JPH0748713B2 - Digital multiplex transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] An intermediate relay station is provided between a transmitting terminal station and a receiving terminal station. In addition to a working line between the transmitting terminal station and the receiving terminal station via the intermediate relay station, a transmitting terminal station is also provided. And an intermediate relay station, and between the intermediate relay station and the receiving end station, respectively, in a configuration including a working line and a backup line,
If the working lines are normal and all the protection lines are not used, or if the protection lines are in use and the protection lines are in use, be sure to monitor the status of the protection lines especially at the receiving station. It intended to so capable of carrying out, in the transmission terminal station only when the protection line P _1-1 is not use, the protection line P _1-1
It includes a pattern generator 11 which is connected to, the intermediate relay station, unused and protection line P of the protection line P _1-1
Backup line P _1-1 only when both _1-1 and P _1-2 are in use
Connected to the pattern detector 22 capable of detecting the pattern signal from the pattern generator of the transmitting end station and the protection line P _1-1
Is connected to the protection line P _1-2 only when is in use, and is provided with a pattern generator 25 that generates a pattern signal, and both protection lines P _1-1 and P _1-2 are not used in the receiving terminal, or When only the protection line P _1-2 is not used, the respective pattern signals connected to the protection line P _1-2 and from the pattern generator 11 of the transmitting terminal station and the pattern generator 25 of the intermediate relay station are distinguished. A pattern detector 31 capable of detecting is provided.

[Industrial application field]

The present invention provides an intermediate relay station between a transmitting terminal station and a receiving terminal station, and in addition to a working line between the transmitting terminal station and the receiving terminal station, the transmitting terminal station and the intermediate relay station for branching / inserting signals in the intermediate relay station. The present invention relates to a digital multiplex transmission system including a working line and a protection line between a relay station and an intermediate relay station.

[Problems to be solved by conventional technology and invention]

In general, the analog multiplex transmission system is a frequency multiplex system, so the signal sent from the transmitting end station is branched at the intermediate relay station, and the signal is inserted into the line to the receiving end station at the intermediate relay station. In this case, the branching / insertion of the signal is easily realized by cutting out the band to be branched with a filter and inserting the signal in the vacant band.

However, in the digital multiplex transmission system, unlike the case of such an analog multiplex transmission system, the branching / inserting technology in the intermediate relay station is not established.

Even so, the digital multiplex transmission system is basically a system in which the number of lines is transmitted from the transmitting end station 1 to the receiving end station 3 through the intermediate relay stations 2 and 2'as shown in FIG. 2 (a). The intermediate relay station 2'has branching or insertion, and the number of lines changes. (D) shows the case where branching and re-insertion are performed in the intermediate relay station 2 ', and the number of lines does not change, but some lines are different.

And in a digital multiplex transmission system in which an intermediate relay station is provided between the transmitting terminal station and the receiving terminal station, a working line in which a signal from the transmitting terminal station to the receiving terminal station is only relayed by the intermediate relay station, In the intermediate relay station, working lines for branching signals from the transmitting end station and inserting signals to the receiving end station are provided between the transmitting end station and the intermediate relay station and between the intermediate relay station and the receiving end station. In addition, a failure occurs in the working line in a configuration in which a protection line is provided between the sending terminal station and the intermediate relay station and between the intermediate relay station and the receiving terminal station for switching when the working line fails. Thus, the method of monitoring the usage status of the protection line when switched to the protection line is not always sufficient.

That is, when switching to the protection line when a failure occurs in the working line according to the method of switching to the protection line in the conventional analog multiplex transmission system, the intermediate relay station and the receiving end station receive the respective working lines. By providing an error rate detection unit for detecting the error rate of the signal, the failure of the working line is detected, and switching to the protection line is performed based on the detection result.

For example, if the error rate detector of the intermediate relay station increases the number of errors in the received signal from the transmitting end station, the intermediate relay station determines that the working line between the transmitting end station and the intermediate relay station has failed, and The switching information is sent from the station to the protection line through the control line to the protection line, whereby the working line in which the failure has occurred is switched to the protection line, and this switching is also performed in the intermediate relay station.

