JPS584503B2 - Preliminary connection method for digital signal transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a time division multiplexing system having a bit rate of about 2 Mbit/s and 30 channels, in which an additional channel is inserted before the first channel and the 16th channel. A C that is designed to transmit service words such as synchronization identification words, signaling information, and dialing information within the additional channels.
CITT Recommendation G. The present invention relates to a preliminary connection method of a digital signal transmission line for connecting a digital working system having a digital signal frame structure according to G.732 to a protection system.

As digital transmission lines come into frequent use,
It is desirable to automatically switch a faulty working system to a backup system.

If at least one line pulse regenerator fails, for example due to a failure of the remote power supply (e.g. due to a lightning strike),
It is necessary to switch the effective signal transmission line to a fault-free standby system.

For such cases, at least one, and possibly several, backup systems are provided in addition to the actual working system.

Furthermore, switching to the standby system is necessary not only when there is a failure but also for equipment maintenance.

In this case, it is known from JP-A-51-53409 to use at least one bit of a supervisory signal or a synchronization signal, which is transmitted in addition to the communication signal, to identify the connection via the backup line.

An object of the present invention is to provide a method for connecting to the protection system that allows switching to the protection system and hardly causes transmission failure even in the case of protection connection.

According to the invention, this problem is achieved by inserting and connecting controlled switches between the two connection points of each connection line and the corresponding individual terminal devices, and by means of these switches controlling the connection lines to the respective corresponding terminals. Switch from the device to the standby system terminal equipment, connect the control input side of the controlled switch to the control device installed in each terminal station, monitor the standby system by monitoring the frame identification word and service word, and check the working identification To transmit a signal or a service signal with the address of the working system to be switched, the 5th, 6th and 7th bits of the service word of the working system are used as the working identification signal in the transmission direction and the alarm inhibit signal. Using the alarm signal indicating the alarm indication signal, the fifth, sixth and seventh bits of the service word provide and receive the address of the active system to be switched to in order to connect the active system to the protection system. The fifth and sixth service words are used as a reception signal from a standby terminal device and are not used for address transmission.
and the seventh bit set are sent back to the standby terminal device that transmits the address, and if a failure notification signal is generated in the active terminal device, the fifth, sixth, and seventh bits of the service word are first transmitted. This problem can be solved by checking the information content in two transmission directions in the backup system.

Next, the method of the present invention will be explained in detail using figures.

The figure shows in principle a protection connection device connected to a transmission device having three working systems 1, 2 and 3 and a protection system 4 provided between the A and B terminal stations.

Also, a control device ST makes preliminary connections to terminal stations A and B, respectively.
A. A STB is provided.

In the illustrated embodiment, all transmission systems and standby systems 6, terminal devices LEA1 and LEA2 provided at terminal stations A and B
, LEA3 , LEAE; LEB1 . LEB2
, LEB3, and LEBE.

A fault occurring in one of the transmission systems n (n = 1.2.3.4) detected by terminal station A is sent out as a fault notification signal An1 of terminal station A, and detected by terminal station B accordingly. The fault that occurred is at terminal B.
It is sent out as a failure notification signal An2.

Further, the terminal equipment of the protection system 4 has a device for supplying the service signal MA or MB to the terminal stations A and B in the digital additional information for the transmission device from A to B or from B to A, and furthermore, At the terminal station B or A, it has an output for a service signal MB or MA which is supplied from B to A or from A to B in the opposite direction.

All fault reporting signals An1 or An2 as well as service signals MB or MA received at the other terminal station B or A are connected to the control device STA or STB of the terminal station A or B.
and evaluated by these control devices.

As a result of these evaluations the service signal MA or MB
is sent out and switches an1, an2 or bn1.
bn2 is switched.

By closing the switch anl or bn1, the transmission side of the protection system is connected in parallel with the working system n at the terminal station A or B.

Therefore, the protection system is synchronized with the digital signal of the working system n.
Ru.

By switching the switch an2 or bn2, the reception direction to the connection points VA and VB is switched from the reception output side of the working system n to the output side of the protection system.

In the case of fault-free operation, the transmission side of the protection system is connected in parallel to the transmission direction of the working system 1, which is the most important system in the embodiment of the invention, by means of switches a11 and b11, which are closed at the terminal stations A and B. All other connected switches an1 and bn1 are open, and the active receiving side is connected to the connection point V via switches an2 and bn2, respectively.
Connected to A and VB.

The control devices STA and STB send working identification signals B as service signals MA and MB to the transmission side of the standby terminal devices, respectively.
Supply A and BB.

