MANAGEMENT APPARATUS, OPTICAL NODE APPARATUS, OPTICAL NETWORK SYSTEM, CONTROL METHOD, AND NON-TRANSITORY COMPUTER-READABLE MEDIUM

A management apparatus (10) includes: a path management unit (11) configured to manage a wavelength resource that can be used in a path of a photonics network including a node that performs wavelength conversion through optical-analog-optical conversion and a usage state of the wavelength resource; a wavelength conversion management unit (12) configured to manage path wavelength conversion information that includes wavelength conversion at the node constituting the path; and a control unit (13) configured to control wavelength conversion at the node, based on the managed wavelength resource and usage state, and to control analog compensation at the node, based on the managed path wavelength conversion information.

TECHNICAL FIELD

The present invention relates to a management apparatus, an optical node apparatus, an optical network system, a control method, and a non-transitory computer-readable medium.

BACKGROUND ART

In recent years, traffic being flowed in a network continues to grow rapidly, due to a rapid spread of a mobile terminal represented by a smartphone and large-capacity data communication such as a high-definition image caused by advancement of the terminal. According to a certain survey, total download traffic of broadband subscribers in a domestic fiscal year of 2020 is about 19 Tbps and continues to increase at an annual rate of about 57%, and traffic is expected to further increase in the future. In response to this, in a core network supporting large-capacity communication, a technique for meeting a demand for an increase in capacity, such as a wavelength division multiplexing (WDM) technique, which transmits a plurality of optical signals having different wavelengths from one another by multiplexing such optical signals into a single optical fiber, or a high-level modulation scheme such as dual polarization differential quadrature phase shift keying (DP-QPSK) and 16-quadrature amplitude modulation (16-QAM) has been developed. Furthermore, along with development of a 5G service in wireless communication, there is an increasing demand not only for an increase in the capacity but also for a reduction in delay of the network. In response to such needs, in recent years, an innovative optical and wireless network (IOWN) initiative being led by NTT has proposed an all-photonics network that achieves a network with greater capacity and less delay. Unlike a network including electrical conversion at an associated switching node, the all-photonics network performs transmission by an optical means in all paths. For this reason, it is possible not only to perform large-capacity communication without limitation caused by a capacity of an electric switch, but also to reduce delay, due to being free from delay accompanying electrical conversion.

However, since same wavelengths cannot be used in an optical fiber, there is a problem that a path of the same wavelength coming from a different route to a switching node cannot be accommodated in the same fiber and thereby efficient path control cannot be performed. For such a problem, a method for switching wavelengths by using a wavelength converter and accommodating the wavelengths in the same fiber is adopted in the switching node.

Further, Patent Literatures 1 and 2, for example, are known as techniques related to signal quality in an optical network. Patent Literature 1 discloses a polarization dependent loss (PDL) compensation technique, and Patent Literature 2 discloses a dispersion compensation technique.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2015-186230Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2010-206539

SUMMARY OF INVENTION

Technical Problem

However, conventional related techniques do not consider wavelength conversion to be applied in an all-photonics network, and hence it is difficult to effectively suppress deterioration in signal quality in a path.

In consideration of the above-described problems, an object of the present disclosure is to provide a management apparatus, an optical node apparatus, an optical network system, a control method, and a non-transitory computer-readable medium that are capable of effectively suppressing deterioration in signal quality.

Solution to Problem

A management apparatus according to the present disclosure includes: a path management means for managing a wavelength resource that can be used in a path of an all-photonics network provided with an optical node apparatus configured to perform wavelength conversion through optical-analog-optical conversion and a usage state of the wavelength resource; a wavelength conversion management means for managing path wavelength conversion information including wavelength conversion at the optical node apparatus constituting the path; and a control means for controlling wavelength conversion at the optical node apparatus, based on the managed wavelength resource and usage state, and controlling analog compensation at the optical node apparatus, based on the managed path wavelength conversion information.

An optical node apparatus according to the present disclosure is an optical node apparatus that constitutes an all-photonics network, and includes: an optical reception means for receiving an optical signal; a wavelength conversion means for performing wavelength conversion on the received optical signal through optical-analog-optical conversion; an optical transmission means for transmitting the wavelength-converted optical signal; and a node control means for controlling the wavelength conversion means in such a way as to perform wavelength conversion and analog compensation in response to a notification from a management apparatus managing the all-photonics network.

An optical network system according to the present disclosure includes: an all-photonics network provided with an optical node apparatus configured to perform wavelength conversion through optical-analog-optical conversion; and a management apparatus configured to manage the all-photonics network, wherein the management apparatus includes a path management means for managing a wavelength resource that can be used in a path of the all-photonics network and a usage state of the wavelength resource, a wavelength conversion management means for managing path wavelength conversion information including wavelength conversion at the optical node apparatus constituting the path, and a control means for controlling wavelength conversion at the optical node apparatus, based on the managed wavelength resource and usage state, and controlling analog compensation at the optical node apparatus, based on the managed path wavelength conversion information.

A control method according to the present disclosure includes: managing a wavelength resource that can be used in a path of an all-photonics network provided with an optical node apparatus configured to perform wavelength conversion through optical-analog-optical conversion and a usage state of the wavelength resource; managing path wavelength conversion information including wavelength conversion at the optical node apparatus constituting the path; and controlling wavelength conversion at the optical node apparatus, based on the managed wavelength resource and usage state, and controlling analog compensation at the optical node apparatus, based on the managed path wavelength conversion information.

