Optical transmission characteristic estimation apparatus, optical transmission characteristic estimation method and program
Provided an optical transmission characteristic estimation device that models an optical effect of an optical transmission line by a nonlinear Schrodinger equation, divides the optical transmission line into N (N is an integer of two or more) sections, obtains a solution of the nonlinear Schrodinger equation by an operation of N steps in which a section length of each of the divided N sections is a step size, and estimates transmission characteristics of the optical transmission line, the optical transmission characteristic estimation device including a step size update unit configured to update each of the N step sizes on the basis of an estimated optical power distribution and an estimated dispersion distribution, which are indicated by the transmission characteristics.
1 . An optical transmission characteristic estimation device that models an optical effect of an optical transmission line by a nonlinear Schrodinger equation, divides the optical transmission line into N (N is an integer of two or more) sections, obtains a solution of the nonlinear Schrodinger equation by an operation of N steps in which a section length of each of the divided N sections is a step size, and estimates transmission characteristics of the optical transmission line, the optical transmission characteristic estimation device comprising:
a step size updater configured to update each of the N step sizes on the basis of an estimated optical power distribution and an estimated dispersion distribution, which are indicated by the transmission characteristics.
2 . The optical transmission characteristic estimation device according to claim 1 ,
wherein the step size updater
detects the new N step sizes such that a rate of a change in the step size obtained by sequentially arranging and linearly interpolating the N step sizes is proportional to a rate of a change indicated by a third distribution obtained by multiplying a first distribution obtained by exponentiating the estimated optical power distribution with a predetermined power exponent p and a second distribution obtained by multiplying the estimated dispersion distribution by a square value of a signal bandwidth of the optical transmission line and then exponentiating the multiplied value with a predetermined power exponent q.
3 . The optical transmission characteristic estimation device according to claim 2 ,
wherein the step size updater
detects the new N step sizes with a power exponent p=−1 in a case where a dispersion coefficient indicated by the estimated dispersion distribution of the optical transmission line is a same value at any position of the optical transmission line.
4 . The optical transmission characteristic estimation device according to claim 1 , further comprising
a split-step Fourier method processor configured to apply a split-step Fourier method, which is a solution of the nonlinear Schrodinger equation, as a method of operating the N steps, to a reception signal subjected to coherent detection,
wherein the split-step Fourier method processor
applies the split-step Fourier method to the reception signal by setting each of initial values of the N step sizes as a length of one section when a length of the optical transmission line is equally divided into N sections.
5 . The optical transmission characteristic estimation device according to claim 1 ,
wherein the step size updater
updates each of the N step sizes by using a loss distribution of the optical transmission line instead of the estimated optical power distribution indicated by the transmission characteristics.
6 . The optical transmission characteristic estimation device according to claim 5 ,
wherein the step size updater
uses, as the loss distribution of the optical transmission line, a loss distribution calculated in advance from a remaining distribution obtained by removing a portion of a measurement dead zone from the estimated optical power distribution, or a loss distribution determined in advance for each type of optical fiber included in the optical transmission line.
7 . An optical transmission characteristic estimation method for modeling an optical effect of an optical transmission line by a nonlinear Schrodinger equation, dividing the optical transmission line into N (N is an integer of two or more) sections, obtaining a solution of the nonlinear Schrodinger equation by an operation of N steps in which a section length of each of the divided N sections is a step size, and estimating transmission characteristics of the optical transmission line, the optical transmission characteristic estimation method comprising:
updating each of the N step sizes on the basis of an estimated optical power distribution and an estimated dispersion distribution, which are indicated by the transmission characteristics.
8 . A non-transitory storage medium that stores a program for making a computer perform processes, the processes comprising:
modeling an optical effect of an optical transmission line by a nonlinear Schrodinger equation, and dividing the optical transmission line into N (N is an integer of two or more) sections;
obtaining a solution of the nonlinear Schrodinger equation by an operation of N steps in which a section length of each of the divided N sections is a step size, and estimating transmission characteristics of the optical transmission line; and
updating each of the N step sizes on the basis of an estimated optical power distribution and an estimated dispersion distribution, which are indicated by the transmission characteristics.