JP6747499B2 - Optical transmission device, optical transmission system, and optical communication method - Google Patents

Description

The present invention relates to an optical transmission device and a control method thereof, and more particularly to an optical transmission device that corrects an optical level and a control method thereof.

Along with the increasing demand for broadband multimedia communication services such as the Internet and video distribution, introduction of long-distance and large-capacity optical fiber communication systems is progressing in trunk lines and metro lines. In an optical transmission system using such an optical fiber, it is important to increase the transmission efficiency per optical fiber. Therefore, Wavelength Division Multiplex (WDM) communication, which multiplexes and transmits a plurality of optical signals of different wavelengths, is widely used.

As a related technique for efficiently expanding the transmission capacity of WDM communication, super-channel (Super-CH:SCH) transmission in which a plurality of subcarriers are arranged at narrow frequency intervals and grouped is known. For example, Patent Document 1 discloses a technique for improving deterioration of SCH transmission quality based on system information of an optical transmission system.

JP, 2013-106328, A

By using the above-mentioned SCH transmission, it becomes possible to realize optical transmission of several hundred Gbps. However, in the SCH transmission like the related technique, there is a problem that the transmission characteristics are deteriorated because an optical level deviation occurs between subcarriers or between groups including subcarriers.

The present invention has been made in view of the above problems, and an object thereof is to provide an optical transmission device capable of improving transmission characteristics and a control method thereof.

An optical transmission device according to the present invention is a multiplexing unit that multiplexes a plurality of subcarrier signals that perform optical wavelength division multiplexing into a wavelength group signal, and an output unit that outputs the multiplexed wavelength group signal to an optical transmission line. And a pre-multiplexing level correction unit that corrects a level deviation of the pre-multiplexing subcarrier signal based on the optical level of the wavelength group signal at the output unit, and an optical level of the wavelength group signal at the output unit And a post-combination level correction unit that corrects a level deviation of the post-combination wavelength group signal including the corrected subcarrier signal.

A method of controlling an optical transmission apparatus according to the present invention includes a multiplexing unit that multiplexes a plurality of subcarrier signals that perform optical wavelength division multiplexing into a wavelength group signal, and outputs the multiplexed wavelength group signal to an optical transmission line. An output unit for controlling the optical transmission apparatus, wherein the output unit corrects the level deviation of the subcarrier signal before the multiplexing based on the optical level of the wavelength group signal in the output unit. The level deviation of the wavelength group signal after the multiplexing including the corrected subcarrier signal is corrected based on the optical level of the wavelength group signal in the section.

According to the present invention, it is possible to provide an optical transmission device capable of improving transmission characteristics and a control method thereof.

It is a block diagram which shows schematic structure of the node which concerns on a basic example. It is a graph which shows the example of the wavelength band of SCH which concerns on a basic example. It is a graph which shows the example of the level deviation of SCH which concerns on a basic example. It is a graph which shows the example of the level deviation of SCH which concerns on a basic example. 6 is a graph for explaining a correction result of SCH level deviation according to the basic example. 6 is a graph for explaining a correction result of SCH level deviation according to the basic example. It is a block diagram for explaining an outline of a node according to an embodiment. FIG. 3 is a configuration diagram showing a schematic configuration of a node according to the first embodiment. FIG. 6 is a diagram for explaining a level correction operation according to the first embodiment. FIG. 6 is a diagram for explaining a level correction operation according to the first embodiment. FIG. 6 is a configuration diagram showing a configuration example of an optical transmission system according to a second embodiment. 7 is a configuration diagram showing a configuration example of a node according to the second embodiment. FIG. FIG. 11 is a configuration diagram showing another configuration example of the node according to the second embodiment. 9 is a flowchart showing an example of level correction operation according to the second embodiment. 9 is a flowchart showing an example of level correction operation according to the second embodiment. 9 is a flowchart showing an example of level correction operation according to the second embodiment. FIG. 9 is a state transition diagram showing an example of state transition of the level correction operation according to the second embodiment.

(Basic example)
First, a basic example that is the basis of the embodiment will be described.

FIG. 1 shows a schematic configuration of a node (optical transmission device) according to the basic example. As shown in FIG. 1, a node 900 according to the basic example includes a transponder TPND and a multiplexer AG as a configuration before combining subcarrier signals, and an optical cross-connect XF as a configuration after combining subcarrier signals. An optical amplifier CA is provided. In the present specification, “combining” means combining subcarriers in the same wavelength group.

The plurality of transponders TPND (TPND_1 to TPND_3) output subcarrier signals S1 having different wavelengths, and the multiplexer AG multiplexes the subcarrier signals S1 to generate a wavelength group signal S2. The optical cross connect XF includes a wavelength selective switch WSS that switches the wavelength group signal S2 to generate an SCH signal (including the wavelength group signal S2) S3. The optical amplifier CA amplifies the SCH signal S3 after switching and outputs the SCH signal S0 to the transmission line.

FIG. 2 is a graph showing the wavelength band of the SCH signal used in the basic example. As shown in FIG. 2, in SCH transmission, a plurality of subcarrier signals S1 are arranged at narrow frequency intervals and grouped into one wavelength group signal S2. The wavelength group signal S2 is a set of a plurality of subcarrier signals S1 (composed of a plurality of subcarrier signals S1), and the signals S2 of the same wavelength group are ADD/DROPed by the same element (node or the like). In the example of FIG. 2, one wavelength group signal S2 includes four subcarrier signals S1_1 to S1_4, but any number of subcarrier signals may be included. The SCH signal is not limited to the two wavelength group signals S2_1 to S2_2, and may include an arbitrary number of wavelength group signals.

3 and 4 show the level deviation that occurs in the SCH signal in the basic example. In the SCH transmission, the plurality of subcarrier signals S1 form the wavelength group signal S2 and the plurality of wavelength group signals S2 form the SCH signal S0, so that a level deviation occurs in the unit forming each signal.

