JPH05167567A - Line switching system - Google Patents

Abstract

PURPOSE:To make it possible to perform a line switching regardless of the patterns of a transmission signal and without losing a high speed when a fault active line is switched to a reserve line. CONSTITUTION:On a reception end side R, a fault active line is detected by a line monitoring circuit 13, the fault active line is made to perform a parallel operation with a reserve line by a transmission end switching circuit 11 on a transmission end side T based on this, and a switching information signal 5 of the transmission end switching circuit 11 is multiplexed with a transmission signal in a multiplex circuit 12A of the reserve line. On the reception end side R, a transmission end switching state signal 6 as the switching information signal is separated in a separation circuit 14A. The state confirmation is performed by this signal and the switching of the line is performed by a reception end switching circuit (hitless switching circuit) 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line switching system in wireless digital transmission, and more particularly to a (1 + N) line switching system.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional line switching system, which is an example of a (1 + N) hitless line switching system. In the figure, N working lines and one protection line are provided between the sending end T and the receiving end R, and the sending end T connects the working line and the protection line in parallel. End switching circuit 11,
Pilot signal generation circuit 1 for generating a pilot signal
8 and a multiplexing circuit 1 for multiplexing this pilot signal
2 and 12A, and a sending end line switching control circuit 16 for controlling the sending end switching circuit 11. Also, on the receiving end side R,
Line monitoring circuit 13, 13A for monitoring the presence or absence of line abnormality
Demultiplexing circuits 14 and 14A for separating a necessary information signal from the multiplexed signal, a hitless switching circuit 15 for hitlessly switching the working line to the protection line, and a receiving end for controlling the hitless switching circuit 15. It has a line switching control circuit 17 and a pilot signal detection circuit 19 for detecting a pilot signal transmitted through the protection line.

Hitless switching in this line switching device is performed as follows. On the receiving end side R, when the line monitoring circuit 13 detects the deterioration of the working line, the fault detection signal 1 is sent to the receiving end line switching control circuit 17.
Then, the line status signal 2 from the line monitoring circuit 13A for the protection line is used to check the presence / absence of a fault in the protection line, and the confirmation signal 7 output from the pilot signal detection circuit 19 is used to confirm the usage condition of the protection line. As a result, when the protection line is available, the sending end side parallel operation signal 3 is sent on the sending end side.
Is sent to the sending end switching circuit 11 of the working line to start sending end parallel operation.

Next, on the receiving side R, the pilot signal detecting circuit 19 detects that the protection line transmission signal 104 is switched from the pilot signal to the input signal 101 in order to confirm the parallel operation of the transmitting end. Then, the confirmation signal 7 of the detection result is output to the receiving end line switching control circuit 17. After this confirmation is made, the working line transmission signal 103 which has deteriorated and the protection line transmission signal 104 are compared with each other, and it is confirmed that the phases of the bit and the signal match, and the hitless switching circuit is switched by the switching control signal 4. Hitless switching is performed by 15. This completes the relief of the faulty line.

[0005]

In this conventional line switching system, a fixed repeating pattern signal, for example, 11001100 ... Is used as a pilot signal. Therefore, if the transmission signal resembles the pilot signal, the transmission signal flows to the protection line when the transmission end parallel operation is performed and the pilot signal detection circuit makes an erroneous detection. When it is determined that the switching operation is not completed, the switching sequence is stopped, and the line cannot be switched.

Further, if this pilot signal is constructed by using a pseudo random pattern signal, the pilot signal detection circuit on the receiving end side R takes a judgment time longer than a fixed pattern signal to judge it as a pseudo random pattern signal. ..
Therefore, there is a problem in that the high speed required for the hitless line switching sequence is lost and the hitless line switching cannot be performed. An object of the present invention is to provide a line switching system that enables line switching regardless of the pattern of a transmission signal and without impairing high speed.