A non-transitory computer-readable medium storing a control program according to the present disclosure is a non-transitory computer-readable medium storing a control program for causing a computer to execute processing of: managing a wavelength resource that can be used in a path of an all-photonics network provided with an optical node apparatus configured to perform wavelength conversion through optical-analog-optical conversion and a usage state of the wavelength resource; managing path wavelength conversion information including wavelength conversion at the optical node apparatus constituting the path; and controlling wavelength conversion at the optical node apparatus, based on the managed wavelength resource and usage state, and controlling analog compensation at the optical node apparatus, based on the managed path wavelength conversion information.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide a management apparatus, an optical node apparatus, an optical network system, a control method, and a non-transitory computer-readable medium that are capable of effectively suppressing deterioration in signal quality.

EXAMPLE EMBODIMENT

Hereinafter, example embodiments are described with reference to the drawings. In the drawings, the same element is denoted by the same reference sign, and redundant descriptions are omitted as necessary.

Examination Leading to Example Embodiments

As described above, at a node in an all-photonics network, wavelength conversion is performed as necessary by a wavelength converter. As a wavelength conversion method, all-optical wavelength conversion utilizing nonlinearity of light, wavelength conversion utilizing transponder function, and the like are proposed or being used. In the all-optical wavelength conversion, there is an advantage that the delay is small since wavelength conversion is performed thoroughly in the form of light, but there are problems that, for example, an optical loss of a wavelength conversion device is large and the transmittable distance is limited.

A functional block of a wavelength converter utilizing a transponder function is illustrated inFIG.1. As illustrated inFIG.1, a wavelength converter900according to an examination example includes a receiver901, a transmitter902, and a digital signal processing unit903. The receiver901receives an optical signal of a first wavelength (λ1), the digital signal processing unit903turns around the optical signal, and the transmitter902transmits an optical signal of a second wavelength (λ2). Thus, the wavelength of the optical signal is converted from λ1to λ2. In the wavelength converter900, since complete waveform molding is performed by so-called 3R (re-amplification (amplification), re-shaping (waveform shaping), and re-timing (bit-spacing adjustment)) regeneration via the digital signal processing unit903, there is no limitation on the transmission range, but there is a problem that a delay occurs in the digital signal processing unit903.

Therefore, a configuration in which an analog electric signal between a transmitter and a receiver is turned around without passing through a digital signal processing unit is examined (hereinafter, wavelength conversion by such a configuration is referred to as an O-A-O (optical-analog-optical) wavelength conversion). The functional block of the present configuration is illustrated inFIG.2. As illustrated inFIG.2, another wavelength converter910according to the examination example includes a receiver901and a transmitter902, similarly to the wavelength converter900, but does not require the digital signal processing unit903. That is, in the another wavelength converter910, an analog electric signal output from the receiver901is directly turned around to the transmitter902without passing through the digital signal processing unit903.

In the present configuration, since digital signal processing is not performed, a different function of compensating for signal deterioration accumulated in a transmission line of a past route needs to be added. For example, there are methods such as, as illustrated inFIG.3, correcting a band by providing an analog signal processing unit913between a coherent reception front-end911and a coherent transmission front-end912.

In the example ofFIG.3, the another wavelength converter910includes the coherent reception front-end911, the coherent transmission front-end912, and the analog signal processing unit913. The coherent reception front-end911is an optical-to-electrical converter, and coherently detects an input optical signal (λ1) to be input, based on a reference light source (local oscillator (LO) light), and outputs an analog electric signal SA1generated by the detection. The coherent transmission front-end912is an electrical-to-optical converter, and coherently modulates an analog electric signal SA2generated by turning around the analog electric signal SA1, based on a transmission light source, and outputs an output optical signal (λ2) generated by the modulation. For example, the wavelength of the output optical signal may be converted from λ1to λ2according to the wavelength of the transmission light source. The analog signal processing unit913is an analog circuit that performs analog signal processing on the analog electric signal SA1in such a way as to compensate for signal quality and generates the analog electric signal SA2. The analog signal processing is analog compensation processing, and compensates for, for example, passband narrowing and the like.

Further, as illustrated inFIG.3, in order to control the analog compensation processing, the another wavelength converter910may include a pre-signal monitoring unit914, a post-signal monitoring unit915, and an analog signal processing control unit916. The pre-signal monitoring unit914monitors the signal characteristics of the analog electric signal SA1before the analog signal processing. The post-signal monitoring unit915monitors the signal characteristics of the analog electric signal SA2after the analog signal processing. The analog signal processing control unit916controls the operation of the analog signal processing of the analog signal processing unit913, based on the monitoring result of the pre-signal monitoring unit914or the post-signal monitoring unit915. For example, the passband of the analog electric signal SA1or the analog electric signal SA2is monitored, and a passband adjustment amount in the analog signal processing unit913is controlled, based on the monitoring result.

FIG.4illustrates a configuration of an all-photonics network using an O-A-O conversion and a node according to the examination example. InFIG.4, the network configuration is illustrated as a configuration having a single, straight transmission line for simplicity. That is, as illustrated inFIG.4, an all-photonics network800according to the examination example includes a plurality of nodes810, and the nodes810are connected to each other via an optical transmission line.

Each of the nodes810includes optical amplifiers811and812for compensating for a transmission loss, a route changeover switch813, and an O-A-O wavelength converter pool814having a plurality of O-A-O wavelength converters mounted therein. The route changeover switch813is connected between the optical amplifier811and the optical amplifier812, and the route changeover switch813switches the route of the path to the O-A-O wavelength converter pool814as necessary. After the path requiring wavelength conversion is connected to the O-A-O wavelength converter pool814, the wavelength is converted from λ1to λ2, for example, and sent to the optical transmission line.

