JP6745915B2 - WDM device - Google Patents

Description

The present invention relates to a wavelength division multiplexing optical device, and more particularly to a wavelength division multiplexing optical device that transmits an optical signal through a predetermined route.

The wavelength division multiplexing optical transmission system has been put to practical use as a system suitable for a core metro network. The wavelength division multiplexing optical transmission system can significantly increase the transmission capacity by multiplexing and transmitting a plurality of optical signals of different wavelengths in one optical fiber and separating the optical signals for each wavelength. ..

In a wavelength division multiplexing optical transmission system, a plurality of wavelength division multiplexing optical devices (hereinafter also referred to as nodes) are connected by optical fibers. Each node is monitored and controlled by an NMS (Network Management System) through a DCN (Data Communication Network) line.

The connection form of each node includes a point-to-point topology configured in a one-to-one correspondence, a linear topology configured in a linear manner, a ring topology configured in a loop type, or a mesh topology configured in a grid pattern. There are various forms such as. Therefore, the wavelength division multiplexing optical transmission system can flexibly configure the system.

In recent years, with the continuous increase in demand for communication traffic, further increase in capacity and cost reduction are demanded in wavelength division multiplexing optical transmission systems. For this reason, the shift to mesh topology by multi-directional technology is accelerating. Wavelength cross-connect technology is applied to multi-directional technology, which enables switching in any direction in wavelength units or wavelength group units as optical signals without converting the optical signals into electrical signals at nodes in the middle of transmission. ..

As a component of a node, the function of demultiplexing optical signals of different wavelengths, and the optical signal of its own node or the optical signals transmitted from different nodes in wavelength units or wavelength group units in arbitrary directions An optical cross-connect unit that has a switching function, an interface with a downstream device, a transponder unit that can set the signal from the downstream device to an optical signal of any wavelength, and a reception that compensates for the loss of the transmission path (optical fiber). There is a side optical amplification section and a transmission side optical amplification section for compensating for the passage loss in the node. Further, as a component of the node, a function of communicating with an NMS through an interface unit to set a wavelength and a route of an optical signal, and notifying an alarm state and performance information in the node to the NMS through the interface unit There is a monitoring control unit having a function to perform, and a monitoring control light unit that monitors and controls alarms and performance information between nodes.

In the wavelength multiplexing optical device, a difference occurs in the optical signal level of each wavelength due to the passage loss in the node and the wavelength dependence of the gain of the reception side optical amplification section and the transmission side optical amplification section. Therefore, the wavelength division multiplexing optical device controls the optical level for each wavelength in order to keep the optical signal level constant. However, in a wavelength division multiplexing optical transmission system configured by connecting a plurality of nodes, the optical level control of a plurality of nodes causes the optical signal level error due to the control delay of the optical level control of a certain node to occur in the subsequent node. This will affect the input optical signal level. Therefore, in the case of multi-stage transmission, an error in the optical signal level propagates every time a node passes, and the completion time of the optical level control is delayed, which causes deterioration of signal quality.

In the conventional wavelength division multiplexing optical transmission system, each node sequentially performs optical level control from the transmission node, as in Japanese Patent Laid-Open Publication No. 2004-242242. The upstream node notifies the downstream node that the optical signal level of the upstream node has reached the target value by the optical level control by the supervisory control light, and the downstream node starts the optical level control after the notification. Therefore, it is possible to prevent the error influence of the optical signal level.

In the optical transmission system described in Patent Document 2, since the latter node starts the optical level control before the optical level control of the former node is completed, the former node has the optical signal level target value and the current value of the former node. The difference is calculated as the optical level control amount corrected by the preceding node, and the optical level control amount is transmitted to the succeeding node using the supervisory control light. The subsequent node sets a new optical signal level target value, which is a value obtained by subtracting the received optical level control amount of the previous node from the optical signal level target value of its own node. As described above, Patent Document 2 discloses a method of limiting the control amount to suppress the error in the optical signal level and shortening the time required for the optical level control.

JP, 2006-33542, A JP, 2013-70198, A

In the conventional system, communication between the nodes using the supervisory control light is indispensable in order to suppress the error of the optical signal level and shorten the required time. Therefore, when the transmission quality of the supervisory control light is deteriorated or the supervisory control light section fails, the conventional system cannot perform the optical level control, which affects the signal quality of the subsequent node. There was a problem.

Further, in recent years, the number of nodes and the number of wavelengths have increased along with the increase in scale, and the mesh topology has enabled optical signals to freely pass through various routes and nodes. Therefore, in the conventional system, since it is necessary to transmit and receive the optical level control amount between the nodes, the control information amount in the wavelength division multiplexing optical transmission system increases and the possibility of delay increases, and the processing time of the optical level control increases. There was also a problem that it became long.

Therefore, the present invention controls the optical level without using the supervisory control light, and suppresses the error of the optical signal level due to the optical level control even when the number of nodes or the number of wavelengths is large and the topology form is complicated. However, it is intended to enable flexible and highly reliable transmission of optical signals.

