JP6455537B2 - Optical transmission device, optical transmission system, and optical communication method - Google Patents

Description

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

  With 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 and metro systems. In an optical transmission system using such an optical fiber, it is important to increase the transmission efficiency per optical fiber. For this reason, wavelength division multiplex (WDM) communication in which a plurality of optical signals having different wavelengths are multiplexed and transmitted 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 and grouped at a narrow frequency interval 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 SCH transmission, optical transmission of several hundred Gbps can be realized. However, in the SCH transmission like the related technique, there is a problem that the transmission characteristic is deteriorated because an optical level deviation occurs between subcarriers or between groups including subcarriers.

  In view of such problems, it is an object of the present invention to provide an optical transmission apparatus capable of improving transmission characteristics and a control method thereof.

  An optical transmission apparatus according to the present invention includes a multiplexing unit that combines a plurality of subcarrier signals for optical wavelength division multiplexing communication with a wavelength group signal, and an output unit that outputs the combined wavelength group signal to an optical transmission line And a pre-combination level correction unit that corrects a level deviation of the subcarrier signal before the combination based on an optical level of the wavelength group signal in the output unit, and an optical level of the wavelength group signal in the output unit And a post-combining level correction unit that corrects a level deviation of the combined wavelength group signal including the corrected subcarrier signal.

  An optical transmission device control method according to the present invention includes a multiplexing unit that combines a plurality of subcarrier signals for optical wavelength division multiplexing communication with a wavelength group signal, and outputs the combined wavelength group signal to an optical transmission line. An output unit that corrects a level deviation of the subcarrier signal before the multiplexing based on an optical level of the wavelength group signal in the output unit, and outputs the output Based on the optical level of the wavelength group signal in the unit, the level deviation of the combined wavelength group signal including the corrected subcarrier signal is corrected.

  ADVANTAGE OF THE INVENTION According to this invention, the optical transmission apparatus which can improve a transmission characteristic, and its control method can be provided.

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 wavelength band example of SCH which concerns on a basic example. It is a graph which shows the example of the level deviation of SCH concerning a basic example. It is a graph which shows the example of the level deviation of SCH concerning a basic example. It is a graph for demonstrating the correction result of the level deviation of SCH which concerns on a basic example. It is a graph for demonstrating the correction result of the level deviation of SCH which concerns on a basic example. It is a block diagram for demonstrating the outline | summary of the node which concerns on embodiment. 2 is a configuration diagram illustrating a schematic configuration of a node according to Embodiment 1. FIG. 6 is a diagram for explaining a level correction operation according to Embodiment 1. FIG. 6 is a diagram for explaining a level correction operation according to Embodiment 1. FIG. FIG. 3 is a configuration diagram illustrating a configuration example of an optical transmission system according to a second embodiment. 6 is a configuration diagram illustrating a configuration example of a node according to Embodiment 2. FIG. FIG. 10 is a configuration diagram illustrating another configuration example of a node according to the second embodiment. 10 is a flowchart showing an example of level correction operation according to the second embodiment. 10 is a flowchart showing an example of level correction operation according to the second embodiment. 10 is a flowchart showing an example of level correction operation according to the second embodiment. FIG. 10 is a state transition diagram illustrating a state transition example of a 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 apparatus) according to a basic example. As shown in FIG. 1, the 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 this specification, “multiplexing” means multiplexing of subcarriers within 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 (consisting of a plurality of subcarrier signals S1), and the signals S2 of the same wavelength group are ADD / DROPed by the same element (node, etc.). In the example of FIG. 2, one wavelength group signal S2 includes four subcarrier signals S1_1 to S1_4. However, 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 level deviations that occur in the SCH signal in the basic example. In SCH transmission, since 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, a level deviation occurs in the unit constituting each signal.

  As a 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 a difference in passing loss due to a difference in passing path of each wavelength group after multiplexing. That is, a plurality of wavelength group signals are input to a node's optical cross-connect XF from a plurality of paths including other nodes, and these wavelength group signals have different paths to be transmitted. Variation in light level (deviation) occurs.

