JP7623974B2 - Optical communication network control device and program - Google Patents

Description

The present invention relates to power control of signal light in optical communication networks.

In order to increase the transmission capacity in optical communication networks, in addition to the conventionally used C-band, L-band, which has a longer wavelength than C-band, and S-band, which has a shorter wavelength than C-band, are used. In such optical communication networks, it is important to suppress the influence of nonlinear effects such as cross-phase modulation (XPM) and inter-channel stimulated Raman scattering (ISRS). The influence of nonlinear effects depends on the number and power level of each signal light accommodated in the same optical fiber, the wavelength interval of each signal light, etc. Therefore, in order to suppress the influence of nonlinear effects, it is important to adjust the power level of each signal light according to the number of signal lights accommodated in the same optical fiber, the wavelength interval of the signal lights, etc.

Non-Patent Document 1 discloses that in order to suppress the influence of nonlinear effects, the power level of each signal light is adjusted in advance according to the wavelength of the signal light.

B. Correia et al. , "Power control strategies and network performance assessment for C+L+S multiband optical transport", J. Opt. Commun. Netw. , vol. 13,2021

In optical communication networks, it is common to gradually add signal light according to demand, rather than setting in advance all the signal light that can be accommodated in each optical fiber. Since the impact of nonlinear effects depends on the number of signal light accommodated in the same optical fiber and the wavelength spacing of the signal light, the appropriate power level value to be set for each signal light changes each time signal light is added to the optical fiber. As described in Non-Patent Document 1, extremely complex calculations are required to determine the appropriate power level value to be set for each signal light for each pattern of signal light accommodated in the optical fiber, so it is difficult to determine in advance the appropriate power level value to be set for each signal light for each pattern of signal light accommodated in the optical fiber.

The present invention provides a technology that appropriately sets the power level of the signal light carried in the optical fiber while minimizing the amount of pre-calculation.

According to one aspect of the present invention, a control device for an optical communication network using one or more wavelength bands includes an acquisition means for acquiring the number of signal lights in each of the one or more wavelength bands for one or more signal lights included in wavelength-multiplexed light output by an optical transmission device to an optical transmission line, a storage means for storing one or more interpolation functions, a determination means for determining a first setting value for the power level of each of the one or more signal lights using the one or more interpolation functions based on the number of signal lights in each of the one or more wavelength bands, and a control means for controlling the optical transmission device so that the power level of each of the one or more signal lights included in the wavelength-multiplexed light output by the optical transmission device becomes the first setting value.

This invention makes it possible to appropriately set the power level of the signal light carried in the optical fiber while minimizing the amount of pre-calculation.

FIG. 1 is a configuration diagram of an optical communication network according to an embodiment. FIG. 1 is a configuration diagram of an optical transmitting device according to an embodiment. FIG. 1 is a configuration diagram of an optical amplifier according to an embodiment. 5 is an explanatory diagram of a process for determining a value to be set for the power level of each signal light in the optical transmission device according to the embodiment. FIG. 2 is a configuration diagram of a control device according to an embodiment.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. In addition, the same reference numbers are used for the same or similar configurations, and duplicate descriptions will be omitted.

Figure 1 is a configuration diagram of an optical communication network according to this embodiment. In Figure 1, solid arrows indicate signals that carry information, and dotted arrows indicate signals for control. The optical communication network according to this embodiment is capable of using the C band, L band, and S band. However, the present invention is also applicable to optical communication networks that can use only one wavelength band, and optical communication networks that can use two or more wavelength bands. Furthermore, the present invention is also applicable to optical communication networks that use other wavelength bands in addition to one or more of the C band, L band, and S band, and to optical communication networks that use only one or more other wavelength bands.

The maximum number of signal lights available in each wavelength band is predetermined. In the following explanation, the maximum number of signal lights available in the C band, L band, and S band will be denoted as the C band maximum number, the L band maximum number, and the S band maximum number, respectively. The number of signal lights actually used is determined according to demand, and for each wavelength band, it is any value between 0 and the maximum number of the corresponding wavelength band.

Each signal light carrying information is input to the optical transmitting device 1. The optical transmitting device 1 wavelength-multiplexes the input signal light to generate wavelength-multiplexed light, and transmits the wavelength-multiplexed light to the optical receiving device 2 via an optical fiber (optical transmission path). In this embodiment, the optical transmission path has one or more optical amplifying devices 2. However, the present invention is also applicable to an optical communication network that does not have an optical amplifying device 2, and in which the optical transmitting device 1 and the optical receiving device 3 are directly connected by an optical fiber. The optical amplifying device 2 optically amplifies each of the C band, L band, and S band separately.

