JP2003046413A - Optical transmission line changeover system and optical transmission line changeover method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission line changeover system and an optical transmission line changeover method that can solve a problem of indispensable provision of an optical switch to both conventional optical transmitters in the case of adopting a duplicating configuration for the two conventional optical transmitters by an active wired transmission line and a standby wireless transmission line. SOLUTION: In the optical transmission line changeover system an optical switch to connect one optical transmitter to an active transmission line or a standby transmission line is provided to the one optical transmitter, a photocoupler to connect the other optical transmitter to the active transmission line or the standby transmission line is provided to the other optical transmitter and an optical attenuator is provided onto the standby transmission line to attenuate the level of a signal given to the photocoupler on the standby transmission line to a level able to be disregarded by the optical transmitter. The optical transmission changeover method is configured such that the optical transmitter disregards the signal attenuated by the optical attenuator in the case of transmission through the active transmission line and the optical transmitter amplifies the signal attenuated by the attenuator in the case of transmission through the standby transmission line to conduct communication.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission line switching system and an optical transmission line switching method.

[0002]

2. Description of the Related Art Conventionally, an optical transmission line between two optical transmission devices is duplicated by a regular transmission line and a standby transmission line, and when a failure occurs in the regular transmission line, the standby transmission line is switched to continue communication. There are possible optical transmission line switching systems. Specifically, as shown in FIG. 4, two optical transmission devices A and B are connected by four optical cables C, D, E, and F, and an optical transmission line configured by two optical cables C and D among them. Is a regular transmission line G, and the optical transmission line formed by the other two optical cables E and F is a backup transmission line H, and the optical transmission line is duplicated. Further, an optical coupler J is provided on the side of one optical transmission device B, and one of the two optical cables C and D (optical cable C) forming the regular transmission line G and the two optical cables E forming the backup transmission line H are provided. , F (optical cable E)
Both of them are connected to the receiving unit R of the optical transmission apparatus B. Further, an optical coupler K is separately provided on the optical transmission device B side, and the other of the two optical cables C and D (optical cable D) forming the regular transmission line G and the two optical cables E forming the backup transmission line H, Both of the other F (optical cable F) are connected to the transmitter S of the optical transmission apparatus B. An optical switch L is provided on the side of the other optical transmission device A, and normally a regular transmission line G is formed.
Of the optical cables C and D of the book, the optical cable C connected to the receiving unit R of the optical transmission apparatus B is connected to the optical transmission apparatus A.
It is connected to the transmitter S of. Further, an optical switch M is separately provided on the side of the optical transmission device A, and the optical transmission device B is usually one of the two optical cables C and D constituting the regular transmission line G.
The optical cable D connected to the transmitter S of the above is connected to the receiver R of the optical transmission apparatus A in advance. As described above, bidirectional optical communication is performed between the two optical transmission devices A and B by the regular transmission line G. Then, when some trouble occurs in the regular transmission line G, the optical switches L and M are automatically switched, and the two-way optical communication is continued using the standby transmission line H.

As a similar optical transmission line switching system, there is a system as shown in FIG. This optical transmission line switching system uses the standby transmission line H shown in FIG. 4 as a wireless system. Specifically, a set of wireless devices N and P is installed in the middle of the backup transmission line H, and signals are transmitted and received between them by a wireless system.

[0004]

Among the conventional optical transmission line switching systems shown in FIGS. 4 and 5, the optical transmission line switching system shown in FIG. 5 has both optical transmission devices A and A for the following reasons. It is necessary to provide an optical switch on the B side. That is, the wireless devices N and P shown in FIG.
Even if the optical signal output from the device is not input, a signal (carrier wave) is transmitted and received between the two devices N and P. Therefore,
For example, an optical switch Q provided on the optical transmission device B side,
When R is replaced with an optical coupler similar to the optical couplers J and K shown in FIG. 4, during transmission through the regular transmission line G, an optical signal is input to the optical coupler through the transmission line G and the wireless device P
Since the carrier wave output from is also input to the same optical coupler,
They interfere with each other and cause deterioration of transmission quality.