A wavelength division multiplexing optical apparatus according to a first aspect of the present invention has a wavelength used as one wavelength division multiplexing optical apparatus included in a plurality of wavelength division multiplexing optical apparatuses that transmit an optical signal through a predetermined path for each wavelength. A multiplexing optical device, wherein an adjusting unit for adjusting the intensity level for each wavelength in the optical signal, and an optical output for detecting the intensity level for each wavelength in the optical signal output from the adjusting unit as an optical output level The level detection unit and the first control amount, which is a control amount for adjusting the intensity level for each wavelength in the optical signal, become smaller as the one wavelength-multiplexing optical device is arranged rearward in the path. A level that is set in the adjustment unit for each wavelength, and the adjustment unit adjusts the intensity level for each wavelength in the optical signal with the first control amount to bring the optical output level close to a target level. And a control circuit section.

A wavelength division multiplexing optical apparatus according to a second aspect of the present invention uses a wavelength division multiplexing optical apparatus included in a plurality of wavelength division multiplexing optical apparatuses that transmit an optical signal through a predetermined path for each wavelength. In the multiplex optical device, an adjusting unit for adjusting the intensity level for each wavelength in the optical signal, and a plurality of intensity levels for each wavelength in the optical signal input to the adjusting unit are set as a plurality of optical input levels. An optical input level detecting section for detecting, an optical output level detecting section for detecting an intensity level for each wavelength in the optical signal output from the adjusting section as an optical output level, and an intensity level for each wavelength in the optical signal. The first control amount, which is a control amount for adjusting the wavelength, is set to the adjustment unit for each wavelength so that the first control amount decreases as the magnitude of the time variation of the plurality of optical input levels increases , and then the adjustment unit. And a level control circuit unit for adjusting the intensity level for each wavelength in the optical signal by the first control amount to bring the optical output level close to a target level.

A wavelength division multiplexing optical apparatus according to a third aspect of the present invention is a wavelength division multiplexing optical apparatus included in a plurality of wavelength division multiplexing optical apparatuses that transmit an optical signal through a predetermined path for each wavelength. In the multiplex optical device, an adjusting unit for adjusting the intensity level for each wavelength in the optical signal, and a plurality of intensity levels for each wavelength in the optical signal output from the adjusting unit as a plurality of optical output levels By removing the control amount adjusted by the adjusting unit from the optical output level detecting unit to detect and the plurality of optical output levels, for each wavelength in the optical signal input to the one wavelength multiplexing optical device. A plurality of optical input levels that are a plurality of intensity levels are calculated, and a first control amount that is a control amount that adjusts the intensity level of each of the wavelengths in the optical signal is set to a time variation of the plurality of optical input levels. After setting the adjustment unit for each wavelength so that the magnitude becomes larger, the adjustment unit adjusts the intensity level for each wavelength in the optical signal by the first control amount, And a level control circuit unit for bringing the light output level detected by the light output level detection unit close to the target level.

According to one aspect of the present invention, the optical level is controlled without using the supervisory control light, and even when the number of nodes and the number of wavelengths are large, and even when the topology form is complicated, the optical signal level of the optical level control It is possible to suppress errors and perform flexible and reliable optical signal transmission.

It is a block diagram which shows roughly the structure of the wavelength division multiplexing optical transmission system which concerns on Embodiments 1-3. FIG. 4 is a block diagram schematically showing an internal configuration of an optical cross connect unit in the first and third embodiments. (A) And (B) is a schematic diagram showing an example of hardware constitutions of Embodiments 1-3. 5 is a flowchart showing an example of light level control in the first embodiment. FIG. 6 is a schematic diagram showing a first variation example of the optical input level and the optical output level in the first embodiment. 5 is a schematic diagram showing a second variation example of the optical input level and the optical output level in the first embodiment. FIG. FIG. 9 is a schematic diagram showing a third variation example of the optical input level and the optical output level in the first embodiment. FIG. 5 is a schematic diagram showing an example of change in control amount in the first embodiment. 5 is a block diagram schematically showing an internal configuration of an optical cross connect unit in the second embodiment. FIG. FIG. 9 is a schematic diagram showing a method of detecting the magnitude of temporal change in optical input level according to the second embodiment. 9 is a flowchart showing an example of light level control in the second embodiment.

Embodiment 1.
FIG. 1 is a block diagram schematically showing the configuration of the wavelength division multiplexing optical transmission system 100 according to the first embodiment.
The wavelength multiplexing optical transmission system 100 includes N wavelength multiplexing optical devices 110. Here, N is an integer of 2 or more. Here, the wavelength division multiplexing optical transmission system 100 uses N wavelength division multiplexing optical devices 110 to transmit an optical signal through a predetermined route (optical path) for each wavelength.
The wavelength multiplexing optical device 110 is connected to another wavelength multiplexing optical device 110 via transmission lines 103A to 103D formed of optical fibers or the like.
Here, when it is not necessary to distinguish each of the transmission paths 103A to 103D, the transmission path 103 is used.
Further, the wavelength multiplexing optical device 110 communicates with the NMS 101 as a control device and the downstream device 102 as a signal processing device such as a layer 2 switch and a router. The NMS 101 manages the arrangement of N wavelength multiplexing optical devices 110 in each optical path.

The wavelength multiplexing optical device 110 includes transmitting side optical amplifying sections 111A and 111B, receiving side optical amplifying sections 112A and 112B, a transponder section 113, an interface section (I/F section) 114, a monitor control section 115, and an optical control section 115. And a cross-connect unit 120.
When there is no particular need to distinguish between the transmission-side optical amplification units 111A and 111B, they are referred to as the transmission-side optical amplification unit 111.
When there is no particular need to distinguish between the receiving-side optical amplification units 112A and 112B, they are referred to as the receiving-side optical amplification unit 112.