As the first level deviation, as shown in FIG. 3, a level deviation occurs between wavelength groups in SCH transmission. The level deviation between the wavelength groups occurs due to the difference in the pass loss due to the difference in the pass paths of the wavelength groups after the multiplexing. That is, a plurality of wavelength group signals are input to the optical cross-connect XF of a node from a plurality of paths including other nodes, and these wavelength group signals have different paths to be transmitted. Light level variations (deviations) occur.

As the second level deviation, as shown in FIG. 4, a level deviation occurs between subcarriers in the wavelength group in SCH transmission. The level deviation between subcarriers occurs due to the difference in passage loss between each subcarrier before multiplexing. That is, a plurality of subcarrier signals are input to the multiplexer AG of the node, and these subcarrier signals pass through different transponders, fibers, etc., so that the optical level depends on the loss of the transponders, fibers, etc. Variation occurs. For example, there are an output deviation of the transponder TPND, a connection loss deviation between the transponder TPND and the multiplexer AG, and a loss deviation inside the multiplexer AG.

In addition, the level deviation between subcarriers also occurs due to the wavelength dependence after multiplexing. That is, a wavelength group signal is input from another node to the optical cross connect XF, and the optical fiber cable between the nodes has wavelength dependency (SRS tilt). This wavelength dependence affects the transmission characteristics of the subcarriers, and thus the optical level of the subcarriers varies. There is also a loss deviation due to non-uniformity within the wavelength group band of the optical cross connect XF (wavelength selective switch WSS) and the optical amplifier CA.

Here, of these level deviations, if the deviation due to the difference in wavelength loss before combining is corrected by the level correction (LEQ) after combining, there is a possibility that the passing waveform may deteriorate. 5 and 6 show spectrum changes before and after the correction when the level deviation correction is simply performed on the wavelength group signals after the multiplexing.

FIG. 5 shows a spectrum in a state in which a deviation between subcarriers occurs before multiplexing. In this example, the optical level difference between the subcarrier signal S1_1 and the subcarrier signal S1_2 is 3 dB.

FIG. 6 shows a spectrum when the signals of FIG. 5 are multiplexed and then level-corrected. As shown in FIG. 6, for example, in order to correct the level deviation, the subcarrier signal S1_1 is attenuated by 3 dB (3 dB lower than S2) with respect to the variable optical attenuator of the wavelength selective switch WSS in the optical cross connect XF. The carrier signal S1_2 is set to be attenuated by 0 dB (3 dB higher than S1). Then, waveform rounding occurs in the ATT setting of the variable optical attenuator between subcarriers (Slice). Near the wavelength of the waveform rounding, the waveform of the subcarrier signal S1_1 rises, so that the signal characteristic (transmission characteristic) deteriorates.

(Outline of Embodiment)
As described above, in SCH transmission, two level deviations occur, so level correction requires correction of the level deviation between wavelength groups and correction of the level deviation of subcarriers within the wavelength group. Therefore, in the embodiment, a means for correcting an optical level deviation between wavelength groups and subcarriers, which is a problem in SCH transmission, is provided, and good transmission characteristics are realized.

FIG. 7 shows an outline of the node (optical transmission device) 10 according to the embodiment. As shown in FIG. 7, the node 10 according to the embodiment includes a combining unit 11, an output unit 12, a pre-combination level correction unit 13, and a post-combination level correction unit 14.

The multiplexing unit 11 multiplexes a plurality of subcarrier signals that perform optical wavelength division multiplexing into wavelength group signals. The output unit 12 outputs the wavelength group signal multiplexed by the multiplexing unit 11 to the optical transmission line. The pre-multiplexing level correction unit 13 corrects the level deviation of the subcarrier signal before the multiplexing by the multiplexing unit 11 based on the optical level of the wavelength group signal in the output unit 12. The post-combination level correction unit 14 calculates the level deviation of the post-combination wavelength group signal including the subcarrier signal corrected by the pre-combination level correction unit 13 based on the optical level of the wavelength group signal at the output unit 12. to correct.

As shown in FIG. 7, in the embodiment, the level deviation between the subcarriers generated before the multiplexing is corrected before the multiplexing, and the level deviation between the wavelength groups generated after the multiplexing (the subcarriers included in the wavelength group) is corrected. By compensating for the level deviation (including the level deviation between), it is possible to surely suppress the level deviation and improve the transmission characteristics.

(Embodiment 1)
Hereinafter, Embodiment 1 will be described with reference to the drawings. In this embodiment, an example in which the configuration of FIG. 7 is applied to the basic example of FIG. 1 will be described.

FIG. 8 shows a schematic configuration of the node according to the present embodiment. As illustrated in FIG. 8, the node 100 according to the present embodiment includes a plurality of transponders TPNDs (TPND_1 to TPND_3), a multiplexer AG, an optical cross connect XF, and an optical amplifier CA, as in the above basic example. Further, an optical channel monitor OCM, a pre-combination level correction unit 13, and a post-combination level correction unit 14 are provided. The pre-multiplexing level correction unit 13 and the post-multiplexing level correction unit 14 may be one control unit, or may be included in the optical amplifier CA or the like.

The transponders TPND_1 to TPND_3 are optical transmission units that generate a plurality of subcarrier signals S1 for SCH transmission (optical wavelength division multiplexing communication) and output the generated plurality of subcarrier signals S1 to the multiplexer AG. For example, each transponder TPND includes a laser TX serving as a light source, and a variable optical attenuator VOA1 that controls the optical level of an optical signal from the laser TX.

The multiplexer AG is a multiplexer that multiplexes the subcarrier signals S1 from the transponders TPND_1 to TPND_3 to generate a wavelength group signal S2 and outputs the generated wavelength group signal S2 to the optical cross connect XF. For example, the multiplexer AG includes a variable optical attenuator VOA2 that controls the optical level of each subcarrier signal S1.