For the above reasons, the conventional optical transmission line switching system or optical transmission line in which the optical transmission line between the two optical transmission devices is duplicated by the regular transmission line of the wired system and the standby transmission line of the wireless system. In the switching method, it is indispensable to provide an optical switch on both sides of the optical transmission device and cut the carrier wave output from the backup transmission line during transmission on the regular transmission line. However, if optical switches are provided on both optical transmission devices, the system becomes large and complicated, and a large number of power supplies for driving the optical switches must be secured.

[0006]

One of the optical transmission line switching systems of the present application is that a normal transmission line of a wire system and a standby transmission line of a wireless system are provided between two optical transmission devices, and the normal transmission line is used. An optical transmission line switching system that automatically switches to transmission on a backup transmission line when a line failure occurs, and an optical switch that connects the optical transmission device side to the regular transmission line or the standby transmission line is provided on one optical transmission device side. An optical coupler is provided on the side of the other optical transmission device for connecting the same device to the regular transmission line and the standby transmission line, and the optical transmission device can ignore the level of the signal input to the optical coupler on the standby transmission line. An optical attenuator that attenuates to the level is provided.

In another one of the optical transmission line switching systems of the present application, a wired regular transmission line and a wireless standby transmission line are provided between two optical transmission devices, and a failure occurs in the regular transmission line. A bidirectional optical transmission line switching system that automatically switches to transmission on a standby transmission line when it occurs, and an optical switch that connects the optical transmission device on one side to the down line of the regular transmission line or the standby transmission line. And an optical switch that connects the device to the upstream line of the regular transmission line or the standby transmission line, and an optical coupler that connects the device to the downstream lines of the regular transmission line and the standby transmission line on the other optical transmission device side. And an optical coupler that connects the device to the upstream lines of the regular transmission line and the standby transmission line, and the signal input to the optical coupler on the downlink of the standby transmission line is a level that can be ignored by the optical transmission device. Light attenuating to Teneta in which is provided.

One of the optical transmission line switching methods of the present application is 2
An optical transmission line switching method in which a wired normal transmission line and a wireless standby transmission line are provided between two optical transmission devices, and when a failure occurs in the regular transmission line, transmission is automatically switched to the standby transmission line. And an optical coupler that connects the optical transmission device to the regular transmission line or the standby transmission line on one side, and connects the device to the regular transmission line and the standby transmission line on the other optical transmission device side. And an optical attenuator that attenuates the level of the signal input to the optical coupler to a level that can be ignored by the optical transmission device on the backup transmission line, and is attenuated by the optical attenuator during transmission on the regular transmission line. The signal is ignored in the optical transmission device, and the signal is amplified in the optical transmission device for communication during transmission on the backup transmission line.

In another one of the optical transmission line switching methods of the present application, a wired normal transmission line and a wireless standby transmission line are provided between two optical transmission devices, and a failure occurs in the normal transmission line. In the case of a bidirectional optical transmission line switching method for automatically switching to transmission on the standby transmission line, an optical switch for connecting the optical transmission device side to the down line of the regular transmission line or the standby transmission line on one optical transmission device side. , An optical switch that connects the device to an upstream line of a regular transmission line or a standby transmission line, and an optical coupler that connects the device to the downstream lines of the regular transmission line and the standby transmission line on the other optical transmission device side, An optical coupler that connects the equipment to the upstream lines of the regular transmission line and the backup transmission line is provided, and the signal input to the optical coupler on the downlink of the backup transmission line is attenuated to a level that the optical transmission device can ignore. An optical attenuator is installed to During transmission of the transmission path, a signal attenuated by the optical attenuator neglected in an optical transmission system, at the time of transmission on the backup transmission line and performs communication by amplified in the optical transmission apparatus of the same signal.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) A first embodiment of an optical transmission line switching system and an optical transmission line switching method according to the present invention will be described below. As shown in FIG. 1, the optical transmission line switching system according to the present embodiment doubles a bidirectional optical transmission line connecting two optical transmission devices 1 and 2 with a regular transmission line 3 and a standby transmission line 4 to perform regular transmission. When some failure occurs in the line 3 and communication using the transmission line 3 becomes difficult or impossible, the communication is continued by switching to the backup transmission line 4.