The transmission-side optical amplification unit 111 compensates for the loss in the wavelength division multiplexing optical device 110 and optically amplifies the optical signal up to the transmission line output level in any direction. Then, the transmission-side optical amplification unit 111 transmits the amplified optical signal to the adjacent wavelength multiplexing optical device 110 via the connected transmission path 103.

The reception-side optical amplification unit 112 compensates the optical level of the optical signal transmitted from the adjacent wavelength multiplexing optical device 110 in an arbitrary direction, which is reduced by the loss due to the connected transmission path 103, and optically amplifies the optical level. As the receiving side optical amplification section 112, different types of optical amplifiers are applied according to the loss amount of the transmission path 103.

The transponder unit 113 converts the signal from the downstream device 102 into an optical signal having an arbitrary wavelength, and transmits the converted optical signal to the optical cross connect unit 120. The transponder unit 113 also converts an optical signal of an arbitrary wavelength into a signal that the downstream device 102 can receive, and transmits the converted signal to the downstream device 102 .

The I/F unit 114 is an interface unit for connecting to the DCN line 104.
The monitor control unit 115 is connected to the NMS 101 via the I/F unit 114 and the DCN line 104.
The monitoring control unit 115 collects the alarm status and performance information in the wavelength division multiplexing optical device 110, and notifies the NMS 101 through the I/F unit 114 and the DCN line 104. Further, the supervisory control unit 115 notifies each unit in the wavelength multiplexing optical device 110 of the optical path setting (optical path setting for each wavelength) and control information from the NMS 101.

The optical cross connect unit 120 is connected to the transponder unit 113, and multiplexes or demultiplexes optical signals of a plurality of different wavelengths. Further, the optical cross-connect unit 120 switches the optical signal of its own node and the optical signal optically amplified by the receiving-side optical amplification unit 112 in arbitrary directions in wavelength units or wavelength group units.

FIG. 2 is a block diagram schematically showing the internal configuration of the optical cross connect unit 120.
The optical cross-connect unit 120 includes cross-connect setting units 121A and 121B, optical output level detection elements 122A and 122B, and level control circuit units 123A and 123B.
The cross-connect setting unit 121A, the optical output level detection element 122A, and the level control circuit unit 123A are input from the transmission line 103A and output to the transmission line 103B, and the transponder unit 113 inputs the transmission line 103B. And the optical signal output to.
On the other hand, the cross-connect setting unit 121B, the optical output level detection element 122B, and the level control circuit unit 123B are input from the transmission path 103C, output to the transmission path 103D, and input from the transponder unit 113 for transmission. The optical signal output to the path 103D is processed.
When it is not necessary to distinguish between the cross-connect setting units 121A and 121B, the cross-connect setting unit 121 will be referred to.
The optical output level detecting elements 122A and 122B are referred to as the optical output level detecting element 122 when there is no particular need to distinguish between them.
When it is not necessary to distinguish between the level control circuit units 123A and 123B, the level control circuit units 123 are referred to as level control circuit units 123.

The cross-connect setting unit 121 functions as an adjusting unit that adjusts the optical level, which is the intensity level for each wavelength in the optical signal. For example, the cross-connect setting unit 121 is configured by combining an optical waveguide grating and a variable optical attenuator or a wavelength selective switch, and adjusts the optical level of each wavelength to an arbitrary level. The wavelength selective switch has a switch function for switching in any direction and a variable optical attenuation function for controlling the transmission loss for each wavelength.

The optical output level detection element 122 functions as an optical output level detection unit that detects the intensity level for each wavelength in the optical signal output from the cross connect setting unit 121 as an optical output level. For example, the optical output level detection element 122 monitors the optical level for each wavelength in the optical signal that has passed through the cross connect setting unit 121, and notifies the level control circuit unit 123 of the monitoring result. The optical output level detecting element 122 is composed of an OCM (Optical Channel Monitor) or the like capable of detecting the optical level of each wavelength.

The level control circuit unit 123 drives the cross-connect setting unit 121 according to the set control amount until the monitoring result reaches the target value. For example, the level control circuit unit 123 decreases the first control amount, which is the control amount for adjusting the intensity level for each wavelength in the optical signal, as the device is arranged rearward in the path for transmitting the optical signal. In this manner, the cross-connect setting unit 121 is set for each wavelength. Then, the level control circuit unit 123 adjusts the intensity level for each wavelength in the optical signal with the first control amount set in the cross-connect setting unit 121 to bring the optical output level close to the target level. When the absolute value of the difference between the optical output level and the target level is equal to or less than the first control amount, the level control circuit unit 123 uses the second control amount that is smaller than the first control amount. A certain minimum value is set in the cross connect setting unit 121. In this case, the cross-connect setting unit 121 adjusts the intensity level for each wavelength in the optical signal with the second control amount that is the minimum value.

The first control amount is predetermined according to the arrangement of the wavelength division multiplexing optical device 110 in the optical path, and the level control circuit unit 123 acquires the information indicating the arrangement of the own device from the NMS 101. , The first controlled variable can be specified.

A part or all of the supervisory control unit 115 and the level control circuit unit 123 described above are, for example, a single circuit, a composite circuit, a programmed processor, as shown in FIG. The processing circuit 10 may be a parallel-programmed processor, an ASIC (Application Specific Integrated Circuits), an FPGA (Field Programmable Gate Array), or the like.

