Communication device and zero dispersion wavelength calculation method

Abstract

Provided is a communication device comprising: a reception unit that receives information pertaining to a communication device that performs communication; and a calculation unit that calculates, on the basis of transmission path information pertaining to a zero dispersion wavelength for each path connecting a plurality of devices and the information pertaining to the communication device received by the reception unit, a zero dispersion wavelength of a communication path formed by a combination of a plurality of paths connected via one or more distribution devices that switch connection paths between communication devices that perform communication.　

Description

Communication device and zero-dispersion wavelength calculation method

[0001] The present invention relates to a communication device and a zero-dispersion wavelength calculation method.

[0002] In an optical communication system that transmits optical signals using optical fiber, if the wavelength deviates from the zero-dispersion wavelength of the optical fiber, the effect of dispersion becomes greater, resulting in an increase in the penalty amount, making long-distance transmission difficult. Therefore, in order to achieve long-distance transmission, it is necessary to set the wavelength used between communication devices of communicating users so that it approaches the zero-dispersion wavelength.

[0003] However, since the zero-dispersion wavelength of an optical fiber fluctuates between 1300 and 1324 nm, if the value of the zero-dispersion wavelength for each optical fiber used is not known, it is not possible to set the wavelength.

[0004] Therefore, a technique for estimating the value of the zero-dispersion wavelength has been proposed in the past (see, for example, Non-Patent Document 1): First, a communication device that performs communication estimates the notch frequency f at which the first notch appears at a frequency other than a multiple (single, double, etc.) of the frequency of the transmission signal, based on data on the frequency spectrum of the received optical signal. ０ Next, the communication device calculates the dispersion D using the oscillation wavelength λ, the speed of light c, the chirp parameter α, and the distance L between the communication devices, and estimates the value of the zero-dispersion wavelength by measuring the amount of deviation from the position of the zero-dispersion wavelength in the optical fiber by dividing the dispersion D by the value of the dispersion slope. Here, the oscillation wavelength is calculated based on the operating state of the transmitter, such as the temperature, and the distance L between the communication devices can be calculated based on a timestamp from a low-speed signal or the like.

[0005] As described above, conventionally, every time a connection is made between user communication devices, the value of the zero-dispersion wavelength between the users is estimated, and the oscillation wavelength of each communication device is adjusted to the estimated value of the zero-dispersion wavelength, thereby suppressing waveform degradation due to chromatic dispersion and realizing long-distance transmission.

[0006] Yasunari Tanaka et al., “Penalty-free 100-km Transmission of 53-Gbps / λ IM-DD Signal Enabled by a Novel Zero-dispersion Wavelength Estimation and Optimization Method”, 2023 Opto-Electronics and Communications Conference (OECC).

[0007] In an optical communication system, as shown in Fig. 18, it is conceivable to accommodate a plurality of communication devices by providing a distribution device having a function of switching paths between communication devices, such as an optical switch. Fig. 18 is a diagram showing an example of the configuration of a conventional optical communication system S. In the optical communication system S, a control device 1 has a function of switching paths of a distribution device 2 connecting a communication device 3 and a communication device 4, and a function of estimating a zero-dispersion wavelength.

[0008] In the conventional configuration, the value of the zero-dispersion wavelength was estimated successively when the connection between the communication devices was switched. For example, if communication device 3-1 and communication device 3-2, and communication device 3-2 and communication device 3-3 were previously connected, and communication device 3-1 and communication device 3-3 were newly connected, the value of the zero-dispersion wavelength was estimated again. As such, in the conventional technology, it was necessary to estimate the zero-dispersion wavelength using the above-mentioned zero-dispersion wavelength estimation method every time the communication devices 3 and 4 were connected, which caused a problem of taking time to set the oscillation wavelength.

[0009] In view of the above circumstances, an object of the present invention is to provide a technique that can shorten the time required to set an oscillation wavelength.

[0010] One aspect of the present invention is a communication device comprising: a receiving unit that receives information regarding a communication device that communicates; transmission path information regarding the zero-dispersion wavelength for each path connecting multiple devices; and a calculation unit that calculates the zero-dispersion wavelength of a communication path formed by a combination of multiple paths connected via one or more distribution devices that switch connection paths between the communication devices that communicate, based on the information regarding the communication devices received by the receiving unit.

[0011] One aspect of the present invention is a zero-dispersion wavelength calculation method that receives information about communication devices that communicate, and calculates the zero-dispersion wavelength of a communication path formed by a combination of multiple paths that are connected via one or more distribution devices that switch connection paths between communication devices that communicate, based on transmission path information about the zero-dispersion wavelength for each path connecting multiple devices and the received information about the communication devices.

[0012] According to the present invention, it is possible to shorten the time required to set the oscillation wavelength.

[0013] 1 is a diagram illustrating an example of the configuration of an optical communication system according to a first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a control device according to the first embodiment. FIG. 3 is a diagram illustrating an example of a transmission path list according to the first embodiment. FIG. 4 is a diagram illustrating another example of the transmission path list according to the first embodiment. FIG. 5 is a diagram illustrating an example of the configuration of a communication device according to the first embodiment. FIG. 6 is a sequence diagram illustrating the flow of processing performed by the optical communication system according to the first embodiment. FIG. 7 is a flowchart illustrating the flow of zero-dispersion wavelength providing processing performed by the control device according to the first embodiment. FIG. 8 is a diagram illustrating an example of the configuration of a control device according to a first modified example of the first embodiment. FIG. 9 is a diagram illustrating an example of the configuration of a control device according to a second modified example of the first embodiment. FIG. 10 is a diagram illustrating an example of the configuration of a communication device according to the second embodiment. FIG. 11 is a sequence diagram illustrating the flow of processing performed by the optical communication system according to the second embodiment. FIG. 12 is a flowchart illustrating the flow of zero-dispersion wavelength providing processing performed by the communication device according to the second embodiment. FIG. 13 is a diagram illustrating an example of the configuration of an optical communication system according to a third embodiment. FIG. 14 is a diagram illustrating another example of the transmission path list according to the third embodiment. FIG. 15 is a diagram illustrating another example of the transmission path list according to the third embodiment. FIG. 16 is a diagram illustrating an example of the configuration of a conventional optical communication system S.

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] First Embodiment Fig. 1 is a diagram illustrating an example of the configuration of an optical communication system 100 according to a first embodiment. The optical communication system 100 includes a control device 10, a distribution device 20, a plurality of communication devices 30, and a plurality of communication devices 40. Each of the communication devices 30, 40 performs optical communication via the distribution device 20. Fig. 1 illustrates an example in which there are three communication devices 30 and three communication devices 40, but the number of communication devices 30 and three communication devices 40 is not particularly limited. In the following description, the direction from the communication device 30 to the communication device 40 is referred to as upstream, and the direction from the communication device 40 to the communication device 30 is referred to as downstream.

[0016] Optical transmission paths connect the control device 10 and the distribution device 20, the distribution device 20 and each communication device 30, and the distribution device 20 and each communication device 40. The optical transmission paths are configured with optical fibers. Note that the optical transmission paths may be provided with one or more optical amplifiers that amplify optical signals.

[0017] The control device 10 is a device that controls the entire optical communication system 100. As in the past, the control device 10 has a function of switching the paths of the distribution device 20 and a function of estimating the zero-dispersion wavelength. Furthermore, the control device 10 holds a transmission path list in which information about the optical fiber of each path is listed, and calculates the zero-dispersion wavelength between the communication devices 30 and 40 that communicate using the held transmission path list. The control device 10 is one aspect of a communication device.

[0018] The information about the optical fiber of each route is information about the optical transmission path connecting each communication device 30, 40 and the distribution device 20, and includes values ​​such as distance, dispersion slope, and estimated zero-dispersion wavelength. Each time a new connection is made between the communication devices 30, 40, the control device 10 refers to the transmission path list and calculates the zero-dispersion wavelength of the new path formed by a combination of the routes it owns. The control device 10 notifies each newly connected communication device 30, 40 of information indicating the calculated zero-dispersion wavelength. As a result, each newly connected communication device 30, 40 can communicate by setting the value of the zero-dispersion wavelength indicated by the notified information indicating the zero-dispersion wavelength.