The optical cross connect XF includes a wavelength selective switch WSS, and the wavelength selective switch WSS outputs an output destination of the wavelength group signal S2 output from the multiplexer AG (including a wavelength group signal input from another node). Is an optical switch unit that generates a SCH signal (including the wavelength group signal S2) S3 by switching between the two, and outputs the generated SCH signal to the optical amplifier CA. For example, the wavelength selective switch WSS in the optical cross connect XF includes a variable optical attenuator VOA3 that controls the optical level of each subcarrier signal of the wavelength group signal.

The optical amplifier CA is an output unit that amplifies the SCH signal S3 (including the wavelength group signal) from the optical cross connect XF to generate the SCH signal S0, and outputs the generated SCH signal S0 to the optical transmission line. The optical channel monitor OCM is, for example, arranged in the optical amplifier CA and is an optical monitor unit that monitors the optical level of each subcarrier signal in the wavelength group signal in the SCH signal S0 output from the optical amplifier CA.

The pre-multiplexing level correction unit 13 corrects the level deviation of the subcarrier signals in the transponders TPND_1 to TPND_3 or the multiplexer AG as the level correction before multiplexing based on the optical level monitor result by the optical channel monitor OCM. .. The post-multiplexing level correction unit 14 corrects the level deviation of the wavelength group signal in the optical cross-connect XF based on the optical level monitoring result by the optical channel monitor OCM as the post-multiplexing level correction.

FIG. 9 and FIG. 10 are operation outlines of the node according to the present embodiment, and respectively show a level correction method before combining and a level correction method after combining.

As shown in FIG. 9, in the level correction method before multiplexing, each subcarrier in the wavelength group is calculated from the monitor value (PM value) of the optical channel monitor OCM arranged in the output section (optical amplifier CA) to the transmission path. Node output (optical level) of the corresponding wavelength group is returned to the transponder TPND or the multiplexer AG of the corresponding wavelength group, and each subcarrier is adjusted to a desired level by using the output adjustment function of the transponder TPND or the multiplexer AG (output. Calibration function: need not be dynamic LEQ).

At this time, the feedback control to the variable optical attenuator VOA inside the optical cross connect XF (wavelength selective switch) is stopped (the initial value setting is kept), and the monitor value of each subcarrier of the optical channel monitor OCM is changed. The output of the variable optical attenuator VOA (or an optical amplifier) in the transponder TPND or the multiplexer AG is adjusted so as to be uniform (target level).

As shown in FIG. 10, in the level correction method after multiplexing, each subcarrier in the wavelength group is calculated from the monitor value (PM value) of the optical channel monitor OCM arranged in the output section (optical amplifier CA) to the transmission path. The node output of the above is returned to the optical cross connect XF, and each subcarrier of the corresponding wavelength group is adjusted to a desired level by using the output adjusting function of the wavelength selective switch WSS in the optical cross connect XF.

At this time, the feedback control to the variable optical attenuator VOA inside the transponder TPND is stopped (the value is set by the level correction before the multiplexing), and the monitor value of each subcarrier of the optical channel monitor OCM becomes uniform. Thus, the output of the variable optical attenuator VOA of the optical cross connect XF (wavelength selective switch WSS) is adjusted.

As described above, in the present embodiment, the output level of the node monitors the optical level of the wavelength group signal (subcarrier signal), and based on the monitoring result of the output level, the level correction of the subcarrier signal before multiplexing ( For example, the level between the wavelength groups is corrected by performing the level correction of the transponder or the multiplexer and the level correction of the wavelength group signal (subcarrier signal) after the multiplexing (for example, the level correction of the optical cross connect XF). Since the deviation correction and the level deviation correction between the subcarriers in the wavelength group can be performed, the transmission characteristic can be improved.

(Embodiment 2)
Embodiment 2 will be described below with reference to the drawings. In this embodiment, a specific example of an optical transmission system including a node will be described.

FIG. 11 shows a configuration example of the optical transmission system according to this embodiment. As shown in FIG. 11, the optical transmission system 1 according to the present embodiment includes a plurality of nodes (optical transmission devices) 100 (100_1 to 100_3) and a network monitoring device (NMS: Network Management System) 200. The optical transmission system 1 is not limited to the three nodes 100_1 to 100_3, and may include any number of nodes.

The nodes 100_1 to 100_3 are connected to each other by an optical transmission line OL such as an optical fiber, and SCH transmission is possible via the optical transmission line OL. The nodes 100_1 to 100_3 configure a WDM (SCH) network 2. As an example, the WDM network 2 is a linear network, but may be a network of other topology such as a ring network or a mesh network. For example, the node 100_1 is a transmitter which is a transmission end of an optical path, the node 100_2 is a relay which relays an optical path, and the node 100_3 is a receiver which is a reception end of an optical path.

The respective nodes 100 have basically the same configuration, and perform control such as setting of the optical transmission unit 101 based on control from the optical transmission unit 101 that performs SCH transmission via the optical transmission line OL and the network monitoring device 200. The node control unit 102 is provided. The node control unit 102 may be provided inside the optical transmission unit 101 (or in the same block as the optical transmission unit 101).

The node control unit 102 detects, for example, an initial setting unit 102a that performs initial setting for the optical transmission unit 101, a level correction unit 102b that corrects the level of a wavelength group signal (subcarrier signal), a failure of an optical signal, and the like. An alarm unit 102c that outputs an alarm to the network monitoring device 200 is provided.

The network monitoring device 200 is a monitoring device (control device) that monitors (controls) the operations of the nodes 100_1 to 100_3. The network monitoring device 200 is connected to the nodes 100_1 to 100_3 via a management network 3 such as a LAN, and manages settings and communication states of the nodes 100_1 to 100_3 via the management network. For example, the network monitoring device 200 includes a group designation unit 201 that designates a wavelength group, a connection information management unit 202 that manages connection information of each node 100, and a path setting unit 203 that sets a communication path through each node 100. ing.