However, in an existing network, although the network range (for example, within 10 hops) is designed in advance in such a way that arrival is guaranteed regardless of the assignment of any wavelength to any path, when O-A-O wavelength conversion is installed in the network, signal quality varies depending on the location (where to be installed between the transmission node and the reception node) of the wavelength conversion, and thus it is difficult to guarantee the arrival. For example, as illustrated inFIG.5, in a case where O-A-O wavelength conversion is performed at a node810A, the effect of analog compensation is small since the node810A is close to the transmission end820and signal deterioration has not proceeded much, and further, since the remaining transmission line is long, there is a possibility that the reception sensitivity may fall below the minimum reception sensitivity midway. In a case where wavelength conversion is performed at a node810E being close to a reception end830, although arrival to the node810E is guaranteed, there is a possibility that the reception sensitivity may fall below the minimum reception sensitivity since signal-to-noise ratio (S/N) deterioration proceeds when analog compensation is performed on a deteriorated signal having low S/N.

In addition, in the network, devices having wavelength characteristics such as an optical amplifier are present, characterized by, for example, poor noise figure (NF) characteristics at short wavelengths. Therefore, the characteristics may change depending on the wavelength before wavelength conversion and the wavelength after wavelength conversion at the time of wavelength conversion. For example, in a case of converting from a short wavelength to a short wavelength, the characteristics may be deteriorated as compared with a case of converting from a long wavelength to a long wavelength.

As described above, as related techniques, a large number of analog compensation techniques have been disclosed, such as an analog PDL compensation technique disclosed in Patent Literature 1 and an analog dispersion compensation technique in Patent Literature 2. However, conventional analog compensation techniques are not designed on the assumption that an O-A-O wavelength conversion is to be arranged, and it is necessary to separately consider the network control considering the location of the wavelength conversion as described above. Therefore, the example embodiments are made in view of the above-described problem.

Specifically, two main problems are considered. The first problem is that it is difficult to guarantee the arrival in a path in an all-photonics network using O-A-O wavelength conversion. The reason is that signal quality varies depending on the location (where to be installed between a transmission node and a reception node) of the wavelength conversion. The second problem is that, in an all-photonics network using O-A-O wavelength conversion, the path arrival guarantee cannot be made uniform. The reason is that there are devices having wavelength characteristics such as an optical amplifier, and the quality of the path depends on the wavelengths before and after the wavelength conversion. Therefore, in the example embodiments, a control method in an optical network that uses analog wavelength conversion is provided, and in particular, a method for ensuring the arrival guarantee in a path is provided.

Summary of Example Embodiments

FIG.6illustrates an outline configuration of a management apparatus according to the example embodiments, andFIG.7illustrates an outline configuration of a node according to the example embodiments.

A node20is an optical node apparatus that performs wavelength conversion through O-A-O conversion (optical-analog-optical conversion), and constitutes an all-photonics network. A management apparatus10manages and controls the all-photonics network including the node20. For example, the management apparatus10is a network management system (NMS) that manages a network.

As illustrated inFIG.6, the management apparatus10includes a path management unit11, a wavelength conversion management unit12, and a control unit13. The path management unit11manages a wavelength resource that may be used in a path of the all-photonics network and a usage state of the wavelength resource. The path management unit11is, for example, a path database that manages and holds wavelength resources (information) and usage states (information).

The wavelength conversion management unit12manages the path wavelength conversion information including wavelength conversion at the node20constituting the path. The wavelength conversion management unit12is, for example, a wavelength conversion management database that manages and holds the path wavelength conversion information.

The control unit13controls the wavelength conversion at the node20, based on the wavelength resource and usage state managed by the path management unit11, and also controls analog compensation at the node20, based on the path wavelength conversion information managed by the wavelength conversion management unit12. For example, the control unit13may notify the node20of the path wavelength conversion information, and thereby control the node20to perform analog compensation on all the paths that are wavelength-converted in a route before the node20.

In addition, wavelength conversion characteristics information including a transmission distance before the wavelength conversion, a transmission distance after the wavelength conversion, an estimated signal deterioration degree, and analog compensation node identification information may be further managed. In such a case, the control unit13may determine a candidate for a path for performing analog compensation, based on the wavelength conversion characteristics information, and control the node20to perform analog compensation on the determined path. Further, the control unit13may divide the entire wavelength band into a plurality of sections, and control in such a way that wavelength conversion is performed in such a way as to average the noise figure (NF) characteristics.

As illustrated inFIG.7, the node20includes an optical reception unit21, a wavelength conversion unit22, an optical transmission unit23, and a node control unit24. The optical reception unit21receives an optical signal from an optical transmission line. The wavelength conversion unit22performs wavelength conversion by O-A-O wavelength conversion, on the optical signal received by the optical reception unit21. The optical transmission unit23transmits the optical signal wavelength-converted by the wavelength conversion unit22to the optical transmission line.

In response to the notification from the management apparatus10, the node control unit24performs control in such a way that the wavelength conversion unit22performs wavelength conversion and analog compensation. For example, the node control unit24may monitor all the paths wavelength-converted in the route before the node20in accordance with the path wavelength conversion information notified from the management apparatus10, and may perform control in such a way as to perform analog compensation, based on a monitoring result. Further, the node control unit24may perform control in such a way that analog compensation is performed on a relevant path, based on information about a path to be subjected to analog compensation notified from the management apparatus10.

With such a configuration, it is possible to effectively suppress deterioration in the signal quality of a path in an all-photonics network using O-A-O wavelength conversion. That is, as a first effect, it is possible to guarantee arrival of the path, due to a node in a path subjected to wavelength conversion appropriately performing analog compensation. Further, as a second effect, it is possible to uniformize the arrival guarantee of the path by performing wavelength conversion in such a way that the NF characteristics are averaged.

First Example Embodiment

Next, a first example embodiment is described. In the present example embodiment, an example is described in which, in a node, all paths that are wavelength-converted in a route before the node are monitored and analog compensation is performed.

