Estimation device, estimation method, and program

Abstract

One aspect of the present invention provides an estimation device comprising a control unit that uses a reception signal resulting from a transmission signal that is an optical signal transmitted by a transmitter being propagated through an optical fiber to estimate a vibration position that is a position on the optical fiber where vibration has been induced by the vibration of the outside environment. The control unit executes estimation processing comprising: compensation processing including wavelength dispersion compensation processing for compensating for wavelength dispersion of the reception signal; transmission signal estimation processing for estimating the transmission signal on the basis of a result of the wavelength dispersion compensation processing; wavelength dispersion re-application processing for re-application the wavelength dispersion to a result of the compensation processing; and vibration position estimation processing for estimating the vibration position on the basis of the result of the transmission signal estimation processing and the result obtained after inverse mapping of a mapping corresponding to the vibration position and indicating changes of the transmission signal due to propagation through the optical fiber acting on the result of the wavelength dispersion re-application processing.

Description

[Technical Field]

[0001] The present invention relates to an estimation device, an estimation method, and a program. [Background technology]

[0002] With the increasing demand for optical communications, optical fibers are being deployed in various locations, and sensing technology is being studied to estimate the position on the optical fiber where vibrations are induced by vibrations in the external environment, which is the environment outside the optical fiber. An example of vibration in the external environment is an earthquake. Although the estimated position is a position on the optical fiber, the vibration of that position is caused by vibrations in the external environment that it is in contact with, so the estimation result indicates the position of the vibration in the external environment. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Ezra Ip, et al., “Distributed fiber sensor network using telecom cables as sensing media: technology advancements and applications [Invited]” Vol. 14, No. 1 / January 2022 / Journal of Optical Communications and Networking A61-A68 [Non-patent document 2] Alan Pak Tao Lau, et al., “Equalization-enhanced phase noise for 100Gb / s transmission and beyond with coherent detection” 2 August 2010 / Vol. 18, No. 16 / OPTICS EXPRESS 17239 [Non-patent document 3] Aditya Kakkar, “Comprehensive Study of Equalization-Enhanced Phase Noise in Coherent Optical Systems” JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 33, NO. 23, DECEMBER 1, 2015, p.4834-4841 Summary of the Invention [Problem to be solved by the invention]

[0004] When adding sensing functionality to existing optical fibers for optical communications, it is desirable to minimize the impact on optical communication systems already in operation. However, the technologies proposed to date require dedicated light for estimating the vibration position to be launched into the optical fiber, occupying a certain frequency band, which reduces the frequency utilization efficiency of the optical communication system and also degrades the signal quality of communication channels propagating in other frequency bands due to nonlinear optical effects.

[0005] In view of the above circumstances, an object of the present invention is to provide a technology for estimating the position on an optical fiber for optical communication where vibrations are induced by vibrations in the external environment, without causing a decrease in the frequency utilization efficiency of the optical communication system and signal degradation of other communication channels. [Means for solving the problem]

[0006] One aspect of the present invention is an estimation device that includes a control unit that estimates a vibration position, which is a position on an optical fiber where vibrations are induced by vibrations in the external environment, based on a received signal that is the result of a transmission signal, which is an optical signal transmitted from a transmitter, propagating through an optical fiber. The control unit executes estimation processes that include: a compensation process including a chromatic dispersion compensation process that compensates for chromatic dispersion on the received signal; a transmission signal estimation process that estimates the transmission signal based on the result of the chromatic dispersion compensation process; a chromatic dispersion re-application process that re-applies the chromatic dispersion to the result of the compensation process; and a vibration position estimation process that estimates the vibration position based on the result of the chromatic dispersion re-application process and the result of the transmission signal estimation process, where the inverse mapping of a mapping that corresponds to the vibration position and represents a change in the transmission signal due to propagation through the optical fiber is applied to the result of the chromatic dispersion re-application process.

