JPS6248828A - Line switching system - Google Patents

Abstract

PURPOSE:To attain efficient line switching by transferring information to the receiving end when an input signal to the transmission end is interrupted and avoiding the line switching even when a radio line whose input signal is interrupted has a fault. CONSTITUTION:When an input interruption detecting section 9 detects that a signal from a carrier terminal station inputted to a T-LOG is interrupted, a detection signal is fed to a multiplex section 15, where the signal is multiplexed with a frame signal or the like and the result is fed to a transmitter. The polarity of an INPUT ALM signal obtained by separating a signal multiplexed at an R-LOG by a separation section 16 is inverted at the reception side and fed to a AND circuit 17. Even when fault information of an active line is detected by a fault detection section 13 and fed to the circuit 17, the information is blocked. A line switch controller does not regard it as a line fault and no changeover to a standby radio line is executed. If a signal is fed from a carrier terminal station and the state of the INPUT ALM is changed, the fault information extracted fault information from the fault detection 13 is fed to a line changeover controller through the circuit 17, then line switching is conducted.

Description

[Detailed Description of the Invention] [Summary] In the line switching system, when the input signal applied to the transmitting end is disconnected, this information is transferred to the receiving end and the input signal is disconnected from the wireless line. Since line switching is not performed even if a failure occurs, efficient line switching can be performed.

[Industrial application field]

The present invention relates to an improvement in a line switching system for digital wireless lines.

FIG. 2 shows an explanatory diagram of line switching operation.

In the figure, if all active wireless lines are normal, a signal from a carrier terminal station 1 passes through a sending-end parallel switch 1 and is sent to a sending-end digital signal processing unit (hereinafter abbreviated as T-LOG) 2. After being digitally processed, it is sent out from the transmitter 3.

Therefore, the original signal is extracted by the receiving end side digital signal processing section (hereinafter abbreviated as 1t-LOG) 5 through the corresponding receiver 4 and sent to the carrier terminal station 1''.

On the other hand, the backup wireless line transmits the output from the test pulse generator (TPG) to the test pulse detector (TPO) via this line.
We constantly check to make sure this line is working properly.

Now, for example, if a failure occurs in the transmitter 3, line switching is performed using the following procedure.

(2) When a fault is detected on the receiving end, a sending end parallel command (to send the signal flowing on the faulty radio line in parallel to the backup radio line) is sent to the sending end via the line switching control device 7.

- On the sending end side, after receiving the command, the sending end parallel switch 1 is driven.

■ Sends a confirmation signal (receiving end switching command) that the sending end parallel switch has operated to the receiving end, and after confirming this on the receiving end, drives the receiving end changeover switch 6 to switch to the backup wireless line. .

■ Regarding recovery, when the receiving end detects failure recovery of the working wireless line, the receiving end changeover switch 6 is restored,
The sending end parallel command issued to the sending end side is stopped, and the sending end switch 1 is also restored.

When switching such lines, it is desired that efficient switching be performed.

[Conventional technology]

FIG. 3 shows a block diagram of a conventional example of the line switching system.

First, on the sending end side, as shown in FIG. 3(a), the input signal (digital signal) from the carrier end station is speed-converted by a speed converter 8 to become a wireless line frame signal.

The signal is multiplexed with a meeting signal, etc. by the multiplexer 10, and sent to the transmitter. Further, the presence or absence of an input signal is detected by an input disconnection detection circuit 9.

Next, on the receiving end side, as shown in FIG. 3(b), the signal demodulated by the receiver is sent to the frame synchronizer 11 to detect the wireless line frame and establish synchronization, and then input to the demultiplexer 12. The signal and the meeting signal are separated, and the former is converted to the original transmission speed by the speed inversion section 14 and sent to the carrier terminal station.

For example, when the failure detection unit 13 cannot detect a wireless line frame, it sends a line failure alarm to the line switching control device. For example, forward protection for frame synchronization, forward protection for frame synchronization, A rear protection circuit can be used.