FIG. 12 shows a configuration example of the node (optical transmission unit) according to the present embodiment. FIG. 12 is a configuration example of the optical transmission unit 101 of the node 100_2 that serves as a repeater, for example. As shown in FIG. 12, the optical transmission unit 101 according to the present embodiment includes transponders 111 to 114, multiplexers 121 and 122, an optical cross connect 130, an optical input unit 141, and an optical output unit 142. For example, the transponders 111 to 114, the multiplexers 121 and 122, the optical cross connect 130, the optical input unit 141, and the optical output unit 142 are each configured as an independent package, and the optical transmission unit 101 (node) is composed of a plurality of packages. It is configured. It should be noted that any number of transponders, multiplexers, optical cross-connects, optical input units, and optical output units may be provided according to subcarriers, wavelength groups, routes, and the like.

The transponders 111 to 114 are each connected to a client device (not shown), convert signals input from the client device into subcarrier signals S1_1 to S1_4 for SCH transmission, and output subcarrier signals S1_1 to S1_4. .. Each of the transponders 111 to 114 includes a laser TX that serves as a light source, and a variable optical attenuator VOA1 that controls the optical level of an optical signal from the laser TX.

The multiplexers 121 and 122 multiplex the subcarrier signal S1 output from the transponders 111 to 114. Each of the multiplexers 121 and 122 includes a variable optical attenuator VOA2 that controls the optical level of each subcarrier signal. The multiplexer 121 is connected to the transponders 111 and 112 via the optical fibers F1 and F2, respectively, and multiplexes the subcarrier signals S1_1 and S1_2 from the transponders 111 and 112 to generate the wavelength group signal S2_1. , And outputs the wavelength group signal S2_1. The multiplexer 122 is connected to the transponders 113 and 114 via the optical fibers F3 and F4, respectively, and multiplexes the subcarrier signals S1_3 and S1_4 from the transponders 113 and 114 to generate the wavelength group signal S2_2. , And outputs the wavelength group signal S2_2.

The optical cross connect 130 includes a wavelength selective switch 131. The optical cross connect 130 may include a plurality of wavelength selective switches 131 depending on routes.

The wavelength selective switch 131 switches (including add/drop) the output destinations of the optical signals input from the multiplexers 121 and 122 and the optical input unit 141 according to the wavelength. The wavelength selective switch 131 includes a variable optical attenuator VOA3 that controls the optical level of each subcarrier signal in the wavelength group signal. The optical cross connect 130 (wavelength selective switch 131) is connected to the multiplexers 121 and 122 via optical fibers F5 and F6, respectively, and to the optical input unit 141 and the optical output unit 142 via optical fibers F7 and F8, respectively. It is connected. The wavelength selective switch 131 switches the wavelength group signal S2_1 from the multiplexer 121, the wavelength group signal S2_2 from the multiplexer 122, and the SCH signal S4 (including the wavelength group signal) from the optical input unit 141 according to the wavelength to switch the SCH. The signal S3 is generated. When the wavelength group signals S2_1 and S2_2 and the wavelength group signals of the SCH signal S4 are set to be output to the optical output unit 142, the SCH signal S3 including these signals is output to the optical output unit 142.

The optical input unit 141 is connected to another node at the transmission end (or the repeater) via the optical transmission line OL, and the SCH signal S0 is input via the optical transmission line OL. For example, the optical input unit 141 includes an optical amplifier AMP1. The optical amplifier AMP1 amplifies the SCH signal S0 (including the wavelength group signal) from another node and outputs it to the optical cross connect 130.

The optical output unit 142 is connected to another node at the receiving end (or the repeater) via the optical transmission line OL, and outputs the SCH signal S0 via the optical transmission line OL. For example, the optical output unit 142 includes an optical amplifier AMP2 and an optical channel monitor OCM. The optical amplifier AMP1 amplifies the SCH signal S3 from the optical cross connect 130 and outputs the amplified SCH signal S0 to another node. The optical channel monitor OCM monitors the optical level of each subcarrier signal in the wavelength group of the amplified SCH signal S0 and outputs the monitoring result to the node controller 102. The node control unit 102 (or a part thereof) may be built in the light output unit 142 or another block (package).

In the example of FIG. 12, the subcarrier signals before the multiplexing (the transponders 111 to 114, the multiplexers 121 and 122) are based on the optical level of each subcarrier signal in the wavelength group of the SCH signal S0 at the optical output unit 142. Of the subcarrier signal (wavelength group signal) after the multiplexing (optical cross connect 130) is corrected.

FIG. 13 shows another configuration example of the node (optical transmission unit) according to the present embodiment. In the example of FIG. 13, the optical transmission unit 101 includes transponders TPND1 to 7, multiplexers (multiplexers/demultiplexers) AG1 to 3, optical cross connects XF1 to XF2, and optical amplifiers CA1 to CA2. The optical amplifiers CA1 and CA2 include the functions of the optical input unit 141 and the optical output unit 142 of FIG.

The multiplexer AG1 multiplexes the subcarrier signals from the transponders TPND1 to 3 and outputs them to the optical cross connect XF1 or XF2 to demultiplex the wavelength group signal from the optical cross connect XF1 or XF2. The multiplexer AG2 multiplexes the subcarrier signals from the transponders TPND4 to 5 and outputs the multiplexed signals to the optical cross connect XF1, and demultiplexes the wavelength group signal from the optical cross connect XF1. The multiplexer AG3 multiplexes the subcarrier signals from the transponders TPND6 to 7 and outputs them to the optical cross connect XF2, and demultiplexes the wavelength group signal from the optical cross connect XF2.