[0007] One aspect of the present invention is an estimation method including a control step of estimating a vibration position, which is a position on an optical fiber where vibrations are induced by vibrations in an external environment, based on a received signal which is a result of a transmission signal, which is an optical signal transmitted from a transmitter, propagating through an optical fiber, wherein the control step executes estimation processes including: a compensation process including a chromatic dispersion compensation process which compensates for chromatic dispersion on the received signal; a transmission signal estimation process which estimates the transmission signal based on a result of the chromatic dispersion compensation process; a chromatic dispersion re-application process which re-applies the chromatic dispersion to the result of the compensation process; and a vibration position estimation process which estimates the vibration position based on a result of an inverse mapping of a mapping according to the vibration position, which represents a change in the transmission signal due to propagation through the optical fiber, acting on a result of the chromatic dispersion re-application process and the result of the transmission signal estimation process.

[0008] One aspect of the present invention is a program for causing a computer to function as the above-described estimation device. [Effects of the Invention]

[0009] According to the present invention, when using an optical fiber for optical communication to estimate the position on the optical fiber where vibrations are induced by vibrations in the external environment, it is possible to estimate the vibration position without causing a decrease in the frequency utilization efficiency of the optical communication system and signal degradation of other communication channels. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an estimation system according to an embodiment. [Figure 2] 3A and 3B are explanatory diagrams illustrating an example of a process in which the waveform of an optical signal propagating through an optical fiber in the embodiment is deformed. [Figure 3] 10 is a flowchart showing an example of the flow of an estimation process in the embodiment. [Figure 4] 10 is a flowchart showing an example of the flow of compensation processing in the embodiment. [Figure 5] 10 is a flowchart showing an example of the flow of a transmission signal estimation process in the embodiment. [Figure 6] 10 is a flowchart showing a first example of the flow of a vibration position estimation process in the embodiment. [Figure 7] 10 is a flowchart showing a second example of the flow of a vibration position estimation process in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Embodiment) FIG. 1 is a diagram showing an example of the configuration of an estimation system 100 according to an embodiment. The estimation system 100 includes an optical fiber 1, and estimates a vibration position, which is a position on the optical fiber 1 where vibration is induced by vibration in the external environment. The external environment refers to the environment outside the optical fiber 1. The optical fiber 1 is an optical fiber that propagates an incident optical signal. The vibration in the external environment is, for example, an earthquake.

[0012] The estimation system 100 further includes a transmitter 2 and an estimation device 3. The transmitter 2 transmits an optical signal. The optical signal transmitted by the transmitter 2 (hereinafter referred to as the “transmitted signal”) enters the optical fiber 1.

[0013] The estimation device 3 receives an optical signal propagating through the optical fiber 1. That is, the estimation device 3 receives a received signal that is the result of the transmitted signal propagating through the optical fiber 1. The estimation device 3 estimates the vibration position based on the received signal.

[0014] The optical fiber 1, the transmitter 2, and the estimation device 3 are also used for optical communications. Therefore, the transmitted signal propagates through the optical fiber 1 and reaches the estimation device 3, where it is decoded, thereby transmitting the information transmitted from the transmitter 2 to the estimation device 3.

[0015] The waveform of the transmitted signal is deformed while propagating through the optical fiber 1. The deformation is caused by, for example, chromatic dispersion, and by, for example, phase noise that is applied to the optical signal due to vibrations at the vibration position.

[0016] Fig. 2 is an explanatory diagram illustrating an example of a process in which the waveform of an optical signal propagating through an optical fiber 1 in an embodiment is deformed. More specifically, Fig. 2 is an explanatory diagram illustrating chromatic dispersion or noise applied to a transmission signal propagating through the optical fiber 1 from the transmitter 2 to the estimation device 3. The transmission signal emitted from the transmitter 2 propagates to position Z on the optical fiber 1, indicated by point P1 in Fig. 2, and chromatic dispersion is applied during propagation. Point P1 is a position on the optical fiber 1 and is a vibration position.