As shown in FIG. 1, the regular transmission line 3 is a downlink line (optical cable 10) connecting a transmitter S of one optical transmission device 1 and a receiver R of the other optical transmission device 2. ,
The receiving unit R of one optical transmission device 1 and the other optical transmission device 2
It is a wired bidirectional transmission path configured with an upstream line (optical cable 11) connecting to the transmission unit S of the.

As shown in FIG. 1, the backup transmission line 3 has a downlink connecting between a transmission section S of one optical transmission apparatus 1 and a reception section R of the other optical transmission apparatus 2, and one optical transmission line. Transmission device 1
Is a bidirectional transmission path of a wireless system realized by a set of radio devices 20 and 21 that connects an upstream line that connects the reception unit R of 1 to the transmission unit S of the other optical transmission device 2.

As shown in FIG. 1, an optical switch 30a is provided on the optical transmission device 1 side, and a transmission section S of the device 1 can be switched and connected to the optical cable 10 and an optical cable 22 drawn from a wireless device 20. There is. Further, another optical switch 30b is provided on the optical transmission device 1 side,
It is possible to switch and connect the receiving section R to the optical cable 11 and the optical cable 23 drawn out from the wireless device 20.
That is, the optical switch 30a enables the transmitter S of the optical transmission device 1 to be switched and connected to the downlink of the regular transmission path 3 or the downlink of the backup transmission path 4, and the optical switch 30b.
Thus, the receiving unit R of the same device 1 can be switched and connected to the uplink of the regular transmission line 3 or the uplink of the backup transmission line 4.

As shown in FIG. 1, an optical coupler 40a is provided on the optical transmission device 2 side, and both the optical cable 10 and the optical cable 24 pulled out from the wireless device 21 through the optical coupler 40a perform the optical transmission. It is connected to the receiver R of the device 2. Further, another optical coupler 40b is provided on the optical transmission device 2 side, and both the optical cable 11 and the optical cable 25 pulled out from the wireless device 21 via the optical coupler 40b are transmitting units of the optical transmission device 2. It is connected to S. That is, the optical coupler 40a connects the receiving section R of the optical transmission device 2 to the downlink of the regular transmission line 3 and the downlink of the backup transmission line 4, and the optical coupler 40b
The transmitter S of the device 2 is connected to the upstream line of the regular transmission line 3 and the upstream line of the backup transmission line 4.

As shown in FIG. 1, an optical attenuator 50 is inserted in the middle of the optical cable 24 so that the wireless device 21
Is attenuated to a predetermined level and input to the optical coupler 40a. That is, the optical attenuator 50 is inserted in the downlink of the backup transmission line 4 so that the level of the signal input to the optical coupler 40a from the same line is attenuated to a predetermined value or less. Specifically, the optical cable 1
The optical signal is attenuated to a level below the level that causes interference with the optical signal input to the optical coupler 40a via 0 and above the minimum light receiving level of the optical transmission device 2.

The optical transmission line switching method of the present invention uses the optical transmission switching system of the present invention to duplicate optical transmission. Specifically, usually, the optical switch 30a shown in FIG.
Is connected to the optical cable 10 side, and the optical switch 30
Connect b to the optical cable 11 side. As a result, the optical signal output from the transmitter S of the optical transmission apparatus 1 is input to the receiver R of the optical transmission apparatus 2 via the optical cable 10, and the optical signal output from the transmitter S of the optical transmission apparatus 2 is It is input to the receiving unit R of the optical transmission device 1 via the optical cable 11.
That is, bidirectional communication is performed between the optical transmission devices 1 and 2 via the regular transmission line 3. Here, since the optical switch 30a is connected to the optical cable 10 side during the transmission on the regular transmission line 3, the optical signal output from the transmitter S of the optical transmission device 1 is not input to the wireless device 20. But the device 20
Always transmits a signal (carrier wave) to the other wireless device 21. Therefore, as shown in FIG. 2A, the optical signal output from the optical transmission device 1 is input to the optical coupler 40a via the optical cable 10, and the wireless device 21
The carrier wave received by is input through the optical cable 24,
These are multiplexed and input to the receiving unit R of the optical transmission device 2. However, the carrier wave output from the wireless device 21 is below the level at which the optical attenuator 50 inserted in the optical cable 24 may cause interference with the optical signal and above the minimum light receiving level of the optical transmission device 2. After being attenuated, it is input to the optical coupler 40a. As a result, the optical transmission device 2 to which the optical signal of sufficiently high level is input
Ignores the attenuated carrier as noise, so that the optical signal and the carrier do not interfere with each other and the transmission quality does not deteriorate.