[0019] If information about a specific route is not registered in the transmission route list, the control device 10 estimates the zero-dispersion wavelength of the corresponding route and registers it in the transmission route list. In this way, the control device 10 registers information about the optical fiber of each route, thereby reducing the number of times that the zero-dispersion wavelength is estimated as in the conventional method.

[0020] The distribution device 20 has a function of switching the connection between the communication devices 30, 40 in accordance with control from the control device 10. The distribution device 20 has a plurality of first ports and a plurality of second ports. A plurality of communication devices 30 are connected to the plurality of first ports of the distribution device 20 via optical transmission paths, and a plurality of communication devices 40 are connected to the plurality of second ports of the distribution device 20 via optical transmission paths. An optical signal input to a certain port of the distribution device 20 is output from another port. For example, an optical signal input to a certain first port of the distribution device 20 is output from one of the plurality of second ports. The distribution device 20 is configured, for example, with an optical switch, a wavelength selective switch, or the like.

[0021] The communication device 30 is a device that communicates with another communication device 30 or a communication device 40. The communication device 30 transmits a connection request to the control device 10 at the time of initial connection. The time of initial connection may be the timing when the communication device 30 connects to the distribution device 20 for the first time, the timing when the communication device 30 reconnects to the distribution device 20 after once disconnecting from the distribution device 20, or the timing when communication is to be performed with another communication device 30, 40. The connection request includes at least information indicating the communication partner. The communication device 30 sets the value of the zero-dispersion wavelength in the transmitter based on the information indicating the value of the zero-dispersion wavelength transmitted from the control device 10. This allows communication with the communication partner to be started.

[0022] The communication device 40 is a device that communicates with another communication device 30 or communication device 40. The communication device 40 transmits a connection request to the control device 10 at the time of initial connection. The communication device 40 sets the value of the zero-dispersion wavelength in the transmitting unit based on information indicating the value of the zero-dispersion wavelength transmitted from the control device 10. This allows communication with the communication partner to begin.

[0023] 2 is a diagram showing an example of the configuration of the control device 10 in the first embodiment. The control device 10 includes a receiving unit 11, a control unit 12, and a transmitting unit 13. Here, the receiving unit 11 and the transmitting unit 13 use different optical transmission paths (two-core optical transmission paths).

[0024] The receiver 11 receives optical signals transmitted from the communication devices 30 and 40 via the distribution device 20. The receiver 11 receives optical signals including, for example, a connection request.

[0025] The control unit 12 controls the entire control device 10. The control unit 12 includes a route determination unit 121, a switching control unit 122, a list storage unit 123, a combination calculation unit 124, an estimation unit 125, and an information provision unit 126.

[0026] The route determination unit 121 determines a destination route in response to a connection request transmitted from the communication devices 30 and 40. For example, when the source of the connection request is the communication device 30-1 and the communication partner is the communication device 40-1, the route determination unit 121 determines, as the destination routes, an optical transmission path connecting the communication device 30-1 and the distribution device 20 and an optical transmission path connecting the communication device 40-1 and the distribution device 20.

[0027] The switching control unit 122 controls the connection between the ports of the distribution device 20 based on information indicating the destination route determined by the route determination unit 121. For example, as described above, when the route determination unit 121 determines the optical transmission path connecting the communication device 30-1 and the distribution device 20 and the optical transmission path connecting the communication device 40-1 and the distribution device 20 as the destination routes, the switching control unit 122 controls the connection between the ports of the distribution device 20 so as to connect the optical transmission path connecting the communication device 30-1 and the distribution device 20 with the optical transmission path connecting the communication device 40-1 and the distribution device 20.

[0028] A transmission path list is stored in the list storage unit 123. The list storage unit 123 is configured using a storage device such as a magnetic storage device or a semiconductor storage device.

[0029] The combination calculation unit 124 calculates the zero-dispersion wavelength of a new route (hereinafter referred to as the "destination route") formed by combining routes based on the information indicating the destination route determined by the route determination unit 121 and the transmission path list.

[0030] Here, if information regarding the optical fiber of some of the routes included in the information indicating the destination route is not registered in the transmission path list, the combination calculation unit 124 causes the estimation unit 125 to estimate the value of the zero-dispersion wavelength of at least the route that is not registered in the transmission path list.

[0031] In addition, if information regarding the optical fibers of some of the routes included in the information indicating the destination routes is not registered in the transmission path list, the combination calculation unit 124 may cause the estimation unit 125 to estimate the values ​​of the zero-dispersion wavelengths of all of the routes indicated in the information indicating the destination routes.

[0032] The estimation unit 125 estimates the value of the zero-dispersion wavelength of the corresponding route in response to an instruction from the combination calculation unit 124. Note that the estimation unit 125 may estimate the value of the zero-dispersion wavelength of the corresponding route using an existing method. Furthermore, the estimation unit 125 also acquires information on the route distance to be used when estimating the value of the zero-dispersion wavelength. The information on the route distance may be registered in advance, or may be calculated based on a timestamp from a low-speed signal or the like. Furthermore, the dispersion slope value may be the dispersion slope value of the optical fiber being used, or may be a dispersion slope value specified in standardization. The estimation unit 125 registers information on the optical fiber of the newly estimated route in the transmission route list.

[0033] The information providing unit 126 transmits information indicating the value of the zero-dispersion wavelength in the destination path obtained by the combination calculation unit 124 or the estimation unit 125 via the transmitting unit 13 to the communication device 30, 40 that is the sender of the connection request and the communication device 30, 40 that is the communication partner.

[0034] The transmitter 13 transmits an optical signal including information indicating the value of the zero-dispersion wavelength output from the information provider 126 to each of the communication devices 30, 40. For example, the transmitter 13 transmits an optical signal including information indicating the value of the zero-dispersion wavelength to the communication device 30, 40 that is the sender of the connection request and the communication device 30, 40 that is the communication partner.

[0035] 3 is a diagram showing an example of a transmission path list in the first embodiment. The transmission path list shown in FIG. 3 has a plurality of records showing information about optical fibers of each route. The records shown in FIG. 3 include ID, distance L, S ０ and λ ０ The ID represents identification information for identifying the device (e.g., the communication device 30, 40) to which the optical fiber is connected. The distance L represents the length of the optical fiber. For example, the distance L represents the length of the optical fiber connecting the communication device 30, 40 and the distribution device 20. S ０ represents the dispersion slope of the optical fiber. ０ represents an estimate of the zero dispersion wavelength of the optical fiber.

[0036] In the example shown in FIG. 3, the transmission path list includes the length of the optical fiber connecting the communication device 30-1 identified by the ID "communication device 30-1" and the distribution device 20 as "L Ａ ", and the dispersion slope of the optical fiber connecting the communication device 30-1 and the distribution device 20 is "S ０Ａ ", and the value of the zero dispersion wavelength of the optical fiber connecting the communication device 30-1 and the distribution device 20 is "λ ０Ａ " has been shown to be

[0037] In FIG. 3, one distance L, one distance S is assigned to each ID. ０ and λ ０ However, when the control device 10 and the communication devices 30, 40 use different optical transmission paths (two-core optical transmission paths) for the transmitter and receiver, the zero-dispersion wavelength differs for each of the upstream and downstream paths (for example, the upstream and downstream paths between the communication devices 30, 40 and the distribution device 20). Therefore, when a two-core optical transmission path is used, the transmission path list shown in FIG. 3 stores, for each ID, the distances L and S for the upstream and downstream paths, respectively. ０ and λ ０The information indicating the value of

[0038] The combination calculation unit 124 refers to the list storage unit 123 when switching to a new route, and can estimate the value of the zero-dispersion wavelength without performing the conventional zero-dispersion wavelength estimation process each time. For example, when the distance L ｉ The dispersion slope value at (i = A, B, ...) is S ０ｉ and the estimated zero-dispersion wavelength is λ ０ｉ In this case, the combination calculation unit 124 calculates the λ of the distance L(j, . . . ). ０ (j, . . . ) is calculated based on the following formula (1): The distance L(j, . . . ) represents the length of the optical fiber from one communication device 30, 40 to the communication device 30, 40 with which it is communicating. ０ (j, . . . ) represents an estimated value of the zero-dispersion wavelength of the optical fiber from a certain communication device 30, 40 to the communication partner communication device 30, 40. Therefore, j=Σi.