In this case, the working identification signals BA and BB are inserted into the signal to be transmitted as the service signals MA and MB on the protection transmission line.

This makes it possible for the receiving point of the protection system to supply a control device connected thereto with a service signal that the protection system in question is already in use.

When there is a fault in the active system, a fault notification signal can be sent depending on whether the cause of the fault is only in terminal station A, only in terminal station B, or in both terminal stations.

Next, a method of transmitting this failure notification signal will be explained.

In this case, it is first assumed that in the working system n, only the terminal station A generates a failure notification signal, and that the terminal station B does not generate a failure notification signal.

The control device STB also supplies a current identification signal BB.

The cause of the failure notification signal that does not occur at terminal station A is a failure in the terminal device of terminal station A, a failure in the transmission line from B to A, a failure in the transmitter of the terminal device in B, or a connection in the transmission direction. This could be due to a failure in the device connected in advance to the connection terminal 11 at point vA.

In this last case, a backup connection has no effect, since it is not possible to connect the faulty part to the backup system.

When the fault notification signal A21 occurs, first the control device STA
checks whether the protection system is not generating the alarm signal A4l and/or whether the working identification signal BB is received from the other station via the protection line.

In such a case, the transmission side of the backup system is connected in parallel to, for example, the transmission side of the faulty working system 2 via the switch a21, and the switch all is opened.

Therefore, when a failure notification signal is generated in the backup system, since the failure is in the previous stage of the connection point, the control device again connects the transmission side of the backup system in parallel to the transmission side of the first working system, and sends the failure notification signal A21. The standby connection device for the active system 2 is cut off until it disappears.

On the other hand, when the protection system is connected in parallel to the working system 2 on the transmitting side, if no fault notification signal is generated in the protection system, the working identification BA
Instead, the address of the active system 2 to be switched is supplied as a service signal MA to the transmission direction of the protection system.

Further, in the transmission direction from A to B in the protection system, synchronization is established with respect to the digital signal to be transmitted from the working system 2.

After synchronization, the standby terminal device at the terminal station B receives the address of the active system 2 to which it should be connected as a standby signal as a service signal MA.

This address is supplied to the control device STB and the control device S
TB switches the corresponding receiving side switch bn2, ie, b22 in this case.

The transmission direction from A to B is thereby pre-connected.

At the same time, the control device STB closes the switch b21, thereby establishing a parallel connection between the faulty working system 2 and the protection system 4 on the transmitting side in the opposite transmission direction.

Since it is assumed that the fault notification signal An2 is not generated at the terminal station B as described above, the control device STB receives only the address signal of the system to be switched as the service signal MA.

Then, the control device STB sends the terminal station A as a service signal MB.
A reception signal QB is transmitted in the direction of.

Therefore, the direction from terminal station B to terminal station A is also synchronized with the system to be switched.

After this synchronization is established, the control device STA receives the reception signal QB as the service signal MB from the terminal device of the backup line.

Furthermore, at the same time, when the control device STA receives the fault notification signal An1, ie, A21, for example, it switches the active system to the standby system on the receiving side using the switch A22.

Fault after the fault has been removed. When the notification signal A21 disappears, first, the receiving side at the terminal station A is switched again to the working system 2 by the control device STA using the switch a22.

The parallel connection on the transmitting side is then maintained as long as the control device STA receives the acceptance signal QB.

Terminal A again uses the working identification signal B as the service signal MA.
A occurs.

When the working identification signal BA is detected at the terminal station B, the switches bn1 and bn2 at the terminal station B are switched to the working position again.

At the same time, the control device STB sends out the working signal BB as the service signal MB.

As a result, the switch an1 at the terminal station A is switched to the current position.

In other cases, if a fault occurs in one active system in which the fault notification signals anl and An2 are generated from terminal stations A and B at the same time, the transmitting side will control the corresponding switches anl and bn1 by the control device at the same time in the two terminal stations. and are connected in parallel.

Address signals of the faulty working system are therefore generated from the control devices STB and STB in both transmission directions of the protection system as service signals MA and MB, respectively.

Therefore, the two control devices STA and STB each receive the address signal and fault notification signal of the other station.

If these two signals relate to the same working system, the receiver is switched by the control device using switches an2 and bn2.

Therefore, if the failure notification signal disappears in one of the two terminal stations A or B, as long as the address signal is received by the other station, the corresponding control device will send the above-mentioned reception signal Q.
A or QB is generated.

Further, the backup system remains connected until the failure notification signal disappears at the second terminal station.

The preliminary connection is then interrupted as shown in the first example.

