JP7156480B2 - Optical transmission device, optical transmission system and optical communication method - Google Patents

Description

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

With the increasing demand for broadband multimedia communication services such as the Internet and video distribution, the introduction of long-distance and large-capacity optical fiber communication systems is progressing in trunk lines and metro systems. In an optical transmission system using such optical fibers, it is important to increase the transmission efficiency per optical fiber. For this reason, wavelength division multiplex (WDM) communication is widely used in which optical signals with different wavelengths are multiplexed and transmitted.

Super-channel (Super-CH: SCH) transmission, in which a plurality of subcarriers are arranged at narrow frequency intervals and grouped, is known as a related technique for efficiently expanding the transmission capacity of WDM communication. For example, Patent Literature 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 SCH transmission, it is possible to realize optical transmission of several hundred Gbps. However, in SCH transmission, such as the related technology, optical level deviation occurs between subcarriers or between groups including subcarriers, so there is a problem of deterioration in transmission characteristics.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical transmission device capable of improving transmission characteristics and a control method thereof.

An optical transmission apparatus according to the present invention includes a multiplexing unit for multiplexing a plurality of subcarrier signals for optical wavelength division multiplexing into a wavelength group signal, and an output unit for outputting the multiplexed wavelength group signal to an optical transmission line. a pre-multiplexing level correction unit that corrects the level deviation of the subcarrier signals before multiplexing 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-multiplexing level correction unit that corrects the level deviation of the post-multiplexing wavelength group signal including the corrected subcarrier signal based on the above.

A control method for an optical transmission apparatus according to the present invention includes a multiplexing unit for multiplexing a plurality of subcarrier signals for optical wavelength division multiplexing into a wavelength group signal, and outputting the multiplexed wavelength group signal to an optical transmission line. and a control method for an optical transmission apparatus comprising: an output section for correcting a level deviation of the pre-multiplexed subcarrier signals based on the optical level of the wavelength group signal at the output section; Based on the optical level of the wavelength group signal in the section, the level deviation of the multiplexed wavelength group signal including the corrected subcarrier signal is corrected.

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

3 is a configuration diagram showing a schematic configuration of a node according to a basic example; FIG. 7 is a graph showing an example wavelength band of SCH according to a basic example; 7 is a graph showing an example of SCH level deviation according to a basic example; 7 is a graph showing an example of SCH level deviation according to a basic example; 7 is a graph for explaining the correction result of the SCH level deviation according to the basic example; 7 is a graph for explaining the correction result of the SCH level deviation according to the basic example; 1 is a configuration diagram for explaining an outline of a node according to an embodiment; FIG. 1 is a configuration diagram showing a schematic configuration of a node according to Embodiment 1; FIG. FIG. 4 is a diagram for explaining a level correction operation according to Embodiment 1; FIG. FIG. 4 is a diagram for explaining a level correction operation according to Embodiment 1; FIG. FIG. 9 is a configuration diagram showing a configuration example of an optical transmission system according to Embodiment 2; FIG. 9 is a configuration diagram showing a configuration example of a node according to Embodiment 2; FIG. 11 is a configuration diagram showing another configuration example of a node according to Embodiment 2; 10 is a flowchart showing an example of level correction operation according to Embodiment 2; 10 is a flowchart showing an example of level correction operation according to Embodiment 2; 10 is a flowchart showing an example of level correction operation according to Embodiment 2; FIG. 11 is a state transition diagram showing an example of state transition of level correction operation according to the second embodiment;

(basic example)
First, a basic example that forms the basis of the embodiments will be described.

FIG. 1 shows a schematic configuration of a node (optical transmission device) according to a 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 multiplexing subcarrier signals, and an optical cross-connect XF as a configuration after multiplexing subcarrier signals. It has an optical amplifier CA. In this specification, "multiplexing" means multiplexing of subcarriers within the same wavelength group.