[0039]

[0040] For example, when connecting the communication device 30-1 and the communication device 30-2, the combination calculation unit 124 calculates the distance L using the information of the IDs "communication device 30-1" and "communication device 30-2" registered in the transmission path list. （Ａ,Ｂ） λ ０（Ａ,Ｂ） is calculated based on the following formula (2).

[0041]

[0042] Here, the case where two optical fibers are combined is shown as an example, but the same applies to a combination of multiple optical fibers.

[0043] As another example of the transmission line list, as shown in FIG. 4, the transmission line list includes ID and dispersion slope S ０ and the value of the product of the distance L, and λ ０ 4 is a diagram showing another example of the transmission path list in the first embodiment. The transmission path list shown in FIG. 4 has a plurality of records showing information about the optical fiber of each route. The record shown in FIG. 4 includes the ID, the distance L×S ０ and λ ０The ID represents identification information for identifying the communication device 30, 40 to which the optical fiber is connected. Distance L×S ０ represents the product of the length (distance) of the optical fiber and the dispersion slope of the optical fiber. The product of the dispersion slope value and the distance can be calculated simultaneously with the value of the zero dispersion wavelength by using two wavelengths. Distance L × S ０ may be registered in advance as a data set in the transmission path list, or may be calculated as described above.

[0044] In FIG. 4, one dispersion slope S is assigned to each ID. ０ and the value of the product of the distance L and λ ０ However, when the control device 10 and the communication devices 30, 40 use different optical transmission paths (two-core optical transmission paths) for the transmitter and receiver, the zero-dispersion wavelength differs for each of the upstream and downstream paths (for example, the upstream and downstream paths between the communication devices 30, 40 and the distribution device 20). Therefore, when a two-core optical transmission path is used, the transmission path list shown in FIG. 4 stores, for each ID, the dispersion slopes S for the upstream and downstream paths, ０ and the value of the product of the distance L and λ ０ The information indicating the value of

[0045] The above-mentioned dispersion slope S ０ and the product S of the distance L ０ The value of L can be calculated, for example, based on the following formula (3): ｉ , f ｎｉ , α ｉ i is λ ０ The wavelength λ used in estimating ｉ For example, the wavelength λ ａ When using f ｎａ , α ａ This becomes:

[0046]

[0047] The above-mentioned formula (3) uses one wavelength to calculate the dispersion slope S ０ and the product S of the distance L ０ The formula for calculating L is the dispersion slope S using two wavelengths. ０and the product S of the distance L ０ The dispersion slope S can be calculated using two wavelengths. ０ and the product S of the distance L ０ When calculating L, for example, λ calculated by the following formula (4) is used. ０ can be calculated by substituting into the above equation (3). ａ , λ ｂ represents the two wavelengths used, and f ｍ,ｂ is the wavelength λ ｂ represents a notch frequency at which a notch appears at a frequency other than the frequency double of the optical signal based on the frequency spectrum of the optical signal, and f ｎ,ａ is the wavelength λ ａ represents the n+1-th notch frequency from the low frequency side in the frequency spectrum of the optical signal, and α a , α b represents multiple chirp values ​​calculated in advance, where n and m are integers equal to or greater than 0.

[0048]

[0049] In the case of only one wavelength, the dispersion slope S ０ λ is assumed to be a standardized value or to be held in advance. ０ Therefore, the dispersion slope S ０ There is little deviation.

[0050] (Configuration example of communication devices 30, 40) Fig. 5 is a diagram showing a configuration example of the communication devices 30, 40 in the first embodiment. Note that since the communication devices 30, 40 have the same functions, the functional units of the communication devices 30, 40 will not be distinguished in the following description. The communication devices 30, 40 each have a receiving unit 31, a wavelength setting unit 32, and a transmitting unit 33. Here, the receiving unit 31 and the transmitting unit 33 use different optical transmission paths (two-core optical transmission paths).

[0051] The receiver 31 receives an optical signal including information indicating the value of the zero-dispersion wavelength transmitted from the control device 10. Furthermore, the receiver 31 receives an optical signal transmitted from the communication devices 30 and 40 with which it is communicating.

[0052] The wavelength setting unit 32 sets the wavelength of the optical signal to be used in the transmitting unit 33 based on the optical signal received by the receiving unit 31 and including information indicating the value of the zero-dispersion wavelength.

[0053] (Processing of Wavelength Setting Unit 32) For example, when the wavelength setting unit 32 controls the wavelength used by the transmitter 33 for communication based on temperature, the wavelength setting unit 32 holds correspondence information indicating the correspondence relationship between wavelength and temperature. For example, the correspondence information includes information indicating the temperature of the laser corresponding to each wavelength, in association with each wavelength. That is, the correspondence information includes information indicating the temperature of the laser corresponding to each wavelength, such as wavelength λ １ Corresponding to the temperature T1 and wavelength λ ２ The information includes information such as temperature T2 associated with the wavelength T1. Note that this is just an example, and the temperature value is determined within a predetermined range. By referring to the correspondence information, the wavelength setting unit 32 acquires temperature information corresponding to the wavelength specified by the received information indicating the zero-dispersion wavelength, and adjusts the temperature of the transmitting unit 33 to the temperature indicated by the acquired temperature information. In this way, the wavelength setting unit 32 sets the wavelength of the optical signal used by the transmitting unit 33 for communication.

[0054] (Another example of wavelength setting unit 32) The wavelength setting unit 32 may set the wavelength of the optical signal used by the transmitter 33 for communication using a method other than temperature. For example, the wavelength setting unit 32 may set the wavelength of the optical signal used by the transmitter 33 for communication based on a current. When configured in this way, the wavelength setting unit 32 holds correspondence information indicating the correspondence relationship between wavelength and current. This correspondence information may, for example, be associated with each wavelength and associated with information indicating the current to be applied to the corresponding laser for each wavelength. That is, the correspondence information may include a wavelength λ １ Corresponding to the current C １ , wavelength λ ２ Corresponding to the current C ２ The information includes the following. Note that this is just an example, and the value of the current is determined within a predetermined range. By referring to the correspondence information, the wavelength setting unit 32 obtains current information corresponding to the wavelength specified by the received information indicating the zero-dispersion wavelength, and applies the current indicated by the obtained current information to the transmitting unit 33. In this way, the wavelength setting unit 32 sets the wavelength of the optical signal that the transmitting unit 33 uses for communication.

[0055] The transmitter 33 is, for example, a wavelength-tunable laser, and transmits an optical signal having a wavelength set by the wavelength setting unit 32 based on temperature or current.

[0056] (Another example of communication devices 30, 40) The communication devices 30, 40 may be configured to include a receiver 31, a wavelength setting unit 32, an array laser, and a multiplexer. The array laser includes multiple lasers capable of oscillating wavelengths λ1 to λp (p is an integer equal to or greater than 1). The array laser drives the oscillation lasers set by the wavelength setting unit 32 to output optical signals. The multiplexer multiplexes optical signals of one or more wavelengths output from the array lasers. The multiplexer outputs the multiplexed optical signal to an optical transmission path.

[0057] The wavelength setting unit 32 selects an oscillation laser corresponding to a desired wavelength and sets the array laser so that a signal is output from the selected oscillation laser. While the desired wavelength is preferably a zero-dispersion wavelength, it is possible that no laser corresponding to the zero-dispersion wavelength exists. Therefore, if no laser corresponding to the zero-dispersion wavelength exists, the wavelength setting unit 32 may select a laser with a wavelength closest to the zero-dispersion wavelength.