[0017] Since position Z is a vibration position, further phase noise is added to the transmission signal at position Z. The transmission signal then propagates to estimation device 3. During this propagation, chromatic dispersion is added to the transmission signal. In this way, the waveform of the transmission signal propagating through optical fiber 1 changes from the waveform when it was emitted by transmitter 2. Estimation device 3 estimates the position where phase noise related to the transmission signal was added based on the received signal.

[0018] Returning to the explanation of Fig. 1, the estimation device 3 includes a control unit 31 having a processor 91 such as a CPU (Central Processing Unit) and a memory 92 connected by a bus, and executes a program. By executing the program, the estimation device 3 functions as a device including the control unit 31, a receiver 32, a storage unit 33, and an input / output interface 34.

[0019] More specifically, the processor 91 reads out a program stored in the storage unit 33 and stores the read program in the memory 92. When the processor 91 executes the program stored in the memory 92, the estimation device 3 functions as a device including the control unit 31, the receiver 32, the storage unit 33, and the input / output interface 34.

[0020] The control unit 31 controls the operation of various functional units included in the estimation device 3. The control unit 31 executes, for example, estimation processing. The estimation processing includes compensation processing, transmission signal estimation processing, chromatic dispersion re-application processing, and vibration position estimation processing. The compensation processing is processing that includes chromatic dispersion compensation processing. The chromatic dispersion compensation processing is processing that compensates for chromatic dispersion in a received signal. The transmission signal estimation processing is processing that estimates a transmission signal based on the result of the chromatic dispersion compensation processing. The chromatic dispersion compensation processing and the transmission signal estimation processing are processing that are also performed in optical communications.

[0021] The chromatic dispersion re-application process is a process of re-applying the chromatic dispersion to the result of the compensation process. The vibration position estimation process is a process of estimating the vibration position based on the result of the chromatic dispersion re-application process and the result of the transmitted signal estimation process, in which the inverse map of the propagation map acts on the result of the chromatic dispersion re-application process. The propagation map is a map that corresponds to the vibration position and represents the change in the transmitted signal due to propagation through the optical fiber 1. Therefore, the inverse map of the propagation map is a map that represents the inverse event of the event in which the transmitted signal propagates through the optical fiber 1 from the transmitter 2 to the receiver 32, that is, the event in which the received signal propagates back from the receiver 32 to the transmitter 2.

[0022] <Technical significance of deliberately applying chromatic dispersion> Here, we will explain the technical significance of intentionally applying chromatic dispersion. That is, we will explain the technical significance of chromatic dispersion re-application processing. Generally, an optical signal propagating through an optical fiber 1 experiences waveform deformation due to chromatic dispersion and waveform deformation due to phase noise. In optical communications, chromatic dispersion is compensated for by performing chromatic dispersion compensation processing. Generally, when chromatic dispersion compensation is performed, phase noise changes to equalization-enhanced phase noise (EEPN). Therefore, when chromatic dispersion compensation is performed, it becomes difficult to estimate phase noise.

[0023] However, the estimation device 3 estimates the position where phase noise was injected. Therefore, the control unit 31 intentionally re-injects chromatic dispersion to the result of chromatic dispersion compensation processing that is also performed in existing optical communications so that existing devices used in optical communications can be used. In this way, the control unit 31 makes it possible to return the EEPN to the phase noise before chromatic dispersion was applied.

[0024] The receiver 32 receives the received signal. The storage unit 33 is configured using a computer-readable storage medium device (non-transitory computer-readable recording medium) such as a magnetic hard disk device or a semiconductor storage device. The storage unit 33 stores various information related to the estimation device 3. The storage unit 33 stores, for example, the results of processing executed by the control unit 31. Therefore, the storage unit 33 stores, for example, the results of estimation processing.