[Problem that the invention seeks to solve]

This line switching is done when a failure occurs in the transmission system from T-LOG to R-LOG, so
For example, even if the input signal to the T-LOG 2 is cut off due to a failure in the carrier terminal station 1, the working wireless line is not switched. However, when the input signal is cut off, for example, if the transmitter 3 becomes impaired, the line is switched to a backup radio line regardless of the input from the carrier terminal station.

Later, when another active wireless line in operation became impaired,
Since the backup wireless line is in use, this line cannot be saved.

That is, there is a problem in that the working radio line, which is not in operation due to the interruption of input from the carrier terminal station, monopolizes the backup radio line, and another working radio line that should originally be rescued is not rescued.

[Means for solving problems]

The above problem is that on the sending end side, the output of the input disconnection detection section 9 is added to the multiplexing section 15, and on the receiving end side, the inverted output of the input disconnection detection circuit from the separation section 16 and the output of the failure detection section 13 are added. (8) Solved by the line switching method of the present invention, which prevents switching to the backup radio line even if a failure occurs in the working radio line where the input signal is cut off. be done.

[Effect]

The present invention transfers input disconnection information from the transmitting end to the receiving end, and uses this information to prevent failure information of a working wireless line where the input signal is disconnected from being sent to the line switching control device.

This makes it possible to prevent unnecessary switching of the working wireless line, thereby allowing efficient switching.

〔Example〕

FIG. 1 is a block diagram of an embodiment of the present invention.
is a block diagram of T-LOG, Figure 1 (bl is R-LOG
The block diagram is shown below. Note that the same reference numerals indicate the same objects throughout the figures.

First, on the sending end side, as shown in Figure 1 (al), the T-LOG
When the input disconnection detection unit 9 detects that the signal from the carrier terminal station input to the
M, for example, l) is added to the multiplexer 15, where it is multiplexed with a frame signal, etc., and then sent to the transmitter.

On the receiving end side, as shown in FIG. 1(b), the Inpu
t The polarity of the ALM signal is inverted and added to the AND circuit (for example, AND circuit H7. Then, the failure information of the working line is detected by the failure detection unit 13 (for example, 1), and the AND circuit 1
7, this information is blocked by the AND circuit.

Therefore, the line switching control device (not shown) does not consider it to be a line failure, and does not switch the working radio line to the backup radio line.

However, a signal is added from the carrier terminal station and the InputAL
When the state of the inverted output of M changes (for example, 1), the fault information (for example, l) extracted from the fault detection section 13 is applied to the line switching control device through the AND circuit 17.
Line switching is performed as described above.

That is, line switching is performed only when a failure occurs in the current wireless line in operation, improving line switching efficiency.

〔Effect of the invention〕

As explained in detail above, switching of a working line whose input signal is cut off to a protection line is prohibited, which has the effect of enabling efficient line switching.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of line switching operation, and FIG. 3 is a block diagram of a conventional example. In the figure, 8 is a speed conversion section, 9 is an input disconnection detection section, 10 and 15 are multiplexing sections, 11 is a frame synchronization section, 13 is a failure detection section, 16 is a separation section, and 17 is an AND circuit. GoR-LOCr Number of times diaphragm switching type power source □7゛Mouth 1. ．． Trouble Figure 3

Claims (1)

[Claims] On the sending end side, there is an input disconnection detection section (9) for detecting disconnection of the input signal.
) and a speed converter (8) that converts the transmission speed of the input signal.
) and a multiplexing unit (15) that multiplexes the output of the speed conversion unit and a wireless line frame signal, etc., and on the receiving end side, it is possible to determine from the received signal whether or not a failure has occurred in the wireless line. A digital radio equipped with a fault detection section (13) that detects a fault, a separation section (16) that separates multiplexed signals, and a speed inversion section (18) that returns speed-converted signals to their original speed. In the line switching device of the line, on the sending end side, the output of the input disconnection detection section is added to the multiplexing section,
On the receiving end side, an AND circuit (
17), even if a failure occurs in the working wireless line where the input signal is cut off,
A line switching method characterized in that the working radio line is not switched to a backup radio line.