[0058] As described above, any method for changing the wavelength may be used. This embodiment is applicable as long as the zero-dispersion wavelength of the optical fiber and the range of the transmission wavelength overlap (not limited to wavelengths of 1300 to 1324 nm).

[0059] (System Operation Example) Next, an operation example of the optical communication system 100 will be described. Fig. 6 is a sequence diagram showing the flow of processing performed by the optical communication system 100 in the first embodiment. Fig. 6 explains an example in which communication device 30-1 and communication device 40-1 communicate with each other.

[0060] First, assume that a user connects communication device 30-1 to the distribution device 20 via an optical transmission path (step S101). At this time, assume that communication device 40-1 is already connected to the distribution device 20 and has issued a connection request to communication device 30-1. Note that communication device 40-1 is not limited to the above-described situation; it may be waiting for a response from the control device 10 regarding route and wavelength settings, or may have established an initial connection similar to communication device 30-1. Communication device 30-1 transmits a connection request (optical signal) (step S102). The connection request transmitted from communication device 30-1 is forwarded to the control device 10 via the distribution device 20. The receiving unit 11 of the control device 10 receives the connection request transmitted from communication device 30-1 (step S103). The receiving unit 11 outputs the received connection request to the control unit 12.

[0061] The control unit 12 performs a zero-dispersion wavelength providing process based on the connection request output from the receiving unit 11 (step S104). The zero-dispersion wavelength providing process is a process of providing information on the zero-dispersion wavelength used between the communication devices 30 and 40 that are communicating. The zero-dispersion wavelength providing process will be described in detail later. The control device 10 transmits wavelength information indicating the value of the zero-dispersion wavelength obtained by the zero-dispersion wavelength providing process to the communication devices 30-1 and 40-1 via the distribution device 20.

[0062] Furthermore, based on the connection request, the switching control unit 122 of the control device 10 generates switching information for instructing the distribution device 20 to switch the path so that communication device 30-1 and communication device 40-1 are connected (step S105). The switching control unit 122 transmits the switching information to the distribution device 20 via the transmitter 13 (step S106). The distribution device 20 receives the switching information transmitted from the control device 10. Based on the received switching information, the distribution device 20 switches the connection between the ports so that the optical transmission path to which communication device 30-1 is connected is connected to the optical transmission path to which communication device 40-1 is connected (step S107).

[0063] The receiver 31 of the communication device 30-1 receives the wavelength information transmitted from the control device 10. The receiver 31 outputs the received wavelength information to the wavelength setting unit 32. The wavelength setting unit 32 sets the wavelength to be used for communication in the transmitter 33 based on the wavelength information output from the receiver 31 (step S108).

[0064] The receiver 31 of the communication device 40-1 receives the wavelength information transmitted from the control device 10. The receiver 31 outputs the received wavelength information to the wavelength setting unit 32. The wavelength setting unit 32 sets the wavelength to be used for communication in the transmitter 33 based on the wavelength information output from the receiver 31 (step S109). Here, it is assumed that the wavelength setting has been performed when communication is performed from the communication device 30-1 to the communication device 40-1. As a result, communication is started between the communication device 30-1 and the communication device 40-1 (step S110). For example, the communication device 30-1 transmits an optical signal to the communication device 40-1 using the set wavelength.

[0065] In the above example, wavelength setting when communication is performed from the communication device 30-1 to the communication device 40-1 (for example, upstream communication) has been described. However, wavelength setting when communication is performed from the communication device 40-1 to the communication device 30-1 (for example, downstream communication) can also be performed using the zero dispersion wavelength λ of the destination path. ０ The calculation method is the same as when communication is performed from the communication device 30-1 to the communication device 40-1 (for example, upstream communication), except that the information used to estimate the is different.

[0066] In the example of FIG. 6, for convenience of explanation, the control device 10 has been described as providing wavelength information to the communication devices 30-1 and 40-1, and then transmitting a switching instruction to the distribution device 20. However, since the provision of wavelength information and the switching instruction are performed independently, they may be performed in a different order. For example, the control device 10 may transmit a switching instruction to the distribution device 20, and provide wavelength information to the communication devices 30-1 and 30-2 after receiving a response from the distribution device 20 indicating that switching has been completed, or the provision of wavelength information and the switching instruction may be performed at the same time. Note that the switching instruction from the control device 10 to the distribution device 20 may be transmitted by an electrical signal via an electrical line.

[0067] (Example of operation of zero-dispersion wavelength provision processing) Next, an example of operation of zero-dispersion wavelength provision processing will be described. Fig. 7 is a flowchart showing the flow of zero-dispersion wavelength provision processing performed by the control device 10 in the first embodiment. Note that Fig. 7, like Fig. 6, describes an example in which communication device 30-1 and communication device 40-1 communicate with each other, and communication device 30-1 communicates (upstream) with communication device 40-1.

[0068] The route determination unit 121 detects an initial connection of the communication device 30-1 based on the connection request received by the receiving unit 11 (step S201). The route determination unit 121 determines a destination route based on information indicating the communication partner included in the connection request (step S202). As an example, it is assumed here that the route determination unit 121 has determined, as destination routes, an optical transmission path connecting the communication device 30-1 and the distribution device 20 and an optical transmission path connecting the communication device 40-1 and the distribution device 20. The route determination unit 121 outputs information indicating the determined destination routes to the combination calculation unit 124.

[0069] The combination calculation unit 124 determines whether or not information on the zero-dispersion wavelengths of all the routes between the devices is registered, based on the information indicating the destination routes output from the route determination unit 121 and the transmission path list stored in the list storage unit 123 (step S203). For example, the combination calculation unit 124 refers to the transmission path list and determines whether or not both information on the zero-dispersion wavelengths of the optical transmission path connecting the communication device 30-1 and the distribution device 20 (e.g., information on the zero-dispersion wavelengths for the upstream) and information on the zero-dispersion wavelengths of the optical transmission path connecting the communication device 40-1 and the distribution device 20 (e.g., information on the zero-dispersion wavelengths for the upstream) are registered.

[0070] In the above example, the combination calculation unit 124 determines that information on the zero-dispersion wavelengths of all paths between the devices is registered if both information on the zero-dispersion wavelength of the optical transmission path connecting the communication device 30-1 and the distribution device 20 and information on the zero-dispersion wavelength of the optical transmission path connecting the communication device 40-1 and the distribution device 20 are registered. On the other hand, if either information on the zero-dispersion wavelength of the optical transmission path connecting the communication device 30-1 and the distribution device 20 or information on the zero-dispersion wavelength of the optical transmission path connecting the communication device 40-1 and the distribution device 20 is not registered, the combination calculation unit 124 determines that information on the zero-dispersion wavelengths of all paths between the devices is not registered.

[0071] When the combination calculation unit 124 determines that information on the zero-dispersion wavelengths of all the paths between the devices is registered (step S203—YES), the combination calculation unit 124 acquires the corresponding information from the transmission path list. For example, the combination calculation unit 124 calculates the distances L and S related to the optical transmission path connecting the communication device 30-1 and the distribution device 20. ０ and λ ０ and the distances L and S of the optical transmission line connecting the communication device 40-1 and the distribution device 20. ０ and λ ０ Here, the combination calculation unit 124 obtains the distances L and S related to the upstream optical transmission line connecting the communication device 30-1 and the distribution device 20. ０ and λ ０ and the distances L and S of the upstream optical transmission line connecting the communication device 40-1 and the distribution device 20. ０ and λ ０ The combination calculation unit 124 uses the acquired information to calculate the zero-dispersion wavelength λ in the upstream direction of the destination route based on the above equation (1). ０ (Step S204). The combination calculation unit 124 calculates the zero-dispersion wavelength λ in the upstream direction of the destination route obtained by the calculation. ０ The information providing unit 126 outputs information indicating the above.

