service by estimating the quality deterioration occurrence time rate of the digital line from the out-of-sync duration of the digital transmission line and the number of code error detections when synchronization is normal. Is.

[Conventional technology]

In accordance with its Recommendation G.821, the International Telegraph and Telephone Consultative Committee (CCITT) adopted ES (Er) as a measure of code error quality for 64 kb / s lines.
rored Second), SES (Severely Errored Second), DM
(Degraded Minute) and UT (Unavailable Time) are used to stipulate the rate of each occurrence in each section of the international connection system, that is, the upper limit of the time rate.

In the definition of Recommendation G.821, ES is the time in which one or more code errors occur (exist) in seconds. In addition, the percentage of ES in a certain observation time (excluding the time when the line is abnormal) is expressed as a percentage (time ratio) and is called% ES. Furthermore, SES represents the time when the bit error rate deteriorated to 10 ^-3 or more in seconds, and the SES time ratio of the observation time (excluding the time when the line is abnormal) is% SES.
Say.

In order to check whether the actual values of% ES and% SES characteristics meet the above recommendations, conventionally, the ministry of each country has extracted a digital line for measurement and measured the number of ES and SES occurrences on that line. Was there. Measuring the code error quality of a digital line when it is not in commercial use is called "out-of-service measurement". Out of
Service measurements can accurately measure the occurrence of ES and SES.

[Problems to be Solved by the Invention]

However, the out-of-service measurement is actually in commercial use (hereinafter referred to as "in-service").
However, there is a drawback in that the bit error quality cannot be grasped. Especially, in recent years, not only 64 kb / s but also the 1.536 kb / s leased line service has become widespread, and user interest in the bit error quality of these digital line services is increasing. There is an urgent need to realize a code error quality monitoring function in service.

It is an object of the present invention to solve the above problems and provide a code error quality monitoring apparatus that estimates the number of occurrences of ES and SES and the values of% ES and% SES in an in-service state.

[Means for Solving the Problems]

The code error quality monitoring apparatus of the present invention is connected to a digital transmission apparatus that transmits a signal including a synchronization code and a code error check code, and a clock means for measuring the out-of-synchronization duration of the digital transmission apparatus and the digital transmission apparatus. Counting means for counting the number of code error detections when the synchronization is normal,
The present invention is characterized by comprising an arithmetic means for estimating the quality deterioration occurrence time of the digital line connected to the digital transmission device from the output of the counting means and the output of the counting means.

The calculating means includes first means for calculating the number of code error bits at the time of out-of-sync and normal synchronization, second means for calculating the probability of occurrence of code error quality deterioration from the number of code error bits, and accumulation of these probabilities. It is desirable to include a third means for calculating the quality deterioration occurrence time rate from the value.

[Action]

In order to monitor the code error quality of the digital line, the monitoring information generated by the digital transmission device connected to the line is used. That is, the duration of the frame out-of-sync signal and the number of times the code error detection signal is generated are measured, and the number of code errors at the time of out-of-sync and normal synchronization is estimated from the results. Next, the probability that the time is ES or SES is calculated from the estimated value of the number of code errors per second. If DM is also required, estimate in about 60 seconds. Such probability calculation is executed for the required time, for example, one month, and the total of the obtained probability values is calculated as ES and SE for that period.
S Considered to be the number of occurrences. This gives the% ES and% SES values.

〔Example〕

FIG. 1 is a block diagram of a code error quality monitoring apparatus according to an embodiment of the present invention.

This device is connected to a digital transmission device 1 for transmitting a signal including a synchronization code and a code error check code, and is provided with a pulse width measuring device 2 as a time measuring means for measuring the out-of-synchronization duration of the digital transmission device 1. The digital transmission device 1 is provided with an inhibition gate 3 and a pulse number counter 4 as counting means for counting the number of code error detections when synchronization is normal, and digital transmission is performed from the output of the pulse width measuring device 2 and the output of the pulse number counter 4. An arithmetic processing unit 5 is provided as an arithmetic means for estimating the quality deterioration occurrence time rate of the digital line connected to the apparatus 1.

The digital transmission device 1 outputs an out-of-synchronization pulse to the signal line 1a when detecting the out-of-synchronization, and outputs a code error pulse to the signal line 1b when detecting a code error. The width of the out-of-sync pulse represents the out-of-sync duration.

The pulse width measuring device 2 measures the width of the out-of-synchronization pulse output from the digital transmission device 1 and outputs the measured value t to the arithmetic processing device 5 in units of 1 second.