In addition, if the signal inserted in the intermediate relay station is sent to the receiving terminal station via the working circuit between the intermediate relay station and the receiving terminal station, if there is a failure in the working circuit, this failure occurs. Is detected by the error rate detector provided at the receiving end station, and based on the detection result, the receiving end station sends the switching request information to the protection line to the intermediate relay station via the control line. The line is switched, and the receiving end station is also switched.

Furthermore, if a failure occurs in the working line that transmits the signal from the transmitting end station to the receiving end station under the relay at the intermediate relay station, if this is detected by the error rate detection unit of the receiving end station, Based on this detection result, the terminal station sends the switching request information to the protection circuit to the transmitting terminal station and the intermediate relay station via the control circuit. It is switched to the series connection of the protection line between the relay station and the receiving end station.

However, even if a failure occurs in the working line between the sending end station and the intermediate relay station as described above and the line is switched to the protection line during this period,
When there is no abnormality in the working line between the intermediate relay station and the receiving end station, the signal is normally transmitted from the intermediate relay station to the receiving end station via this working line, so the error rate detection unit of the receiving end station is in use. It indicates the normal status of the line.

Therefore, the receiving end station is in a state where it cannot monitor that the working line is switched to the protection line between the sending end station and the intermediate relay station, resulting in a failure of the working line between the sending end station and the intermediate relay station.
The switching to the protection line can be recognized only by the sending terminal station and the intermediate relay station. Therefore, in such a state, if a failure occurs in the working line such that the signal from the transmitting end station is received by the receiving end station under the relay at the intermediate relay station,
This failure is detected by the error rate detection unit of the receiving end station, and the receiving end station sends request information for switching the working line to the protection line to the transmitting end station through the control line based on the detection result.

However, since the protection line is already in use between the sending end station and the intermediate relay station, the sending end station cannot meet the request from the receiving end station.

This results in confusion in the new switching control from the working line to the protection line in such a transmission system, and the present invention particularly relates to the status of the protection line when the working line is normal in the receiving end station. It is an object of the present invention to be able to sufficiently monitor and monitor the status of a protection line that has been switched due to a failure in the working line.

[Means for solving problems]

According to the present invention, at least one intermediate relay station 2 is provided between the transmitting terminal station 1 and the receiving terminal station 3 and is relayed by the intermediate relay station between the transmitting terminal station and the receiving terminal station. Working line M ₂ and working line M _1-1 and protection line P _1-1 between transmitting terminal station and intermediate relay station, working line M _1-2 and protection line P ₁ between intermediate relay station and receiving terminal station ₂ , and the working lines M _1-1 and M _1-2 are connected to the demultiplexing unit at the intermediate relay station, and only when either of the protection lines P _1-1 and P _1-2 is in use.
In a digital multiplex transmission system in which the connection between the protection lines P _1-1 and P _1-2 is separated by an intermediate relay station, the protection line P _1-1 is not used at the sending end station only when the protection line P _1-1 is not in use. _1-1
It includes a pattern generator 11 which is connected to, the intermediate relay station, unused and protection line P of the protection line P _1-1
Backup line P _1-1 only when both _1-1 and P _1-2 are in use
Connected to the pattern detector 22 capable of detecting the pattern signal from the pattern generator of the transmitting end station and the protection line P _1-1
Is connected to the protection line P _1-2 only when is in use, and is provided with a pattern generator 25 that generates a pattern signal, and both protection lines P _1-1 and P _1-2 are not used in the receiving terminal, or When only the protection line P _1-2 is not used, the respective pattern signals connected to the protection line P _1-2 and from the pattern generator 11 of the transmitting terminal station and the pattern generator 25 of the intermediate relay station are distinguished. It is solved by a digital multiplex transmission system characterized in that it comprises a detectable pattern detector 31.