  As the second level deviation, as shown in FIG. 4, a level deviation occurs between subcarriers in a wavelength group in SCH transmission. The level deviation between subcarriers occurs due to the difference in passing loss between subcarriers before multiplexing. That is, a plurality of subcarrier signals are input to the node multiplexer AG, and these subcarrier signals are routed through different transponders, fibers, etc., so that the optical level depends 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 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). Due to this wavelength dependency, the transmission characteristics of the subcarriers are affected, so that the optical levels of the subcarriers vary. 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, among these level deviations, when the deviation due to the difference in wavelength loss before the multiplexing is corrected by the level correction (LEQ) after the multiplexing, there is a possibility that the passing waveform may be deteriorated. 5 and 6 show the spectrum change before and after correction when the level deviation correction is simply performed on the wavelength group signal after being combined.

  FIG. 5 shows a spectrum in a state where 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 in the case of level correction after combining the signals of FIG. 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). As a result, waveform rounding occurs in the ATT setting of the variable optical attenuator between subcarriers (Slice). In the vicinity of this rounded wavelength, the waveform of the subcarrier signal S1_1 is raised, so that the signal characteristics (transmission characteristics) deteriorate.

(Outline of the 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 in 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 to realize good transmission characteristics.

  FIG. 7 shows an overview of a node (optical transmission apparatus) 10 according to the embodiment. As illustrated in FIG. 7, the node 10 according to the embodiment includes a multiplexing 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 for performing optical wavelength multiplexing communication into a wavelength group signal. The output unit 12 outputs the wavelength group signal combined by the combining unit 11 to the optical transmission line. The pre-combination 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-combining level correction unit 14 calculates the level deviation of the combined wavelength group signal including the subcarrier signal corrected by the pre-combining level correction unit 13 based on the optical level of the wavelength group signal in the output unit 12. to correct.

  As shown in FIG. 7, in the embodiment, the level deviation between subcarriers generated before multiplexing is corrected before multiplexing, and the level deviation between wavelength groups generated after multiplexing (subcarriers included in the wavelength group). (Including the level deviation between them) is corrected after multiplexing, it is possible to reliably suppress the occurrence of level deviation and improve transmission characteristics.

(Embodiment 1)
The first embodiment 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 the node according to the present 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, as in the above basic example. Furthermore, an optical channel monitor OCM, a pre-combination level correction unit 13 and a post-combination level correction unit 14 are provided. The pre-combination level correction unit 13 and the post-combination level correction unit 14 may be a single 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 that perform SCH transmission (optical wavelength division multiplexing) and output the generated 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 multiplexing unit that combines the subcarrier signals S1 from the transponders TPND_1 to TPND_3 to generate the 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 output destination of the wavelength group signal S2 output from the multiplexer AG (including wavelength group signals input from other nodes) by the wavelength selective switch WSS. Are switched to generate an SCH signal (including a 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 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 an optical monitor unit that is disposed in the optical amplifier CA as an example, and 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 signal 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 as the level correction before the multiplexing. . The post-combining 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-combining level correction.

  9 and 10 are outlines of the operation of the node according to the present embodiment, and show a level correction method before multiplexing and a 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 determined from the monitor value (PM value) of the optical channel monitor OCM arranged at the output section (optical amplifier CA) to the transmission line. Is returned to the transponder TPND or multiplexer AG of the corresponding wavelength group, and each subcarrier is adjusted to a desired level using the output adjustment function of the transponder TPND or multiplexer AG (output) Calibration function: does not have to be a dynamic LEQ).

  At this time, feedback control to the variable optical attenuator VOA in the optical cross connect XF (wavelength selective switch) is stopped (the initial value is set), 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) 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 determined from the monitor value (PM value) of the optical channel monitor OCM arranged at the output section (optical amplifier CA) to the transmission line. 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 by the level correction before 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.