[0072] The information providing unit 126 receives the zero-dispersion wavelength λ in the upstream direction output from the combination calculation unit 124. ０The information indicating the above is transmitted to each communication device (for example, communication device 30-1 and communication device 40-1) via the transmitting unit 13 (step S205).

[0073] In the process of step S203, if the combination calculation unit 124 determines that information on the zero-dispersion wavelengths of all the paths between the devices has not been registered (step S203-NO), the combination calculation unit 124 instructs the estimation unit 125 to estimate the value of the zero-dispersion wavelength in the upstream direction of the destination path. In accordance with the instruction from the combination calculation unit 124, the estimation unit 125 performs a zero-dispersion wavelength estimation process to estimate the value of the zero-dispersion wavelength in the upstream direction of the destination path (step S206). For example, an existing method may be used for the zero-dispersion wavelength estimation process.

[0074] Note that, since the estimation unit 125 is provided in the control device 10, when the estimation unit 125 performs the zero-dispersion wavelength estimation process, it is possible that the path between the control device 10 and the distribution device 20 may affect the estimation of the zero-dispersion wavelength. For example, if the path between the control device 10 and the distribution device 20 is relatively long, it is highly likely that it will affect the estimation of the zero-dispersion wavelength. Therefore, it is desirable that the path between the control device 10 and the distribution device 20 has a small influence of dispersion (for example, a short path) so that it does not affect the value of the zero-dispersion wavelength. Alternatively, the estimation unit 125 may also store a list of paths between the control device 10 and the distribution device 20, and when performing the zero-dispersion wavelength estimation process, the zero-dispersion wavelength may be estimated by thinning out the influence of the path between the control device 10 and the distribution device 20.

[0075] The estimation unit 125 estimates the distances L and S obtained by the zero-dispersion wavelength estimation process. ０ and λ ０ The control device 10 stores the value of (a) in the transmission path list in association with the identification information of each communication device 30, 40 (step S207). As a result, information on the route that was not registered in the transmission path list is newly registered in the transmission path list, and it becomes unnecessary to perform the zero-dispersion wavelength estimation process when the same route is used. Thereafter, the control device 10 performs the process of step S205.

[0076] Although the method for estimating the value of the zero-dispersion wavelength in the upstream direction of the destination route has been described with reference to FIG. 7, the method for estimating the value of the zero-dispersion wavelength in the downstream direction of the destination route can be performed by using the zero-dispersion wavelength λ ０ The method is the same as the method for estimating the value of the zero-dispersion wavelength in the upstream direction of the destination route, except that the information used to estimate the distances L and S ０ and λ ０ and the distances L and S of the downstream optical transmission line connecting the communication device 40-1 and the distribution device 20. ０ and λ ０ The value of the zero-dispersion wavelength in the downstream direction of the destination route can be estimated based on the values ​​of

[0077] The optical communication system 100 configured as described above includes a list storage unit 123 that stores at least information regarding the zero-dispersion wavelength for each of a plurality of routes connecting a plurality of communication devices 30, 40 and a distribution device 20, and a combination calculation unit 124 that calculates the zero-dispersion wavelength of a destination route formed by a combination of a plurality of routes connecting communication devices that communicate, based on the information regarding the zero-dispersion wavelength stored in the list storage unit 123.

[0078] In this way, the control device 10 holds information on the zero-dispersion wavelength for each route, and when a new route is switched, the combination calculation unit 124 performs calculations based on the held information. This makes it possible to estimate the value of the zero-dispersion wavelength without having to perform a zero-dispersion wavelength estimation process each time a new route is switched, as was done in the past. By providing the zero-dispersion wavelength value thus obtained to each communication device 30, 40, it is possible to bring the oscillation wavelength closer to the value of the zero-dispersion wavelength. This makes it possible to shorten the time required to set the oscillation wavelength. As a result, it becomes possible to start communication between the communication devices 30, 40 earlier.

[0079] (First Modification of First Embodiment) The receiver 11 included in the control device 10 may be configured to perform differential output. FIG. 8 is a diagram showing an example configuration of a control device 10a in the first modification of the first embodiment. The control device 10a includes a receiver 11a, a controller 12a, and a transmitter 13. The receiver 11a outputs a received connection request to a path determiner 121 and an estimator 125a. As a result, in this configuration, the combination calculator 124a and the estimator 125a execute processing at the same time.

[0080] The control unit 12a controls the entire control device 10a and includes a route determination unit 121, a switching control unit 122, a list storage unit 123, a combination calculation unit 124a, an estimation unit 125a, and an information providing unit 126.

[0081] The combination calculation unit 124a calculates the zero-dispersion wavelength of the destination route based on the information indicating the destination route determined by the route determination unit 121 and the transmission route list. Here, if information on the zero-dispersion wavelengths of all destination routes is registered in the transmission route list, the estimation process by the estimation unit 125a is unnecessary. Therefore, if information on the zero-dispersion wavelengths of all destination routes is registered in the transmission route list, the combination calculation unit 124a instructs the estimation unit 125a to stop the zero-dispersion wavelength estimation process.

[0082] The estimation unit 125a estimates the value of the zero-dispersion wavelength of the destination path based on the connection request output from the receiving unit 11a. Furthermore, the estimation unit 125a stops the estimation process of the zero-dispersion wavelength in response to an instruction to stop from the combination calculation unit 124a.

[0083] (Variant 2 of the First Embodiment) In the above example, the control device 10 and the communication devices 30, 40 use different optical transmission paths (two-core optical transmission paths) for the transmitting unit and the receiving unit, but the control device 10 and the communication devices 30, 40 may be configured to use the same optical transmission path (single-core optical transmission path) for the transmitting unit and the receiving unit.

[0084] 9 is a diagram showing an example of the configuration of a control device 10b in Modification 2 of the first embodiment. The control device 10b includes a receiving unit 11, a control unit 12, a transmitting unit 13, and a multiplexing / demultiplexing device 14b. The multiplexing / demultiplexing device 14b multiplexes or demultiplexes wavelengths. Examples of the multiplexing / demultiplexing device 14b include a circulator and a multiplexing / demultiplexing coupler. It is desirable that the multiplexing / demultiplexing device 14b be wavelength independent. The multiplexing / demultiplexing device 14b outputs the optical signal output from the transmitting unit 13 to the optical transmission path. The multiplexing / demultiplexing device 14b outputs the optical signal transmitted from the optical transmission path to the receiving unit 11.

[0085] 10 is a diagram showing an example of the configuration of communication devices 30b, 40b in Modification 2 of the first embodiment. The communication devices 30b, 40b include a receiving unit 31, a wavelength setting unit 32, a transmitting unit 33, and a multiplexing / demultiplexing device 34b. The multiplexing / demultiplexing device 34b multiplexes or demultiplexes wavelengths. Examples of the multiplexing / demultiplexing device 34b include a circulator and a multiplexing / demultiplexing coupler. It is desirable that the multiplexing / demultiplexing device 34b be wavelength independent. The multiplexing / demultiplexing device 34b outputs the optical signal output from the transmitting unit 33 to the optical transmission path. The multiplexing / demultiplexing device 34b outputs the optical signal transmitted from the optical transmission path to the receiving unit 31.

[0086] Second Embodiment In the first embodiment, a configuration was shown in which a control device calculates the value of the zero-dispersion wavelength of a destination route using a transmission line list. In the second embodiment, a configuration will be described in which a communication device that performs communication and has requested a connection calculates the value of the zero-dispersion wavelength of a destination route using a transmission line list.

[0087] 11 is a diagram showing a configuration example of the control device 10c according to the second embodiment. The control device 10c includes a receiving unit 11, a control unit 12c, and a transmitting unit 13. Here, the receiving unit 11 and the transmitting unit 13 use different optical transmission paths (two-core optical transmission paths).

[0088] The control unit 12c controls the entire control device 10c. The control unit 12c includes a route determination unit 121c, a switching control unit 122, and an information providing unit 126c. The control unit 12c differs in configuration from the control unit 12 in that it does not include the list storage unit 123, the combination calculation unit 124, and the estimation unit 125, and in that it includes the route determination unit 121c and the information providing unit 126c instead of the route determination unit 121 and the information providing unit 126. The following description will focus on the differences from the control unit 12.