Part or all of the monitoring control unit 115 and the level control circuit unit 123 are, for example, as shown in FIG. 3B, a memory 11 and a CPU that executes a program stored in the memory 11. It can also be configured with a processor 12 such as (Central Processing Unit). Such a program may be provided via a network, or may be provided by being recorded in a recording medium.

FIG. 4 is a flowchart showing an example of light level control.
The wavelength multiplexing optical device 110 that executes the flowchart shown in FIG. 4 is assumed to be located at the i-th position of the optical path among the N wavelength multiplexing optical devices 110 that constitute the wavelength multiplexing optical transmission system 100. To do. Here, i is an integer that satisfies 1≦i≦N, and the optical path is a path for transmitting an optical signal from the 1st to the Nth. That is, the larger the number of i, the more the i-th wavelength multiplexing optical device 110 is arranged behind the optical path. Further, when transmitting the optical signals from the 1st to the Nth, the optical crossconnect unit 120 uses the crossconnect setting unit 121A, the optical output level detection element 122A, and the level control circuit unit 123A. To do.

Further, in the wavelength multiplexing optical device 110, the maximum value Vmax [dB/cycle] and the minimum value Vmin [dB/cycle] of the control amount of the light level and the target value D [dBm] of the light level are set in advance. And Here, the maximum value Vmax is the maximum value of the control amount that can be set in the first WDM optical device 110. The minimum value Vmin is the minimum value of the control amount that can be set in the wavelength division multiplexing optical device 110. Further, the control cycle T [ms] is assumed to be equivalent to the time until the actual light level is reflected after the control amount is set.

First, the monitor control unit 115 acquires, from the NMS 101 via the I/F unit 114, an optical path setting, which is a light path for each wavelength, as information indicating the arrangement of the own device (S10). This optical path setting includes the number N of nodes from the transmitting end to the receiving end and the node number i.

Next, the monitoring control unit 115 sets the level of the optical level control amount Vi [dB/cycle] such that the value becomes smaller as it is arranged behind the optical path, depending on the number N of nodes and the node number i. The value is set in the control circuit unit 123A (S11).

For example, the monitoring control unit 115 classifies the node numbers “1” to “N” into a plurality of sections according to the number N of nodes. At least one node is included in one section. Further, when a plurality of nodes are included in one section, those node numbers are assumed to be consecutive. The monitoring control unit 115 specifies the control level Vi [dB/cycle] of the optical level such that the value increases as the classification includes the node with the smaller node number. Then, the monitoring controller 115 sets the specified light level control amount Vi (first control amount) in the level control circuit unit 123A.

Specifically, the number of nodes N is “3”, and the monitoring control unit 115 divides the three nodes into the first division: node number 1, the second division: node number 2, and the third division: When divided into three sections of node number 3, the control amount V1 of the node of node number 1, the control amount V2 of the node of node number 2, and the control amount V3 of the node of node number 3 are V1>V2 >V3.
Further, when the number of nodes N is “3”, the monitoring control unit 115 divides the three nodes into two sections of the first section: the node number 1 and the node number 2, and the second section: the node number 3. When divided, the control amount V1 of the nodes having the node numbers 1 and 2 and the control amount V2 of the node having the node number 3 are V1>V2.
It is assumed that the manner of division and the control amount for each division as described above are predetermined according to the number N of nodes.

Next, the optical output level detecting element 122A detects the current optical output level Pi [dBm] (S12).

Next, the level control circuit unit 123A absolute value of the difference between the target value D [dBm] of the optical level and the monitoring result (detected optical output level) Pi of the optical output level detecting element 122A for each control cycle T. A value is calculated, and it is determined whether the absolute value of the difference is smaller than the control amount Vi (S13). If the absolute value of the difference is greater than or equal to the control amount Vi (No in S13), the process proceeds to step S14. If the absolute value of the difference is smaller than the control amount Vi (Yes in S13), the process is performed. Proceeds to step S15.
Here, the control timing for performing the process of step S13 is control timing m×T (m is an integer of 1 or more).

In step S14, the level control circuit unit 123A drives the cross-connect setting unit 121A with the control amount Vi at the next control timing (m+1)×T. Then, the process returns to step S12.

On the other hand, in step S15, the level control circuit unit 123A determines whether or not the detected light output level Pi has reached the target value D. If the detected light output level Pi has reached the target value D (Yes in S15), the flow ends, and if the detected light output level Pi has not reached the target value D (No in S15), the processing is performed. Proceeds to step S16.

In step S16, the level control circuit unit 123A changes the setting of the cross-connect setting unit 121A to the control amount Vmin (second control amount) at the next control timing (m+1)×T.
Then, the level control circuit unit 123A drives the cross-connect setting unit 121A with the control amount Vmin at the next control timing (m+2)×T. Then, the process returns to step S12.

Even if the optical output level from the cross-connect setting unit 121 changes, the optical level control is performed in the same flow as in FIG.

With reference to FIGS. 5 to 8, the wavelength division multiplexing optical transmission system 100 is configured by three nodes 1, node 2 and node 3, and an optical path has optical signals in the order of node 1, node 2 and node 3. The effect of the flow of FIG. 4 will be described by taking the case of being configured to be transmitted as an example.
5 is a schematic diagram showing a change example of the optical input level and the optical output level of the node 1, FIG. 6 is a schematic diagram showing a change example of the optical input level and the optical output level of the node 2, and FIG. 6 is a schematic diagram showing an example of changes in the optical input level and the optical output level of the node 3. FIG. FIG. 8 is a schematic diagram showing an example of changes in the control amounts in the nodes 1, 2, and 3.