Due to a line fault, multiple working systems are simultaneously disconnected from terminals A and/or
or in the case of reporting a failure to B, the control device ST
A and STB are provided with a priority control circuit that controls the order in which they are connected to the backup system.

For this purpose, it is first detected which service signals MB or MA have been received from the partner station and which service signals MA or MB have already been supplied in the direction of the partner station.

If a working address or a reception signal is received from the other station, for which the fault reporting signal and address have already been supplied at the terminal station, a backup connection has already been made at another terminal station.

Other fault reporting signals then remain unconsidered.

However, if the working identification signal or the working address is received from a remote partner station without the working address or reception signal already being supplied in the forward direction, the failure notification signal An has priority. Generally, it is processed prior to the fault notification signal A(n+m) occurring at the same time.

In addition, the control devices STA and STB can be provided with devices that prevent the parent system from being automatically reconnected from the protection line to the working line.

In such a device, the failure notification signal An1 or An2 for the control devices STA and STB does not originate from the active terminal device, but from a device connected upstream or downstream of the connection point VA or VB. is necessary.

The reason why the above-mentioned additional device is necessary in such a case is that after connecting to the backup system, the fault notification of the active system connected to the backup system disappears.

Further, switches SA and SB are connected upstream of the control devices STA and STB, and the active system can be connected to the backup system by manual operation using these switches.

By actuating switch SA or SB, a fault reporting signal is simulated at the input of the corresponding control device for the active system to be switched over.

Therefore, connection to the standby system is automatically performed as described in the first example.

Also, when manually connecting to the backup line, you can install a delay line corresponding to each switch on the receiving side, and use the delay line to match the delay time through each working line to the delay time of the backup line. This is advantageous for maintenance.

In an ideal case, preliminary connections can be made without interruption.

Next, CCITT's observation G. A method for making a preliminary connection in a digital transmission system having a digital signal frame structure according to G.732 will be explained.

This CCITT Recommendation concerns a time division multiplexing system with a bit rate of approximately 2 Mbit/s and 30 channels:
In that case, an additional channel is inserted before the 1st channel and the 16th channel, and in the additional channel, signals related to the synchronization signal and the transmission of service signals such as signaling and selection signals are transmitted. is transmitted.

In this case, the backup line is monitored by monitoring the frame identification word and service word.

A frame identification word and a service word are transmitted alternately in an additional channel preceding the first channel for communication signals and indicate the start of a frame.

The frame identifier and service word each consist of 8 bits like other channel signals, where the first bit of the frame identifier and service word is reserved for international use, and Other bits are used for transmitting alarm signals and identifying the round-trip transmission direction, as well as for information that the time division multiplexed signal being transmitted does not occupy individual channels.

For the service signal MA or MB between the two terminal stations A and B, the fifth, sixth and seventh bits of the service word are used.

An alarm signal (AIS) is also supplied in the transmission direction as a working identification signal BA or BB.

The alarm signal is abbreviated as AIS in English, and indicates an alarm instruction signal as well as an alarm prohibition signal.

The alarm signal AIS is transmitted within the system in conjunction with the faulty transmission section and ensures synchronization in the connected parts of the transmission system.

Furthermore, even if the transmission system contains a signal that does not itself cause an alarm, the receiving terminal station can evaluate the signal and detect from the shape of the incoming signal that it is not a digital transmission signal.

Therefore, in order to be easily identified, the alarm signal AI
As S, we simply use a bit string having the form, for example, +1, -1, +1, -1.

In this case, this signal can be scrambled on the transmitting side of the transmission line and descrambled on the receiving side.

In order to start connecting the active system to the protection system, the address of the system to be connected to the protection system is inserted into the fifth, sixth, and seventh bits of the service word.

Since the acceptance signals QA and QB are transmitted as a response to the transmitted address, there is no need to include an address signal.

Therefore, the 5th, 6th and 7th bits of the service word, which do not contain an address, may be combined and used as an acceptance signal, and alternately and periodically transmitted as a working identification signal and the address of the system to be switched. I can do it.

Therefore, if a fault signal occurs, first the control device
The information content of the fifth, sixth and seventh bits of the service word of the two transmission directions is examined.

In the first case, the AIS signal is transmitted in two directions on the standby system until a failure notification signal occurs.

Therefore, first, the backup transmission side is connected in parallel to the failed active transmission side.

At the same time, the address of the faulty system is supplied to the protection system in the transmission direction.

After receiving the received signal via the protection system at the same terminal station, the receiving side is switched from the working system to the protection system.

In the second case, the address of the faulty system is received in the receiving direction of the protection system.

If a fault notification signal is not generated at the terminal station where the address of the system is received, the transmitting side of the relevant working system is connected in parallel to the protection system, and the receiving side is switched to the protection system.