[0089] The route determination unit 121c determines a destination route in response to a connection request transmitted from the communication devices 30 and 40. For example, when the source of the connection request is the communication device 30-1 and the communication partner is the communication device 40-1, the route determination unit 121c determines, as the destination routes, an optical transmission path connecting the communication device 30-1 and the distribution device 20 and an optical transmission path connecting the communication device 40-1 and the distribution device 20.

[0090] The information providing unit 126c transmits, via the transmitting unit 13, information indicating the connection destination route determined by the route determining unit 121c to the communication device 30, 40 that is the source of the connection request.

[0091] (Configuration Example of Communication Devices 30c, 40c) Figure 12 is a diagram showing a configuration example of communication devices 30c, 40c in the second embodiment. Note that since communication devices 30c, 40c have the same functions, the functional units of communication devices 30c, 40c will not be distinguished in the following description. Communication devices 30c, 40c include a receiver 31, a wavelength setting unit 32c, a transmitter 33, a list storage unit 35c, a combination calculation unit 36c, and an estimation unit 37c. Here, it is assumed that the receiver 31 and the transmitter 33 use different optical transmission paths (two-core optical transmission paths).

[0092] The communication devices 30c and 40c differ in configuration from the communication devices 30 and 40 in that they include a wavelength setting unit 32c instead of the wavelength setting unit 32, and in that they newly include a list storage unit 35c, a combination calculation unit 36c, and an estimation unit 37c. The following description will focus on the differences from the communication devices 30 and 40.

[0093] The receiver 31 receives an optical signal including information indicating a connection route transmitted from the control device 10. Furthermore, the receiver 31 receives an optical signal transmitted from the communication device 30, 40, which is the communication partner. Here, when the receiver 31 acquires a value of the zero-dispersion wavelength from the communication device 30, 40, which is the communication partner, the receiver 31 outputs information indicating the acquired value of the zero-dispersion wavelength to the wavelength setting unit 32c.

[0094] The list storage unit 35c stores a transmission path list. The list storage unit 35c is configured using a storage device such as a magnetic storage device or a semiconductor storage device.

[0095] The combination calculation unit 36c calculates the zero-dispersion wavelength of the destination route based on the information indicating the destination route received by the receiving unit 31 and the transmission path list stored in the list storage unit 35c.

[0096] Here, if information regarding the optical fibers of some of the routes included in the information indicating the destination route is not registered in the transmission path list, the combination calculation unit 36c causes the estimation unit 37c to estimate the value of the zero-dispersion wavelength of at least the route that is not registered in the transmission path list.

[0097] In addition, if information regarding the optical fibers of some of the routes included in the information indicating the destination routes is not registered in the transmission path list, the combination calculation unit 36c may cause the estimation unit 37c to estimate the values ​​of the zero-dispersion wavelengths of all of the routes indicated in the information indicating the destination routes.

[0098] The estimation unit 37c estimates the value of the zero-dispersion wavelength of the corresponding route in response to an instruction from the combination calculation unit 36c. Note that the estimation unit 37c may estimate the value of the zero-dispersion wavelength of the corresponding route using an existing method. Furthermore, the estimation unit 37c also acquires information on the route distance used when estimating the value of the zero-dispersion wavelength. The estimation unit 37c registers information on the optical fiber of the newly estimated route in the transmission route list.

[0099] The wavelength setting unit 32c sets the wavelength of the optical signal to be used in the transmitting unit 33 based on information indicating the value of the zero-dispersion wavelength received by the receiving unit 31, the value of the zero-dispersion wavelength of the destination route calculated by the combination calculation unit 36c, or the value of the zero-dispersion wavelength of the destination route estimated by the estimation unit 37c.

[0100] (System Operation Example) Next, an operation example of the optical communication system 100 in the second embodiment will be described. Fig. 13 is a sequence diagram showing the flow of processing performed by the optical communication system 100 in the second embodiment. Fig. 13 describes an example in which communication devices 30c-1 and 40c-1 communicate with each other. In Fig. 13, the same processes as in Fig. 6 are assigned the same reference numerals as in Fig. 6, and descriptions thereof will be omitted.

[0101] After the processes from step S101 to step S103 are executed, the route determination unit 121 of the control unit 12c determines a route to the connection destination based on information indicating the communication partner included in the connection request. The route determination unit 121 outputs information indicating the determined route to the connection destination to the information providing unit 126c. The information providing unit 126c transmits route information including the information indicating the route to the connection destination output from the route determination unit 121 to the communication device 30c-1, which is the sender of the connection request, via the transmitting unit 13 and the distribution device 20 (step S301).

[0102] The receiver 31 of the communication device 30c-1 receives the routing information transmitted from the control device 10c. The communication device 30c-1 executes a zero-dispersion wavelength providing process based on the received routing information (step S302). The zero-dispersion wavelength providing process will be described in detail later.

[0103] Based on the connection request, the switching control unit 122 of the control device 10c generates a switching instruction to instruct the distribution device 20 to switch the path so that communication device 30c-1 and communication device 40-1 are connected (step S303). The switching control unit 122 outputs switching information including the generated switching instruction to the transmitter 13. The transmitter 13 transmits the switching information output from the switching control unit 122 to the distribution device 20 (step S304). The distribution device 20 receives the switching information transmitted from the control device 10c. Based on the received switching information, the distribution device 20 switches the connection between ports so that the optical transmission path to which communication device 30c-1 is connected is connected to the optical transmission path to which communication device 40-1 is connected (step S305).

[0104] The communication device 30c-1 transmits wavelength information indicating the value of the zero-dispersion wavelength obtained by the zero-dispersion wavelength providing process to the communication device 40c-1, with which it will communicate (step S306). The receiver 31 of the communication device 40c-1 receives the wavelength information transmitted from the communication device 30c-1. The receiver 31 outputs the received wavelength information to the wavelength setting unit 32. The wavelength setting unit 32 sets the wavelength to be used for communication in the transmitter 33 based on the wavelength information output from the receiver 31 (step S307). Here, it is assumed that the wavelength setting has been performed when communication is to be performed from the communication device 30c-1 to the communication device 40c-1. This initiates communication between the communication device 30c-1 and the communication device 40c-1 (step S308). For example, the communication device 30c-1 transmits an optical signal to the communication device 40c-1 using the set wavelength.

[0105] In the above example, wavelength setting has been described for communication from the communication device 30c-1 to the communication device 40c-1 (for example, upstream communication). However, wavelength setting for communication from the communication device 40c-1 to the communication device 30c-1 (for example, downstream communication) can also be performed using the zero-dispersion wavelength λ of the destination path. ０ The calculation method is the same as when communication is performed from the communication device 30c-1 to the communication device 40c-1 (for example, upstream communication), except that the information used to estimate the is different.

[0106] The switching instruction from the control device 10c to the sorting device 20c may be transmitted by an electrical signal via an electrical line.

[0107] (Example of Operation of Zero-Dispersion Wavelength Provision Processing) Next, an example of operation of the zero-dispersion wavelength provision processing will be described. Fig. 14 is a flowchart showing the flow of the zero-dispersion wavelength provision processing performed by the communication device 30c in the second embodiment. Note that Fig. 14, like Fig. 13, will be described by taking as an example a case where communication devices 30c-1 and 40c-1 communicate with each other, and where communication (upstream) is performed from the communication device 30c-1 to the communication device 40c-1.

[0108] The receiver 31 receives the route information transmitted from the control device 10c (step S401). The receiver 31 outputs the received route information to the combination calculation unit 36c. The combination calculation unit 36c determines whether information on the zero-dispersion wavelengths of all routes between the devices is registered based on the information indicating the destination routes included in the route information output from the receiver 31 and the transmission path list stored in the list storage unit 35c (step S402). For example, the combination calculation unit 36c refers to the transmission path list to determine whether information on the zero-dispersion wavelengths of the optical transmission path connecting the communication device 30c-1 and the distribution device 20 (e.g., information on the zero-dispersion wavelengths for the upstream) and information on the zero-dispersion wavelengths of the optical transmission path connecting the communication device 40c-1 and the distribution device 20 (e.g., information on the zero-dispersion wavelengths for the upstream) are both registered.