A plurality of transponders TPND (TPND_1 to TPND_3) output subcarrier signals S1 of different wavelengths, and a 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 produce the SCH signal (containing 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 wavelength bands of SCH signals 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. A 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/DROP at 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 may include any number of subcarrier signals. The SCH signal is not limited to two wavelength group signals S2_1-S2_2, and may include any number of wavelength group signals.

3 and 4 show the level deviations occurring in the SCH signal in the basic example. In SCH transmission, a plurality of subcarrier signals S1 constitute a wavelength group signal S2, and a plurality of wavelength group signals S2 constitute an SCH signal S0. Therefore, level deviation occurs in units constituting each signal.

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

As the second level deviation, as shown in FIG. 4, level deviation occurs between subcarriers within a wavelength group in SCH transmission. A level deviation between subcarriers occurs due to a difference in passage loss between subcarriers before multiplexing. That is, a plurality of subcarrier signals are input to the multiplexer AG of the node, and since these subcarrier signals pass through different transponders, fibers, etc., the optical level varies depending on the loss of the transponders, fibers, etc. variation occurs. For example, there is 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 wavelength dependency after multiplexing. That is, the 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, resulting in variations in the optical levels of the subcarriers. 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 optical amplifier CA.

Of these level deviations, if the deviation due to the difference in wavelength loss before multiplexing is corrected by level correction (LEQ) after multiplexing, it may lead to degradation of the passing waveform. 5 and 6 show spectral changes before and after correction when level deviation correction is simply performed on the wavelength group signal after multiplexing.

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

FIG. 6 shows the spectrum when level correction is performed after the signals of FIG. 5 are multiplexed. As shown in FIG. 6, for example, in order to correct the level deviation, the subcarrier signal S1_1 is attenuated by 3 dB (lowered by 3 dB from S2) 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 (raised by 3 dB from S1). As a result, waveform rounding occurs in the ATT setting of the variable optical attenuator between subcarriers (slices). The waveform of the subcarrier signal S1_1 rises in the vicinity of the wavelength where the waveform is rounded, so that the signal characteristics (transmission characteristics) are degraded.

(Overview of Embodiment)
As described above, since two level deviations occur in SCH transmission, level correction requires correction of level deviation between wavelength groups and correction of level deviation of subcarriers within a wavelength group. Therefore, in the embodiment, means for correcting 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 a node (optical transmission device) 10 according to the embodiment. As shown in FIG. 7, the node 10 according to the embodiment includes a multiplexing unit 11, an output unit 12, a pre-multiplexing level correction unit 13, and a post-multiplexing level correction unit .

The multiplexer 11 multiplexes a plurality of subcarrier signals for optical wavelength division multiplexing into a wavelength group signal. 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 signals before multiplexing by the multiplexing unit 11 based on the optical level of the wavelength group signal at the output unit 12 . The post-multiplexing level correction unit 14 corrects the level deviation of the post-multiplexing wavelength group signal including the subcarrier signals corrected by the pre-multiplexing 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 subcarriers occurring before multiplexing is corrected before multiplexing, and the level deviation between wavelength groups (subcarriers included in the wavelength group) occurring after multiplexing is corrected. By correcting the level deviation after multiplexing, the occurrence of the level deviation can be reliably suppressed, and the transmission characteristics can be improved.

(Embodiment 1)
Embodiment 1 will be described below 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 a node according to this embodiment. As shown in FIG. 8, the node 100 according to the present embodiment includes a plurality of transponders TPND (TPND_1 to TPND_3), a multiplexer AG, an optical cross-connect XF, and an optical amplifier CA, similar to the basic example described above. Furthermore, it has an optical channel monitor OCM, a pre-multiplexing level corrector 13 and a post-multiplexing level corrector 14 . 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) and output the generated plurality of subcarrier signals S1 to the multiplexer AG. For example, each transponder TPND has a laser TX serving as a light source and a variable optical attenuator VOA1 for controlling the optical level of the optical signal from the laser TX.