  Thus, in the present embodiment, the optical level of the wavelength group signal (subcarrier signal) is monitored at the output unit of the node, and the level correction of the subcarrier signal before multiplexing (based on the monitoring result of the output unit) For example, level correction of the transponder or multiplexer, and level correction of the wavelength group signal (subcarrier signal) after multiplexing (for example, level correction of the optical cross-connect XF) are performed, so that the level between the wavelength groups Since the deviation correction and the level deviation correction between subcarriers in the wavelength group can be performed, the transmission characteristics can be improved.

(Embodiment 2)
The second embodiment 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 the optical transmission system according to the present embodiment. As illustrated in FIG. 11, the optical transmission system 1 according to the present embodiment includes a plurality of nodes (optical transmission apparatuses) 100 (100_1 to 100_3) and a network monitoring apparatus (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 an arbitrary number of nodes.

  The nodes 100_1 to 100_3 are respectively 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 another topology such as a ring network or a mesh network. For example, the node 100_1 is a transmitter serving as a transmission end of the optical path, the node 100_2 is a repeater that relays the optical path, and the node 100_3 is a receiver serving as the reception end of the optical path.

  Each node 100 has basically the same configuration, and performs 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. A 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 the wavelength group signal (subcarrier signal), a failure in the 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 operation 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, communication states, and the like of the nodes 100_1 to 100_3 via the management network. For example, the network monitoring apparatus 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 via each node 100. ing.

  FIG. 12 shows a configuration example of a 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 serving 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 configured by independent packages, and the optical transmission unit 101 (node) is configured by a plurality of packages. It is configured. Note that an arbitrary 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 connected to client devices (not shown), respectively, 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. . The transponders 111 to 114 each include 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 multiplexers 121 and 122 multiplex the subcarrier signals S1 output from the transponders 111 to 114. The multiplexers 121 and 122 include 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 optical fibers F1 and F2, respectively, and generates a wavelength group signal S2_1 by multiplexing the subcarrier signals S1_1 and S1_2 from the transponders 111 and 112. The wavelength group signal S2_1 is output. The multiplexer 122 is connected to the transponders 113 and 114 via optical fibers F3 and F4, respectively, and generates a wavelength group signal S2_2 by multiplexing the subcarrier signals S1_3 and S1_4 from the transponders 113 and 114. The wavelength group signal S2_2 is output.

  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 the route.

  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 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 selection 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. A signal S3 is generated. When the switching is set so that the wavelength group signals S2_1 and S2_2 and the SCH signal S4 are 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 repeater) through the optical transmission line OL, and the SCH signal S0 is input through 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 other nodes and outputs it to the optical cross connect 130.

  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 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 control unit 102. Note that the node control unit 102 (or a part thereof) may be incorporated in the light output unit 142 or another block (package).

  In the example of FIG. 12, based on the optical level of each subcarrier signal in the wavelength group of the SCH signal S0 in the optical output unit 142, the subcarrier signals before multiplexing (transponders 111 to 114, multiplexers 121 and 122). The level deviation 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 TPND1, multiplexers (multiplexers / demultiplexers) AG1 to AG3, 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 TPND1 to output to the optical cross connect XF1 or XF2, and demultiplexes 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 them 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 the wavelength group signal (SCH signal) from the multiplexers AG1 and AG2, the optical amplifier CA1, and the optical cross-connect XF2 (and other optical cross-connects XF) and outputs it to one of the paths. 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 it to any one of the paths.

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

  Of these wavelength group signals, signals output from the optical amplifiers CA1 and CA2 to the optical transmission line are the targets 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 the monitoring 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). Correct the level deviation.

  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 multiplexing (transponders TPND1 to TPND3, multiplexer AG1) is corrected, and the subcarrier signal (wavelength group) after multiplexing (optical cross-connect XF2) is corrected. Signal) level deviation is corrected. Since the wavelength group signal of wavelength f5 is not multiplexed in the node (optical transmission unit 101), the subcarrier signal (wavelength group signal) after multiplexing (optical cross-connects XF1 and XF2) is based on the monitoring result of wavelength f5. ) Level deviation is corrected.

  14A to 14C show a level correction method according to the present embodiment. Here, an example will be described with reference to the 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 via the optical fibers F1 and F2, and connects the transponders 113 and 114 and the multiplexer 122 via the optical fibers F3 and F4. To do.