The optical cross-connect XF1 switches wavelength group signals (SCH signals) from the multiplexers AG1 and AG2, the optical amplifier CA1, and the optical cross-connect XF2 (and other optical cross-connects XF) and outputs them to any route. To do. The optical cross-connect XF2 switches the wavelength group signal (SCH signal) from the multiplexers AG1 and AG3, the optical amplifier CA2, and the optical cross-connect XF1 (and the optical cross-connect XF) and outputs the signal to one of the routes.

As shown in FIG. 13, in this example, the wavelength group signal of the wavelength f1 is transmitted in the route via the optical amplifier CA1-optical cross connect XF1-optical cross connect XF2-optical amplifier CA2. The wavelength group signal of the wavelength f2 is transmitted in the route via the optical amplifier CA1-optical cross connect XF1-multiplexer AG2. The wavelength group signal of the wavelength f3 is transmitted in the route via the multiplexer AG2-optical cross connect XF1-optical amplifier CA1. The wavelength group signal of the wavelength f4 is transmitted in the route via the multiplexer AG1-optical cross connect XF2-optical amplifier CA2. The wavelength group signal of the wavelength f5 is transmitted in the route via the optical amplifier CA2-optical cross connect XF2-multiplexer AG1.

Among these wavelength group signals, the signals output from the optical amplifiers CA1 and CA2 to the optical transmission line are the target of application of this embodiment.

Since the wavelength group signal of the wavelength f3 is output from the optical amplifier CA1, the optical channel monitor OCM of the optical amplifier CA1 monitors the optical level of each subcarrier signal in the wavelength group signal of the wavelength f3. Based on this monitoring result, the level deviation of the subcarrier signal before the multiplexing (transponders TPND4 to TPND5, the multiplexer AG2) is corrected, and the subcarrier signal (wavelength group signal) after the multiplexing (optical cross connect XF1). Correct the level deviation of.

Since the wavelength group signals of the wavelengths f1 and f4 are output from the optical amplifier CA2, the optical channel monitor OCM of the optical amplifier CA2 monitors the optical level of each subcarrier signal in the wavelength group signals of the wavelengths f1 and f4. Based on the monitoring result of the wavelength f4, the level deviation of the subcarrier signal before the multiplexing (transponders TPND1 to TPND3, the multiplexer AG1) is corrected, and the subcarrier signal (wavelength group) after the multiplexing (optical cross connect XF2) is corrected. Signal) level deviation is corrected. Since the wavelength group signal of the wavelength f5 is not multiplexed in the node (optical transmission unit 101), the subcarrier signal (wavelength group signal) after the multiplexing (optical cross connects XF1 and XF2) is based on the monitoring result of the wavelength f5. ) Level deviation is corrected.

14A to 14C show a level correction method according to this embodiment. Here, as an example, description will be given with reference to a configuration example of the node in FIG.

As shown in FIGS. 14A to 14C, first, in the node 100, a transponder is installed (S101), and the transponder and the multiplexer (multiplexer/demultiplexer) are connected by an optical fiber (S102). For example, as shown in FIG. 12, the user of the node 100 connects the transponders 111 and 112 and the multiplexer 121 with the optical fibers F1 and F2, and connects the transponders 113 and 114 and the multiplexer 122 with the optical fibers F3 and F4. To do.

On the other hand, the network monitoring device 200 performs wavelength grouping (S103). For example, the group designation unit 201 of the network monitoring device 200 groups subcarriers into wavelength groups according to an instruction from the user, and sets configurations of wavelength groups and subcarriers used in SCH transmission.

Then, the network monitoring device 200 registers the fiber connection information (or detects the connection) (S104). For example, the connection information management unit 202 of the network monitoring device 200 registers connection information indicating the connection relationship between the nodes 100 according to a user's instruction in order to enable path setting. Alternatively, the connection information management unit 202 may generate the connection information based on the information collected from each node 100.

Then, the network monitoring device 200 sets a path to the node 100 (S105). For example, the path setting unit 203 of the network monitoring device 200 sets a path (for example, the route of FIG. 13) between the nodes 100 for performing SCH transmission according to a user's instruction.

Subsequently, the node 100 detects the type of the connected package from the registration information, the fiber connection information, and the path setting information (S106). For example, the initial setting unit 102a of the node control unit 102 uses the fiber connection information (connection information may be detected by the node itself) and path setting information from the network monitoring device 200, and the registration information of each package held by the node 100. , The connection destination (connected package) of the fiber connected to each port of each package (transponder, multiplexer, optical cross connect, optical input unit, optical output unit, etc.) is detected.

Subsequently, the node 100 sets the switch of the optical cross connect 130 and causes the transponders 111 to 114 to emit light (S107). For example, the initial setting unit 102a of the node control unit 102 sets the wavelength switching (input/output relationship according to wavelength) of the wavelength selective switch 131 from the registration information, the fiber connection information, and the path setting information.

Then, the node 100 sets the variable optical attenuator VOA in the optical cross connect 130 and/or the transponders 111 to 114 so that the optical output per carrier of the own package becomes a desired value based on the detection result in S106. Initial settings are made (S108). For example, the initialization unit 102a of the node control unit 102 initializes the variable optical attenuator VOA (subcarrier unit) inside the package so that the detected optical output level in the package of the connection destination becomes a desired value. .. That is, in order to set the optical level of the SCH signal S0 output from the optical output unit 142 to a desired value, the variable optical attenuator VOA1 of the transponders 111 to 114, the variable optical attenuator VOA2 of the multiplexer 121, and the optical cross connect 130. Initially set the attenuation amount of the variable optical attenuator VOA3.

Next, in the loop L1 (first loop) of S109 to S112, the level correction process before multiplexing (first correction process) is executed. In the level correction processing before multiplexing, the node 100 first detects the optical level of each subcarrier in the wavelength group by the optical channel monitor OCM (S109).