The multiplexer AG is a multiplexing unit 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 has a variable optical attenuator VOA2 that controls the optical level of each subcarrier signal S1.

The optical cross connect XF has a wavelength selective switch WSS, and the wavelength group signal S2 output from the multiplexer AG (including wavelength group signals input from other nodes) is output by this wavelength selective switch WSS. , to generate the SCH signal (including the wavelength group signal S2) S3, and output the generated SCH signal to the optical amplifier CA. For example, the wavelength selective switch WSS in the optical cross-connect XF has 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, an optical monitor unit arranged in the optical amplifier CA and monitoring the optical level of each subcarrier signal in the wavelength group signal in the SCH signal S0 output from the optical amplifier CA.

As level correction before multiplexing, 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 based on the optical level monitoring 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 outline the operation of the node according to this embodiment, and show the level correction method before multiplexing and the level correction method after multiplexing, respectively.

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 at the output section (optical amplifier CA) to the transmission line. node output (optical level) is returned to the transponder TPND or multiplexer AG of the corresponding wavelength group, and the output adjustment function of the transponder TPND or multiplexer AG is used to adjust each subcarrier to the desired level (output Calibration function: does not have to 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 is left as it is), and the monitor value of each subcarrier of the optical channel monitor OCM is The output of the transponder TPND or the variable optical attenuator VOA (or an optical amplifier may be used) in 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 at the output section (optical amplifier CA) to the transmission line. node output is returned to the optical cross-connect XF, and each subcarrier of the corresponding wavelength group is adjusted to a desired level using the output adjustment 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 set in the level correction before multiplexing is used), and the monitor values of the subcarriers of the optical channel monitor OCM become uniform. , the output of the variable optical attenuator VOA of the optical cross connect XF (wavelength selective switch WSS) is adjusted.

As described above, in this embodiment, the optical level of the wavelength group signal (subcarrier signal) is monitored at the output section of the node, and the level correction ( For example, level correction of transponders or multiplexers) is performed, and further level correction of wavelength group signals (subcarrier signals) after multiplexing (for example, level correction of optical cross-connect XF) is performed. Since deviation correction and level deviation correction between subcarriers within a wavelength group can be performed, transmission characteristics 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 nodes will be described.

FIG. 11 shows a configuration example of an optical transmission system according to this embodiment. As shown in FIG. 11, the optical transmission system 1 according to this 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. FIG. The optical transmission system 1 is not limited to three nodes 100_1 to 100_3, and may have any number of nodes.

The nodes 100_1 to 100_3 are connected 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 constitute a WDM (SCH) network 2. As an example, the WDM network 2 is a linear network, but may be a network of other topologies such as a ring network or a mesh network. For example, the node 100_1 is a transmitter that is the transmission end of the optical path, the node 100_2 is a repeater that relays the optical path, and the node 100_3 is the receiver that is the reception end of the optical path.

Each node 100 has basically the same configuration, an optical transmission unit 101 that performs SCH transmission via the optical transmission line OL, and performs control such as setting of the optical transmission unit 101 based on control from the network monitoring device 200. A node control unit 102 is provided. Note that 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 includes, for example, an initial setting unit 102a that performs initial settings for the optical transmission unit 101, a level correction unit 102b that corrects the level of the wavelength group signal (subcarrier signal), and detects optical signal failures. 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 the 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 communication paths via each node 100. ing.