[0025] The input / output interface 34 inputs and outputs various types of information. The input / output interface 34 is an interface that outputs information and is configured to include a display device such as a CRT (Cathode Ray Tube) display, a liquid crystal display, or an organic EL (Electro-Luminescence) display. The interface that outputs information may be configured as an interface that connects these display devices to the estimation device 3.

[0026] The input / output interface 34 is configured as an interface for accepting input of information, and as an interface for connecting input devices such as a mouse, keyboard, or touch panel to the estimation device 3. The interface for accepting input of information may be configured to include these input devices. The input / output interface 34 outputs, for example, the results of processing executed by the control unit 31. Therefore, the input / output interface 34 outputs, for example, the results of estimation processing.

[0027] 3 is a flowchart showing an example of the flow of the estimation process in the embodiment. The control unit 31 executes a compensation process (step S101). Next, the control unit 31 executes a transmission signal estimation process (step S102). Next, the control unit 31 executes a chromatic dispersion re-application process (step S103). Next, the control unit 31 executes a vibration position estimation process (step S104).

[0028] The process of step S102 may be executed at any timing after the process of step S101 and before the process of step S104.

[0029] 4 is a flowchart showing an example of the flow of compensation processing in the embodiment. The control unit 31 executes chromatic dispersion compensation processing (step S201). Next, the control unit 31 compensates for polarization fluctuation, frequency offset, and carrier phase based on the result of the chromatic dispersion compensation processing (step S202).

[0030] 5 is a flowchart showing an example of the flow of a transmitted signal estimation process in an embodiment. The control unit 31 determines the symbol to be determined based on the result of the compensation process (step S301). Next, the control unit 31 decodes the content indicated by the result of step S301 (step S302). Next, the control unit 31 estimates the transmitted signal based on the result of step S302 (step S303).

[0031] In the estimation of the transmitted signal in step S303, for example, the result of step S302 is subjected to remapping and filtering using a Nyquist filter. Remapping is a process of assigning information to the amplitude and phase of the light wave. Filtering using a Nyquist filter is a process of narrowing the spectral width of the wave resulting from remapping.

[0032] 6 is a flowchart showing a first example of the flow of vibration position estimation processing in an embodiment. The control unit 31 determines a candidate vibration position according to a predetermined rule (step S401). Next, the control unit 31 executes a first partial compensation process on the processing object as a result of the chromatic dispersion re-application process (step S402). The first partial compensation process is a process for compensating the processing object for chromatic dispersion that is applied to the optical signal while the optical signal propagates from the receiver 32 to the candidate position determined in step S401.

[0033] Next, the control unit 31 performs fixed phase compensation on the processing object as a result of the first partial compensation process (step S403). The fixed phase compensation process is a process of applying fixed phase compensation to the processing object at the candidate position estimated in step S401.

[0034] The following equation (1) represents the fixed phase compensation.

[0035]

number

[0036]

number

[0037]

number

[0038] u out represents the result of fixed phase compensation.in represents the processing target before compensation by fixed phase compensation. The phase ε compensated in fixed phase compensation is a predetermined value that is fixed regardless of the candidate measurement position. The phase ε is an example of a phase fluctuation value. Note that u out,x means the x-polarized signal output from this processing. out,y means the y-polarized signal output from this processing. in,x means the x-polarized signal input to this processing. in,y means the y-polarized signal input to this process. Note that exp(-jε) is an example of a function that approximates the phase fluctuation. Note that j represents the imaginary unit.

[0039] Next, the control unit 31 executes a second partial compensation process on the processing object as a result of the fixed phase process (step S404). The second partial compensation process is a process for compensating for the chromatic dispersion applied to the optical signal while the optical signal propagates from the candidate position determined in step S401 to the transmitter 2.

