公开(公告)号：US20240283544A1

公开(公告)日：2024-08-22

申请号：US18570122

申请日：2021-06-23

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Masanori NAKAMURA ,  Takeo SASAI ,  Etsushi YAMAZAKI ,  Yoshiaki KISAKA

IPC: H04B10/58 ,  H04B10/54 ,  H04B10/69

CPC classification number: H04B10/58 ,  H04B10/54 ,  H04B10/6971

Abstract: A transmission apparatus causes a digital-to-analog conversion unit to perform digital-to-analog conversion on transmission signals pre-equalized by using a compensation filter, then converts electrical signals into optical signals, and outputs the optical signals. A receiving apparatus converts the received optical signals into received electrical signals, then performs analog-to-digital conversion, and demodulates the received signals. A scale estimation unit calculates a slope near an amplitude 0 in a correlation between an amplitude distribution of the pre-equalized transmission signals and an amplitude distribution of the received signals. A scale unit scales amplitude of the received signals on the basis of the calculated slope. A coefficient estimation unit calculates a filter coefficient of the compensation filter on the basis of the pre-equalized transmission signals and the scaled received signals. An output amplitude level determination unit determines output levels of the transmission signals from the digital-to-analog conversion unit on the basis of a correlation between distributions of amplitudes of non-pre-equalized and pre-equalized transmission signals.

公开(公告)号：US20250105917A1

公开(公告)日：2025-03-27

申请号：US18727661

申请日：2022-01-21

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Takeo SASAI ,  Etsushi YAMAZAKI ,  Masanori NAKAMURA

IPC: H04B10/073 ,  H04B10/2543 ,  H04B10/61

Abstract: 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.

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：US20230421420A1

公开(公告)日：2023-12-28

申请号：US18038194

申请日：2020-11-25

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Etsushi YAMAZAKI ,  Seiji OKAMOTO ,  Masanori NAKAMURA ,  Kengo HORIKOSHI ,  Takeo SASAI ,  Yoshiaki KISAKA

IPC: H04L27/01 ,  H04L25/03

CPC classification number: H04L27/01 ,  H04L25/03057

Abstract: An aspect of the present invention is an adaptive equalization filter for an optical transmission system, including: a main signal filter; and a coefficient computation unit that updates the filter coefficient of the main signal filter. The pre-stage filter and the post-stage filter receive a sample of the main signal as an input. The pre-stage coefficient computation unit obtains the filter coefficient of the pre-stage filter by feedback control using the gradient method. The post-stage coefficient computation unit obtains the filter coefficient of the post-stage filter by feedforward control. The convolution computation unit obtains the filter coefficient of the main signal filter by convolution computation of the filter coefficient of the pre-stage filter obtained by the pre-stage coefficient computation unit and the filter coefficient of the post-stage filter obtained by the post-stage coefficient computation unit.

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：US20220416890A1

公开(公告)日：2022-12-29

申请号：US17782957

申请日：2019-12-16

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Takeo SASAI ,  Fukutaro HAMAOKA ,  Masanori NAKAMURA ,  Seiji OKAMOTO

IPC: H04B10/2543 ,  H04B10/61

Abstract: An optical reception device includes a coefficient update section which optimizes a dispersion coefficient used in compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and a phase rotation amount used in compensation of a nonlinear optical effect of the received signal, and a transmission characteristic estimation section which estimates a transmission characteristic of a transmission line by using the optimized dispersion coefficient and the optimized phase rotation amount.