[Action]

In the present invention, in order to like it can monitor the state of use the presence or absence of the protection line, with respect to the protection line P _1-1, the pattern detector 22 of the pattern generator 11 and the intermediate relay station transmission terminal station is a pair ,
For the protection line P _1-2 , the pattern generator of the intermediate relay station
25 and the pattern detector 31 of the receiving terminal are provided as a pair.

And in such a configuration, the protection line P _1-1 and the protection line P
_When both _1-2 are not used, that is, when the working lines are all normal, the pattern detectors 22 and 31 of the intermediate relay station and the receiving station are both the patterns from the pattern generator 11 of the transmitting station. By detecting the signal, the receiving end station can monitor that the protection lines P _1-1 and P _1-2 are both unused.

Also, the working line M _1-1 is switched to the protection line P _1-1 due to a failure, and when this protection line is in use, the pattern generator 11
And since the pattern detector 22 are both in a state of non-connecting to the protection line P _1-1, the pattern detector 22 uses the P _1-1 by non-detection of the pattern signal is monitored.

In this case, the pattern generator 25 is connected to the protection line P _{1-2 at the} intermediate relay station and the pattern detector 31 is connected at the receiving station, and the pattern detector 31 is different from the pattern generator 25. By receiving this pattern signal, the receiving end station can monitor that the protection line P _1-1 is in use.

Meanwhile working line M _1-1 is normal, the protection channel P _1-1 nonuse state, the standby line P _1-2 the failure of the working line M _1-2
When is in use, the pattern detector 22 in the intermediate relay station detects the pattern signal from the pattern generator 11, but the connection between the protection lines P _1-1 and P _1-2 in the intermediate relay station is cut off, Since neither the pattern generator 25 nor the pattern detector 31 of the receiving end station is connected to the protection line, the pattern detector 31 of the reception end station does not detect any pattern signal, which causes the reception end station to detect the protection line P. Know that _1-2 is in use.

In addition, when both the protection lines P _1-1 and P _1-2 are switched to the use state due to a failure of the working line M ₂ between the transmitting end station and the receiving end station, the intermediate relay station detects a pattern. The device 22 detects the pattern signal from the pattern generator 11, but the pattern detector 31 of the receiving end station does not receive any pattern signal, and the fault of the working line M ₂ is a separate error rate of the receiving end station. It has already been detected by the detector, which results in protection lines P _1-1 and P
_Since it is switched to _1-2 and is in use, the detection result and the non-detection of the pattern detector 31 cause the receiving end station to confirm that both the protection lines P _1-1 and P _1-2 are in use. It will be possible to monitor.

〔Example〕

In FIG. 1 (a), the working line between the sending end station 1 and the intermediate relay station 2 is shown by M _1-1 , and the protection line is shown by P _1-1 , and the intermediate relay station 2 and the receiving end station 3 are shown. The working line between and is shown as M _1-2 , and the protection line is shown as P _1-2 . These working lines M _1-1 and M
_1-2 are connected to the demultiplexer 24 so that signals can be dropped and added.

Further, a working line M ₂ is provided between the transmitting end station 1 and the receiving end station 3 so that the intermediate relay station 2 only relays signals.

Meanwhile pattern generator 11 to the protection line P _1-1 in the transmission terminal station 1
, But this pattern generator 11 is
When P _1-1 is switched from the working line M _1-1 or M ₂ and is in use, it is disconnected from the protection line P _1-1 by the operation of the switch 12 or 13.

In the intermediate relay station 2, the protection line P _1-1 is the hybrid 2
1, connected to the protection line P _1-2 via the switch 23, the pattern detector is branched from the hybrid 21,
The pattern generator 25 can be connected to the position preceding 23.

Furthermore the pattern detector 31 at the reception terminal station 3 are connected to the protection line P _1-2, the protection channel P _1-2 are separated by the case of the use-state switch 32 or 33.

In this FIG. 1 (a), the working lines M _1-1 , M _1-2 and the working line M ₂ are all normal, and therefore the protection lines P _1-1 and P 1
_1-2 shows the unused state.