On the other hand, when some trouble occurs in the regular transmission line 3 and communication using the transmission line 3 becomes difficult or impossible, the optical switch 30a is triggered by an alarm of the optical transmission device 1 or 2. The optical cable 22 is switched and connected, and the optical switch 30b is switched and connected to the optical cable 23 side. However, systematically, these switching connections are automatically performed. As a result, the optical signal output from the transmitter S of the optical transmission device 1 is transmitted to the wireless device 2 via the optical cable 22.
0, is wirelessly transmitted from the device 20 to the other wireless device 21, and is input to the receiving unit R of the optical transmission device 2 via the optical cable 24. The optical signal output from the transmission unit S of the optical transmission device 2 is input to the wireless device 21 via the optical cable 25, wirelessly transmitted from the same device 21 to the other wireless device 20, and transmitted via the optical cable 23. It is input to the receiving unit R of the device 1. That is, bidirectional communication is continued between the optical transmission devices 1 and 2 via the backup transmission line 4. here,
At the time of transmission on the backup transmission line 4, since the optical switch 30a is connected to the optical cable 22 side, no signal is input to the optical cable 10. Therefore, since the optical signal is input to the optical coupler 40a only from the optical cable 24, there is no risk of interference. A signal (optical signal) input from the optical cable 24 to the optical coupler 40a at the time of transmission on the backup transmission line 4 is attenuated by the optical attenuator 50 similarly to a signal (carrier wave) input at the transmission on the regular transmission line 3. Has been done. However, as shown in FIG. 2B, the optical coupler 4 is connected via the optical cable 10 during transmission on the backup transmission line 4.
Since there is no signal input to 0a, the optical transmission device 2
Does not ignore the low-level optical signal attenuated by the optical attenuator 50 (recognizes it as a signal rather than noise), amplifies it to a predetermined level, and continues communication.

(Second Embodiment) A second embodiment of the optical transmission line switching system and the optical transmission line switching method of the present invention will be described below. The basic configurations of the optical transmission line switching system and the optical transmission line switching method shown in this embodiment are the same as those shown in the first embodiment. The difference is that a monitoring light is transmitted along with an optical signal to the regular transmission line, and the occurrence of a fault in the regular transmission line can be detected based on the level fluctuation of the supervisory light, and the standby transmission line is detected when the occurrence of the fault is detected. It is to be automatically switched to the transmission in.

Specifically, as shown in FIG. 3, a light source 60 for generating monitoring light is provided on the optical transmission device 1 side, and the light source 6 is provided.
The monitoring light generated from 0 is made incident on the optical cable 10 by the wavelength selection optical coupler 61a and transmitted to the other optical transmission device 2 side, and the monitoring light is extracted by the wavelength selection optical coupler 61b on the other optical transmission device 2 side. The wavelength selective optical coupler 61c causes the optical cable 11 to enter the optical cable 11 and returns it to the optical transmission device 1 side. Further, the returned monitoring light is taken out by the wavelength selection optical coupler 61d, received by the light receiving element 62 and its level is measured, and when the level drops below a predetermined value, it is connected to the regular transmission line 3 (optical cable 11) until then. The optical switch 30b that was previously installed is automatically replaced by the backup transmission line 4
(Optical cable 23) is switched and connected.

In the optical transmission line switching system according to this embodiment, the optical switch 30a shown in FIG. 1 is replaced by the optical coupler 70, and only one optical switch 30b is operated. The path 4 can be switched. Therefore, the system is smaller and simpler than the optical transmission line switching system according to the first embodiment. In addition, the number of power supplies required to drive the optical switches is reduced by the number of the optical switches.

