公开(公告)号：US20230097193A1

公开(公告)日：2023-03-30

申请号：US17766994

申请日：2019-10-09

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Masanori NAKAMURA ,  Shuto YAMAMOTO ,  Asuka MATSUSHITA ,  Fukutaro HAMAOKA ,  Yoshiaki KISAKA

IPC: H04B10/079 ,  H04B17/15 ,  H04B17/336

Abstract: A tentative decision is made for symbols on the basis of a received signal and a decision threshold, and a tentative decision signal including a sequence of the symbols is output. A scale value indicating a rate of increase or reduction of the received signal or a threshold change rate indicating a degree of change in the decision threshold is updated so that an appearance frequency of each of symbols included in the tentative decision signal matches an appearance frequency of each of symbols in a reference signal obtained by modulating a transmitted signal with a modulation method used in transmission which is shared between a transmitting side and a receiving side, and an SN ratio is calculated using the scale value or the threshold change rate when a degree of agreement between the appearance frequencies is within a predetermined permissible range. When the scale value is updated, a tentative decision is made for the symbols on the basis of the received signal increased or reduced by the updated scale value and the decision threshold, and when the threshold change rate is updated, the tentative decision for the symbols is made on the basis of the received signal and the decision threshold to which the updated threshold change rate is applied.

公开(公告)号：US20210328666A1

公开(公告)日：2021-10-21

申请号：US17269023

申请日：2020-02-03

Applicant: NTT Electronics Corporation ,  NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Akihiro YAMAGISHI ,  Atsushi HOKI ,  Masayuki SUGASAWA ,  Masanori NAKAMURA ,  Asuka MATSUSHITA

IPC: H04B10/071 ,  H04B10/61 ,  H04B10/50 ,  H04B10/588

Abstract: A process of estimating a transfer function or an inverse transfer function of the optical transmitter from first data obtained by the optical receiver when a first known signal is transmitted from the transmitter to the receiver, and a temporary transfer function or a temporary inverse transfer function of the optical receiver, is performed for multiple frequency offsets between the optical transmitter and the optical receiver. At this time, the transfer function or the inverse transfer function of the optical transmitter is estimated by comparing the first data obtained by compensating at least one or none of a temporary transfer function of the optical receiver and transmission path characteristics detected in the receiver, with a first known signal before transmission to which what is not compensated for the first data between the temporary transfer function of the optical receiver and the transmission path characteristic is added.

公开(公告)号：US20220173807A1

公开(公告)日：2022-06-02

申请号：US17593518

申请日：2020-05-21

Applicant: NTT Electronics Corporation ,  NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Akihiro YAMAGISHI ,  Atsushi HOKI ,  Katsuya TANAKA ,  Eisuke TSUCHIYA ,  Masanori NAKAMURA ,  Asuka MATSUSHITA

IPC: H04B10/2507 ,  H04B10/079 ,  H04B10/58

Abstract: Part of compensation of the transmission characteristics of the optical transmitter is performed by transmitter compensation circuitry disposed at a stage prior to the optical transmitter. Remaining part of compensation of the transmission characteristics of the optical transmitter and compensation of the transmission characteristics of the optical receiver is performed by a receiver compensation circuitry disposed at a stage subsequent to the optical receiver. Transmitter compensation characteristics of the transmitter compensation circuitry is set so that a peak-to-average-power ratio of an output signal from the transmitter compensation circuitry becomes equal to or smaller than a predetermined value.

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：US20230097741A1

公开(公告)日：2023-03-30

申请号：US17909884

申请日：2020-03-11

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Kengo HORIKOSHI ,  Masanori NAKAMURA ,  Seiji OKAMOTO ,  Etsushi YAMAZAKI ,  Asuka MATSUSHITA ,  Takeo SASAI

IPC: H04B10/2525 ,  H04B10/61

Abstract: An optical reception apparatus includes a wavelength dispersion compensation unit that performs wavelength dispersion compensation individually on reception signals that are obtained by receiving, by a coherent detecting scheme, an optical signal modulated in a subcarrier modulation scheme and by performing division on a subcarrier-by-subcarrier basis, and a plurality of delay compensation units that compensate for a delay between reception signals at different subcarriers among the reception signals at subcarriers obtained by the wavelength dispersion compensation.

公开(公告)号：US20220069921A1

公开(公告)日：2022-03-03

申请号：US17424766

申请日：2020-01-15

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

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

IPC: H04B10/69 ,  H04B10/548 ,  H04B10/67

Abstract: There are provided an optical transmission apparatus that subjects a transmission signal including a plurality of sequences to Hadamard transform to obtain a signal in which a predetermined delay is added to one of the sequences, optically modulates the obtained signal, and transmits the modulated signal, and an optical reception apparatus that demodulates a reception signal received from the optical transmission apparatus by subjecting the reception signal to adaptive equalization processing with a predetermined number of taps. The optical reception apparatus includes: an adaptive equalization processing unit that subjects the reception signal to adaptive equalization processing of wavelength distortion compensation with a number of taps obtained by subtracting a number in accordance with the delay from the predetermined number of taps; a delay compensation unit that subjects the reception signal subjected to the wavelength distortion compensation to delay compensation in accordance with the delay; and an inverse Hadamard transform unit that subjects the reception signal subjected to the delay compensation to inverse Hadamard transform.

公开(公告)号：US20220216923A1

公开(公告)日：2022-07-07

申请号：US17595161

申请日：2019-05-23

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Asuka MATSUSHITA ,  Masanori NAKAMURA ,  Kengo HORIKOSHI ,  Shoichiro KUWAHARA ,  Yoshiaki KISAKA

IPC: H04B10/61

Abstract: An optical transmission system according to an embodiment includes: an optical transmission unit which modulates an optical signal into which a known signal is inserted and transmits the optical signal; and an optical reception unit which receives the optical signal from the optical transmission unit, wherein the optical reception unit includes: an optical receiver which performs coherent detection of a reception signal of the optical signal received from the optical transmission unit; a receiver transfer function estimation section which estimates a nonlinear response transfer function of the optical receiver based on the known signal included in the reception signal after the detection by the optical receiver; and a receiver compensation section which compensates nonlinear distortion of the reception signal after the detection based on the nonlinear response transfer function which the receiver transfer function estimation section estimates.

公开(公告)号：US20200036440A1

公开(公告)日：2020-01-30

申请号：US16470800

申请日：2017-11-08

Applicant: NTT Electronics Corporation ,  NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Akihiro YAMAGISHI ,  Tetsuya MARUYAMA ,  Masanori NAKAMURA ,  Asuka MATSUSHITA ,  Shogo YAMANAKA

IPC: H04B10/079 ,  H04B10/61 ,  H04B10/58 ,  H04B10/40

Abstract: A method estimating transmission characteristics of an optical transmitter of a transmission unit and an optical receiver of a reception unit, including: estimating a temporary transfer or inverse transfer function of the optical receiver; estimating a transfer or inverse transfer function of the optical transmitter from first data acquired by the reception unit when a first known signal is transmitted from the transmission unit, and the estimated temporary transfer or inverse transfer function of the optical receiver, a difference between the first known signal and an original first known signal is minimized; and estimating a transfer or inverse transfer function of the optical receiver from second data acquired by the reception unit when a second known signal is transmitted from the transmission unit, and the estimated transfer or inverse transfer function of the optical transmitter, a difference between the second known signal and an original second known signal is minimized.

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.