In this case, the pattern generator 11 is connected to the protection line P _1-1 at the transmitting terminal station, and the pattern signal from the pattern generator 11 reaches the intermediate relay station 2 via the protection line P _1-1 , and the hybrid 21 and the switch 23 are connected. It is sent to the protection line P _1-2 through, is branched by the hybrid 21, and is given to the pattern detector 22.

Therefore, the pattern detector 22 detects the pattern of the pattern generator 11.

On the other hand, the pattern signal from the pattern generator 11 given to the protection line P _1-2 is given to the pattern detector 31 in the receiving end station 3 to detect the pattern signal of the pattern generator 11.

That is, the pattern detectors 22 and 31 are both the pattern generator 11
To detect the pattern signal of the working line M _1-1 and M ₂
Indicates that both of them are normal and therefore the protection lines P _1-1 and P _1-2 are both unused.

Since the FIG. 1 (b) the working line M _1-1 is down, indicating that the protection line P _1-1 is in the switched with use.

In this case, since the switch 12 is switched to the protection line P _1-1 side as shown in the figure, the pattern generator 11 is disconnected from this protection line.

As a result, in the intermediate relay station 2, the pattern detector 22 does not detect the pattern signal from the pattern generator 11, whereby the switch 27 operates, the pattern generator 25 is connected, and the pattern signal from it is transmitted via the switch 23. _Are given to the protection line P _1-2 .

Therefore, in the receiving end station 3, the pattern detector 31 detects the pattern signal from the pattern generator 25, and since this pattern signal is different from the pattern signal from the pattern generator 11, in the receiving end station 3, the working line M Know that _1-1 is faulty, protection line P _1-1 is in use, working lines M _1-2 and M ₂ are normal, and thus protection line P _1-2 is not in use .

Since a failure occurs in Figure 1 (c) the working line M _1-2, show that the protection line P _1-2 is in the switched with use. Since the switch 23 is linked with the switch 28, the switch 23 is in the open state.

Therefore, the pattern signal from the pattern generator 11 passes through the protection line P _1-1 and is transmitted to the pattern detector in the intermediate relay station 2.
Detected at 22. However, since the switch 23 is in the open state, the pattern signal from the pattern generator 11 is not given to the protection line _P1-2 .

The protection line P _1-2 in the reception terminal station are connected by the switch 32, since a use state, the pattern detector 31 is disconnected from the protection line P _1-2, also can be detected any pattern signal Absent. That is, at the receiving end station, the working line M _1-2
To know that the protection line P _1-2 is in use.

Figure 1 (d) are due to a failure in the working line M ₂ occurs, indicating that the protection line P _1-1 and P _1-2 is in the both switching use.

Such a failure of the working line M ₂ is detected by the receiving end station 3, and based on the detection result, the receiving end station sends a request signal for switching to the protection line to the transmitting end station 1 and the intermediate relay station via the control line. , The protection lines P _1-1 and P _1-2 are both in use.

Therefore, in the intermediate relay station, the pattern detector 22
Although it is connected to P _1-1 , the pattern generator 11
Are separated, the pattern detector 22 does not detect the pattern signal.

On the other hand since the pattern detector 31 at the reception terminal station is disconnected from the protection line P _1-2, it is not able to detect any pattern signals.

However, since the receiving end station has already detected the failure of the working line M ₂ , and the pattern detector 31 does not detect the pattern signal, the working line M ₂ has a failure and therefore the protection lines P _1-1 and P _1-2 Know that they are switched to each other and are in use.

That is, in the reception terminal station, working line M _1-1 all, unused protection channel P _1-1 and P _1-2 by normal operation of the M _1-2 and M _2, the pattern detector 31 is pattern The pattern detector 31 detects the pattern signal from the pattern generator 25 by detecting the pattern signal from the generator 11 and the use state of the protection line P _1-1 due to the failure of the working line M _1-1. In addition, the pattern detector 31 cannot detect the pattern signal in the use state of the protection line P _1-2 due to the failure of the working line M _1-2 , and further the failure of the working line M ₂ is caused by the receiving end station first. It is detected, and the use state of the protection lines P _1-1 and P _1-2 switched by this is known by the pattern detector 31 not detecting any pattern signal.