First, the configuration of the present example embodiment is described with reference toFIGS.8and9.FIG.8illustrates a configuration example of an optical network system according to the present example embodiment. As illustrated inFIG.8, an optical network system1according to the present example embodiment includes an NMS100and a plurality of nodes200. The plurality of nodes200are connected to each other via an optical transmission line300in such a way as to be capable of optical communication. The plurality of nodes200and the NMS100are also connected to each other via, for example, the optical transmission line300, but may be communicably connected to each other via any other transmission line.

The plurality of nodes200are optical communication apparatuses that perform O-A-O wavelength conversion. That is, the plurality of nodes200constitute an all-photonics network2using O-A-O wavelength conversion. In the example ofFIG.8, the plurality of nodes200constitute a mesh-shaped network, but may constitute another form of network such as a ring shape. Further, the plurality of nodes200constitute a path from a transmission node (transmission end) to a reception node (reception end) in accordance with control from the NMS100, and transmit data (optical signal) on the route of the path.

The NMS100is a management apparatus that manages and controls the all-photonics network2including the plurality of nodes200. The NMS100manages and controls a path configured by the node200in the all-photonics network2. The NMS100manages the route and wavelength of the path from the transmission node to the reception node, and sets the route and wavelength for the node200on the path.

FIG.9illustrates a configuration example of each apparatus in the optical network system according to the present example embodiment. As illustrated inFIG.9, the NMS100includes a path database (DB)101, a wavelength conversion management database (DB)102, and a network control unit103.

The path database101manages the path of the plurality of nodes200of the all-photonics network2, and manages and holds a wavelength resource (wavelength resource information) that may be used in the paths and usage state (usage state information) of the wavelength resource. The path database101holds the wavelength resource and usage state in each node200constituting the path. The wavelength resource (wavelength resource information) indicates all wavelengths that may be used in the path, and the usage state (usage state information) indicates the wavelength being used in the path.

The wavelength conversion management database102manages and holds wavelength conversion by the nodes200constituting the path. The wavelength conversion management database102holds the wavelength conversion information regarding each node200constituting the path. The wavelength conversion information is information capable of identifying the wavelength conversion at each node200on the route of the path, and may indicate, for example, the presence or absence of the wavelength conversion in each node200, the wavelength before and after the conversion in each node, and the like.

The network control unit103refers to the path database101and the wavelength conversion management database102, and controls the path and the nodes200constituting the path. The network control unit103performs wavelength conversion of a path requiring wavelength conversion, based on the wavelength resource and usage state in the path database101. That is, the network control unit103instructs each node200on the path to perform the wavelength conversion of the path as necessary, and holds wavelength conversion information indicating a result of the wavelength conversion in the wavelength conversion management database102. In addition, the network control unit103notifies all the nodes200of the wavelength conversion information about all the paths in the wavelength conversion management database102.

Further, the node200includes a transmission loss compensation optical amplifier201(201aand201b), an optical switch (SW)202, a node loss compensation optical amplifier203(203aand203b), a wavelength selective switch (WSS)204(204aand204b), a tap coupler205, an optical path monitor206, an analog wavelength converter pool210, and a node controller207.

The transmission loss compensation optical amplifier201is an optical amplifier that compensates for transmission loss occurring in an optical fiber by amplifying an optical signal. The transmission loss compensation optical amplifier201ais a reception amplifier that receives an optical signal. The transmission loss compensation optical amplifier201areceives an optical signal in fiber units from an adjacent node on the transmission node side via an input optical fiber300a, and compensates for the transmission loss of the input optical fiber300ain fiber units. The transmission loss compensation optical amplifier201aoutputs the optical signal after the transmission loss compensation to the optical switch202.

The transmission loss compensation optical amplifier201bis a transmission amplifier that transmits an optical signal. The transmission loss compensation optical amplifier201bcompensates for the transmission loss of the optical signal from the optical switch202in fiber units. The transmission loss compensation optical amplifier201boutputs the optical signal in fiber units after the transmission loss compensation to an adjacent node on the reception node side via an output optical fiber300b.

The optical switch202is an optical switch capable of switching a route of an optical signal in wavelength units. The optical switch202is connected between the transmission loss compensation optical amplifier201aon the reception side and the transmission loss compensation optical amplifier201bon the transmission side. The optical switch202switches add/drop of a predetermined optical signal (path) in accordance with control from the node controller207. The optical switch202performs switching in wavelength units on the optical signal in fiber units from the transmission loss compensation optical amplifier201a, and outputs the optical signal of a wavelength to be dropped to the node loss compensation optical amplifier203avia a wavelength conversion port. Further, the optical switch202receives, through the analog wavelength converter pool210, an optical signal from the node loss compensation optical amplifier203bvia the wavelength conversion port, performs switching in wavelength units on the received optical signal in fiber units, and outputs the optical signal of a wavelength to be added to the transmission loss compensation optical amplifier201b.

The node loss compensation optical amplifier203is an optical amplifier that compensates for a loss occurring at a node by amplifying an optical signal. The node loss compensation optical amplifier203aon the reception side (drop side) compensates for the loss of the optical signal in fiber units from the wavelength conversion port of the optical switch202, and outputs the optical signal after the loss compensation to the wavelength switch204a. The node loss compensation optical amplifier203bon the transmission side (add side) compensates for the loss of the optical signal in fiber units from the wavelength switch204bthrough the analog wavelength converter pool210, and outputs the optical signal after the loss compensation to the wavelength conversion port of the optical switch202.