[0021]

The optical transmission line switching system of the present application has two
In an optical transmission line switching system in which a wired normal transmission line and a wireless standby transmission line are provided between two optical transmission devices, and when a failure occurs in the regular transmission line, transmission is automatically switched to the standby transmission line, While one optical transmission device is always connected to the regular transmission line and the standby transmission line by an optical coupler,
An optical attenuator that attenuates the level of the signal input to the optical coupler to a level that can be ignored by the optical transmission apparatus is provided on the backup transmission line. Therefore, at the time of transmission on the regular transmission line, even if signals are input to the optical transmission device from both the transmission line and the standby transmission line, the signal input from the standby transmission line is ignored in the optical transmission device. There is no risk of signals interfering with each other. Therefore, it is not necessary to provide an optical switch on the side of the optical transmission device for switching and connecting the device to the regular transmission line and the standby transmission line, and the system is downsized and simplified. In addition, the number of required power sources is reduced as the number of optical switches is reduced.

In the optical transmission line switching method of the present application, a wired normal transmission line and a wireless standby transmission line are provided between two optical transmission devices, and the standby transmission is performed when a failure occurs in the regular transmission line. In an optical transmission line switching method for automatically switching to transmission on a line, one optical transmission device is always connected to a regular transmission line and a standby transmission line by an optical coupler, and a signal input to the optical coupler on the standby transmission line is An optical attenuator that attenuates the level to a level that can be ignored by the optical transmission device is provided, and during transmission on the regular transmission line, among signals input to the optical transmission device from both the transmission line and the standby transmission line, The signal input from the backup transmission line is ignored in the optical transmission device. Therefore, there is no possibility that two signals input to the optical transmission device will interfere with each other during transmission on the regular transmission line. Therefore, it is not necessary to provide an optical switch on the side of the optical transmission device for switching and connecting the device to the regular transmission line and the standby transmission line, and the system is downsized and simplified. In addition, the number of required power sources is reduced as the number of optical switches is reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an optical transmission line switching system according to a first embodiment of the present invention.

2A and 2B are diagrams showing a signal input state to the optical coupler shown in FIG. 1, where FIG. 2A is an explanatory diagram when a regular transmission line is used, and FIG.
Is an explanatory view when using a backup transmission line.

FIG. 3 is an explanatory diagram showing a configuration of an optical transmission line switching system of the present invention shown in a second embodiment.

FIG. 4 is an explanatory diagram showing an example of a conventional optical transmission line switching system.

FIG. 5 is an explanatory diagram showing another example of the conventional optical transmission line switching system.

[Explanation of symbols]

1 One optical transmission device 2 Other optical transmission device 3 Normal transmission line 4 Backup transmission line 10 One optical cable constituting the regular transmission line 11 The other optical cable 20 constituting the regular transmission line 20 One wireless device 21 The other wireless device 22 Optical cable 23 that connects one wireless device and the transmission unit of one optical transmission device 23 Optical cable 24 that connects one wireless device and the reception unit of one optical transmission device 24 Reception of the other wireless device and the other optical transmission device Optical cable 25 for connecting the other part to the other wireless device and an optical cable for connecting the transmitting part of the other optical transmission device 40 Optical coupler 50 Optical attenuator 60 Light source 61 Wavelength selection optical coupler 62 Light receiving element

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Maki Hattori             2-6-1, Marunouchi, Chiyoda-ku, Tokyo             Kawa Electric Industry Co., Ltd. (72) Inventor Masahiko Yamamoto             4-7-1, Hatchobori, Chuo-ku, Tokyo Japan             Telecom Co., Ltd. F-term (reference) 5K002 BA02 BA04 EA33 FA01 FA03                 5K014 AA01 CA06 FA01 HA01                 5K021 BB01 CC13 CC14 DD02 FF11

Claims (4)