Subsequently, the node 100 calculates the difference between the optical level of each subcarrier detected in S109 and the output target value (S110), and based on the difference, the transponders 111 to 111 so that the optical level of each subcarrier becomes the output target value. The variable optical attenuator VOA in 114 is set (S111). At this time, the difference may be notified to the transponder. For example, the level correction unit 102b of the node control unit 102 calculates the difference between the optical level of each subcarrier in the wavelength group monitored by the optical channel monitor OCM and the output target value, and the difference is applied to the corresponding transponder 111 to 114 ( And the multiplexer 121). The transponders 111 to 114 (or the level correction unit 102b) uses the variable optical attenuator VOA1 (and the multiplexer 121 of the multiplexer 121) in the transponders 111 to 114 so that the optical level of each subcarrier becomes the output target value based on the notified difference. Set the attenuation amount of the variable optical attenuator VOA2).

Subsequently, the node 100 determines whether or not the optical levels of all the subcarriers in the wavelength group have reached the target value (S112). For example, the level correction unit 102b of the node control unit 102 determines whether the optical level of the subcarriers in each wavelength group monitored by the optical channel monitor OCM has reached the target value (or is included in the target range), When the target value is reached, the loop L1 (level correction process before combining) after S109 is ended, and when the target value is not reached, the loop L1 is repeated. For example, until the subcarrier signals S1_1 and S1_2 in the wavelength group signal S2_1 become the target values and the subcarrier signals S1_3 and S1_4 in the wavelength group signal S2_2 become the target values (in the example of FIG. 13, the wavelengths f3 and f4 Level correction is performed until the subcarrier signal in each wavelength group reaches a target value).

Next, in the loop L2 (second loop) of S113 to S116, the level correction process (second correction process) after the multiplexing is executed. In the level correction processing after multiplexing, first, when the first loop ends, the node 100 detects the optical level of each subcarrier of all wavelength groups by the optical channel monitor OCM (S113).

Subsequently, the node 100 calculates the difference between the optical level of each subcarrier in the wavelength group detected in S113 and the output target value (S114), and the optical level of each subcarrier becomes the output target value based on the difference. The variable optical attenuator VOA in the optical cross connect 130 (wavelength selective switch 131) is set (S115). At this time, the difference may be notified to the optical cross connect. For example, the level correction unit 102b of the node control unit 102 calculates the difference between the optical level of each subcarrier in all wavelength groups monitored by the optical channel monitor OCM and the output target value, and notifies the optical cross connect 130 of the difference. To do. The optical cross-connect 130 (or the level correction unit 102b) sets the optical level of each sub-carrier within the corresponding wavelength group in the optical cross-connect 130 (wavelength selective switch 131) based on the notified difference. The attenuation amount of the variable optical attenuator VOA3 of the subcarrier is set. For example, the subcarrier signals S1_1 and S1_2 in the wavelength group signal S2_1, the subcarrier signals S1_3 and S1_4 in the wavelength group signal S2_2, and the subcarrier signal (SCH signal S4) in the wavelength group signal received from another node are target values. 13 (until the subcarrier signals in each wavelength group of wavelengths f3, f4, and f1 reach the target value in the example of FIG. 13).

Subsequently, the node 100 determines whether or not an optical level break of any subcarrier has been detected (S116). For example, the level correction unit 102b of the node control unit 102 determines whether the optical level disconnection of the subcarrier (the optical level is lower than a predetermined value) is determined based on the monitoring result of the optical channel monitor OCM, and when the optical level disconnection is not detected, If the optical level break is detected by repeating the loop L2 (level correction process after multiplexing) after S113, the loop L2 is ended, the process returns to S108, and the level correction before multiplexing is restarted. At this time, the alarm unit 102c notifies the network monitoring apparatus 200 of the optical level break of the subcarrier.

FIG. 15 shows the state transition of the level correction method according to the present embodiment shown in FIGS. 14A to 14C. First, the state ST1 is an initial state, in which the switch is not connected and the output of the variable optical attenuator is OFF. When the initial setting (S101 to S105) is performed in the state ST1, the state transits to the state ST2.

In the state ST2, the optical switch/optical attenuator is initialized (S106 to S108), and when the initialization is completed in the state ST2, the state is changed to the state ST3. In state ST3, loop L1 processing (level correction processing before multiplexing) is executed, and S109 to S112 are repeated until the output target value is reached. When the output target value is reached in state ST3, the state transits to state ST4. In state ST4, loop L2 processing (level correction processing after multiplexing) is executed, and S113 to S116 are repeated so as to maintain the output target value.

In the state ST3, if the output target value is not reached and time-out occurs, the state transitions to the state ST5. In the state ST5, the target value unreached alarm is issued. When the issuance of the target value non-arrival warning is completed in state ST5, the state transits to state ST4. That is, after the initial setting, if a certain period of time elapses before the level correction process before combining is completed (subcarrier reaches the target level), an alarm is output from the alarm unit 102c, and the level correction process after combining is performed. To start.

Further, in the state ST4, when a light level break is detected (due to a failure or the like), the state returns to the state ST2. That is, when the level correction process after the combination is completed (or is being processed) and a failure occurs in the subcarrier, an alarm is output from the alarm unit 102c, and the level correction process before the combination is restarted. Further, when the path is deleted in the state ST4, the state returns to the state ST1. That is, if the path is deleted due to an instruction or the like from the network monitoring device 200 after the level correction processing after combining is completed (or is being processed), the level correction processing before combining is restarted.

As described above, in the present embodiment, the optical level of the wavelength group signal (subcarrier signal) is monitored at the output section of the node and level correction is performed based on the monitoring result, as in the first embodiment. First, in the level correction before multiplexing, the optical level in the transponder or the multiplexer is controlled so that the subcarrier signals in the wavelength group have a constant level. Further, in the level correction after multiplexing, the optical level in the optical cross connect (wavelength selective switch) is controlled so that the subcarrier signals in all wavelength groups have a constant level. This makes it possible to accurately correct the level deviation between the wavelength groups and the level deviation between the subcarriers in the wavelength group, so that the transmission characteristics can be improved.