[0040] In this way, the series of processes in steps S402 to S404 is a process for estimating the result of a reversal event of the event in which the transmission signal propagates through the optical fiber 1 from the transmitter 2 to the receiver 32. Therefore, the series of processes in steps S402 to S404 is an example of a process for obtaining a result in which the inverse mapping of the propagation map acts on the result of the chromatic dispersion re-application process. Therefore, the result obtained in step S404 is an example of a result in which the inverse mapping of the propagation map acts on the result of the chromatic dispersion re-application process.

[0041] After step S404, the control unit 31 obtains the level of signal similarity based on the result obtained in step S404 and the result of the transmitted signal estimation process (step S405). The signal similarity is the similarity between the result of the inverse mapping of the propagation map acting on the result of the chromatic dispersion re-application process and the result of the transmitted signal estimation process. Therefore, the signal similarity in step S405 is the similarity between the result obtained in step S404 and the result of the transmitted signal estimation process. The level of similarity may be evaluated, for example, by correlation or squared error.

[0042] Next, the control unit 31 determines whether a predetermined termination condition (hereinafter referred to as a "first termination condition") related to the acquisition of the level of signal similarity is satisfied (step S406). The first termination condition is, for example, a condition that the level of signal similarity has been acquired for all vibration position candidates prepared in advance.

[0043] If the first end condition is not satisfied (step S406: NO), the process returns to step S401. The predetermined rule in the process of step S401 is, for example, a rule that candidates for vibration positions are determined excluding candidates whose vibration positions have already been estimated.

[0044] On the other hand, if the first termination condition is satisfied (step S406: YES), the control unit 31 estimates the candidate with the highest signal similarity as the vibration position (step S407). That is, in the vibration position estimation process, the position with the highest signal similarity is estimated as the vibration position.

[0045] For example, in this manner, the control unit 31 estimates the vibration position based on the result of the inverse map of the propagation map acting on the result of the chromatic dispersion re-application process and the result of the transmission signal estimation process.

[0046] 7 is a flowchart showing a second example of the flow of the vibration position estimation process in the embodiment. The control unit 31 determines candidates for the vibration position according to a predetermined rule (step S501). Next, the control unit 31 executes a first partial compensation process on the processing target as a result of the chromatic dispersion re-application process (step S502).

[0047] Next, the control unit 31 performs phase fluctuation compensation on the processing object as a result of the first partial compensation process (step S503). Phase fluctuation compensation is a process for compensating the processing object for the phase noise applied at the candidate position estimated in step S501. Phase fluctuation compensation differs from fixed phase compensation in that the angular frequency ε of the phase fluctuation is not fixed.

[0048] Next, the control unit 31 executes a second partial compensation process on the processing target as a result of the phase fluctuation compensation (step S504). Next, the control unit 31 obtains the level of signal similarity based on the result obtained in step S504 and the result of the transmitted signal estimation process (step S505). The signal similarity in step S505 is the similarity between the result obtained in step S504 and the result of the transmitted signal estimation process. The level of similarity may be evaluated, for example, by correlation or squared error.

[0049] Next, the control unit 31 determines whether a predetermined condition (hereinafter referred to as the "second termination condition") related to the optimization of the angular frequency ε of the phase fluctuation is satisfied (step S506). The second termination condition is, for example, a condition that the similarity obtained in step S505 is at a maximum. If the second termination condition is not satisfied (step S506: NO), the control unit 31 updates the angular frequency ε of the phase fluctuation in accordance with a predetermined rule (step S507). The predetermined rule is, for example, a rule that the angular frequency ε of the phase fluctuation is updated so as to increase the similarity obtained in step S505. Next, the process returns to step S503. When returning to step S503, the updated angular frequency ε is used.

[0050] On the other hand, if the second termination condition is satisfied (step S506: YES), the control unit 31 determines whether the first termination condition is satisfied (step S508). If the first termination condition is not satisfied (step S508: NO), the process returns to step S501. The predetermined rule in the process of step S501 is, for example, a rule that determines candidates for vibration positions excluding candidates for which vibration positions have already been estimated.