FIG. 12 shows a configuration example of a node (optical transmission unit) according to this embodiment. FIG. 12 shows, for example, a configuration example of the optical transmission unit 101 of the node 100_2 that functions as a repeater. As shown in FIG. 12, the optical transmission section 101 according to this embodiment includes transponders 111 to 114, multiplexers 121 and 122, an optical cross connect 130, an optical input section 141, and an optical output section 142. FIG. For example, the transponders 111 to 114, the multiplexers 121 and 122, the optical cross connect 130, the optical input section 141, and the optical output section 142 are each configured as an independent package, and the optical transmission section 101 (node) is composed of a plurality of packages. It is configured. 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 respectively connected to client devices (not shown), convert signals input from the client devices into subcarrier signals S1_1 to S1_4 for SCH transmission, and output the subcarrier signals S1_1 to S1_4. . Each of the transponders 111 to 114 has a laser TX serving as a light source and a variable optical attenuator VOA1 for controlling the optical level of the optical signal from the laser TX.

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

The optical cross connect 130 has a wavelength selective switch 131 . Note that the optical cross connect 130 may include a plurality of wavelength selective switches 131 according to routes and the like.

The wavelength selective switch 131 switches (including add/drop) the output destination of the optical signal input from the multiplexers 121 and 122 and the optical input unit 141 according to the wavelength. The wavelength selective switch 131 has 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 section 141 and the optical output section 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 section 141 according to the wavelengths. Generate signal S3. When switching is set so that the wavelength group signals S2_1 and S2_2 and the wavelength group signals of the SCH signal S4 are output to the optical output section 142, the SCH signal S3 including these signals is output to the optical output section 142. FIG.

The optical input unit 141 is connected to another node at the transmission end (or repeater) via the optical transmission line OL, and receives the SCH signal S0 via the optical transmission line OL. For example, the optical input section 141 has 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. FIG.

The optical output unit 142 is connected to another node at the receiving end (or 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 has 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 within the wavelength group of the amplified SCH signal S0 and outputs the monitor result to the node control section 102. FIG. Note that the node control unit 102 (or part thereof) may be incorporated in the optical output unit 142 or another block (package).

In the example of FIG. 12, based on the optical level of each subcarrier signal within the wavelength group of the SCH signal S0 in the optical output section 142, the subcarrier signal before multiplexing (transponders 111 to 114, multiplexers 121 and 122) , and corrects the level deviation of the subcarrier signal (wavelength group signal) after multiplexing (optical cross connect 130).

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

The multiplexer AG1 multiplexes the subcarrier signals from the transponders TPND1 to TPND3, outputs them to the optical crossconnect XF1 or XF2, and demultiplexes the wavelength group signals from the optical crossconnect XF1 or XF2. The multiplexer AG2 multiplexes the subcarrier signals from the transponders TPND4 and TPND5, outputs them to the optical cross connect XF1, and demultiplexes the wavelength group signals from the optical cross connect XF1. The multiplexer AG3 multiplexes the subcarrier signals from the transponders TPND6 to TPND7, outputs them to the optical cross connect XF2, and demultiplexes the wavelength group signals from the optical cross connect XF2.

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

As shown in FIG. 13, in this example, the wavelength group signal of wavelength f1 is transmitted in a route via optical amplifier CA1-optical cross connect XF1-optical cross connect XF2-optical amplifier CA2. A wavelength group signal of wavelength f2 is transmitted in a route via optical amplifier CA1-optical cross connect XF1-multiplexer AG2. A wavelength group signal of wavelength f3 is transmitted along a route via multiplexer AG2-optical cross connect XF1-optical amplifier CA1. A wavelength group signal of wavelength f4 is transmitted along a route via multiplexer AG1-optical cross connect XF2-optical amplifier CA2. A wavelength group signal of wavelength f5 is transmitted along a route via 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 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 wavelength f3. Based on this monitor result, the level deviation of the subcarrier signal before multiplexing (transponders TPND4 to TPND5, multiplexer AG2) is corrected, and the subcarrier signal (wavelength group signal) after multiplexing (optical cross connect XF1) is corrected. corrects the level deviation of

Since the wavelength group signals of 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 wavelengths f1 and f4. Based on the monitoring result of wavelength f4, the level deviation of subcarrier signals before multiplexing (transponders TPND1 to TPND3, multiplexer AG1) is corrected, and the subcarrier signal (wavelength group signal) level deviation. Since the wavelength group signal of wavelength f5 is not multiplexed within the node (optical transmission unit 101), the subcarrier signal (wavelength group signal ) to correct the level deviation.