[0109] In the above example, the combination calculation unit 36c determines that information on the zero-dispersion wavelengths of all paths between the devices is registered if both information on the zero-dispersion wavelengths of the optical transmission path connecting the communication device 30c-1 and the distribution device 20 and information on the zero-dispersion wavelengths of the optical transmission path connecting the communication device 40c-1 and the distribution device 20 are registered. On the other hand, if either information on the zero-dispersion wavelengths of the optical transmission path connecting the communication device 30c-1 and the distribution device 20 or information on the zero-dispersion wavelengths of the optical transmission path connecting the communication device 40c-1 and the distribution device 20 is not registered, the combination calculation unit 36c determines that information on the zero-dispersion wavelengths of all paths between the devices is not registered.

[0110] When the combination calculation unit 36c determines that information on the zero-dispersion wavelengths of all the paths between the devices is registered (step S402—YES), the combination calculation unit 36c acquires the corresponding information from the transmission path list. For example, the combination calculation unit 36c calculates the distances L and S of the optical transmission paths connecting the communication device 30c-1 and the distribution device 20. ０ and λ ０ and the distances L and S of the optical transmission line connecting the communication device 40c-1 and the distribution device 20. ０ and λ ０ Here, the combination calculation unit 36c obtains the distances L and S of the upstream optical transmission line connecting the communication device 30c-1 and the distribution device 20. ０ and λ ０ and the distances L and S of the upstream optical transmission line connecting the communication device 40c-1 and the distribution device 20. ０ and λ ０ The combination calculation unit 36c uses the acquired information to calculate the zero dispersion wavelength λ in the upstream direction of the destination route based on the above equation (1). ０ (Step S403). The combination calculation unit 36c calculates the zero-dispersion wavelength λ in the upstream direction of the destination route obtained by the calculation. ０ The wavelength setting unit 32c outputs information indicating the above to the wavelength setting unit 32c.

[0111] The wavelength setting unit 32c calculates the zero-dispersion wavelength λ in the upstream direction of the destination route output from the combination calculation unit 36c or the estimation unit 37c. ０ The wavelength of the transmitting unit 33 is adjusted in accordance with the information indicating the above (step S404).

[0112] In the process of step S402, if the combination calculation unit 36c determines that information on the zero-dispersion wavelengths of all the paths between the devices has not been registered (step S402-NO), the combination calculation unit 36c instructs the estimation unit 37c to estimate the value of the zero-dispersion wavelength in the upstream direction of the destination path. In accordance with the instruction from the combination calculation unit 36c, the estimation unit 37c performs a zero-dispersion wavelength estimation process to estimate the value of the zero-dispersion wavelength in the upstream direction of the destination path (step S405). For example, an existing method may be used for the zero-dispersion wavelength estimation process.

[0113] The estimation unit 37c estimates the distances L and S obtained by the zero-dispersion wavelength estimation process. ０ and λ ０ The value of is stored in the transmission path list in association with the identification information of each communication device 30c, 40c (step S406). As a result, information on the route that was not registered in the transmission path list is newly registered in the transmission path list, and there is no need to perform the zero-dispersion wavelength estimation process when the same route is used. The estimation unit 37c outputs the estimated value of the zero-dispersion wavelength of the destination route to the wavelength setting unit 32c. Thereafter, the communication device 30c-1 performs the process of step S404.

[0114] In addition, in FIG. 14, a method for estimating the value of the zero-dispersion wavelength in the upstream direction of the destination route has been described. However, a method for estimating the value of the zero-dispersion wavelength in the downstream direction of the destination route can be performed by using the zero-dispersion wavelength λ ０ The method is the same as the method for estimating the value of the zero-dispersion wavelength in the upstream direction of the destination route, except that the information used to estimate the distances L and S ０ and λ ０ and the distances L and S of the downstream optical transmission line connecting the communication device 40c-1 and the distribution device 20. ０ and λ ０ The value of the zero-dispersion wavelength in the downstream direction of the destination route can be estimated based on the values ​​of

[0115] According to the optical communication system 100 of the second embodiment configured as above, the same effects as those of the first embodiment can be obtained even in the configuration in which the communication devices 30c and 40c estimate the zero-dispersion wavelength of the destination path.

[0116] (First Modification of the Second Embodiment) The receiver 31 included in each of the communication devices 30 c and 40 c may be configured to perform differential output. In this configuration, the receiver 31 outputs the received path information to the combination calculation unit 36 ​​c and the estimation unit 37 c. As a result, in this configuration, the combination calculation unit 36 ​​c and the estimation unit 37 c perform processing at the same time.

[0117] The combination calculation unit 36c calculates the zero-dispersion wavelength of the destination route based on the information indicating the destination route included in the received route information and the transmission route list. Here, if information on the zero-dispersion wavelengths of all destination routes is registered in the transmission route list, the estimation process by the estimation unit 37c is unnecessary. Therefore, if information on the zero-dispersion wavelengths of all destination routes is registered in the transmission route list, the combination calculation unit 36c instructs the estimation unit 37c to stop the zero-dispersion wavelength estimation process.

[0118] The estimation unit 37c estimates the value of the zero-dispersion wavelength of the destination route based on the route information output from the receiving unit 31. Furthermore, the estimation unit 37c stops the estimation process of the zero-dispersion wavelength in response to an instruction to stop from the combination calculation unit 36c.

[0119] (Variation 2 of the Second Embodiment) In the example described above, the control device 10c and the communication devices 30c, 40c use different optical transmission paths (two-core optical transmission paths) for the transmitter and receiver, but the control device 10c and the communication devices 30c, 40c may be configured to use the same optical transmission path (single-core optical transmission path) for the transmitter and receiver. This configuration has been described in FIG. 9, so its description will be omitted.

[0120] Third Embodiment In the first and second embodiments, a configuration in which one distribution device is provided between communication devices has been described. However, multiple distribution devices may be provided between communication devices. Therefore, a configuration in which multiple distribution devices are provided between communication devices will be described.

[0121] Fig. 15 is a diagram showing an example of the configuration of an optical communication system 300 according to the third embodiment. The optical communication system 300 includes a control device 10, a plurality of distribution devices 20, a plurality of communication devices 30, and a plurality of communication devices 40. Each of the communication devices 30, 40 performs optical communication via the plurality of distribution devices 20. Fig. 15 shows an example in which there are three distribution devices 20, communication devices 30, and communication devices 40, but the numbers of distribution devices 20, communication devices 30, and communication devices 40 are not particularly limited.

[0122] Optical transmission paths connect the control device 10 and the distribution device 20-1, between the control device 10 and the distribution device 20-2, between the control device 10 and the distribution device 20-3, between the distribution device 20-1 and each communication device 30, between the distribution device 20-2 and the communication devices 40-1 and 40-2, and between the distribution device 20-3 and the communication device 40-3.

[0123] 15, in an optical communication system 300, a plurality of distribution devices 20 are connected between a communication device 30 and a communication device 40. The distribution devices 20-1, 20-2, and 20-3 may each have a different configuration. For example, the distribution device 20-1 is configured with an optical switch 21, a WSS 22, and a WSS 23 as shown in FIG. 15, but the distribution devices 20-2 and 20-3 may each be configured with only one optical switch, or may each be configured with only one wavelength selective switch, or may each be configured with a combination of an optical switch and a wavelength selective switch.

[0124] In this way, when a plurality of distribution devices 20 are connected between the communication device 30 and the communication device 40, the transmission path list also has a configuration as shown in Fig. 16. Fig. 16 is a diagram showing an example of the transmission path list in the third embodiment. The transmission path list shown in Fig. 16 has a plurality of records showing information about the optical fiber of each route. The record shown in Fig. 16 includes information such as ID, distance L, S ０ and λ ０ 16, information about optical fibers connecting the distribution devices 20 is also registered.