Here, the case where the optical input level of each wavelength of the node 1 sharply increases is taken as an example. The optical output level of each wavelength of each node 1 to 3 has an initial value of -20 dBm when the shutdown is released. The target value of the light output level is -10 dBm, the minimum value Vmin of the control amount is 0.1 dB/cycle, and the control cycle is 5 ms.
Further, when the wavelength division multiplexing optical transmission system 100 is composed of three nodes 1, node 2 and node 3, the control amount V1 set in the node 1 is 2 dB/cycle, and the control amount set in the node 2 is V2 is 0.7 dB/cycle, and the control amount V3 set in the node 3 is 0.3 dB/cycle. On such a premise, the light level control is performed by the flow shown in FIG.

At the optical input level and the optical output level as shown in FIG. 5, the node 1 is controlled toward the target value by the controlled variable V1 (=2 dB/cycle) as shown in FIG. The control is completed when the target value is reached.

As shown in FIG. 6, the optical signal is input to the node 2 at the optical output level of the node 1. At the optical input level and the optical output level as shown in FIG. 6, the node 2 detects the control amount V2 (=0.7 dB/) after detecting the increase of the optical input level as shown in FIG. The cycle is controlled by aiming for the target value.
The optical input level of the node 2 is affected by the level change amount under the control of the node 1. Therefore, as shown in FIG. 6, the optical output level of the node 2 increases by the optical level controlled by the node 1 during the control cycle until the control by the control amount V2 is performed. When the optical output level of the node 2 exceeds the target value due to the influence of the control of the node 1, the optical level is reduced by the control amount V2.
When the absolute value of the difference between the optical output level of the node 2 and the target value becomes equal to or less than the control amount V2, the control amount Vmin (=0.1 dB/cycle) is set, and the control is continued until the target value is reached.

As shown in FIG. 7, an optical signal is input to the node 3 at the optical output level of the node 2. At the optical input level and the optical output level as shown in FIG. 7, the node 3 detects the increase of the optical input level, and then the control amount V3 (=0.3 dB/) as shown in FIG. The cycle is controlled by aiming for the target value.
The optical input level of the node 3 is affected by the level change amount under the control of the nodes 2 and 1. Therefore, as shown in FIG. 7, the optical output level of the node 3 increases by the optical level controlled by the nodes 2 and 1 during the control period until the control by the control amount V3 is performed. When the optical output level of the node 3 exceeds the target value due to the influence of the control of the node 1 and the node 2, the optical level is reduced by the control amount V3, and the control is continued until the target value is reached.
In this example, the time required to complete the control of the node 3 is 50 ms. As described above, since the control amount of the subsequent node is suppressed, it is possible to suppress excessive level fluctuation.

As described above, in the first embodiment, it is possible to autonomously change the control amount in the node to perform the optical level control, and to reduce the control amount in the subsequent node affected by the level control error from the preceding node. Since it is set, it is possible to suppress an excessive level fluctuation due to an optical signal level error.

Further, in the first embodiment, since a plurality of nodes can perform autonomous optical level control independent of the supervisory control light, the optical signal of each wavelength can have high reliability.

In the first embodiment described above, the NMS 101 notifies each wavelength multiplexing optical device 110 of the optical path setting, but the first embodiment is not limited to the above example. For example, the NMS 101 notifies an optical path setting to a specific wavelength multiplexing optical device 110 included in the plurality of wavelength multiplexing optical devices 110, and the specific wavelength multiplexing optical device 110 transmits an optical path to another wavelength multiplexing optical device 110. The setting may be notified.

Embodiment 2.
As shown in FIG. 1, the WDM optical transmission system 200 according to the second embodiment includes N WDM optical devices 210.
The wavelength multiplexing optical device 210 includes a transmission side optical amplification section 111, a reception side optical amplification section 112, a transponder section 113, an I/F section 114, a monitoring control section 215, and an optical cross connect section 220.
The wavelength multiplexing optical device 210 according to the second embodiment has the same configuration as the wavelength multiplexing optical device 110 according to the first embodiment except for the monitoring controller 215 and the optical cross connect unit 220.

The monitoring controller 215 according to the second embodiment collects the alarm status and performance information in the wavelength division multiplexing optical apparatus 210 and notifies the NMS 101 through the I/F unit 114 and the DCN line 104. Further, the supervisory control unit 215 notifies each unit in the wavelength multiplexing optical device 210 of the optical path setting and control information from the NMS 101. Here, the number of nodes N and the node number i do not have to be included in the optical path setting in the second embodiment.

The optical cross-connect unit 220 is connected to the transponder unit 113 and multiplexes or demultiplexes optical signals of a plurality of different wavelengths. Further, the optical cross-connect unit 220 switches the optical signal of its own node and the optical signal optically amplified by the receiving-side optical amplification unit 112 in arbitrary directions in wavelength units or wavelength group units.