[0051] On the other hand, if the first end condition is satisfied (step S508: YES), the control unit 31 estimates the candidate with the highest signal similarity as the vibration position (step S509). That is, in the vibration position estimation process, the position with the highest signal similarity is estimated as the vibration position.

[0052] For example, in this manner, the control unit 31 estimates the vibration position based on the result of the inverse map of the propagation map acting on the result of the chromatic dispersion re-application process and the result of the transmission signal estimation process.

[0053] As described above, the second termination condition may be a condition that the similarity obtained in step S504 is at its maximum (hereinafter referred to as an "example condition"). The predetermined rule in step S507 may be a rule that the angular frequency ε of the phase fluctuation is updated so as to increase the similarity obtained in step S505 (hereinafter referred to as an "example rule"). In such a case, the value of ε at the vibration position estimated in step S509 is a value that satisfies the condition for best removing phase noise at the vibration position compared to other values ​​of ε.

[0054] 7, in which the second termination condition is the above-described example condition and the predetermined rule in step S507 is the above-described example rule, is an example of a process of executing a elimination condition optimization process on one or more of the vibration position candidates. The elimination condition optimization process is a process of estimating a condition that best eliminates phase noise at the vibration position based on the result of the inverse mapping acting on the result of the chromatic dispersion re-application process and the result of the transmission signal estimation process.

[0055] 7, the value of ε at the vibration position estimated in step S509 may be a value that satisfies the condition for best eliminating phase noise at the vibration position compared with other values ​​of ε. Therefore, in estimating the condition for best eliminating phase noise at the vibration position, for example, the value of the angular frequency of the phase fluctuation at the vibration position is estimated.

[0056] The estimation device 3 in this embodiment configured as described above estimates the vibration position based on the result of the inverse mapping of the propagation map acting on the result of the chromatic dispersion re-application process and the result of the transmission signal estimation process. As a result, when estimating the vibration position using the estimation device 3, it is not necessary to inject dedicated light such as optical pulses into the optical fiber for estimation, and estimation is possible only by signal analysis of the received signal of the communication signal used in optical communication. Therefore, since a part of the WDM (Wavelength Division Multiplexing) channel of the optical communication is not monopolized, there is an advantage that the spectral efficiency is not reduced and the quality degradation of the optical communication signal to other communication channels due to nonlinear optical effects is not caused. In other words, when using the optical communication optical fiber to estimate the position on the optical fiber where vibration is induced by vibration in the external environment, the estimation device 3 can estimate the vibration position without causing a decrease in the spectral efficiency of the optical communication system and signal degradation of other communication channels.

[0057] Furthermore, the estimation device 3 in this embodiment configured as above estimates the vibration position by simply analyzing the received communication signal, which means that there is no need to provide an additional optical system to the optical communication system in order to estimate the vibration position, and there is also the advantage that there is no need to make any changes to the configuration of an optical communication system that has already been installed.

[0058] (Variation) The control unit 31 may perform estimation processing on a plurality of received signals that have propagated through the optical fiber 1 at different times. The results of such estimation processing are output, for example, from the input / output interface 34. In this case, the user of the estimation device 3 can obtain information indicating the time change in the initial phase of the optical signal due to phase noise. This allows the user of the estimation device 3 to estimate the frequency of vibration and its time fluctuations.

[0059] In the removal condition optimization process, a function expressed by the nth-order term (n is an integer equal to or greater than 1) of the Taylor expansion of exp(-jε) may be used as a function approximating the phase variation at the vibration position. The zeroth-order term of the Taylor expansion of exp(-jε) is 1. Therefore, the value of the zeroth-order term of the Taylor expansion of exp(-jε) does not depend on the value of ε. Therefore, by using a function approximating the phase variation at the vibration position that excludes the zeroth-order term of the Taylor expansion of exp(-jε), the control unit 31 can extract only the effect of changes in ε, thereby enabling more accurate phase estimation. Therefore, the function approximating the phase variation at the vibration position may be, for example, (-jε).