The present invention is not limited to the above-mentioned embodiments, but can be modified as appropriate without departing from the spirit of the present invention.

Each configuration (optical transmission device and network monitoring device) in the above-described embodiment is configured by hardware or software, or both, and may be configured by one piece of hardware or software, or a plurality of pieces of hardware or software. You may comprise from. Each function (each process) of the wireless device may be realized by a computer having a CPU, a memory, and the like. For example, a program for performing the level correction method according to the embodiment may be stored in the storage device, and each function may be realized by executing the program stored in the storage device by the CPU.

This program can be stored using various types of non-transitory computer readable media, and can be supplied to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of the non-transitory computer readable medium include a magnetic recording medium (for example, flexible disk, magnetic tape, hard disk drive), magneto-optical recording medium (for example, magneto-optical disk), CD-ROM (Read Only Memory), CD-R, It includes a CD-R/W and a semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). Further, the program may be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

1 optical transmission system 2 WDM network 3 management network 10 node 11 multiplexing unit 12 output unit 13 pre-combining level correction unit 14 post-combining level correction unit 100 node 101 optical transmission unit 102 node control unit 102a initial setting unit 102b level correction Unit 102c Alarm unit 111 to 114 Transponder 121 to 233 Multiplexer 130 Optical cross connect 131 Wavelength selective switch 141 Optical input unit 142 Optical output unit 200 Network monitoring device 201 Group designation unit 202 Connection information management unit 203 Path setting unit AG Multiplexing AMP1, AMP2 Optical amplifier CA Optical amplifier F1 to F8 Optical fiber OCM Optical channel monitor OL Optical transmission line S0, S3, S4 SCH signal S1 Subcarrier signal S2 Wavelength group signal TPND Transponder TX laser VOA1 to VOA3 Variable optical attenuator WSS wavelength Select switch XF Optical cross connect

Claims (39)

