公开(公告)号：US20220158731A1

公开(公告)日：2022-05-19

申请号：US17425994

申请日：2020-01-15

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Kengo HORIKOSHI ,  Masanori NAKAMURA ,  Yoshiaki KISAKA ,  Seiji OKAMOTO ,  Fukutaro HAMAOKA

IPC: H04B10/2507

Abstract: A wavelength dispersion amount estimation apparatus includes a correlation signal generation unit configured to generate, from a receive signal, a first signal including a main signal of the receive signal and a second signal, which includes an image signal corresponding to the main signal, with a shift by a baud rate of the receive signal relative to the first signal in a frequency domain, a correlation calculation unit configured to calculate a cross correlation of the first signal and the second signal, and a dispersion amount calculation unit configured to calculate a wavelength dispersion amount, based on a position of a peak of the cross correlation.

公开(公告)号：US20220149974A1

公开(公告)日：2022-05-12

申请号：US17433149

申请日：2020-01-31

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Takayuki KOBAYASHI ,  Masanori NAKAMURA ,  Fukutaro HAMAOKA ,  Yutaka MIYAMOTO

IPC: H04J14/06 ,  H04B10/2507 ,  H04B10/61 ,  H04L27/01 ,  H04L27/38

Abstract: A receiver convolutes each of a real component and an imaginary component of each polarization of a polarization-multiplexed reception signal with an impulse response for compensating for frequency characteristics of the receiver and a complex impulse response for wavelength dispersion compensation, and generates, as input signals, the convoluted real component and imaginary component of each polarization and phase conjugations thereof, for each polarization. The receiver generates, for each polarization, a first addition signal obtained by multiplying each of the real component and the imaginary component of each polarization by a complex impulse response, thereafter adding together the multiplied real component and imaginary component, and applying a phase rotation for frequency offset compensation to the added components, and a second addition signal obtained by multiplying each of the phase conjugation of the real component of and the phase conjugation of the imaginary component of each polarization by a complex impulse response, thereafter adding together the multiplied phase conjugations, and applying a phase rotation opposite to the phase rotation for frequency offset compensation to the added phase conjugations, and adds or subtracts a transmission data bias correction signal to or from a signal obtained by adding together the generated first addition signal and second addition signal.

公开(公告)号：US20250158721A1

公开(公告)日：2025-05-15

申请号：US18834073

申请日：2022-02-10

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Masanori NAKAMURA ,  Takayuki KOBAYASHI ,  Fukutaro HAMAOKA ,  Yutaka MIYAMOTO

IPC: H04B10/61 ,  H04J14/06

Abstract: A signal processing method includes performing first equalization processing for converting a real component and an imaginary component of each polarization of a polarization multiplexed reception signal into a frequency domain signal, receiving, as input signals, a frequency domain signal of the real component and a frequency domain signal of the imaginary component of each polarization, and a signal obtained by performing frequency inversion on the frequency domain signal of the real component and the frequency domain signal of the imaginary component of each polarization and performing complex conjugate, performing, for each polarization, multiplying the real component and the imaginary component of each polarization by a complex transfer function, adding results, and performing inverse transform from the frequency domain signal to a time domain signal, performing second equalization processing for performing frequency inversion of the real component of each polarization included in the input signal, performing frequency inversion of a real component signal and an imaginary component subjected to complex conjugate, multiplying the imaginary component signals subjected to complex conjugation by a complex transfer function, adding results of the multiplications, and performing inverse transform from a frequency domain signal to a time domain signal, and adding or subtracting a transmission data bias correction signal to or from a signal obtained by adding a first addition signal to a second addition signal.

公开(公告)号：US20210211218A1

公开(公告)日：2021-07-08

申请号：US17059238

申请日：2019-05-20

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Fukutaro HAMAOKA ,  Kyo MINOGUCHI ,  Seiji OKAMOTO ,  Yoshiaki KISAKA

IPC: H04J14/02 ,  H04B10/2537 ,  H04B10/548

Abstract: An optical transmission system includes an optical transmitter, an optical receiver, and a control apparatus. The control apparatus repeatedly performs an adjustment process for adjusting power of an optical signal of a frequency band to be adjusted while switching the frequency band to be adjusted between at least two frequency bands including at least a frequency band where stimulated Raman scattering occurs among frequency bands that are multiplexed in a multiplexed optical signal transmitted by the optical transmission system. In the adjustment process, when power of an optical signal of the frequency band to be adjusted transmitted from the optical transmitter has been changed, the control apparatus determines the power of the optical signal of the frequency band to be adjusted on the basis of a signal quality measured by the optical receiver that has received the optical signal.

公开(公告)号：US20190273560A1

公开(公告)日：2019-09-05

申请号：US16320065

申请日：2017-07-26

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Kengo HORIKOSHI ,  Seiji OKAMOTO ,  Asuka MATSUSHITA ,  Mitsuteru YOSHIDA ,  Fukutaro HAMAOKA ,  Yoshiaki YAMADA ,  Yoshiaki KISAKA

IPC: H04B10/516 ,  H04J14/08 ,  H04B10/60

Abstract: An optical transmitter of an optical data transmission system transmitting data through an optical fiber transmission path includes a main signal generator that converts first transmission data into a predetermined signal format to generate a first signal, a DCSK modulator that DCSK-modulates second transmission data to generate a second signal, a signal-multiplexer that performs time-division multiplexing of the first signal and the second signal, and an electro-optical converter that converts a multiplexed signal obtained by the time-division multiplexing of the signal-multiplexer from an electric signal into an optical signal, and outputs the optical signal to the optical fiber transmission path.