[0060] The signal similarity may be expressed by any index as long as it represents the similarity between the result of the inverse mapping of the propagation mapping acting on the result of the chromatic dispersion re-application processing and the result of the transmission signal estimation processing.

[0061] Therefore, for example, the processing target of the chromatic dispersion re-application process may be the execution result of step S201, but the result when the compensations of step S202 are not executed (hereinafter referred to as the "first result"). In such a case, the signal similarity may be, for example, the similarity between the result in which polarization variation, frequency offset, and carrier phase are applied to the result of the transmitted signal estimation process and the first result. Note that the amounts applied are the same as the amounts of compensation that would have been obtained if compensation had been applied. The process of applying polarization variation, frequency offset, and carrier phase to the result of the transmitted signal estimation process is executed by, for example, the control unit 31.

[0062] The target of the chromatic dispersion re-application process may be the execution result of step S201, which is a result in which polarization fluctuation compensation, among the compensations in step S202, is not performed (hereinafter referred to as the "second result"). In such a case, the signal similarity may be, for example, the similarity between the result in which polarization fluctuation is applied to the result of the transmitted signal estimation process and the second result. Note that each amount applied is the same as the amount of compensation that would have been obtained if compensation had been performed. The process of applying polarization fluctuation to the result of the transmitted signal estimation process is performed, for example, by the control unit 31.

[0063] The target of the chromatic dispersion re-application process may be the execution result of step S201, which is a result in which the frequency offset compensation of the compensation in step S202 has not been performed (hereinafter referred to as the "third result"). In such a case, the signal similarity may be, for example, the similarity between the result in which a frequency offset has been applied to the result of the transmitted signal estimation process and the third result. Note that each amount applied is the same as the amount of compensation that would have been obtained if compensation had been performed. The process of applying a frequency offset to the result of the transmitted signal estimation process is performed by, for example, the control unit 31.

[0064] The target of the chromatic dispersion re-application process may be the execution result of step S201, which is a result in which carrier phase compensation, among the compensations in step S202, is not performed (hereinafter referred to as the "fourth result"). In such a case, the signal similarity may be, for example, the similarity between the result in which a carrier phase is applied to the result of the transmitted signal estimation process and the fourth result. Note that each amount applied is the same as the amount of compensation that would have been obtained if compensation had been performed. The process of applying a carrier phase to the result of the transmitted signal estimation process is performed, for example, by the control unit 31.

[0065] The target of the chromatic dispersion re-application process may be the execution result of step S201, which is a result in which the compensation for polarization fluctuation and frequency offset in the compensation of step S202 is not performed (hereinafter referred to as the "fifth result"). In such a case, the signal similarity may be, for example, the similarity between the fifth result and a result in which polarization fluctuation and frequency offset are applied to the result of the transmitted signal estimation process. Note that the amounts applied are the same as the amounts of compensation that would have been obtained if compensation had been performed. The process of applying polarization fluctuation and frequency offset to the result of the transmitted signal estimation process is performed by, for example, the control unit 31.

[0066] The target of the chromatic dispersion re-application process may be the execution result of step S201, which is a result in which the compensation for frequency offset and carrier phase in the compensation of step S202 has not been performed (hereinafter referred to as the "sixth result"). In such a case, the signal similarity may be, for example, the similarity between the sixth result and a result in which frequency offset and carrier phase have been applied to the result of the transmitted signal estimation process. Note that the amounts applied are the same as the amounts of compensation that would have been obtained if compensation had been performed. The process of applying frequency offset and carrier phase to the result of the transmitted signal estimation process is performed by, for example, the control unit 31.