[0125] The combination calculation unit 124 can estimate the value of the zero-dispersion wavelength without performing the conventional zero-dispersion wavelength estimation process each time by referring to the list storage unit 123 when switching to a new route. As an example, when the communication device 30-1 and the communication device 40-1 are connected via the distribution devices 20-1 and 20-2, the combination calculation unit 124 calculates the distance L using the information of the IDs "communication device 30-1" and "communication device 40-1" registered in the transmission path list and the information associated with the IDs "distribution device 20-1 to distribution device 20-2." （Ａ,ｎｏｄｅＡ－Ｂ,Ｂ） λ0(A, node A-B, B) is calculated based on the above equation (2).

[0126] As another example of a transmission line list, as shown in FIG. 17, the transmission line list includes IDs and dispersion slopes S ０ and the value of the product of the distance L, and λ ０ 17 is a diagram showing another example of the transmission path list in the third embodiment. Details have been explained in FIG. 4 and are therefore omitted here.

[0127] According to the optical communication system 300 configured as above, even in a configuration in which the communication devices 30 and 40 are connected by a plurality of distribution devices 20, it is possible to obtain the same effects as in the first embodiment.

[0128] (Variation 1 of the Third Embodiment) The optical communication system 300 may be configured such that the communication devices 30 and 40 calculate the value of the zero-dispersion wavelength of the destination path using a transmission path list, as in the second embodiment. When configured in this manner, the optical communication system 300 includes a control device 10c instead of the control device 10, and communication devices 30c and 40c instead of the communication devices 30 and 40. However, the transmission path list used is the transmission path list shown in FIG. 16 or 17.

[0129] (Modification 2 of the Third Embodiment) The optical communication system 300 may be modified in the same manner as the first embodiment.

[0130] (Modifications common to the first to third embodiments) In each of the above-mentioned embodiments, a configuration was shown in which the combination calculation unit and the list storage unit were provided in the same device. For example, in the first embodiment, the list storage unit 123 and the combination calculation unit 124 were provided in the control device 10, and in the second embodiment, the list storage unit 35c and the combination calculation unit 36c were provided in the communication devices 30c and 40c. Furthermore, in the third embodiment, a configuration was shown in which the combination calculation unit and the list storage unit were provided in the control device 10 or the communication devices 30 and 40.

[0131] Alternatively, the combination calculation unit and the list storage unit may be provided in separate devices. For example, in the first embodiment, the combination calculation unit 124 may be provided in the control device 10 (including the control devices 10a and 10b), and the list storage unit 123 may be provided in an external device. In the second embodiment, the combination calculation unit 36c may be provided in the communication devices 30c and 40c, and the list storage unit 35c may be provided in an external device. Here, the external device is a device different from the device that includes the combination calculation unit.

[0132] In this configuration, the control device 10 (including the control devices 10a and 10b) or the communication devices 30c and 40c that do not have a list storage unit can perform the same processing as the processing described above by accessing an external device that has a list storage unit. Here, as an example, a configuration for calculating the zero-dispersion wavelength between the communication devices 30 and 40 that communicate with each other will be described using the first embodiment.

[0133] When switching to a new route, the combination calculation unit 124 included in the control device 10 accesses the list storage unit 35c included in the external device to acquire a transmission route list. The access method may be, for example, by an electrical signal via an electrical line or by an optical signal via an optical transmission line, and any access means is acceptable. The combination calculation unit 124 then determines whether or not information on the zero-dispersion wavelengths of all routes between the devices is registered, based on the transmission route list acquired from the external device and the information indicating the destination routes output from the route determination unit 121. Thereafter, the processing shown in the first embodiment is performed. If information on the zero-dispersion wavelengths of all routes between the devices is not registered in the transmission route list and the estimation unit 125 has performed zero-dispersion wavelength estimation processing, the estimation unit 125 uses the transmission route information (e.g., distances L, S) obtained by the zero-dispersion wavelength estimation processing to calculate the transmission route information. ０ and λ ０ The external device notifies the external device of the transmission path information notified by the estimation unit 125 in the transmission path list stored in the storage unit 123.

[0134] The control devices 10, 10c or the communication devices 30, 30c, 40, and 40c in the above-described embodiments may be partially or entirely implemented by a computer. In this case, a program for implementing the functions may be recorded on a computer-readable recording medium, and the program may be read and executed by a computer system. Note that the term "computer system" as used herein includes hardware such as an operating system (OS) and peripheral devices.

[0135] Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs (Read Only Memory), and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, and devices that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as servers or clients in such cases. The above programs may also be recorded on computer-readable recording media. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and semiconductor storage devices (e.g., solid-state drives (SSDs)), as well as storage devices such as hard disks and semiconductor storage devices built into computer systems. The above programs may also be transmitted via telecommunications lines.

[0136] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0137] The present invention is applicable to an optical communication system that performs communication via an optical transmission line.

[0138] 10, 10a, 10b, 10c... control device, 20... distribution device, 30, 30b, 30c, 30-1 to 30-3, 40, 40b, 40c, 40-1 to 40-3... communication device, 100, 300... optical communication system, 11, 11a, 31... receiving unit, 12, 12c... control unit, 13, 33... transmitting unit, 14b, 34b... multiplexing / demultiplexing device, 32c... wavelength setting unit, 35c, 123... list storage unit, 36c, 124, 124a... combination calculation unit, 37c, 125, 125a... estimation unit, 121, 121c... route determination unit, 122... switching control unit, 126, 126c... information providing unit, 203...

Claims

1. A communication device comprising: a receiving unit that receives information related to communication devices that communicate; transmission path information related to the zero-dispersion wavelength for each path connecting multiple devices; and a calculation unit that calculates the zero-dispersion wavelength of a communication path formed by a combination of multiple paths connected via one or more distribution devices that switch connection paths between the communication devices that communicate, based on the information related to the communication devices received by the receiving unit.

2. The communication device according to claim 1, wherein the memory unit that stores the transmission path information is provided in the device itself or an external device, and the calculation unit calculates the zero-dispersion wavelength of the communication path by referring to the transmission path information stored in the memory unit provided in the device itself or an external device.

3. The communication device according to claim 2, further comprising an estimation unit that estimates the value of the zero-dispersion wavelength for at least some of the routes when information indicating the zero-dispersion wavelength for the some of the routes is not registered in the storage unit.

4. The communication device described in claim 3, wherein the receiving unit outputs the received information about the communication device to the calculation unit and the estimation unit, the calculation unit and the estimation unit start processing at the time when the information about the communication device is obtained from the receiving unit, and the calculation unit outputs an instruction to the estimation unit to stop processing when the information necessary to calculate the zero dispersion wavelength of the communication path is stored in the memory unit.

5. The communication device according to any one of claims 1 to 4, further comprising a providing unit that provides information indicating the zero-dispersion wavelength of the communication path calculated by the calculating unit to a communication device that performs the communication.

6. The communication device according to any one of claims 1 to 4, further comprising a transmitter that sets the zero-dispersion wavelength of the communication path calculated by the calculator and communicates with a communication partner.

7. A communication device as described in any one of claims 2 to 4, wherein, when the communication devices performing the communication are connected via a plurality of distribution devices, the memory unit stores transmission path information regarding the zero-dispersion wavelength of a first path connecting the communication device and the plurality of distribution devices and a second path connecting between the plurality of distribution devices, and the calculation unit calculates the zero-dispersion wavelength of the communication path by taking into account the transmission path information of each of the first path and the second path stored in the memory unit.

8. A zero-dispersion wavelength calculation method that receives information about communication devices that communicate, and calculates the zero-dispersion wavelength of a communication path formed by a combination of multiple paths connected via one or more distribution devices that switch connection paths between the communication devices that communicate, based on transmission path information about the zero-dispersion wavelength for each path connecting multiple devices and the received information about the communication devices.

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