[0007]

In the line switching system of the present invention, a transmission end switching circuit for switching a fault working line to a protection line on the transmission end side, and a switching state of this transmission end switching circuit are multiplexed into a transmission signal. And a multiplexing circuit for separating the sending end switching status signal from the multiplexed signal on the receiving end side, and a receiving end switching for switching between the fault working line signal and the protection line signal. And a circuit. Here, the sending end switching circuit on the sending end side is configured to perform a sending end parallel operation in which the transmission signal of the fault working line is branched to the protection line. Further, the receiving end switching circuit on the receiving end side is configured as a hitless switching circuit for performing hitless switching by checking the bit and phase of the fault working line signal and the protection line signal.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. 1 is a block diagram of an embodiment of the present invention.
The same reference numerals are given to the same parts as. At the sending end T,
The sending end switching circuit 11, the multiplexing circuits 12 and 12A, and the sending end line switching control circuit 16 are provided.
The switching information signal 5 is input to the multiplexing circuit 12A of the protection line so that the switching information signal 5 can be multiplexed with the transmission signal. No pilot signal generation circuit is provided. Also, on the receiving end side R, the line monitoring circuits 13, 13A,
The separation circuits 14 and 14A, the hitless switching circuit 15, and the receiving end line switching control circuit 17 are provided, but the pilot signal detection circuit is not provided. Then, the protection line separation circuit 14A separates the transmission end switching state signal 6 as the switching information signal 5 and receives it from the reception end line switching control circuit 1
It is configured to output to 7.

According to this structure, when the working line is deteriorated, the line monitoring circuit 13 outputs the fault detection signal 1 to the receiving end line switching control circuit 17. In addition, the line status signal 2 of the protection line is output from the line monitoring circuit 13A to the reception line switching control circuit 17 to determine the status of the protection line, and when the lines can be switched, the transmission line of the transmission side T The switching control circuit 16 outputs the sending end parallel operation signal 3 for carrying out the sending end parallel operation to the sending end switching circuit 11 of the working line having the trouble. As a result, in the sending end switching circuit 11, the input signal 101 is branched and input as the protection line signal 102 to the protection line multiplexing circuit 12A. At the same time, the switching information signal 5 is also output to this multiplexing circuit 12A. The multiplexing circuit 12A multiplexes the switching information signal 5 with the protection line signal 102.

At the receiving end R, the switching information signal 5 multiplexed at the sending end T is extracted as a sending end switching state signal 6 by the demultiplexing circuit 14A to check the sending end parallel operation, and the receiving end line is switched. Output to the control circuit 17. After this confirmation is obtained, the fault working line transmission signal 103 is compared with the protection line transmission signal 104, and after it is confirmed that the phases of the bit and the signal match, the hitless switching circuit 15 is switched by the switching control signal 4.
To switch between hitless. This completes the relief of the faulty line.

[0011]

As described above, according to the present invention, on the transmitting end side, the switching information signal for confirming the usage state of the protection line is multiplexed with the transmission signal and transmitted, and on the receiving end side, this is switched to the transmitting end. Since the line status is checked by using a resin as the status signal, there is no false detection of the pilot signal, and no pseudo-random pattern signal is used. There is an effect that the line can be switched without being damaged.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a line switching system of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional line switching system.

[Explanation of symbols]

 11 sending end switching circuit 12, 12A multiplexing circuit 13, 13A line monitoring circuit 14, 14A demultiplexing circuit 15 hitless switching circuit 16 sending end line switching control circuit 17 receiving end line switching control circuit

Claims (3)

[Claims] 1. A line switching system having a working line and a protection line for switching a failed working line to a protection line, and a sending end switching circuit for switching a failure working line to a protection line on the sending end side, and this sending end. A multiplexing circuit that multiplexes the switching state of the switching circuit with the transmission signal, and a separation circuit that separates the transmission side switching state signal from the multiplexed signal on the receiving end side, the fault working line signal and the protection line A line switching system comprising a receiving end switching circuit for switching signals. 2. The line switching system according to claim 1, wherein the sending end switching circuit on the sending end side is configured to perform a sending end parallel operation for branching the transmission signal of the fault working line to the protection line. 3. The line switching according to claim 1 or 2, wherein the receiving end switching circuit on the receiving end side is a hitless switching circuit for performing hitless switching by checking the bit and phase of the fault working line signal and the protection line signal. method.