[0067] The target of the chromatic dispersion re-application process may be the execution result of step S201, which is a result in which compensation for carrier phase and polarization fluctuations among the compensations in step S202 has not been performed (hereinafter referred to as the "seventh result"). In such a case, the signal similarity may be, for example, the similarity between the seventh result and a result in which carrier phase and polarization fluctuations have been applied to the result of the transmitted signal estimation process. Note that the amounts applied are the same as the amounts of compensation that would have been obtained if compensation had been performed. The process of applying carrier phase and polarization fluctuations to the result of the transmitted signal estimation process is performed, for example, by the control unit 31.

[0068] The signal similarity may be evaluated based on the similarity between the amplitudes of the two signals.

[0069] The estimation device 3 may be implemented using a plurality of information processing devices communicably connected via a network, in which case the respective functional units of the estimation device 3 may be distributed and implemented among the plurality of information processing devices.

[0070] All or part of the functions of the estimation device 3 may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The program may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. The program may be transmitted via a telecommunications line.

[0071] Although an embodiment of the present invention has been described above in detail 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. [Explanation of symbols]

[0072] 100...estimation system, 1...optical fiber, 2...transmitter, 3...estimation device, 31...control unit, 32...receiver, 33...storage unit, 34...input / output interface, 91...processor, 92...memory

Claims

1. a control unit that estimates a vibration position, which is a position on the optical fiber where vibration is induced by vibration in the external environment, based on a received signal that is a result of a transmission signal that is an optical signal transmitted from a transmitter propagating through the optical fiber; Equipped with The control unit a compensation process including a chromatic dispersion compensation process for compensating for chromatic dispersion of the received signal; a transmission signal estimation process for estimating the transmission signal based on a result of the chromatic dispersion compensation process; a wavelength dispersion reapplication process for reapplying the wavelength dispersion to the result of the compensation process; a vibration position estimation process for estimating the vibration position based on a result of the transmission signal estimation process and a result of the wavelength dispersion re-application process, in which an inverse map of a map corresponding to the vibration position and representing a change in the transmission signal due to propagation through the optical fiber is applied to the result of the wavelength dispersion re-application process; performing an estimation process including Estimation device.

2. In the vibration position estimation process, a position where a similarity between a result of the inverse mapping acting on a result of the chromatic dispersion re-application process and a result of the transmission signal estimation process is highest is estimated to be the vibration position. The estimation device according to claim 1 .

3. The control unit performing the estimation process on a plurality of received signals that have propagated through the optical fiber at different timings; The estimation device according to claim 1 .

4. the vibration position estimation process executes a removal condition optimization process for estimating a condition that best removes phase noise at the vibration position based on a result of the inverse mapping acting on a result of the chromatic dispersion re-application process and a result of the transmission signal estimation process, for one or more of the vibration position candidates; The estimation device according to claim 1 .

5. In the estimation of the condition, a value of a phase variation at the vibration position is estimated. The estimation device according to claim 4 .

6. In the removal condition optimization process, a function expressed by an n-th order (n is an integer equal to or greater than 1) term of a Taylor expansion of exp(-jε) is used as a function that approximates a phase fluctuation at the vibration position. The estimation device according to claim 4 .

7. a control step of estimating a vibration position, which is a position on the optical fiber where vibration is induced by vibration in the external environment, based on a received signal, which is a result of a transmission signal, which is an optical signal transmitted from a transmitter, propagating through the optical fiber; and The control step a compensation process including a chromatic dispersion compensation process for compensating for chromatic dispersion of the received signal; a transmission signal estimation process for estimating the transmission signal based on a result of the chromatic dispersion compensation process; a wavelength dispersion reapplication process for reapplying the wavelength dispersion to the result of the compensation process; a vibration position estimation process for estimating the vibration position based on a result of the transmission signal estimation process and a result of the wavelength dispersion re-application process, in which an inverse map of a map corresponding to the vibration position and representing a change in the transmission signal due to propagation through the optical fiber is applied to the result of the wavelength dispersion re-application process; performing an estimation process including Estimation method.

8. A program for causing a computer to function as the estimation device according to any one of claims 1 to 6.

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