FIG. 9 is a block diagram schematically showing the internal configuration of the optical cross connect unit 220.
The optical cross-connect unit 220 includes cross-connect setting units 121A and 121B, optical output level detecting elements 122A and 122B, level control circuit units 223A and 223B, and optical input level detecting elements 224A and 224B.
The cross-connect setting unit 121A, the optical output level detecting element 122A, the level control circuit unit 223A, and the optical input level detecting element 224A are input from the transmission line 103A and output to the transmission line 103B, and from the transponder unit 113. The optical signal that is input and output to the transmission path 103B is processed.
On the other hand, the cross-connect setting unit 121B, the light output level detecting device 122B, the level control circuit unit 2 23B and the optical input level detecting device 224B is input from a transmission line 103C, and the optical signal output to the transmission path 103D, the transponder The optical signal input from the unit 113 and output to the transmission path 103D is processed.
When there is no particular need to distinguish between the level control circuit units 223A and 223B, they are referred to as the level control circuit unit 223.
The optical input level detecting elements 224A and 224B are referred to as the optical input level detecting element 224 when there is no particular need to distinguish between them.

The cross connect setting unit 121 and the optical output level detecting element 122 in the second embodiment are the same as the cross connect setting unit 121 and the optical output level detecting element 122 in the first embodiment.

The optical input level detection element 224 is an optical input level detection unit that detects a plurality of intensity levels for each wavelength in the optical signal input to the cross connect setting unit 121 as a plurality of optical input levels. For example, the optical input level detection element 224 monitors the optical level for each wavelength in the optical signal input to the cross connect setting unit 121, and notifies the level control circuit unit 223 of the monitoring result (optical input level). The optical input level detecting element 224 is composed of an OCM or the like capable of detecting the optical level for each wavelength.

The level control circuit unit 223 drives the cross-connect setting unit 121 according to a preset control amount until the monitor result reaches the target value. The level control circuit unit 223 according to the second embodiment calculates the magnitude of the time variation of the optical input level based on the monitoring result of the optical input level detecting element 224. Then, the level control circuit unit 223 sets and changes the optical level control amount for each wavelength based on the calculation result.
For example, the level control circuit unit 223 sets the first control amount, which is a control amount for adjusting the optical level for each wavelength in the optical signal, to the time of a plurality of optical input levels detected by the optical input level detecting element 224. It is set in the cross-connect setting unit 121 for each wavelength so that it becomes smaller as the magnitude of fluctuation increases. In addition, when the absolute value of the difference between the optical output level and the target level is equal to or less than the first control amount, the level control circuit unit 223 uses the second control amount smaller than the first control amount. A certain minimum value is set in the cross connect setting unit 121.

FIG. 10 is a schematic diagram showing a method of detecting the magnitude of the time variation of the optical input level.
The optical input level detection element 224 monitors the optical input level PIN1 [dBm] M times within one cycle of the control cycle T. That is, the optical input level detecting element 224 monitors every T/M. Here, M is an integer of 2 or more.
Then, the level control circuit unit 223 calculates an absolute value (input level fluctuation amount) of the difference between the h-th and h+1-th monitoring results (optical input level), and the number of times the value exceeds a predetermined threshold Th. Count C. Here, h is an integer that satisfies 1≦h<M.
The level control circuit unit 223 specifies the control amount based on the number of times C. Here, it is shown that when the number of times C is large, the time variation of the optical input level is large, and when the number of times C is small, the time variation of the optical input level is small.

FIG. 11 is a flowchart showing an example of light level control in the second embodiment.
The maximum value Vmax [dB/cycle] and the minimum value Vmin [dB/cycle] of the control amount of the light level, the target value D [dBm] of the light level, and the threshold value Th [dB] are set in advance in the wavelength multiplexing optical device 210. Have been done. Here, the maximum value Vmax is the maximum value of the control amount that can be set in the wavelength multiplexing optical device 210. Further, the control cycle T [ms] is assumed to be equivalent to the time until the actual light level is reflected after the control amount is set.
Here, it is assumed that the optical cross-connect unit 220 uses the cross-connect setting unit 121A, the optical output level detecting element 122A, the level control circuit unit 223A, and the optical input level detecting element 224A to transmit an optical signal.

First, the light input level detection element 224A detects the light input level PIN1 [dBm] M times within one control cycle, for example, from the control timing (m−1)×T to the control timing m×T (S20) . Here, m is an integer of 1 or more.

Next, the level control circuit unit 223A calculates the input level fluctuation amount based on the detected light input level PIN1 and compares the input level fluctuation amount with the threshold value Th [dB]. Then, the level control circuit unit 223A counts the number C of times that the input level fluctuation amount exceeds the threshold Th (S21). The number of times C indicates the magnitude of the time variation of the optical input level.

Next, the level control circuit unit 223A specifies the control amount Vj [dB/cycle] based on the magnitude of the time variation of the optical input level, and determines the specified control amount Vj (first control amount). It is set in the cross connect setting unit 121 (S22) .
For example, the level control circuit unit 223A decreases the control amount Vj as the temporal variation of the optical input level increases. Specifically, when the number C of times is larger than M/2, the level control circuit unit 223 A sets the control amount Vj1 in order to suppress the influence because the time variation is large. Count C is greater than M / 4, in the case of M / 2 or less, the time variation is slightly larger, level control circuit 223 A is the intermediate control amount Vj2 (Vj2> Vj1). When the number of times C is M/4 or less, the time variation is small, so the control amount Vj3 (Vj3>Vj2) is set to a large value and the arrival time to the target value D is shortened.