A first optical signal transmitter that outputs a first subcarrier optical signal;
A second optical signal transmitter that outputs a second subcarrier optical signal;
A first multiplexing unit that multiplexes the first subcarrier optical signal and the second subcarrier optical signal to output as a first wavelength group optical signal;
A second multiplexing that multiplexes and outputs the first wavelength group optical signal and a second wavelength group optical signal including optical signals having different wavelengths from the first and second subcarrier optical signals. Department,
Light for adjusting a power difference between the first subcarrier optical signal and the second subcarrier optical signal and a power difference between the first wavelength group optical signal and the second wavelength group optical signal And a power adjustment unit ,
The optical transmission device , wherein the optical power adjustment unit adjusts the power difference between the first subcarrier optical signal and the second subcarrier optical signal to be small . The optical transmission device according to claim 1, wherein the second wavelength group optical signal includes a third subcarrier optical signal and a fourth subcarrier optical signal. A third optical signal transmitter for outputting the third subcarrier optical signal,
A fourth optical signal transmission unit that outputs the fourth subcarrier optical signal,
The third multiplexing unit that multiplexes the third subcarrier optical signal and the fourth subcarrier optical signal and outputs the multiplexed wavelength-group optical signal as the second wavelength group optical signal. Optical transmission equipment. The optical transmission device according to claim 1, wherein the second wavelength group optical signal is input to the second multiplexer from another optical transmission device. The optical power adjustment unit,
A first optical attenuator that adjusts the power of the first subcarrier optical signal;
A second optical attenuator for adjusting the power of the second subcarrier optical signal;
The optical transmission device according to claim 1, further comprising a third optical attenuator that adjusts the power of the first wavelength group optical signal. The first multiplexing unit includes the first subcarrier optical signal whose power is adjusted by the first optical attenuating unit, and the second subcarrier whose power is adjusted by the second optical attenuating unit. The optical transmission device according to claim 5, wherein the optical signal is multiplexed with a carrier optical signal and output. The optical power adjusting unit adjusts a power difference between the first subcarrier optical signal and the second subcarrier optical signal based on a power level target value of the subcarrier optical signal.
The optical transmission device according to claim 1. The optical power adjustment unit adjusts a power difference between the first wavelength group optical signal and the second wavelength group optical signal based on a power level target value of the wavelength group optical signal.
The optical transmission device according to claim 1. An optical power monitor unit for monitoring the power of the first subcarrier optical signal and the power of the second subcarrier optical signal,
The optical power adjusting unit adjusts a power difference between the first subcarrier optical signal and the second subcarrier optical signal based on a monitoring result of the optical power monitoring unit.
The optical transmission device according to claim 1. The optical power monitor unit further monitors the power of the first wavelength group optical signal and the power of the second wavelength group optical signal,
The optical power adjustment unit adjusts a power difference between the first wavelength group optical signal and the second wavelength group optical signal based on a monitor result of the optical power monitor unit,
The optical transmission device according to claim 9. Further comprising an optical switch for switching the output destination of the first wavelength group optical signal,
The optical transmission device according to claim 1. A fault monitoring unit that detects a fault in either the first subcarrier optical signal or the second subcarrier optical signal,
The optical transmission device according to claim 1. The optical transmission according to any one of claims 1 to 12, wherein the optical power adjusting unit adjusts the power difference between the first wavelength group optical signal and the second wavelength group optical signal to be small. apparatus. An optical transmission device,
A control device for controlling the optical transmission device,
The optical transmission device,
A first optical signal transmitter that outputs a first subcarrier optical signal;
A second optical signal transmitter that outputs a second subcarrier optical signal;
A first multiplexing unit that multiplexes the first subcarrier optical signal and the second subcarrier optical signal to output as a first wavelength group optical signal;
A second multiplexing that multiplexes and outputs the first wavelength group optical signal and a second wavelength group optical signal including optical signals having different wavelengths from the first and second subcarrier optical signals. Department,
Light for adjusting a power difference between the first subcarrier optical signal and the second subcarrier optical signal and a power difference between the first wavelength group optical signal and the second wavelength group optical signal And a power adjustment unit ,
The optical transmission system , wherein the optical power adjusting unit adjusts the power difference between the first subcarrier optical signal and the second subcarrier optical signal to be small . The optical transmission system according to claim 14, wherein the second wavelength group optical signal includes a third subcarrier optical signal and a fourth subcarrier optical signal. A third optical signal transmitter for outputting the third subcarrier optical signal,
A fourth optical signal transmission unit that outputs the fourth subcarrier optical signal,
The third multiplexing unit that multiplexes the third subcarrier optical signal and the fourth subcarrier optical signal and outputs the multiplexed wavelength-group optical signal as the second wavelength group optical signal. Optical transmission system. The optical transmission system according to claim 14, wherein the second wavelength group optical signal is input to the second multiplexing unit from an optical transmission device different from the optical transmission device. The optical power adjustment unit,
A first optical attenuator that adjusts the power of the first subcarrier optical signal;
A second optical attenuator for adjusting the power of the second subcarrier optical signal;
The optical transmission system according to claim 14, further comprising: a third optical attenuator that adjusts the power of the first wavelength group optical signal. The first multiplexing unit includes the first subcarrier optical signal whose power is adjusted by the first optical attenuating unit, and the second subcarrier whose power is adjusted by the second optical attenuating unit. The optical transmission system according to claim 18, wherein the carrier optical signal is multiplexed and output. The optical power adjusting unit adjusts a power difference between the first subcarrier optical signal and the second subcarrier optical signal based on a power level target value of the subcarrier optical signal.
The optical transmission system according to any one of claims 14 to 19. The optical power adjustment unit adjusts a power difference between the first wavelength group optical signal and the second wavelength group optical signal based on a power level target value of the wavelength group optical signal.
The optical transmission system according to any one of claims 14 to 20. An optical power monitor unit for monitoring the power of the first subcarrier optical signal and the power of the second subcarrier optical signal,
The optical power adjusting unit adjusts a power difference between the first subcarrier optical signal and the second subcarrier optical signal based on a monitoring result of the optical power monitoring unit.
The optical transmission system according to any one of claims 14 to 21. The optical power monitor unit further monitors the power of the first wavelength group optical signal and the power of the second wavelength group optical signal,
The optical power adjustment unit adjusts a power difference between the first wavelength group optical signal and the second wavelength group optical signal based on a monitor result of the optical power monitor unit,
The optical transmission system according to claim 22. Further comprising an optical switch for switching the output destination of the first wavelength group optical signal,
The optical transmission system according to any one of claims 14 to 23. A fault monitoring unit that detects a fault in either the first subcarrier optical signal or the second subcarrier optical signal,
The optical transmission system according to any one of claims 14 to 24. The optical transmission according to any one of claims 14 to 25, wherein the optical power adjusting unit adjusts the power difference between the first wavelength group optical signal and the second wavelength group optical signal to be small. system. Outputs a first subcarrier optical signal,
Outputs a second subcarrier optical signal,
The first subcarrier optical signal and the second subcarrier optical signal are multiplexed and output as a first wavelength group optical signal,
The first wavelength group optical signal and the second wavelength group optical signal including optical signals having different wavelengths from the first and second subcarrier optical signals are multiplexed and output.
The power difference between the first subcarrier optical signal and the second subcarrier optical signal is adjusted to be small, and the power difference between the first wavelength group optical signal and the second wavelength group optical signal is adjusted. And, the optical communication method to adjust. The optical communication method according to claim 27, wherein the second wavelength group optical signal includes a third subcarrier optical signal and a fourth subcarrier optical signal. Outputting the third subcarrier optical signal,
Outputting the fourth subcarrier optical signal,
29. The optical communication method according to claim 28, wherein the third subcarrier optical signal and the fourth subcarrier optical signal are multiplexed and output as the second wavelength group optical signal. 30. The optical communication method according to claim 27, wherein the second wavelength group optical signal is input from another optical transmission device. Adjusting the power of the first subcarrier optical signal,
Adjusting the power of the second subcarrier optical signal,
31. The optical communication method according to claim 27, wherein the power of the first wavelength group optical signal is adjusted. The optical communication method according to claim 31, wherein the first subcarrier optical signal whose power is adjusted and the second subcarrier optical signal whose power is adjusted are multiplexed and output. Adjusting a power difference between the first subcarrier optical signal and the second subcarrier optical signal based on a power level target value of the subcarrier optical signal.
The optical communication method according to any one of claims 27 to 32. Adjusting a power difference between the first wavelength group optical signal and the second wavelength group optical signal based on a power level target value of the wavelength group optical signal,
The optical communication method according to any one of claims 27 to 33. Monitoring the power of the first subcarrier optical signal and the power of the second subcarrier optical signal and outputting a monitoring result,
Adjusting a power difference between the first subcarrier optical signal and the second subcarrier optical signal based on the monitoring result,
The optical communication method according to any one of claims 27 to 34. Monitoring the power of the first wavelength group optical signal and the power of the second wavelength group optical signal,
Adjusting the power difference between the first wavelength group optical signal and the second wavelength group optical signal based on the monitoring result,
The optical communication method according to claim 35. The optical communication method according to any one of claims 27 to 36, wherein an output destination of the first wavelength group optical signal is switched. The optical communication method according to any one of claims 27 to 37, wherein a failure in either the first subcarrier optical signal or the second subcarrier optical signal is detected. The optical communication method according to any one of claims 27 to 38, wherein adjustment is made so as to reduce a power difference between the first wavelength group optical signal and the second wavelength group optical signal.

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