The wavelength switch204is an optical switch capable of switching a route of an optical signal in wavelength units. The reception-side wavelength switch204aseparates in wavelength units the optical signal in fiber units from the node loss compensation optical amplifier203a, and outputs the separated optical signal to an O-A-O wavelength converter211in the analog wavelength converter pool210. The transmission-side wavelength switch204bbundles in fiber units the optical signals in wavelength units from the O-A-O wavelength converter211in the analog wavelength converter pool210, and outputs the optical signals in fiber units to the node loss compensation optical amplifier203b.

The tap coupler205taps some or all of the optical signals in wavelength units output from the wavelength switch204aon the reception side. The optical path monitor206monitors the quality of the optical signal tapped by the tap coupler205. In response to control from the node controller207, the tap coupler205taps a predetermined optical signal, and the optical path monitor206monitors the tapped optical signal.

The analog wavelength converter pool210includes a plurality of O-A-O wavelength converters211. The plurality of O-A-O wavelength converters211are provided in association with the wavelength of input optical signals and the wavelength of output optical signals. The O-A-O wavelength converter211is a wavelength converter capable of performing O-A-O wavelength conversion and performing analog compensation. The O-A-O wavelength converter211includes, for example, a coherent reception front-end, a coherent transmission front-end, and an analog signal processing unit (analog compensator) as illustrated inFIG.3, but may have other configurations as long as O-A-O wavelength conversion is possible. The O-A-O wavelength converter211performs analog compensation or wavelength conversion and analog compensation, on the optical signal in wavelength units from the wavelength switch204aaccording to control from the node controller207, and outputs the optical signal subjected to wavelength conversion or analog compensation to the wavelength switch204b.

For example, as an analog compensator in the O-A-O wavelength converter211, a compensator that performs band compensation, PDL compensation, dispersion compensation, and the like is installed. The optical path monitor206differs depending on the configuration of the analog compensator, and is, for example, a spectrum analyzer in a case where band compensation is performed, a PDL monitor in a case where PDL compensation is performed, and a dispersion monitor in a case where dispersion compensation is performed.

The node controller207controls each device in the node200. The node controller207controls the operation of each device under the control of the NMS100. Upon receiving a wavelength conversion instruction from the NMS100, the node controller207controls the optical switch202to switch the relevant wavelength, and controls the O-A-O wavelength converter211to convert the wavelength. Upon receiving the wavelength conversion information about all the paths from the NMS100, the node controller207determines a path (wavelength) to be monitored, and controls analog compensation of the corresponding O-A-O wavelength converter211, based on a result of monitoring performed by the tap coupler205and the optical path monitor206.

Next, an operation of the present example embodiment is described with reference toFIG.10while referring toFIGS.8and9.FIG.10is a flowchart illustrating an operation example of the optical network system according to the present example embodiment.

As illustrated inFIG.10, first, the NMS100performs wavelength conversion of the path (S101). When a path request is issued, the NMS100refers to the path database101, determines a path for which wavelength conversion is required, based on the wavelength resource and the usage state, and notifies the node200that performs wavelength conversion of the determined path information. For example, information identifying a path, a wavelength before conversion, a wavelength after conversion, and the like are notified. The node controller207of each node200controls the optical switch202and the O-A-O wavelength converter211to convert the wavelength of the relevant path, based on the information received from the NMS100. When each node200performs wavelength conversion, the NMS100holds, in the wavelength conversion management database102, path wavelength conversion information indicating that each node200has performed wavelength conversion in the path.

Next, the NMS100notifies the wavelength conversion information of all the paths (S102). When the wavelength conversion and update of the wavelength conversion management database102are completed, the NMS100refers to the wavelength conversion management database102and notifies the node controllers207of all the nodes200of the wavelength conversion information about all the wavelength-converted paths.

Then, each node200performs drop setting of the path (S103). Upon receiving the wavelength conversion information about all the paths from the NMS100at each node200, the node controller207determines a path (wavelength) to drop, based on the wavelength conversion information about all the paths. A path to be dropped is a path being a target of monitoring (analog compensation candidate). Specifically, a path in which another node200has performed the wavelength conversion in the route prior to the own node (before the own node) is extracted from the path wavelength conversion information, and the optical switch202is set so as to drop all the extracted paths (wavelengths).

Then, each node200connects the wavelength switch204ato the O-A-O wavelength converter211(S104). At each node200, the node controller207sets the wavelength switch204ain such a way that the paths (wavelengths) which are set to drop, that is, all the paths wavelength-converted in the route before the own node, are connected to the post-demultiplexing O-A-O wavelength converter211.

Then, each node200monitors the path (S105). At each node200, the optical path monitor206connected to the tap coupler205monitors qualities of the paths (wavelengths) which are set to drop, that is, all the paths wavelength-converted in the route before the own node.

Then, each node200performs analog compensation, based on a path monitoring result (S106). At each node200, the node controller207determines whether the monitored path quality exceeds a predetermined deterioration threshold. When there is a path exceeding the deterioration threshold, analog compensation (or wavelength conversion and analog compensation) is performed in the O-A-O wavelength converter211to which the path exceeding the deterioration threshold is connected. That is, the O-A-O wavelength converter211performs analog compensation for a path the quality of which is deteriorated more than a predetermined threshold, and the O-A-O wavelength converter211does not perform analog compensation for a path the quality of which is not deteriorated more than a predetermined threshold. Note that the analog compensation amount may be adjusted according to the deterioration amount of the quality of the path.

Then, each node200performs add setting of the path (S107), and completes the operation (setting) (S108). At each node200, when the analog compensation is performed in response to the monitoring result, the node controller207sets the optical switch202and the wavelength switch204bin such a way that the dropped path (wavelength), that is, the path where the analog compensation is performed in response to the monitoring result, is added to the original fiber. Note that the same operation is also performed in a node200in the subsequent stage.