Figure 2 is a configuration diagram of the optical transmitter 1. The signal light input to the optical transmitter 1 is input to the intra-band multiplexer 12 via a variable optical attenuator (VOA) 11. The VOA 11 attenuates each signal light to adjust the power level of the signal light. The amount of attenuation of each signal light can be set individually.

The intra-band multiplexing unit 12 wavelength-multiplexes the signal light for each wavelength band and outputs multiplexed light for each wavelength band. In the following description, the multiplexed light for the C band, L band, and S band will be referred to as C-band multiplexed light, L-band multiplexed light, and S-band multiplexed light, respectively.

The optical amplifier 13 has an optical amplifier for each wavelength band. The optical amplifier 13 amplifies the C-band multiplexed light, the L-band multiplexed light, and the S-band multiplexed light, and outputs the amplified light to the inter-band multiplexer 14. The inter-band multiplexer 14 wavelength-multiplexes the C-band multiplexed light, the L-band multiplexed light, and the S-band multiplexed light, and outputs the wavelength-multiplexed light to the optical transmission path.

Figure 3 is a configuration diagram of the optical amplifier 2. The inter-band separation unit 22 separates the wavelength multiplexed light into each wavelength band and outputs C-band multiplexed light, L-band multiplexed light, and S-band multiplexed light. The optical amplification unit 23 has an optical amplifier for each wavelength band. The optical amplification unit 23 amplifies each of the C-band multiplexed light, L-band multiplexed light, and S-band multiplexed light, and outputs the light to the inter-band multiplex unit 24. The inter-band multiplex unit 24 wavelength-multiplexes the C-band multiplexed light, L-band multiplexed light, and S-band multiplexed light, and outputs the light to the optical transmission path or the optical receiving device 3.

Returning to FIG. 1, the optical spectrum analyzer (OSA) 4 analyzes the wavelength components of the wavelength-multiplexed light transmitted by the optical transmitter 1, and outputs information about the signal light of each wavelength band contained in the wavelength-multiplexed light to the control device 5. In this embodiment, the OSA 4 outputs the number of signal lights actually used in each wavelength band to the control device 5. In the following description, the number of signal lights actually used in the C band, L band, and S band are referred to as the C band usage number, the L band usage number, and the S band usage number.

The control device 5 determines and sets the amount of attenuation of each signal light in the VOA 11 of the optical transmitter 1, the gain of each optical amplifier in the optical amplifier unit 13, and the gain of each optical amplifier in the optical amplifier unit 23 of each optical amplifier 2, based on the number of C bands used, the number of L bands used, and the number of S bands used. First, the process of determining the amount of attenuation of each signal light in the VOA 11 of the optical transmitter 1 and the gain of each optical amplifier in the optical amplifier unit 13 will be described below.

Figure 4 shows multiplexed light of one wavelength band included in the wavelength multiplexed light output by the optical transmitter 1, for example, C-band multiplexed light. In this embodiment, one signal light in each wavelength band is set as the reference signal light. The reference signal light is the signal light that is set first in the wavelength band. In the example of Figure 4, the signal light 70 with the smallest wavelength in the wavelength band is set as the reference signal light. However, the present invention is not limited to setting the signal light with the smallest wavelength in the wavelength band as the reference signal light, and any signal light, such as the signal light with the largest wavelength or the signal light in the center of the wavelength band, can be set as the reference signal light. In addition, in this embodiment, the order of adding the signal light is set. In this example, after setting the signal light 70, the signal lights are added in ascending order of wavelength, such as signal light 71, signal light 72, signal light 73, and signal light 74, according to demand. Note that the order of addition is not limited to this example, and the signal lights may be added in descending order of wavelength. Also, the signal lights may be added in any order, not just in ascending or descending order of wavelength.

The control device 5 determines the set value of the power level of the reference signal light 70 of the C-band multiplexed light and the "slope" (coefficient) 60 indicating the amount of change in the optical power level with respect to the wavelength change based on the number of C-band users, the number of L-band users, and the number of S-band users. The control device 5 determines the set value of the power level of the signal light 71 to 74 different from the reference signal light 70 from the set value of the power level of the reference signal light 70 and the slope 60. The control device 5 sets the attenuation of the signal light 70 to 74 in the VOA 11 and the gain of the optical amplifier for the C-band in the optical amplifier unit 13 so that the power levels of the signal light 70 to 74 included in the C-band multiplexed light included in the wavelength multiplexed light become the determined set values. The same applies to the L-band and the S-band.