Next, the optical output level detecting element 122A detects the current optical output level Pi [dBm] (S23).

Next, the level control circuit unit 223A absolute value of the difference between the target value D [dBm] of the optical level and the monitoring result (detected optical output level) Pi of the optical output level detecting element 122A for each control cycle T. A value is calculated, and it is determined whether the absolute value of the difference is smaller than the control amount Vj (S24). If the absolute value of the difference is greater than or equal to the control amount Vj (No in S24), the process proceeds to step S25. If the absolute value of the difference is smaller than the control amount Vj (Yes in S24), the process is It proceeds to step S26.
Here, the control timing for performing the process of step S24 is set to control timing m×T.

In step S25, the level control circuit unit 223A drives the cross-connect setting unit 121A with the control amount Vj at the next control timing (m+1)×T. Then, the process returns to step S23.

On the other hand, in step S26, the level control circuit unit 223A determines whether or not the detected light output level Pi has reached the target value D. If the detected light output level Pi has reached the target value D (Yes in S26), the flow ends, and if the detected light output level Pi has not reached the target value D (No in S26), the processing is performed. Advances to step S27.

In step S27, the level control circuit unit 223A changes the setting of the cross-connect setting unit 121A to the control amount Vmin (second control amount) at the next control timing (m+1)×T.
Then, the level control circuit unit 223A drives the cross-connect setting unit 121A with the control amount Vmin at the next control timing (m+2)×T. Then, the process returns to step S23.

As described above, in the second embodiment, the control amount is specified based on the magnitude of the time variation of the optical input level, so that the control amount can be set in consideration of the convergence status of the optical level control of the preceding node. it can. If the optical level control of the preceding node has not converged, reducing the control amount suppresses the error effect of the optical level control of the preceding node, and if the optical level control of the preceding node has converged, control amount By increasing the value of, it is possible to shorten the convergence time until the completion of the light level control.

The second embodiment can also be implemented in combination with the first embodiment. For example, by combining the second embodiment with the first embodiment, at the start of the flow chart of FIG. 11 (at the start of control), the number N of nodes and the node number included in the optical path setting notified from the NMS 101. The control amount Vi may be set based on i, and the control amount Vj may be set in step S22. In the second embodiment, at the start of the flowchart of FIG. 11, processing is performed with a predetermined control amount.

In the second embodiment, since a plurality of nodes can perform autonomous optical level control independent of the supervisory control light, the optical signal of each wavelength can have high reliability.

Embodiment 3.
As shown in FIG. 1, the wavelength multiplexing optical transmission system 300 according to the third embodiment includes N wavelength multiplexing optical devices 310.

The wavelength multiplexing optical device 310 includes a transmission side optical amplification section 111, a reception side optical amplification section 112, a transponder section 113, an I/F section 114, a monitor control section 315, and an optical cross connect section 320.
The wavelength multiplexing optical device 310 according to the third embodiment has the same configuration as the wavelength multiplexing optical device 110 according to the first embodiment except for the monitoring controller 315 and the optical cross connect unit 320.

The monitoring control unit 315 according to the third embodiment collects the alarm status and performance information in the wavelength division multiplexing optical apparatus 310 and notifies the NMS 101 through the I/F unit 114 and the DCN line 104. Further, the supervisory control unit 315 notifies each unit in the wavelength multiplexing optical device 310 of the optical path setting and control information from the NMS 101. Here, the number of nodes N and the node number i do not have to be included in the optical path setting in the third embodiment.

The optical cross connect unit 320 is connected to the transponder unit 113, and multiplexes or demultiplexes optical signals having a plurality of different wavelengths. Further, the optical cross-connect unit 320 switches the optical signal of its own node and the optical signal optically amplified by the receiving-side optical amplification unit 112 in arbitrary directions in wavelength units or wavelength group units.

As shown in FIG. 2, the optical cross-connect unit 320 according to the third embodiment includes cross-connect setting units 121A and 121B, optical output level detection elements 122A and 122B, and level control circuit units 323A and 323B. Prepare
When there is no particular need to distinguish between the level control circuit units 323A and 323B, they are referred to as the level control circuit unit 323.
Optical crossconnect unit 320 in the third embodiment, except for the level control circuit section 323 is the same as the optical cross-connect unit 1 20 in the first embodiment.

In the second embodiment, by detecting the magnitude of the time variation of the optical input level has been set to control the amount of light level, the components of the level control circuit unit 323 identifies the set value of the light level control amount If it is possible to synchronize the time when the control is performed and the time when the optical output level detecting element 122 monitors, the control is performed by detecting the time variation of the optical output level as in the third embodiment. You can set the amount.

The level control circuit unit 323 drives the cross connect setting unit 121 according to a preset control amount until the monitor result reaches the target value.
Here, similarly to the second embodiment, the level control circuit unit 323 of the third embodiment decreases the control amount of the light level as the temporal variation of the optical input level increases.
However, the level control circuit unit 323 of the third embodiment specifies the optical input level by removing the control amount of the own node from the monitor result (optical output level) notified from the optical output level detection element 122. Then, the level control circuit unit 323 calculates the magnitude of the time variation of the optical input level based on the specified optical input level, as in the second embodiment.

In the light level control example in the third embodiment, after the magnitude of the time variation of the light input level (the number of times C) is calculated as described above, the processes of steps S22 to S28 of FIG. 11 are performed.