As described above, in the present example embodiment, in the all-photonics network using O-A-O wavelength conversion, the NMS refers to the path database that manages the wavelength resource and the usage state in the NMS, notifies the node of the path information that requires the wavelength conversion, performs wavelength conversion, and holds data in the wavelength conversion management database. The NMS refers to the wavelength conversion management database and notifies the node controllers of all the nodes of the wave crest conversion information about all the wavelength-converted paths. At each node, all the paths that have been wavelength-converted in the route before the own node are dropped, and the signal quality is monitored. Each node performs analog compensation (or wavelength conversion and analog compensation) in the O-A-O wavelength converter for a path that exceeds a predetermined deterioration threshold, based on the monitor information. Thus, it is possible to ensure the arrival of the path by monitoring the signal quality of the wavelength-converted path and performing analog compensation according to the deterioration state.

Second Example Embodiment

Next, a second example embodiment is described. In the present example embodiment, an example in which an NMS determines a path for performing analog compensation is described.

First, a configuration of the present example embodiment is described with reference toFIG.11.FIG.11illustrates a configuration example of each apparatus in an optical network system according to the present example embodiment. Herein, only differences from the configuration in the first example embodiment is described, and description of the same configuration will be omitted.

In the present example embodiment, the signal quality of the path is not monitored at each node200. Therefore, in the node200, the tap coupler205and the optical path monitor206in the first example embodiment are omitted.

Further, an NMS100includes a wavelength conversion characteristics database104(DB) in addition to the configuration of the first example embodiment. The wavelength conversion characteristics database104holds wavelength conversion characteristics information indicating wavelength conversion characteristics of a path. The wavelength conversion characteristics information includes a transmission distance (A) before wavelength conversion, a transmission distance (B) after wavelength conversion, an estimated signal deterioration degree (C), and an analog compensation (band re-compensation) node number (D). The wavelength conversion characteristics information preferably includes all of the transmission distance (A) before wavelength conversion, the transmission distance (B) after wavelength conversion, the estimated signal deterioration degree (C), and the analog compensation node number (D), but may include at least any of such information. For example, the estimated signal deterioration degree (C) and the analog compensation node number (D) may be included.

The transmission distance (A) before wavelength conversion is a transmission distance (for example, the number of hops) from a transmission end to a node where the wavelength conversion is performed in the path. The transmission distance (B) after wavelength conversion is a transmission distance from a node that performs the wavelength conversion to a reception end in the path. The estimated signal deterioration degree (C) is a deterioration degree of an optical signal estimated in the path. The deterioration degree is a deterioration degree of an optical signal received at the reception end relative to an optical signal transmitted from the transmission end. For example, the deterioration degree may be estimated from the transmission distance (A) before wavelength conversion and the transmission distance (B) after wavelength conversion. The analog compensation node number (D) is a number (identification information) of a node that performs analog compensation in the path. The wavelength conversion characteristics information stored in the wavelength conversion characteristics database104may be set, based on the wavelength conversion information about the path stored in a wavelength conversion management database102. Further, the wavelength conversion characteristics information is map information acquired by mapping each piece of information. Specifically, a route of a path is illustrated on a network map indicating a connection relationship between each node in the network, and the transmission distance (A) before wavelength conversion, the transmission distance (B) after wavelength conversion, the estimated signal deterioration degree (C), and the analog compensation node number (D) are illustrated for each path.

Next, an operation of the present example embodiment is described with reference toFIG.12while referring toFIGS.6and11.FIG.12is a flowchart illustrating an operation example of the optical network system according to the present example embodiment.

As illustrated inFIG.12, first, the NMS100performs wavelength conversion of the path (S201). Similarly to the first example embodiment, when a path request is issued, the NMS100refers to the path database101that manages a wavelength resource and a usage state, notifies the node200of the information about a path that requires wavelength conversion, performs wavelength conversion, and holds the path wavelength conversion information about the path in the wavelength conversion management database102.

Next, the NMS100generates the wavelength conversion characteristics database104(S202). By generating the wavelength conversion characteristics database104, the NMS100selects a path that is assumed to be deteriorated in advance. Specifically, map information (wavelength conversion characteristics information) acquired by mapping the transmission distance (A) before wavelength conversion, the transmission distance (B) after wavelength conversion, the estimated signal deterioration degree (C), and the analog compensation node number (D) is generated, and the map information is held in the wavelength conversion characteristics database104. For example, for each path, the transmission distance (A) before wavelength conversion and the transmission distance (B) after wavelength conversion are acquired from the wavelength conversion information (route and wavelength conversion node) of the path, and the estimated signal deterioration degree (C) is acquired from the transmission distance (A) before wavelength conversion and the transmission distance (B) after wavelength conversion. A node for performing analog compensation is selected from nodes capable of analog compensation on the path, and the analog compensation node number (D) is determined. The NMS100refers to the wavelength conversion characteristics database104and determines a candidate path for performing analog compensation according to the map information. For example, the path to be subjected to analog compensation is determined, based on the estimated signal deterioration degree (C) of the path.

As a specific example, in a case where the number of hops to guarantee reachability is 10, and path 1 (A=1, B=9, C=5, D=8) and path 2 (A=7, B=3, C=6, D=9) are used, when a path having C=5 or more is to be subjected to analog compensation, path 1 and path 2 are determined to be subjected to analog compensation.

Then, the NMS100notifies of information about the path to be subjected to analog compensation (S203). The NMS100notifies the node200that performs analog compensation of wavelength conversion information (the wavelength conversion management database102) about the path determined to be subjected to analog compensation and the wavelength conversion characteristics information (the wavelength conversion characteristics database104) of the path. In the above-described specific example, since the analog compensation node number (D) of path 1 is 8, the information about path 1 is notified to a node200having a node number 8, and since the analog compensation node number (D) of path 2 is 9, the information about path 2 is notified to a node200having a node number 9.