At the same time, a reception signal is inserted into the standby service word.

On the other hand, if a fault notification signal for the same system is generated at the same time at the terminal station where the address of the system is received, switching is performed in the same manner as in the previous case, but the address of the same system is inserted in the service word. .

Furthermore, if a fault notification signal of a higher priority system occurs at the same time at the terminal station where the address of the faulty system is received, the terminal station of the higher priority system receives the address of the faulty system, unless the receiving signal or the address of the system to be received is supplied in the transmitting direction. The thread is connected in parallel to the standby system on the sending side, and the address of that system is inserted into the transmitted service word.

After the failure notification signal disappears, only if the AIS signal is always received from the opposite direction via the backup line.
The backup line will be reconnected to the working line.

[Brief explanation of the drawing]

The figure is a block diagram showing the principle of an apparatus for implementing the method of connecting a digital signal transmission line to a backup system according to the present invention. LEAI, LEA2. LEA3, LEAE, L
EB1, LEB2. LEB3, LEBE・・・・・・
Terminal device, STA, STB...control device, VA
, VB...Connection point.

Claims (1)

[Scope of Claims] 1 In a time division multiplexing system having a bit rate of about 2 Mbit/s and 30 channels, the first channel and the first
A CCI in which an additional channel is inserted before the sixth channel, and service words such as synchronization identification words, signaling information, and dialing information are transmitted within the additional channel.
TT Recommendation G. In a preliminary connection method of a digital signal transmission line for connecting a digital working system having a digital signal frame structure according to G.732 to a protection system, two connection points VA, VB of each connection line and corresponding individual terminal devices LEA1, LEA2. LEA3;LE
B1. Controlled switches a11, a12, a21, a22 . a31, a32
; b12, b11, b22. b21. b32 and b31 are inserted and connected, and the switch connects the connection lines from the respective corresponding terminal devices to the standby systems LEAE and LEBE.
The control input side of the controlled switch is connected to the control devices STA and STB installed in each terminal station, and the standby system is monitored by monitoring the frame identification word and service word, and the working identification signal is BA, BB or service signals MA, MB with the address of the working system to be switched
The fifth, sixth and seventh bits of the service word of the daily active system are used to transmit the working identification signal BA. Using the alarm signal AIS indicating an alarm prohibition signal or an alarm instruction signal as BB, the address of the working system to be switched is determined by the 5th, 6th, and 7th bits of the service word in order to connect the working system to the protection system. a reception signal Q from a standby terminal device that supplies the address and receives the address.
．． As A and QB, the fifth, sixth, and seventh bit sets of the service word when not used for transmitting the address are returned to the standby terminal device that transmits the address,
In addition, when a failure notification signal is generated in the active terminal device, the information contents of the fifth, sixth and seventh bits of the service word are first checked in the two transmission directions of the protection system. Features of a preliminary connection method for digital signal transmission lines. 2. Transmit the alarm signal AIS in both transmission directions of the backup system until a failure notification signal is generated, and if a failure notification signal occurs, first connect the transmission side of the backup system in parallel to the transmission side of the active system with the failure, When the address of the faulty system is supplied to the transmission direction of the protection system and a reception signal transmitted in the opposite direction to the transmission direction is received, the receiving side of the working system is switched to the protection system by the same control device. A method according to claim 1, characterized in that: 3. When the address of a faulty system is received in the receiving direction of the standby system, if the fault notification signal of the same working system is not generated at the receiving terminal station of the address of the said system, the control device controls and the receiving terminal At the station, the relevant working system is connected in parallel to the protection system on the transmitting side, and connected to switch to the protection system on the receiving side, and the fifth service word of the protection system is connected in parallel to the protection system on the transmission side.
, using the sixth and seventh bits to transmit an acceptance signal;
If the same working system failure notification signal occurs at the receiving end station of the system address, the working system is connected in parallel to the protection system on the transmitting side, and connected so as to be switched to the protection system on the receiving side. The 5th, 6th, and 7th bits of the word are used to transmit the address of the same system, and additionally, to the receiving terminal of the address of the system, a fault notification signal of another high-priority active system is transmitted simultaneously. If this occurs, unless a receiving signal or the address of the receiving system has been supplied in the transmitting direction, the system with the higher priority is connected in parallel to the protection system on the transmitting side and the address of that system is set as the service word. After the fault notification signal disappears, the alarm signal AIS is transmitted from the control device in the opposite direction to the above respective cases via the backup system. 2. The method according to claim 1, wherein the connection is switched from the standby system to the active system only when the signal is received.