  On the other hand, the network monitoring apparatus 200 performs wavelength grouping (S103). For example, the group specifying unit 201 of the network monitoring apparatus 200 groups subcarriers into wavelength groups according to instructions from the user, and sets the wavelength group and subcarrier configurations used for SCH transmission.

  Subsequently, the network monitoring apparatus 200 registers fiber connection information (or detects connection) (S104). For example, the connection information management unit 202 of the network monitoring apparatus 200 registers connection information indicating a connection relationship between the nodes 100 according to a user 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 apparatus 200 sets a path to the node 100 (S105). For example, the path setting unit 203 of the network monitoring apparatus 200 sets a path (for example, a route in FIG. 13) between the nodes 100 for performing SCH transmission according to a user instruction.

  Subsequently, the node 100 detects the type of the connected package from the registration information, fiber connection information, and path setting information (S106). For example, the initial setting unit 102a of the node control unit 102 uses fiber connection information (connection information may be detected by the node itself) and path setting information from the network monitoring apparatus 200, and registration information of each package of 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 performs switch setting 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 the wavelength) of the wavelength selective switch 131 from the registration information, the fiber connection information, and the path setting information.

  Subsequently, 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 package becomes a desired value based on the detection result in S106. Initial setting is performed (S108). For example, the initial setting unit 102a of the node control unit 102 initializes the variable optical attenuator VOA (subcarrier unit) inside the package so that the optical output level in 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, and the optical cross-connect 130. The attenuation amount of the variable optical attenuator VOA3 is initially set.

  Next, a level correction process (first correction process) before multiplexing is executed in the 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 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 converts the difference into the corresponding transponders 111 to 114 ( And the multiplexer 121). Based on the notified difference, the transponders 111 to 114 (or the level correction unit 102b) change the variable optical attenuator VOA1 (and the multiplexer 121) in the transponders 111 to 114 so that the optical level of each subcarrier becomes the output target value. The attenuation amount of the variable optical attenuator VOA2) is set.

  Subsequently, the node 100 determines whether or not the optical levels of all 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 or not the optical level of the subcarrier 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 after S109 (level correction processing before multiplexing) is terminated, 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 target values and the subcarrier signals S1_3 and S1_4 in the wavelength group signal S2_2 become 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 the target value.

  Next, level correction processing (second correction processing) after multiplexing is executed in the loop L2 (second loop) of S113 to S116. 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 level correction unit 102b) is connected to the corresponding wavelength group in the optical cross-connect 130 (wavelength selective switch 131) so that the optical level of each subcarrier becomes the output target value based on the notified difference. The attenuation amount of the subcarrier variable optical attenuator VOA3 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. (In the example of FIG. 13, level correction is performed until the subcarrier signal in each wavelength group of wavelengths f3, f4, and f1 reaches the target value).

  Subsequently, the node 100 determines whether or not a light level break of an arbitrary subcarrier is detected (S116). For example, the level correction unit 102b of the node control unit 102 determines whether the optical level of the subcarrier is interrupted (the optical level is lower than a predetermined value) based on the monitoring result of the optical channel monitor OCM. When the loop L2 after S113 (level correction processing after multiplexing) is repeated and the light level break is detected, the loop L2 is terminated, the process returns to S108, and the level correction before multiplexing is resumed. At this time, the alarm unit 102c notifies the network monitoring device 200 of the light level interruption 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 variable optical attenuator output is OFF. When 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 to S108), and when the initial setting is completed in state ST2, the state transitions to state ST3. In the state ST3, a loop L1 process (level correction process 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.

  When the time-out occurs without reaching the output target value in the state ST3, the state transitions to the state ST5. In the state ST5, a target value non-reaching warning is issued. When the issue of the target value non-reaching alarm is completed in state ST5, the state transitions to state ST4. That is, after the initial setting, when a certain period of time elapses before the level correction process before multiplexing is completed (the subcarrier reaches the target level), an alarm is output from the alarm unit 102c and the level correction process after multiplexing is performed. To start.

