公开(公告)号：US20230291482A1

公开(公告)日：2023-09-14

申请号：US18012051

申请日：2020-07-30

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shuto YAMAMOTO ,  Masanori NAKAMURA ,  Hiroki TANIGUCHI ,  Yoshiaki KISAKA

IPC: H04B10/58 ,  H04B10/2513

CPC classification number: H04B10/58 ,  H04B10/2513

Abstract: An optical transmission system is an optical transmission system for transmitting a signal from an optical transmitter to an optical receiver via at least a transmission line among one or more optical nodes and the transmission line, wherein the optical transmitter includes a digital filter that compensates for, between ripple components that are micro-fluctuating components in a frequency region representing a transmission characteristic of the signal in the optical transmitter and the optical receiver and non-ripple components of the transmission characteristic, at least the ripple components of the transmission characteristic, and at least one of the optical node and the optical transmitter includes an optical filter that compensates for the non-ripple components of the transmission characteristic.

公开(公告)号：US20230261759A1

公开(公告)日：2023-08-17

申请号：US18017890

申请日：2020-08-03

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shuto YAMAMOTO ,  Masanori NAKAMURA ,  Hiroki TANIGUCHI ,  Yoshiaki KISAKA

IPC: H04B10/69

CPC classification number: H04B10/69

Abstract: According to an aspect of the present invention, there is provided an optical signal demodulator including an optical reception unit, an AD conversion unit, a digital signal processing unit, and a signal determination unit, in which the signal determination unit includes: a spectrum shaping filter processing unit that receives a reception signal sequence of the digital signal from the digital signal processing unit and outputs a value obtained by performing a convolution operation on the reception signal sequence which is received; a transmission line simulation filter processing unit that outputs a value obtained by performing a convolution operation on a candidate signal sequence which is determined based on a symbol transition of the reception signal; an error information acquisition unit that acquires error information between the value output from the spectrum shaping filter processing unit and the value output from the transmission line simulation filter processing unit; and a bit determination unit that determines a value of a bit included in the symbol transmitted by a transmission unit based on the error information acquired by the error information acquisition unit.

公开(公告)号：US20220224415A1

公开(公告)日：2022-07-14

申请号：US17614686

申请日：2019-06-06

Applicant: Nippon Telegraph and Telephone Corporation

Inventor： Masanori NAKAMURA ,  Seiji Okamoto ,  Kengo HORIKOSHI ,  Shuto YAMAMOTO ,  Takayuki KOBAYASHI ,  Yoshiaki KISAKA ,  Masahito TOMIZAWA

IPC: H04B10/2513 ,  H04B10/61 ,  H03H17/02

Abstract: An electric digital received signal obtained from a received optical signal is segmented into blocks of a certain length with an overlap of a length determined in advance with an adjacent block. Fourier transformation is performed for each of the blocks. The blocks subjected to the Fourier transformation are stored consecutively in time series, a coefficient determined based on a wavelength dispersion compensation amount according to one of frequency positions and a delay amount according to one of the frequency positions and one of time positions is applied to each of frequency component values included in a plurality of the stored blocks, and the blocks to which the coefficient has been applied and which are obtained by adding up the frequency component values to which the coefficient has been applied for each of the frequency positions are generated. Inverse Fourier transformation is performed on the generated blocks to which the coefficient has been applied. A part of the overlap subjected to the inverse Fourier transformation is removed.

公开(公告)号：US20200244369A1

公开(公告)日：2020-07-30

申请号：US16842117

申请日：2020-04-07

Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION

Inventor： Shuto YAMAMOTO ,  Akira MASUDA ,  Yoshiaki SONE ,  Mitsunori FUKUTOKU

IPC: H04B10/54 ,  H04J14/02

Abstract: An encoding device includes an encoding unit, DA converters, light sources, intensity modulators, and wavelength multiplexers. The encoding unit adds (NM/2) to an encoded signal having a negative minimum value in a range of the encoded signal among encoded signals of N channels of (NM+1) values obtained by calculating an inner product of a Hadamard matrix of N rows and N columns and a matrix having elements of N intensity signals of (M+1) values. The DA converters of the channels convert the encoded signals of the channels from digital signals into electrical analog signals. The light sources output light of wavelengths for use in the channels. The light intensity modulators of the channels intensity-modulate the light output from the light sources with the encoded signals converted into the electrical analog signals by the DA converters. The wavelength multiplexer outputs a wavelength-multiplexed signal obtained by wavelength-multiplexing the light intensity-modulated by the light intensity modulators.