[Claims] 1. A regular transmission line (3) and a standby transmission line (4) of a wireless system are provided between two optical transmission devices (1) and (2), and the regular transmission line (3) is provided. An optical transmission line switching system that automatically switches to transmission on a standby transmission line (4) when a failure occurs in the optical transmission line (4), and the optical transmission device (1 or 2) is normally transmitted to one optical transmission device (1 or 2) side. An optical switch (30) connected to the line (3) or the backup transmission line (4) is provided, and the device (2 or 1) is connected to the regular transmission line (3) and the optical transmission device (2) on the side of the other optical transmission device (2 or 1). An optical coupler (40) connected to the backup transmission line (4) is provided, and the backup transmission line (4) is provided.
An optical transmission line characterized in that an optical attenuator (50) for attenuating the level of a signal input to the optical coupler (40) to a level that can be ignored by the optical transmission device (2 or 1) is provided on the top. Switching system. 2. A regular transmission line (3) and a standby transmission line (4) of a wireless system are provided between two optical transmission devices (1) and (2), and the regular transmission line (3) is provided. A bidirectional optical transmission line switching system that automatically switches to transmission on a standby transmission line (4) when a failure occurs in the optical transmission line (1 or 2) on one optical transmission device (1 or 2) side. The optical switch (30a) for connecting the optical transmission line (3) or the standby transmission line (4) to the downlink of the normal transmission line (3) or the standby transmission line (4), and the device (1 or 2) An optical switch (30b) for connecting to the line is provided, and the device (2 or 1) is connected to the other side of the optical transmission device (2 or 1) on the down line of the regular transmission line (3) and the standby transmission line (4). The optical coupler (40a) to be connected to the above and the device (2 or 1) are connected to the upstream of the regular transmission line (3) and the standby transmission line (4). An optical coupler (40b) connected to the optical line, and a signal input to the optical coupler (40a) on the downlink of the backup transmission line (4) can be ignored by the optical transmission device (2 or 1). An optical transmission line switching system, which is provided with an optical attenuator (50) for attenuating the light. 3. A wire type regular transmission line (3) and a wireless type standby transmission line (4) are provided between two optical transmission devices (1) and (2), and the regular transmission line (3) is provided. An optical transmission line switching method for automatically switching to transmission on a backup transmission line (4) when a failure occurs, in which one device (1 or 2) is used for regular transmission. The optical switch (30) connected to the line (3) or the backup transmission line (4) is provided, and the device (2 or 1) is provided on the other optical transmission device (2 or 1) side. An optical coupler (40) connected to the transmission line (4) is provided, and the level of the signal input to the optical coupler (40) on the backup transmission line (4) can be ignored by the optical transmission device (2 or 1). An optical attenuator (50) for attenuating to a level is provided, and the optical attenuator (50) is used at the time of transmission through the regular transmission line (3). The signal attenuated by 50) is ignored in the optical transmission device (2 or 1), and the same signal is amplified in the optical transmission device (2 or 1) at the time of transmission on the backup transmission line (4) to perform communication. A characteristic optical transmission line switching method. 4. A wire type regular transmission line (3) and a wireless type standby transmission line (4) are provided between two optical transmission devices (1) and (2), and the regular transmission line (3) is provided. A two-way optical transmission line switching method for automatically switching to transmission on a backup transmission line (4) when a failure occurs, wherein one optical transmission device (1 or 2) has the same device (1 or 2). Optical switch (3) for connecting the transmission line to the downlink of the regular transmission line (3) or the standby transmission line (4)
0a) and an optical switch (30b) for connecting the device (1 or 2) to the upstream line of the regular transmission line (3) or the backup transmission line (4), and the other optical transmission device (2 or 1) An optical coupler (40a) for connecting the same device (2 or 1) to the downlink of the regular transmission line (3) and the backup transmission line (4) on the side
And an optical coupler (40b) for connecting the device (2 or 1) to the upstream lines of the regular transmission line (3) and the standby transmission line (4)
And an optical attenuator (50) for attenuating a signal input to the optical coupler (40a) to a level that can be ignored by the optical transmission device (2 or 1) on the downlink of the backup transmission line (4). The optical transmission device (2 or 1) ignores the signal attenuated by the optical attenuator (50) during transmission through the regular transmission line (3), and the same signal during transmission through the backup transmission line (4). A method for switching an optical transmission line, characterized in that the optical transmission device (2 or 1) is amplified for communication.