14A to 14C show a level correction method according to this embodiment. Here, an example will be described with reference to the configuration example of the node in FIG. 12 .

As shown in FIGS. 14A to 14C, first, in the node 100, a transponder is installed (S101), and the transponder and multiplexer (multiplexer/multiplexer) are connected by an optical fiber (S102). For example, as shown in FIG. 12, the user of node 100 connects transponders 111 and 112 and multiplexer 121 by optical fibers F1 and F2, and connects transponders 113 and 114 and multiplexer 122 by optical fibers F3 and F4. 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 instructions from the user, and sets the wavelength groups and subcarrier configurations used in SCH transmission.

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

Subsequently, 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 in FIG. 13) between the nodes 100 for SCH transmission according to the user's instruction.

Next, the node 100 detects the type of package to be connected 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 fiber connection information from the network monitoring device 200 (the connection information may be detected by the node itself), path setting information, and 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 section, optical output section, etc.).

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

Next, based on the detection result in S106, the node 100 adjusts 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 its own package becomes a desired value. Initialize (S108). For example, the initial setting unit 102a of the node control unit 102 initializes the variable optical attenuator VOA (in units of subcarriers) inside the package so that the optical output level of the detected connection destination package 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, the optical cross connect 130 Initialize the attenuation of the variable optical attenuator VOA3.

Next, level correction processing (first correction processing) before multiplexing is executed in a loop L1 (first loop) of S109 to S112. In the level correction process before multiplexing, first, the node 100 detects the optical level of each subcarrier in the wavelength group with 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 to the transponders 111 to 110 so that the optical level of each subcarrier becomes the output target value. A 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 calculates the difference from the corresponding transponders 111 to 114 ( and multiplexer 121). The transponders 111-114 (or the level correction unit 102b) adjust the variable optical attenuator VOA1 (and the multiplexer 121) in the transponders 111-114 so that the optical level of each subcarrier becomes the output target value based on the notified difference. Sets the attenuation of the variable optical attenuator VOA2).

Next, the node 100 determines whether the optical levels of all subcarriers within 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 subcarriers in each wavelength group monitored by the optical channel monitor OCM has reached the target value (or is included in the target range), If the target value has been reached, the loop L1 (level correction processing before multiplexing) after S109 is terminated, and if the target value has not been reached, the loop L1 is repeated. For example, until the subcarrier signals S1_1 and S1_2 in the wavelength group signal S2_1 reach the target values and the subcarrier signals S1_3 and S1_4 in the wavelength group signal S2_2 reach the target values (in the example of FIG. Level correction is performed until the subcarrier signal in each wavelength group reaches the target value).

Next, level correction processing (second correction processing) after multiplexing is executed in loop L2 (second loop) of S113 to S116. In the level correction process after multiplexing, first, when the first loop ends, the node 100 detects the optical level of each subcarrier of all wavelength groups with 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. Then, 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. do. The optical cross-connect 130 (or the level correction unit 102b) adjusts the optical level of each subcarrier to the output target value based on the notified difference. Sets the attenuation of the subcarrier variable optical attenuator VOA3. 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 the target values. Level correction is performed so that (in the example of FIG. 13, the subcarrier signals in each wavelength group of wavelengths f3, f4, and f1 reach the target value).

Next, the node 100 determines whether or not an interruption in the optical level of any subcarrier has been detected (S116). For example, the level correction unit 102b of the node control unit 102 determines whether or not there is a subcarrier optical level interruption (the optical level is lower than a predetermined value) based on the monitoring result of the optical channel monitor OCM. Loop L2 (level correction processing after multiplexing) is repeated after S113, and when light level disconnection is detected, loop L2 is terminated, the process returns to S108, and level correction before multiplexing is resumed. At this time, the alarm unit 102c notifies the network monitoring device 200 of the subcarrier optical level interruption.