公开(公告)号：US20250150194A1

公开(公告)日：2025-05-08

申请号：US18832739

申请日：2022-02-10

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Masanori NAKAMURA ,  Takayuki KOBAYASHI ,  Fukutaro HAMAOKA ,  Yutaka MIYAMOTO

IPC: H04J14/06

Abstract: A signal processing method of converting a real number component and an imaginary number component of each polarization of a sub-carrier-multiplexed and polarization-multiplexed received signal into a frequency domain signal; selecting a frequency domain signal corresponding to a sub-carrier; receiving, as input signals, a real number component and an imaginary number component of each polarization of each sub-carrier and frequency inversion and phase conjugation, performing a first equalization process of multiplying, for each sub-carrier and polarization, the real number component and the imaginary number component of each polarization included in the input signal by a complex transfer function and then adding them and performing inverse conversion from a frequency domain signal into a time domain signal and a second equalization process of performing a signal of a real number component obtained by subjecting the real number component of each polarization included in the input signal to frequency inversion and taking complex conjugation and a signal of an imaginary number component obtained by subjecting the imaginary number component to frequency inversion and taking complex conjugation by a complex transfer function and then adding them, and performing inverse conversion from a frequency domain signal into a time domain signal, and adding or subtracting the transmission data bias correction signal to or from the signal obtained by adding the first addition signal and the second addition signal.

公开(公告)号：US20220131619A1

公开(公告)日：2022-04-28

申请号：US17435105

申请日：2020-03-02

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Takeo SASAI ,  Fukutaro HAMAOKA

IPC: H04B10/61

Abstract: An optical reception device includes a nonlinear optical compensation section which performs compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and compensation of a nonlinear optical effect of the received signal N (N is an integer of at least 1) step(s), and a coefficient update section which updates a coefficient so as to optimize the coefficient used in each step of the nonlinear optical compensation section based on a signal having been subjected to the compensation by the nonlinear optical compensation section and a predetermined training signal.

公开(公告)号：US20210218476A1

公开(公告)日：2021-07-15

申请号：US17272790

申请日：2019-08-27

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Akira MASUDA ,  Seiji OKAMOTO ,  Shuto YAMAMOTO ,  Fukutaro HAMAOKA ,  Masanori NAKAMURA ,  Asuka MATSUSHITA ,  Yoshiaki KISAKA

IPC: H04B10/61 ,  H04J14/06 ,  H04B10/079

Abstract: A digital coherent receiver includes: an adaptive equalizer configured to execute, using a first tap coefficient, adaptive equalization processing on a digital signal that corresponds to a signal; a first coefficient updating unit configured to update the first tap coefficient based on the digital signal on which the adaptive equalization processing has not been executed, the digital signal on which the adaptive equalization processing has been executed, and a first step size; a second coefficient updating unit configured to update a second tap coefficient based on the digital signal on which the adaptive equalization processing has not been executed, the digital signal on which the adaptive equalization processing has been executed, and a second step size; and a control unit configured to detect a fluctuation speed of a state of polarization of the digital signal based on the second tap coefficient, and change the first tap coefficient to the updated second tap coefficient if it is determined that the fluctuation speed is higher than or equal to a speed threshold.

公开(公告)号：US20200052793A1

公开(公告)日：2020-02-13

申请号：US16342909

申请日：2017-10-25

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Fukutaro HAMAOKA ,  Seiji OKAMOTO ,  Masanori NAKAMURA ,  Kengo HORIKOSHI ,  Yoshiaki KISAKA

IPC: H04B10/61 ,  H04B3/06 ,  H04L27/01

Abstract: An optical receiver that demodulates an optical modulation signal into a baseband signal, which is an electrical signal, and decodes a received symbol acquired by converting the baseband signal. The optical receiver includes: an analog-to-digital converter that converts the baseband signal into a digital signal of which the number of samples per received symbol is M/N (samples/symbol), M and N being positive integers, M/N being not an integer, and “M >N” being satisfied; and an adaptive equalization processing unit that executes an equalization operation set in advance to output the received symbol on the basis of the digital signal of which the number of samples per received symbol is M/N (samples/symbol) and a predetermined tap coefficient digital signal equalization tap coefficients used for equalization of a signal, the coefficient being updated in any sampling period.

公开(公告)号：US20250038767A1

公开(公告)日：2025-01-30

申请号：US18716635

申请日：2021-12-08

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Takeshi KAKIZAKI ,  Masanori NAKAMURA ,  Fukutaro HAMAOKA

IPC: H03M7/30 ,  H03M9/00 ,  H03M13/11

Abstract: An encoding circuit including: a serial-parallel circuit that performs serial-parallel conversion on input data of a uniform sequence to divide the data into a plurality of pieces of divided data; a sequence conversion unit that encodes the divided data and converts the encoded divided data into divided data of a non-uniform sequence; a parallel-serial circuit that converts the divided data and the divided data of the non-uniform sequence converted by the sequence conversion unit into serial data by performing parallel-serial conversion; an external encoding unit that adds an error correction code to the serial data and encodes the serial data; a division unit that divides the serial data to which the error correction code is added into a plurality of pieces of divided data; a bit conversion circuit that regards the plurality of pieces of divided data divided as data to be transmitted in different subchannels and converts a bit sequence to make a communication channel capacity of each subchannel non-uniform; and a conversion unit that allocates data of a uniform sequence to a least significant bit and allocates data of a non-uniform sequence to a most significant bit among the plurality of pieces of divided data.