JPS62278835A - Branching and inserting system in middle repeating station - Google Patents

Abstract

PURPOSE:To use efficiently a spare line and facilitate the architecture of a line control by changing over a presentuse line with a spare line in a repeating station, providing a pattern generating device and a pattern detecting device corresponding between respective stations and executing the changing-over control in accordance with the detecting condition, in a digital multiplex transmission system. CONSTITUTION:Present-use lines M1 and M2 and a spare line P are changed over by switches 12 and 13. The defect occurs at a transmission line between a transmission terminal station 1 and a middle repeating station 2 of the line M1 to execute the branching and re-inserting. In this case, the usual control signal is transmitted and received between the transmission terminal station 1 and the middle repeating station 2, the station 1 transmits the transmission signal of the line M1 even to the spare line P by the switch 12, and the station 2 changes over the reception signal of the line M1 to the line P by a switch 26. At the time, since a pattern is not detected by a pattern detecting device 22, a switch 27 is changed over and the signal of a pattern generating device 25 flows at the line P. A reception terminal station 3, since the pattern of the test signal of the line P is changed, knows that the spare line between the transmission terminal station 1 and the middle relaying station 2 is used.

Description

[Detailed Description of the Invention] [Summary] By generating and detecting a test signal for each cycle, line control of each drop/add section is made possible [Industrial Application] This invention relates to add/drop methods for multiplex transmission systems.

Since the analog multiplex transmission system uses frequency multiplexing, if drop/add is required at an intermediate relay station, it is easy to cut out that band with a filter and insert it into the vacant band.

Even in digital transmission systems that perform time division multiplexing, it is desired that intermediate relay stations be able to perform drop-add.

When an intermediate relay station branches and adds only required signals from n working lines and protection lines, an important issue is how to perform line switching.

Generally, in a digital multiplex transmission system, as shown in Fig. 2(a), data is transmitted from a transmitting end station 1 to a receiving end station 3 via intermediate relay stations 2 and 2'.
The basic configuration is a system in which data is transmitted without changing the number of lines. (b) and (c) are cases where there is branching or addition at the intermediate relay station 2', and the number of lines changes. (d) shows a case where there is branching and reinsertion at the intermediate relay station 2', and although the number of lines remains the same, some lines are different.

In cases such as those shown in FIGS. 2(b) to 2(d), the problem is how to efficiently utilize the protection line and how to implement the line control architecture in a simple manner.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is configured such that, as shown in FIG. 11.25 and pattern detectors 22.31 are provided, and line switching control between each station is performed according to the pattern detection state of each pattern detector.

[Effect]

Since a pattern generator and a pattern detector are installed between each station, the use status of the protection line can be grasped regardless of the transmission and reception of control signals during normal line switching, making it possible to change the control sequence during normal line switching. Instead, line control between each station can be performed using a simple additional circuit.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention, where (a) shows a normal state, and (b) to (d) show a case where a failure occurs.

FIG. 1(a) shows an example in which a digital multiplex transmission system is configured by two working lines Ml and M2 and a protection line P, and one working line M1 is dropped and reinserted at an intermediate relay station. .

The sending end station 1 has a pattern generator 11, and sends a predetermined pattern to the protection line P as a test signal. The intermediate relay station 2 branches the received signal of the protection line P by the hybrid 21, one side is sent to the pattern detector 22 to monitor whether the test signal is normally received, and the other side is sent to the switch 23'l.
In the receiving end station 3, a pattern detector 31 monitors whether the test signal is normally received in the received signal on the protection line P.

Further, the intermediate relay station has a demultiplexing section 24 for branching and reinserting the working line M1, and a pattern generator 25t separate from the transmitting end station 1. Then, only the working line M1 that is to be branched and reinserted can be switched to a protection line, and the working line M1 that is not to be branched and reinserted.
2 is only used for relaying.

FIG. 1(b) shows an example in which a failure has occurred in the transmission path between the transmitting end station 1 and the intermediate relay station 2 of the working line M1 that performs drop/reinsertion. In this case, the transmitting end station 1 Normal transmission and reception of control signals is performed between the terminal station 1 and the intermediate relay station 2, and the transmitting end station 1 uses the switch 12 to send the transmission signal of the working line M1 to the protection line P, and the intermediate relay station 2 uses the switch 26 to send the transmission signal of the working line M1 to the protection line P. Switch the received signal of the working line M1 to the protection line @P.0 At this time, since the pattern detector 22 does not detect a predetermined number of turns, the switch 27 is switched to send the signal of the pattern generator 25 to the protection line P. . The receiving end station 3 can know that the protection line between the sending end station 1 and the intermediate relay station 2 is being used because the pattern of the test signal on the protection line P has changed. c) shows an example in which a failure has occurred in the transmission path between the intermediate relay station 2 and the receiving end station 3 of the working line M1 that performs branching and reinsertion. In this case, the intermediate relay station 2 and the receiving end station 3, the intermediate relay station 2 uses the switch 28 to send the transmission signal of the working line M1 to the protection line P, and the receiving end station 3 uses the switch 32 to send the transmission signal of the working line M1 to the protection line P. At this time, the switch 23 is opened in conjunction with the switch 28 when the signal on the line M1 is switched to the protection line P. The receiving end station 3 has a pattern detector 31
Since no pattern is detected in , it can be known that the protection line between intermediate relay station 2 and receiving terminal station 3 is being used.

FIG. 1(d) shows an example in which a failure occurs somewhere between the transmitting end station 1 and the receiving end station 3 of the working line M2 that does not perform drop/add.

In this case, normal control signals are exchanged between the transmitting end station 1 and the receiving end station 3, and the transmitting end station 1 uses the switch 13 to transmit the signal of the working line M2 to the protection line P, and the receiving end station Station 3 transfers the received signal of the working line M2 to the protection line P through the switch 33.
Switch to.

At this time, if the pattern detector 22 of the intermediate relay station does not detect a predetermined pattern, it can be determined that the protection line P is being used.

In this way, by providing a pattern generator and a pattern detector compatible with each station, the control signal transmission and reception during normal line switching can be performed between each station of the working line for branching and re-insertion without changing the kW. It is possible to cut out obstacles and split bamboo.

In addition, if a failure occurs in both of the two working lines, switching is performed in consideration of the priority based on the pattern detection state of the pattern detector 22 or pattern detector 31 at the time when the latter failure occurs. .

Furthermore, in order to support non-stop switching, a delay circuit for the time required for dropping/reinserting another line may be inserted into the working line that does not perform dropping/reinserting at the intermediate relay station.

〔Effect of the invention〕

As described above, according to the present invention, branching and insertion can be performed by adding a simple circuit to the intermediate relay station, so there is no need for a terminal station configuration, and branching and insertion can be performed at low cost. This has the advantage that line control can be performed independently between each station, and the number of intermediate relay stations that can perform drop-add in the same way can be increased.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing branching and insertion. 1...Transmitting end station, 2.2'...Intermediate relay station, 3...Receiving end station, 11.25...Pattern generator, 22.31...・Pattern detector, 21...hybrid, 24...demultiplexer, 12.13, 23, 26, 27, 28, 32.33...
・Switch 0 shows the insertion of the 0 minute switch.

Claims (1)

[Scope of Claims] In a digital multiplex transmission system in which drop/add is performed at an intermediate relay station, the working line for drop/add is configured to be switched to a protection line at the intermediate relay station, and a pattern generator corresponding to each station is provided. (11, 25) and pattern detectors (22, 31), and performs line switching control between each station according to the pattern detection state of each pattern detector.