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

In state ST2, the optical switch/optical attenuator is initialized (S106-S108), and when the initialization is completed in state ST2, the state transitions to 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 transitions 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.

If a timeout occurs in state ST3 without reaching the output target value, the state transitions to state ST5. In state ST5, a target value non-arrival warning is issued. In state ST5, when the issuance of the target value non-arrival warning is completed, the state transitions to state ST4. That is, after initial setting, if a certain period of time elapses before the pre-multiplexing level correction processing is completed (the subcarrier reaches the target level), an alarm is output from the alarm unit 102c, and the post-multiplexing level correction processing is performed. to start.

In addition, in state ST4, if an optical level cutoff (due to failure or the like) is detected, the state returns to state ST2. That is, if a fault occurs in a subcarrier after the level correction processing after multiplexing is completed (or during processing), an alarm is output from the alarm unit 102c, and the level correction processing before multiplexing is restarted. Further, when the path is deleted in state ST4, the state returns to state ST1. That is, when a path is deleted by an instruction from the network monitoring device 200 or the like while the level correction processing after multiplexing is completed (or is being processed), the level correction processing before multiplexing is restarted.

As described above, in this embodiment, as in the first 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. First, in the level correction before multiplexing, the optical level in the transponder or multiplexer is controlled so that the subcarrier signal within the wavelength group has a constant level. Furthermore, 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. As a result, level deviation correction between wavelength groups and level deviation correction between subcarriers within a wavelength group can be performed with high accuracy, so that transmission characteristics can be improved.

It should be noted that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the scope of the invention.

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

The program can be stored and delivered to the computer using various types of non-transitory computer readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (eg, flexible discs, magnetic tapes, hard disk drives), magneto-optical recording media (eg, magneto-optical discs), CD-ROMs (Read Only Memory), CD-Rs, CD-R/W, semiconductor memory (eg, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). The program may also be delivered to the computer on various types of transitory computer readable medium. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. Transitory computer-readable media can deliver the program to the computer via wired channels, such as wires and optical fibers, or wireless channels.

1 optical transmission system 2 WDM network 3 management network 10 node 11 multiplexing unit 12 output unit 13 pre-multiplexing level correction unit 14 post-multiplexing level correction unit 100 node 101 optical transmission unit 102 node control unit 102a initial setting unit 102b level correction Unit 102c Alarm units 111 to 114 Transponders 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 Selection switch XF Optical cross connect

Claims (44)