Next, a method for determining a set value of the power level of the reference signal light 70 of the C-band multiplexed light based on the number of C-band users, the number of L-band users, and the number of S-band users will be described. An interpolation function for determining a set value of the power level of the reference signal light 70 of the C-band multiplexed light based on the number of C-band users, the number of L-band users, and the number of S-band users is preset in the control device 5. In this example, tricubic interpolation is used. Therefore, for example, if the set value of the power level of the reference signal light 70 of the C-band multiplexed light is P _cr , P _cr can be determined by the following formula (1).

In formula (1), x is the ratio of the number of C bands in use to the maximum number of C bands, y is the ratio of the number of L bands in use to the maximum number of L bands, and z is the ratio of the number of S bands in use to the maximum number of S bands. Furthermore, the coefficients a _{i, j, and k} are coefficients that are calculated in advance.

For example, for each of x, y, and z, 0%, 33.3%, 66.7%, and 100%, that is, 64 combinations of x, y, and z, the optimum value of _Pcr can be calculated in advance to obtain 64 coefficients a _i,j,k . The control device 5 obtains the current values of x, y, and z based on the number of users of the C band, the number of users of the L band, and the number of users of the S band received from the OSA 4, and substitutes the values into formula (1) to obtain the setting value of the power level of the reference signal light 70 of the C band multiplexed light.

The control device 5 similarly determines the slope 60 using an interpolation function. Furthermore, the control device 5 also determines the set values of the power levels of the reference signal light in the L band and S band, and the slopes of the L band and S band using an interpolation function. Therefore, the control device 5 determines the attenuation to be set in the VOA 11 of the optical transmitter 1 and the gain of each optical amplifier in the optical amplifier unit 13 using three interpolation functions for determining the set values of the power levels of the reference signal light in the C band, L band, and S band, respectively, and three interpolation functions for determining the "slope" of the C band, L band, and S band, respectively.

The reason for providing the slope 60 as shown in FIG. 4 is to compensate in advance for the fact that the power level of the signal light propagating through the optical fiber changes differently for each wavelength due to nonlinear effects.

The control device 5 also uses an interpolation function to determine the gain to be set for each optical amplifier in the optical amplifier section 23 of each optical amplifier 2. For this reason, the control device 5 has three interpolation functions for the C band, L band, and S band for each optical amplifier 2.

The number of signal lights can not only increase but also decrease according to demand. In this case, the order in which the signal lights are stopped may not be the reverse of the order in which the signal lights were added. Since each coefficient of the interpolation function is the optimal value when the signal lights are added according to the order in which the signal lights were added, if the use of the signal lights is stopped in an arbitrary order, the power level and the value of the slope of the reference signal light may not be optimal, but they may be values that approximately suppress the influence of nonlinear effects. In addition, even if the demand decreases, the signal lights can be left as they are. Furthermore, considering that the use of the signal lights can be stopped in an arbitrary order, multiple patterns of the order in which the signal lights are stopped can be prepared, and an interpolation function for each pattern of the stop order can be prepared in advance. In this case, when the use of the signal lights is stopped, the interpolation function of the closest pattern can be used.

Furthermore, in this embodiment, the power levels of signals other than the reference signal light are determined based on the power level of the reference signal light, so the reference signal light must be stopped last. For this reason, for example, the reference signal light can be configured to be always set. Alternatively, multiple interpolation functions using different signal lights as the reference signal light can be prepared, and when the reference signal light is stopped, the signal light among the remaining signal lights for which an interpolation function is set can be changed to the reference signal light.

Figure 5 is a functional block diagram of the control device 5 according to this embodiment. The storage unit 54 stores an interpolation function. An interpolation function is provided corresponding to each wavelength band. The interpolation function includes a first interpolation function for determining a set value of the power level of the reference signal light for each wavelength band, and a second interpolation function for determining a rate of change of the power level with respect to the wavelength for each wavelength band. When one or more optical amplifiers 2 are provided in the optical transmission path, the interpolation function includes a third interpolation function associated with each optical amplifier 2 for each wavelength band. The third interpolation function for each wavelength band associated with the optical amplifier 2 is used to determine a set value of the gain of the optical amplifier for each wavelength band of the optical amplifier 2.

The communication unit 51 performs communication processing with the optical transmission device 1, the optical amplifier device 2, and the OSA 4. The determination unit 52 acquires information on the number of signal lights actually used in each wavelength band from the OSA 4. The determination unit 52 uses the interpolation function stored in the storage unit 54 based on the number of signal lights actually used in each wavelength band to determine the first setting value of the power level of each signal light included in the wavelength multiplexed signal light transmitted by the optical transmission device 1, as described above. The control unit 53 controls the VOA 11 and the optical amplifier unit 13 of the optical transmission device 1 so that the power level of each signal light included in the wavelength multiplexed signal light transmitted by the optical transmission device 1 becomes the first setting value determined by the determination unit 52.