The inhibit gate 3 transmits the code error pulse from the digital transmission device 1 to the pulse number counter 4 when the digital transmission device 1 does not output the out-of-synchronization pulse. Therefore, the output pulse of the inhibition gate 3 represents the number of code error detections in the normal synchronization by the number of occurrences.

The pulse number counter 4 counts the output pulse of the inhibition gate 3 and outputs the count value c to the arithmetic processing unit 5 in units of 1 second.

The arithmetic processing unit 5 calculates the occurrence probabilities of ES and SES according to the measured value t and the count value c sent every second.

FIG. 2 shows the flow of processing by the arithmetic processing unit 5. Here, the transmission method is 1544 kb / s, and the line whose quality should be estimated is
The case of a 64 kb / s line will be described as an example.

First, the error bit number Ne included in the 1544 kb / s signal per second is obtained. The value of Ne is given as the sum of the number of error bits Ne ₁ when synchronization is lost and the number of error bits Ne ₂ when synchronization is normal. Ne ₁ and Ne ₂ are respectively calculated by Ne ₁ = B ₁ · t · 0.5 (1) Ne ₂ = B ₁ · (1-t) · e (2). However, B ₁ : 1544kb / s ε: Bit error rate when synchronization is normal. For the value of ε, the code error detection frequency P _C = c · γ _C / (1-t) is obtained from the code error detection number c, and this P
_From the value of _C , The relationship is used to obtain. This relationship is shown in FIG. In the expression of the code error detection frequency P _{C and} the expression (3), γ _C : code error check period, 3 ms L: code error monitoring block length, 4632 bits m: code error monitoring block when multiple errors are included Distance between code error bits at both ends Q: Code error miss probability. At 1544 kb / s, it is 0 when m is 6 bits or less, 0.5 ² when m is 7 bits, and 0.5 ⁶ when m is 8 bits or more. is there. In the above equation, the bit error rate at the time of loss of synchronization is assumed to be 0.5.

Next, from the value of Ne (= Ne ₁ + Ne ₂ ), the probability P (E
S), P (SES) Ask by. However, Is.

Equation (5) is the probability that the 1544 kb / s line will be SES, and strictly speaking, it is not the probability that the 64 kb / s line will be SES. However, normally, when the 1544 kb / s line is the SES, the 64 kb / s line included therein is also considered to be the SES. Therefore, the equation (5) is used as the SES occurrence probability of the 64 kb / s line.

Next, the sum of P (ES) and P (SES) is calculated every predetermined time T [second], Calculate% ES and% SES by. About the value of T CCITT
Recommendation G.821 defines one month excluding the time when communication is not possible. In this case, T = 2592000 if no communicable state occurs. ΣP (SE) and ΣP (SES) in equations (6) and (7) respectively represent estimated values of the number of ESs and SESs that occur during a predetermined time.

By the above calculation, the code error quality deterioration time rate of the digital line connected to the digital transmission device 1 can be estimated in the in-service state. Regarding the calculation of the equations (4) and (5), P (SE) and P for the measured value t of the pulse width measuring device 2 and the counted value c of the pulse number counter 4 are calculated.
The value of (SES) can be obtained in advance and tabulated in the arithmetic processing unit 5.

〔The invention's effect〕

As described above, the code error quality monitoring apparatus of the present invention monitors the transmission path monitoring information from the digital transmission apparatus, that is, the out-of-frame detection output and the code error detection output, to thereby determine the code error quality deterioration time rate. There is an effect that can be estimated in the in-service state.

[Brief description of drawings]

FIG. 1 is a block diagram of a code error monitoring apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a flow of processing by the arithmetic processing unit. FIG. 3 is a diagram showing the relationship between the code error detection frequency P _C and the bit error rate ε when synchronization is normal. DESCRIPTION OF SYMBOLS 1 ... Digital transmission device, 2 ... Pulse width measuring device, 3 ... Forbidden gate, 4 ... Pulse number counter, 5 ... Arithmetic processing device.

Claims (1)

[Claims] 1. A code error quality monitoring device for monitoring the code error quality of a digital line, which is connected to a digital transmission device for transmitting a signal containing a synchronization code and a code error check code, and the synchronization loss continuation time of the digital transmission device. And a counting means for counting the number of code error detections during normal synchronization of the digital transmission device, and a digital line connected to the digital transmission device from the output of the timing means and the output of the counting means. And a calculation means for estimating the quality deterioration occurrence time rate of the code error quality monitoring apparatus.