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 multiplexer for multiplexing the first subcarrier optical signal and the second subcarrier optical signal and outputting the first wavelength group optical signal;
a second multiplexing for multiplexing and outputting the first wavelength group optical signal and a second wavelength group optical signal including an optical signal having a wavelength different from that of the first and second subcarrier optical signals; Department and
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 power adjuster adjusts the power difference between the first subcarrier optical signal and the second subcarrier optical signal, and then adjusts the power difference between the first wavelength group optical signal and the second wavelength group optical signal. Perform power difference adjustment with signal
Optical transmission equipment. 2. 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 that outputs the third subcarrier optical signal;
a fourth optical signal transmitter that outputs the fourth subcarrier optical signal;
3. The third multiplexing unit that multiplexes the third subcarrier optical signal and the fourth subcarrier optical signal and outputs the multiplexed signal as the second wavelength group optical signal. Optical transmission equipment. 3. The optical transmission device according to claim 1, wherein the second wavelength group optical signal is input from another optical transmission device to the second multiplexer. The optical power adjustment unit
a first optical attenuator that adjusts the power of the first subcarrier optical signal;
a second optical attenuator that adjusts the power of the second subcarrier optical signal ;
5. The optical transmission device according to any one of claims 1 to 4, further comprising a third optical attenuator that adjusts power of the first wavelength group optical signal. The first multiplexer combines the first subcarrier optical signal whose power is adjusted by the first optical attenuator and the second subcarrier optical signal whose power is adjusted by the second optical attenuator. 6. The optical transmission device according to claim 5, wherein the carrier optical signal is multiplexed and output. The optical power adjustment 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.
7. The optical transmission device according to claim 1. The optical power adjuster 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 any one of claims 1 to 7. further comprising 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 adjustment unit adjusts the power difference between the first subcarrier optical signal and the second subcarrier optical signal based on the monitoring result of the optical power monitor unit.
The optical transmission device according to any one of claims 1 to 8. The optical power monitor unit measures the power of the first subcarrier optical signal and the power of the second subcarrier optical signal based on multiplexed light obtained by multiplexing the first wavelength group optical signal and the second wavelength group optical signal. monitoring the power of the subcarrier optical signal;
10. The optical transmission device according to claim 9. 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 the power difference between the first wavelength group optical signal and the second wavelength group optical signal based on the monitoring result of the optical power monitor unit.
The optical transmission device according to claim 9 or 10. The optical power monitor unit measures the power of the first wavelength group optical signal and the power of the second wavelength group optical signal based on combined light obtained by combining the first wavelength group optical signal and the second wavelength group optical signal. monitor the power of the wavelength group optical signal;
12. The optical transmission device according to claim 11. further comprising an optical switch that switches an output destination of the first wavelength group optical signal;
The optical transmission device according to any one of claims 1 to 12. further comprising 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 any one of claims 1 to 13. The optical power adjuster adjusts the power difference between the first subcarrier optical signal and the second subcarrier optical signal to reduce the power difference between the first wavelength group optical signal and the second wavelength group optical signal. 15. The optical transmission device according to any one of claims 1 to 14, wherein adjustment is made so as to reduce a power difference from the group optical signal. an optical transmission device;
a control device that controls the optical transmission device;
The optical transmission device is
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 multiplexer for multiplexing the first subcarrier optical signal and the second subcarrier optical signal and outputting the first wavelength group optical signal;
a second multiplexing for multiplexing and outputting the first wavelength group optical signal and a second wavelength group optical signal including an optical signal having a wavelength different from that of the first and second subcarrier optical signals; Department and
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 power adjuster adjusts the power difference between the first subcarrier optical signal and the second subcarrier optical signal, and then adjusts the power difference between the first wavelength group optical signal and the second wavelength group optical signal. Perform power difference adjustment with signal
Optical transmission system. 17. The optical transmission system of Claim 16, wherein the second wavelength group optical signal comprises a third subcarrier optical signal and a fourth subcarrier optical signal. a third optical signal transmitter that outputs the third subcarrier optical signal;
a fourth optical signal transmitter that outputs the fourth subcarrier optical signal;
18. The third multiplexing unit according to claim 17, which multiplexes the third subcarrier optical signal and the fourth subcarrier optical signal and outputs the multiplexed signal as the second wavelength group optical signal. Optical transmission system. 19. The optical transmission system according to any one of claims 16 to 18, wherein the second wavelength group optical signal is input to the second multiplexer 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 that adjusts the power of the second subcarrier optical signal ;