When an optical amplifier 2 is provided, the determination unit 52 uses the interpolation function stored in the storage unit 54 based on the number of signal lights actually used in each wavelength band to determine the second setting value of the optical amplifier for each wavelength band of the optical amplifier 2, as described above. The control unit 53 controls the optical amplifier 2 so that the gain of the optical amplifier for each wavelength band of the optical amplifier 2 becomes the second setting value.

In this embodiment, the optical amplifiers 13 and 23 each have an optical amplifier for each wavelength band, and the control device 5 determines the gain for each wavelength band. This is because the optical amplifiers for the C, L, and S bands have different configurations. However, for example, when an optical amplifier capable of amplifying the C and L bands collectively is used, the band including the C and L bands becomes one wavelength band (hereinafter, C+L band). In this case, the control device 50 uses a first interpolation function to obtain the power level of the reference signal light for the C+L band, a second interpolation function to obtain the slope, and a third interpolation function to obtain the gain of the optical amplifier for the C+L band of the optical amplifier device 2. In other words, one wavelength band corresponds to the wavelength range that the optical amplifier can amplify collectively.

The control device 5 according to the present invention can be realized by having a device having one or more processors, for example, one or more processors of a computer, execute an appropriate computer program. These computer programs can be stored in a computer-readable storage medium or distributed via a network.

The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the invention.

The above configuration makes it possible to appropriately set the power level of the signal light contained in the optical fiber while minimizing the amount of pre-calculation. This makes it possible to contribute to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

52: Determination unit, 53: Control unit, 54: Storage unit

Claims (7)

1. A control device for an optical communication network using one or more wavelength bands, comprising:
an acquisition unit that acquires the number of signal lights in each of the one or more wavelength bands for one or more signal lights included in wavelength multiplexed light output from an optical transmission device to an optical transmission line;
storage means for storing one or more interpolation functions;
a determination means for determining a first set value of a power level of each of the one or more signal lights using the one or more interpolation functions based on the number of signal lights in each of the one or more wavelength bands;
a control means for controlling the optical transmission device so that each of the power levels of the one or more signal lights included in the wavelength multiplexed light output from the optical transmission device becomes the first set value;
A control device comprising: the one or more interpolation functions include a first interpolation function corresponding to each of the one or more wavelength bands;
2. The control device according to claim 1, wherein the determination means determines, for each of the one or more wavelength bands, the first setting value of a power level of a first signal light of a predetermined wavelength in the wavelength band based on the number of signal lights in each of the one or more wavelength bands by using the first interpolation function corresponding to the wavelength band. the one or more interpolation functions include a second interpolation function corresponding to each of the one or more wavelength bands;
3. The control device according to claim 2, wherein the determination means uses the second interpolation function corresponding to each of the one or more wavelength bands to determine a rate of change of power level with respect to wavelength in the wavelength band based on the number of signal lights in each of the one or more wavelength bands, and determines the first setting value of a power level of a second signal light different from the first signal light in the wavelength band based on the first setting value and the rate of change of the power level of the first signal light in the wavelength band. The control device according to claim 3, wherein the control means controls the amount of attenuation of each of the one or more signal lights by the variable optical attenuator of the optical transmission device and the gain of the optical amplifier of each of the one or more wavelength bands of the optical transmission device so that the power level of the one or more signal lights included in the wavelength multiplexed light output by the optical transmission device becomes the first set value. the signal light is set in a predetermined order in each of the one or more wavelength bands;
The control device according to claim 2 , wherein the first signal light in the wavelength band is a signal light that is set first in the wavelength band. the optical transmission line has one or more optical amplifiers for amplifying the wavelength-multiplexed light,
the one or more interpolation functions include a third interpolation function associated with each of the one or more optical amplifier units corresponding to each of the one or more wavelength bands;
the determining means determines, for each of the one or more wavelength bands, a second setting value of a gain to be set in an optical amplifier of the optical amplifier for the wavelength band based on the number of signal lights of each of the one or more wavelength bands, using the third interpolation function associated with the optical amplifier corresponding to the wavelength band;
The control device according to claim 1 , wherein the control means controls the gain of an optical amplifier in each of the one or more wavelength bands in each of the one or more optical amplifying devices to the second set value. A program that causes a computer to function as a control device according to any one of claims 1 to 5.

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