  Further, in the state ST4, when a light level break is detected (due to a failure or the like), the process returns to the state ST2. That is, when a failure occurs in the subcarrier when 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 resumed. Further, when the path is deleted in the state ST4, the process returns to the state ST1. That is, when the level correction process after multiplexing is completed (or being processed) and the path is deleted by an instruction from the network monitoring apparatus 200, the level correction process before multiplexing is resumed.

  As described above, in the present embodiment, as in the first embodiment, the optical level of the wavelength group signal (subcarrier signal) is monitored at the output unit 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 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. 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.

  Note that the present invention is not limited to the above-described embodiment, and can be changed 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 and / or software, and may be configured by one piece of hardware or software, or a plurality of pieces of hardware or software. You may comprise. 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 in 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 supplied to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / W and semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)) are included. The program may also 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 temporary 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.

DESCRIPTION OF SYMBOLS 1 Optical transmission system 2 WDM network 3 Management network 10 Node 11 Multiplexing part 12 Output part 13 Level correction part before multiplexing 14 Level correction part after multiplexing 100 Node 101 Optical transmission part 102 Node control part 102a Initial setting part 102b Level correction Unit 102c alarm unit 111-114 transponder 121-233 multiplexer 130 optical cross-connect 131 wavelength selection 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-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-VOA Variable optical attenuator WSS WSS XF optical cross-connect

Claims (24)