20. The optical transmission system according to any one of claims 16 to 19, further comprising a third optical attenuator that adjusts power of the first wavelength group optical signal. The first multiplexer combines the first subcarrier optical signal whose power is adjusted by the first optical attenuator and the second subcarrier optical signal whose power is adjusted by the second optical attenuator. 21. The optical transmission system according to claim 20, wherein the carrier optical signal is multiplexed and output. The optical power adjustment 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.
22. An optical transmission system according to any one of claims 16-21. The optical power adjuster 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.
23. An optical transmission system according to any one of claims 16-22. further comprising 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 adjustment unit adjusts the power difference between the first subcarrier optical signal and the second subcarrier optical signal based on the monitoring result of the optical power monitor unit.
24. An optical transmission system according to any one of claims 16-23. The optical power monitor unit measures the power of the first subcarrier optical signal and the power of the second subcarrier optical signal based on multiplexed light obtained by multiplexing the first wavelength group optical signal and the second wavelength group optical signal. monitoring the power of the subcarrier optical signal;
25. An optical transmission system according to claim 24. 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 the power difference between the first wavelength group optical signal and the second wavelength group optical signal based on the monitoring result of the optical power monitor unit.
26. An optical transmission system according to claim 24 or 25. The optical power monitor unit measures the power of the first wavelength group optical signal and the power of the second wavelength group optical signal based on combined light obtained by combining the first wavelength group optical signal and the second wavelength group optical signal. monitor the power of the wavelength group optical signal;
27. An optical transmission system according to claim 26. further comprising an optical switch that switches an output destination of the first wavelength group optical signal;
28. An optical transmission system according to any one of claims 16-27. further comprising a fault monitoring unit that detects a fault in either the first subcarrier optical signal or the second subcarrier optical signal;
29. An optical transmission system according to any one of claims 16-28. 30. The optical transmission according to any one of claims 16 to 29, wherein said optical power adjuster adjusts so as to reduce a power difference between said first wavelength group optical signal and said second wavelength group optical signal. system. outputting a first subcarrier optical signal;
outputting a second subcarrier optical signal;
combining the first subcarrier optical signal and the second subcarrier optical signal to output as a first wavelength group optical signal;
combining and outputting the first wavelength group optical signal and a second wavelength group optical signal including an optical signal having a wavelength different from that of the first and second subcarrier optical signals;
power of the first subcarrier optical signal and power of the second subcarrier optical signal based on combined light obtained by combining the first wavelength group optical signal and the second wavelength group optical signal; monitor and
After adjusting the power difference between the first subcarrier optical signal and the second subcarrier optical signal, adjusting the power difference between the first wavelength group optical signal and the second wavelength group optical signal. run
Optical communication method. power of the first wavelength group optical signal and power of the second wavelength group optical signal based on combined light obtained by combining the first wavelength group optical signal and the second wavelength group optical signal; 32. The optical communication method of claim 31, further comprising monitoring and. 33. The optical communication method according to claim 31 or 32, wherein said 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;
34. The optical communication method according to claim 33, wherein said third subcarrier optical signal and said fourth subcarrier optical signal are multiplexed and output as said second wavelength group optical signal. 35. The optical communication method according to any one of claims 31 to 34, wherein said 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;
36. The optical communication method according to any one of claims 31 to 35, further comprising adjusting the power of said first wavelength group optical signal. 37. The optical communication method according to claim 36, wherein the power-adjusted first subcarrier optical signal and the power-adjusted second subcarrier optical signal 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;
38. The optical communication method according to any one of claims 31-37. 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;
39. The optical communication method according to any one of claims 31-38. monitoring the power of the first subcarrier optical signal and the power of the second subcarrier optical signal and outputting a monitor result;
adjusting a power difference between the first subcarrier optical signal and the second subcarrier optical signal based on the monitoring result;
40. The optical communication method according to any one of claims 31-39. monitoring the power of the first wavelength group optical signal and the power of the second wavelength group optical signal;
adjusting a power difference between the first wavelength group optical signal and the second wavelength group optical signal based on the monitoring result;
41. The optical communication method according to claim 40. 42. The optical communication method according to any one of claims 31 to 41, wherein an output destination of said first wavelength group optical signal is switched. 43. The optical communication method according to any one of claims 31 to 42, further comprising detecting a fault in either said first subcarrier optical signal or said second subcarrier optical signal. 44. The optical communication method according to any one of claims 31 to 43, wherein adjustment is performed so as to reduce a power difference between said first wavelength group optical signal and said second wavelength group optical signal.

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