Then, the notified node200performs drop setting of the path (S204). In the node200, upon receiving the information about the path to be subjected to analog compensation from the NMS100, a node controller207sets an optical switch202in such a way as to drop the notified path (wavelength) to be subjected to analog compensation.

Then, the node200connects a wavelength switch204ato the O-A-O wavelength converter211(S205). At the node200, the node controller207sets the wavelength switch204ain such a way that the path to be subjected to analog compensation, which is set to drop, is connected to a post-demultiplexing O-A-O wavelength converter211.

Then, the node200performs analog compensation on a relevant path (S206). At the node200, analog compensation (or wavelength conversion and analog compensation) is performed, by the O-A-O wavelength converter211, on the relevant path connected to the O-A-O wavelength converter211.

Then, the node200performs add setting of the path (S207), and completes the operation (setting) (S208). In the node200, when analog compensation is performed on the path to be subjected to analog compensation, the node controller207sets the optical switch202and a wavelength switch204bin such a way that the dropped path (wavelength) is added to the original fiber. Note that the present operation is performed only by the node200that has received the notification from the NMS100.

As described above, in the present example embodiment, as a different method for performing analog compensation in an all-photonics network using O-A-O wavelength conversion, a wavelength conversion characteristics database in which a transmission distance before wavelength conversion, a transmission distance after wavelength conversion, an estimated signal deterioration degree, and an analog compensation node number are mapped is generated and held, candidates for a path for performing analog compensation are determined according to the map, and analog compensation is performed only for a relevant path. By calculating the signal quality of the wavelength-converted path in advance and performing analog compensation according to the deterioration state as described above, it is possible to guarantee the arrival of the path.

Third Example Embodiment

Next, a third example embodiment is described. Since the configuration in the present example embodiment may be either of the configuration of the first example embodiment or the configuration of the second example embodiment, description of the configuration will be omitted.

Next, an operation of the present example embodiment is described with reference toFIGS.13and14while referring toFIGS.8and9.FIG.13is a flowchart illustrating an operation of an optical network system according to the present example embodiment.

As illustrated inFIG.13, first, an NMS100performs wavelength conversion of a path in consideration of wavelength characteristics (S301). When a path request is issued, the NMS100refers to a path database101that manages a wavelength resource and a usage state, notifies a node200of information about a path that requires wavelength conversion, performs wavelength conversion, and holds the wavelength conversion information about the path in a wavelength conversion management database102.

At this time, the NMS100performs wavelength conversion in consideration of the wavelength characteristics of apparatuses within the network. For example, the wavelength characteristic is an NF characteristic or the like of an optical amplifier mounted on the node200. The NF characteristic of an optical amplifier is characterized in that the short wavelength side is inferior to the long wavelength side.FIG.14is a conceptual diagram illustrating an NF characteristic and an algorithm for wavelength allocation. For example, the entire wavelength band is divided into 10, and wavelength conversion is performed, based on a wavelength band, in such a way that the NF characteristics are averaged. In one example, at the node200, the NF characteristics may be averaged by controlling wavelength band 1 to be converted to wavelength band 10, wavelength band 4 to be converted to wavelength band 5, and the like. That is, the wavelength is converted between wavelength bands in which an amount of decrease (amount of deterioration) from an average value and an amount of increase (amount of improvement) from the average value are the same value (i.e., the absolute value is equal). Since operations of S102and subsequent steps are the same as the operations in the first example embodiment, the description thereof is omitted.

As described above, in the present example embodiment, the wavelength conversion may be performed in consideration of the wavelength characteristics of the devices in the network. For example, the entire wavelength band may be divided into a plurality of sections and the wavelength conversion may be performed in such a way that NF characteristics are averaged. As described above, by performing wavelength conversion in consideration of characteristics such as an NF, it is possible to uniformize the quality of the path and reduce the paths requiring analog compensation.

The present disclosure is not limited to the above-described example embodiments, and may be appropriately modified without departing from the scope of the present disclosure.

Each configuration in the above-described example embodiments is configured by hardware or software, or both, and may be configured by one piece of hardware or software, or may be configured by a plurality of pieces of hardware or software. Each device and each function (processing) may be achieved by a computer30including a processor31such as a central processing unit (CPU) and a memory32being a storage device, as illustrated inFIG.15. For example, a program for performing the method (management method or control method) according to the example embodiments may be stored in the memory32, and each function may be implemented by executing the program stored in the memory32by the processor31.

Such programs include instructions (or software codes) that, when loaded into a computer, cause the computer to perform one or more of the functions described in the example embodiments. The programs may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example, and not limitation, the computer-readable media or the tangible storage media include a random-access memory (RAM), a read-only memory (ROM), a flash memory, a solid-state drive (SSD) or other memory techniques, a CD-ROM, a digital versatile disc (DVD), a Blu-ray (registered trademark) disk or other optical disk storages, a magnetic cassette, a magnetic tape, a magnetic disk storage or other magnetic storage devices. The program may be transmitted on a transitory computer readable medium or a communication medium. By way of example, and not limitation, the transitory computer-readable media or the communication media include electrical, optical, acoustic, or other forms of propagated signals.

Although the present disclosure has been described with reference to the example embodiments, the present disclosure is not limited to the above-described example embodiments. Various changes that can be understood by a person skilled in the art within the scope of the present disclosure can be made to the configuration and details of the present disclosure.

Some or all of the above-described example embodiments may be described as the following supplementary notes, but are not limited thereto.