A first optical signal transmitter for outputting a first subcarrier optical signal;
A second optical signal transmitter for outputting a second subcarrier optical signal;
A first optical power adjustment unit for adjusting the power of the first subcarrier optical signal;
A second optical power adjustment unit for adjusting the power of the second subcarrier optical signal;
A multiplexing unit that combines the first subcarrier optical signal and the second subcarrier optical signal to output a first wavelength group optical signal;
A third optical power adjustment unit for adjusting the power of the first wavelength group optical signal,
The first optical power adjustment unit and the second optical power adjustment unit adjust a power difference between the first subcarrier optical signal and the second subcarrier optical signal,
The third optical power adjustment unit adjusts a power difference between the first wavelength group optical signal and a second wavelength group optical signal transmitted through an optical transmission line;
Optical transmission device. The first optical power adjustment unit and the second optical power adjustment unit are configured to determine whether the first subcarrier optical signal and the second subcarrier optical signal are based on a setting value of a subcarrier optical power level. Adjust the power difference,
The optical transmission device according to claim 1. The third 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 set value of a wavelength group optical power level.
The optical transmission device according to claim 1. A subcarrier optical power monitor for monitoring the power of the first subcarrier optical signal and the power of the second subcarrier optical signal;
The first optical power adjustment unit and the second optical power adjustment unit are configured to output the first subcarrier optical signal and the second subcarrier optical signal based on a monitoring result of the subcarrier optical power monitoring unit. To adjust the power difference with
The optical transmission device according to claim 1. A second multiplexing unit that multiplexes the first wavelength group optical signal and the second wavelength group optical signal and outputs a wavelength multiplexed optical signal;
A wavelength group optical power monitor that monitors the power of the first wavelength group optical signal and the power of the second wavelength group optical signal;
The third 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 monitoring result of the wavelength group optical power monitoring unit;
The optical transmission apparatus as described in any one of Claims 1-4. An optical switch for switching an output destination of the first wavelength group optical signal;
The optical transmission device according to claim 1. A failure monitoring unit for detecting a failure of either the first subcarrier optical signal or the second subcarrier optical signal;
The optical transmission device according to claim 1.   The said 3rd optical power adjustment part adjusts so that the power difference of the said 1st wavelength group optical signal and the said 2nd wavelength group optical signal may be made small. Optical transmission equipment. An optical transmission device;
A control device for controlling the optical transmission device,
The optical transmission device is:
A first optical signal transmitter for outputting a first subcarrier optical signal;
A second optical signal transmitter for outputting a second subcarrier optical signal;
A first optical power adjustment unit for adjusting the power of the first subcarrier optical signal;
A second optical power adjustment unit for adjusting the power of the second subcarrier optical signal;
A multiplexing unit that combines the first subcarrier optical signal and the second subcarrier optical signal to output a first wavelength group optical signal;
A third optical power adjustment unit that adjusts the power of the first wavelength group optical signal,
The first optical power adjustment unit and the second optical power adjustment unit adjust a power difference between the first subcarrier optical signal and the second subcarrier optical signal,
The third optical power adjustment unit adjusts a power difference between the first wavelength group optical signal and a second wavelength group optical signal transmitted through an optical transmission line;
Optical transmission system. The first optical power adjustment unit and the second optical power adjustment unit are configured to determine whether the first subcarrier optical signal and the second subcarrier optical signal are based on a setting value of a subcarrier optical power level. Adjust the power difference,
The optical transmission system according to claim 9 . The third 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 set value of a wavelength group optical power level.
The optical transmission system according to claim 9 or 10 . The optical transmission device further includes a subcarrier optical power monitor that monitors the power of the first subcarrier optical signal and the power of the second subcarrier optical signal,
The first optical power adjustment unit and the second optical power adjustment unit are configured to output the first subcarrier optical signal and the second subcarrier optical signal based on a monitoring result of the subcarrier optical power monitoring unit. To adjust the power difference with
The optical transmission system according to any one of claims 9-1 1. The optical transmission device is:
A second multiplexing unit that multiplexes the first wavelength group optical signal and the second wavelength group optical signal and outputs a wavelength multiplexed optical signal;
A wavelength group optical power monitor for monitoring the power of the first wavelength group optical signal and the power of the second wavelength group optical signal;
The third 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 monitoring result of the wavelength group optical power monitoring unit;
The optical transmission system according to any one of claims 9 to 12 . The optical transmission device further includes an optical switch that switches an output destination of the first wavelength group optical signal.
The optical transmission system according to any one of claims 9-1 3. The optical transmission device further includes a failure monitoring unit that detects a failure of either the first subcarrier optical signal or the second subcarrier optical signal and notifies the control device of the failure.
The optical transmission system according to any one of claims 9-1 4.   The third optical power adjustment unit adjusts so as to reduce a power difference between the first wavelength group optical signal and the second wavelength group optical signal. Optical transmission system. Outputting a first subcarrier optical signal;
Outputting a second subcarrier optical signal;
Adjusting a power difference between the first subcarrier optical signal and the second subcarrier optical signal;
Combining the first subcarrier optical signal and the second subcarrier optical signal to output a first wavelength group optical signal;
Adjusting the power difference between the first wavelength group optical signal and the second wavelength group optical signal transmitted through the optical transmission line;
Optical communication method. Adjusting a power difference between the first subcarrier optical signal and the second subcarrier optical signal based on a set value of a subcarrier optical power level;
The optical communication method according to claim 17 . Adjusting a power difference between the first wavelength group optical signal and the second wavelength group optical signal based on a set value of the wavelength group optical power level;
The optical communication method according to claim 17 or 18 . Monitoring the power of the first subcarrier optical signal and the power of the second subcarrier optical signal;
Based on the monitoring result of the power of the first subcarrier optical signal and the power of the second subcarrier optical signal, the power difference between the first subcarrier optical signal and the second subcarrier optical signal is calculated. adjust,
Optical communication method according to claim 1 7-1 9. Combining the first wavelength group optical signal and the second wavelength group optical signal to output a wavelength multiplexed optical signal;
Monitoring the power of the first wavelength group optical signal and the power of the second wavelength group optical signal;
Based on the monitoring result of the power of the first wavelength group optical signal and the power of the second wavelength group optical signal, the power difference between the first wavelength group optical signal and the second wavelength group optical signal is calculated. adjust,
Optical communication method according to any one of claims 1 7-20. Switching the output destination of the first wavelength group optical signal;
Optical communication method according to any one of claims 1 7-21. Detecting any failure of the first subcarrier optical signal and the second subcarrier optical signal;
Optical communication method according to any one of claims 1 7-22.   The optical communication method according to any one of claims 17 to 23, wherein adjustment is performed to reduce a power difference between the first wavelength group optical signal and the second wavelength group optical signal.

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