As described above, according to the present invention, the pattern generator 1 in the transmission terminal station 1 is
1, pattern detector 22 and pattern generator 25 of intermediate relay station 2
And the combination of the pattern detector 31 of the receiving end station 3 causes each of the working lines M _1-1 , M _1-2 , M ₂ and the protection line in the receiving end station 3.
The states of P _1-1 and P _1-2 can be reliably grasped.

Then, as in the previous example, when the protection line P _1-1 is in use due to the failure of the working line M _1-1 and a new failure occurs in the working line M ₂ , the receiving end station 3 After knowing the usage status of the protection line P _1-1 , the transmission terminal station 1 is notified of the failure occurrence of the working line M ₂ through the control line.

In this case, the sending terminal station considers the priority of the working lines M _1-1 and M ₂ and continues switching from the working line M _1-1 to P _1-1 , or the working line M ₂ to the protection line P _{2. It} will be decided whether to switch to _{1-1 or} P _1-2 .

In the embodiment, one intermediate relay station is arranged between the transmitting terminal station and the receiving terminal station, but a plurality of intermediate relay stations are arranged between the transmitting terminal station and the receiving terminal station. In this case, the present invention can be applied such that the intermediate relay station at the front of one intermediate relay station corresponds to the transmitting terminal station and the intermediate relay station at the rear of the one intermediate relay station corresponds to the receiving terminal station.

〔The invention's effect〕

As described above, according to the present invention, since branching / insertion can be performed by adding a simple circuit to the intermediate relay station, the intermediate relay station does not have to be a terminal station configuration, and branching can be performed at low cost. There is an effect that insertion can be performed, line control can be performed independently between each station, and similarly, the number of intermediate relay stations capable of branching / insertion can be increased.

[Brief description of drawings]

1 (a) to 1 (d) are block diagrams showing the operation of the embodiment of the present invention, and FIG. 2 is a diagram showing system branching / insertion in a digital multiplex transmission system. 1 …… Sending terminal station, 2,2 ′ …… Intermediate relay station, 3 …… Reception terminal station, 11,25 …… Pattern generator, 22,31 …… Pattern detector, 21 …… Hybrid, 24 …… Demultiplexer, 12,13,23,26,27,28,32,33 …… Switch.

Claims (1)

[Claims] 1. At least 1 is provided between a transmitting end station 1 and a receiving end station 3.
A plurality of intermediate relay stations 2 are provided, and a working line M ₂ relayed by the intermediate relay station between the transmitting end station and the receiving end station, and a working line M _1-1 between the transmitting end station and the intermediate relay station. A protection line P _1-1 , a working line M _1-2 and a protection line P _1-2 are provided between the intermediate relay station and the receiving end station, and the working lines M _1-1 and M _1-2 are multiplexed by the intermediate relay station. Only when connected to the separation part and using either of the protection lines P _1-1 and P _1-2 ,
In a digital multiplex transmission system in which the connection between the protection lines P _1-1 and P _1-2 is separated by an intermediate relay station, the protection line P _1-1 is not used at the sending end station only when the protection line P _1-1 is not in use. _1-1
It includes a pattern generator 11 which is connected to, the intermediate relay station, unused and protection line P of the protection line P _1-1
Backup line P _1-1 only when both _1-1 and P _1-2 are in use
Connected to the pattern detector 22 capable of detecting the pattern signal from the pattern generator of the transmitting end station and the protection line P _1-1
Is connected to the protection line P _1-2 only when is in use, and is provided with a pattern generator 25 that generates a pattern signal, and both protection lines P _1-1 and P _1-2 are not used in the receiving terminal, or When only the protection line P _1-2 is not used, the respective pattern signals connected to the protection line P _1-2 and from the pattern generator 11 of the transmitting terminal station and the pattern generator 25 of the intermediate relay station are distinguished. A digital multiplex transmission system comprising a pattern detector 31 capable of detecting.