A management apparatus including:a path management means for managing a wavelength resource that can be used in a path of an all-photonics network provided with an optical node apparatus configured to perform wavelength conversion through optical-analog-optical conversion and a usage state of the wavelength resource;a wavelength conversion management means for managing path wavelength conversion information including wavelength conversion at the optical node apparatus constituting the path; anda control means for controlling wavelength conversion at the optical node apparatus, based on the managed wavelength resource and usage state, and controlling analog compensation at the optical node apparatus, based on the managed path wavelength conversion information.

The management apparatus according to supplementary note 1, wherein the control means notifies the optical node apparatus of the path wavelength conversion information, and thereby controls the optical node apparatus in the path in such a way as to perform analog compensation on all paths that are wavelength-converted in a route before the optical node apparatus.

The management apparatus according to supplementary note 1, further including a wavelength conversion characteristics management means for managing wavelength conversion characteristics information indicating wavelength conversion characteristics of the path,wherein the control means determines a candidate for a path for performing analog compensation, based on the wavelength conversion characteristics information, and controls the optical node apparatus in such a way as to perform analog compensation on the determined path.

The management apparatus according to supplementary note 3, wherein the wavelength conversion characteristics information includes a transmission distance before wavelength conversion in the path, a transmission distance after wavelength conversion in the path, an estimated signal deterioration degree of the path, and identification information about a node that performs analog compensation on the path.

The management apparatus according to any one of supplementary notes 1 to 4, wherein the control means divides an entire wavelength band into a plurality of sections, and controls the wavelength conversion in such a way that a noise figure (NF) characteristic is averaged.

An optical node apparatus constituting an all-photonics network, including:an optical reception means for receiving an optical signal;a wavelength conversion means for performing wavelength conversion on the received optical signal through optical-analog-optical conversion;an optical transmission means for transmitting the wavelength-converted optical signal; anda node control means for controlling the wavelength conversion means in such a way as to perform wavelength conversion and analog compensation in response to a notification from a management apparatus managing the all-photonics network.

The optical node apparatus according to supplementary note 6, further including a monitoring means for monitoring an optical signal being input to the wavelength conversion means,wherein the node control means performs control in such a way that the monitoring means monitors all paths that include the optical node apparatus and that are wavelength-converted in a route before the optical node apparatus, based on the path wavelength conversion information being notified from the management apparatus, and analog compensation is performed based on a result of the monitoring.

The optical node apparatus according to supplementary note 7, wherein the node control means performs control in such a way that analog compensation is performed on a path, among the monitored paths, quality of which has deteriorated to below a predetermined threshold.

The optical node apparatus according to supplementary note 6, wherein the node control means performs control in such a way that analog compensation is performed on a relevant path, based on information about a path to be subjected to analog compensation notified from the management apparatus.

An optical network system including:an all-photonics network provided with an optical node apparatus configured to perform wavelength conversion through optical-analog-optical conversion; anda management apparatus configured to manage the all-photonics network, whereinthe management apparatus includesa path management means for managing a wavelength resource that can be used in a path of the all-photonics network and a usage state of the wavelength resource,a wavelength conversion management means for managing path wavelength conversion information including wavelength conversion at the optical node apparatus constituting the path, anda control means for controlling wavelength conversion at the optical node apparatus, based on the managed wavelength resource and usage state, and controlling analog compensation at the optical node apparatus, based on the managed path wavelength conversion information.

A control method including:managing a wavelength resource that can be used in a path of an all-photonics network provided with an optical node apparatus configured to perform wavelength conversion through optical-analog-optical conversion and a usage state of the wavelength resource;managing path wavelength conversion information including a wavelength conversion at the optical node apparatus constituting the path; andcontrolling wavelength conversion at the optical node apparatus, based on the managed wavelength resource and usage state, and controlling analog compensation at the optical node apparatus, based on the managed path wavelength conversion information.

A non-transitory computer-readable medium storing a control program for causing a computer to execute processing of:managing a wavelength resource that can be used in a path of an all-photonics network provided with an optical node apparatus configured to perform wavelength conversion through optical-analog-optical conversion and a usage state of the wavelength resource;managing path wavelength conversion information including wavelength conversion at the optical node apparatus constituting the path; andcontrolling wavelength conversion at the optical node apparatus, based on the managed wavelength resource and usage state, and controlling analog compensation at the optical node apparatus, based on the managed path wavelength conversion information.

A path control scheme for an all-photonics network using analog wavelength conversion for performing wavelength conversion by directly connecting an analog signal output of an optical receiver to an analog signal input of an optical transmitter, whereinan NMS includes a path database configured to manage wavelength resources and usage states, anda wavelength management database configured to manage wavelength conversion information,the path control scheme including performing wavelength conversion, based on the path database, and performing analog compensation with reference to the wavelength conversion management database.

The path control scheme according to supplementary note 13, further including, in a node on a communication path, monitoring all paths that are wavelength-converted in a route before the node, with reference to information in the wavelength conversion management base, and performing analog compensation, based on monitor information.

The path control scheme according to supplementary note 13, wherein the NMS includes a wavelength conversion characteristics database holding a transmission distance before wavelength conversion, a transmission distance after wavelength conversion, an estimated signal deterioration degree, and an analog compensation node number, the path control scheme further including determining a candidate for a path for performing analog compensation, by referring to the wavelength conversion characteristics database, and performing analog compensation only on the determined path.

The path control scheme according to supplementary note 13 or 14, including dividing the entire wavelength band into a plurality of sections, and performing the wavelength conversion in such a way that NF characteristics are averaged.

A network management system including the path control scheme according to supplementary note 13.

An optical network apparatus including the path control scheme according to supplementary note 13.

An optical network control program including the path control scheme according to supplementary note 13.

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