Unlike the second embodiment, the third embodiment can obtain the light input level from the light output level without using the light input level detecting element 224 and obtain the magnitude of the time variation thereof. With a simpler and cheaper configuration than the form 2, the control amount can be set in consideration of the convergence state of the optical level control of the preceding node.

Note that, similarly to the second embodiment, the third embodiment can also be implemented in combination with the first embodiment.

Also in the third embodiment, since a plurality of nodes can perform autonomous optical level control independent of the supervisory control light, the optical signal of each wavelength can have high reliability.

100, 200, 300 wavelength multiplexing optical transmission system, 101 NMS, 102 downstream apparatus, 110, 210, 310 wavelength multiplexing optical apparatus, 111 transmission side optical amplification section, 112 reception side optical amplification section, 113 transponder section, 114 I/F Section, 115 monitoring control section, 120, 220, 320 optical cross-connect section, 121 cross-connect setting section, 122 optical output level detecting element, 123, 223, 323 level control circuit section, 224 optical input level detecting element.

Claims (8)

A wavelength-multiplexing optical device used as one wavelength-multiplexing optical device included in a plurality of wavelength-multiplexing optical devices for transmitting an optical signal through a predetermined path for each wavelength,
An adjusting unit that adjusts the intensity level of each of the wavelengths in the optical signal,
An optical output level detection unit that detects an intensity level for each wavelength in the optical signal output from the adjustment unit as an optical output level,
For each wavelength, the first control amount, which is the control amount for adjusting the intensity level for each wavelength in the optical signal, becomes smaller as the one wavelength-multiplexing optical device is arranged rearward in the path. And a level control circuit unit that adjusts the intensity level for each wavelength in the optical signal with the first control amount, and causes the optical output level to approach a target level. A wavelength-multiplexing optical device comprising: The arrangement of the one WDM optical device in the path is managed by a control device,
The first control amount is predetermined according to the arrangement of the one wavelength multiplexing optical device in the path,
From the control device, further comprising an interface unit for receiving information indicating the arrangement of the one wavelength division multiplexing optical device in the path,
The wavelength multiplexing optical device according to claim 1, wherein the level control circuit unit sets the first control amount based on the information. A wavelength-multiplexing optical device used as one wavelength-multiplexing optical device included in a plurality of wavelength-multiplexing optical devices for transmitting an optical signal through a predetermined path for each wavelength,
An adjusting unit that adjusts the intensity level of each of the wavelengths in the optical signal,
An optical input level detection unit that detects a plurality of intensity levels for each wavelength in the optical signal input to the adjustment unit as a plurality of optical input levels;
An optical output level detection unit that detects an intensity level for each wavelength in the optical signal output from the adjustment unit as an optical output level,
The first control amount, which is a control amount for adjusting the intensity level for each wavelength in the optical signal, is adjusted for each wavelength so that the first control amount decreases as the magnitude of the time variation of the plurality of optical input levels decreases. after setting the parts, and a said by adjusting the intensity level of each wavelength, the level control circuit part closer to the light output level to the target level in the optical signal in the first control amount on the adjuster A wavelength division multiplexing optical device characterized in that The level control circuit unit, from the plurality of light input levels detected by the light input level detection unit within a predetermined time, the absolute value of the difference between the two continuously detected light input levels. The wavelength-multiplexed optical device according to claim 3, wherein the magnitude of the time variation of the optical input level is specified by the number of times the absolute value is calculated and exceeds the predetermined threshold value. A wavelength-multiplexing optical device used as one wavelength-multiplexing optical device included in a plurality of wavelength-multiplexing optical devices for transmitting an optical signal through a predetermined path for each wavelength,
An adjusting unit that adjusts the intensity level of each of the wavelengths in the optical signal,
An optical output level detection unit that detects a plurality of intensity levels for each wavelength in the optical signal output from the adjustment unit as a plurality of optical output levels,
By removing the control amount adjusted by the adjusting unit from the plurality of light output levels, a plurality of lights having a plurality of intensity levels for each wavelength in the optical signal input to the one wavelength multiplexing optical device. While calculating the input level, the first control amount, which is the control amount for adjusting the intensity level for each wavelength in the optical signal, is set to become smaller as the magnitude of the time fluctuation of the plurality of optical input levels increases. After setting in the adjusting unit for each wavelength, the adjusting unit adjusts the intensity level for each wavelength in the optical signal with the first control amount, and the optical output level detecting unit detects the intensity level. A wavelength division multiplexing optical device comprising: a level control circuit unit that brings an optical output level closer to a target level. The level control circuit unit, from the plurality of optical input levels calculated within a predetermined time, calculates the absolute value of the difference between the two continuously detected optical input levels, the absolute value is The wavelength division multiplexing optical apparatus according to claim 5, wherein the magnitude of the time variation of the optical input level is specified by the number of times a predetermined threshold value is exceeded. When the absolute value of the difference between the optical output level and the target level is equal to or less than the first control amount, the level control circuit unit controls the second control smaller than the first control amount. Set the amount in the adjustment unit,
The wavelength multiplexing optical device according to any one of claims 1 to 6, wherein the adjusting unit adjusts the intensity level for each wavelength in the optical signal with the second control amount. The wavelength multiplexing optical device according to claim 7, wherein the second control amount is a minimum value that can be set in the adjusting unit.

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