公开(公告)号：US20220149940A1

公开(公告)日：2022-05-12

申请号：US17431504

申请日：2020-02-19

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA ,  Toshiharu ITO

IPC: H04B10/11

Abstract: Tracking control of a light beam is achieved at high speed and with good precision, without requiring preparation of an optical system that causes high signal loss when coupling a reception light beam with an optical fiber. A reception device for optical space communication comprises: fibers having a plurality of propagation modes with spatially different characteristics; an optical coupling system for coupling the reception light beam to the fibers; and a mode separator that separates the coupled light into a plurality of propagation modes, the adjustment axes of the optical coupling system for coupling the reception light beam to one end of the fibers being controlled on the basis of the total coupling strength to all of the modes, and the priority of control of the axes being adjusted on the basis of information about the coupling strength ratio for each mode.

公开(公告)号：US20210083779A1

公开(公告)日：2021-03-18

申请号：US16498138

申请日：2018-03-22

Applicant: NEC CORPORATION

Inventor： Manabu ARIKAWA ,  Yasunori FUTATSUGI ,  Toshiharu ITO

IPC: H04B10/61 ,  H04B7/08

Abstract: A signal processing device combines a plurality of received signals, and includes: a phase reference signal selection means for selecting a signal serving as a phase reference from among the plurality of received signals on the basis of the quality of the plurality of received signals; a relative phase calculation means for obtaining information about the relative phases of the plurality of received signals before the combining; a phase compensation means for performing relative phase compensation on each of the plurality of received signals on the basis of the relative phases; and a phase correction means for calculating a phase correction amount based on the relative phase information and performing phase correction on the received signals, wherein when switching occurs in the selected phase reference signal, the phase correction amount is changed by as much as the relative phase difference between the phase reference signals before and after the switching.

公开(公告)号：US20180323904A1

公开(公告)日：2018-11-08

申请号：US15773035

申请日：2016-11-01

Applicant: NEC CORPORATION

Inventor： Kohei HOSOKAWA ,  Toshiharu ITO ,  Manabu ARIKAWA ,  Seigo TAKAHASHI ,  Takashi ISHIKAWA ,  Yoshimasa ONO

IPC: H04L1/00 ,  H04L27/22 ,  H04B10/61 ,  H04B10/118 ,  H04L27/00

CPC classification number: H04L1/0057 ,  H04B10/118 ,  H04B10/61 ,  H04L27/0014 ,  H04L27/22 ,  H04L2027/0057

Abstract: An appropriate synthesized signal cannot be obtained by only correcting relative phase errors of a plurality of received signals; therefore, a received signal processor according to an exemplary aspect of the present invention includes a plurality of signal-to-noise ratio estimation means for estimating respective signal-to-noise ratios of a plurality of digital signal sequences in which relative phase errors of a plurality of received signal sequences having been corrected; a plurality of temporary decision means for performing symbol decisions of the plurality of digital signal sequences and outputting symbol signal sequences; symbol-map-rotation determination means for determining respective phase rotation amounts of the plurality of digital signal sequences from the plurality of symbol signal sequences and the respective signal-to-noise ratios of the plurality of digital signal sequences; and a plurality of phase rotation means for rotating phases of the plurality of digital signal sequences respectively based on the phase rotation amounts.

公开(公告)号：US20180069625A1

公开(公告)日：2018-03-08

申请号：US15559150

申请日：2016-03-17

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA ,  Emmanuel LE TAILLANDIER DE GABORY ,  Toshiharu ITO

IPC: H04B10/079 ,  H04B10/077 ,  H04B10/25

CPC classification number: H04B10/07951 ,  H04B10/077 ,  H04B10/25 ,  H04B10/2513 ,  H04B10/2581

Abstract: In the optical transmission system to transmit optical signals using a plurality of adjacent paths, it is difficult to detect a delay difference between a plurality of paths and chromatic dispersion with a high degree of accuracy due to a crosstalk; therefore, a method for detecting optical signal information according to an exemplary aspect of the present invention includes generating a plurality of data signal sequences corresponding to a plurality of paths multiplexed spatially, each of the plurality of data signal sequences obtained by inserting periodically a training signal with a plurality of frequency components in a data signal, in the plurality of data signal sequences, the training signals respectively included in the data signal sequences to be propagated through adjacent paths at least having different frequency components from each other at the same timing, each of a plurality of the training signals included in one of the data signal sequences having the plurality of frequency components whose frequency difference differing depending on a position to be inserted; and calculating a propagation delay difference between the plurality of paths and chromatic dispersion amounts in the plurality of paths from the plurality of frequency components included in the training signals having been propagated through the plurality of paths by optical signals.

公开(公告)号：US20240214247A1

公开(公告)日：2024-06-27

申请号：US18538140

申请日：2023-12-13

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA

IPC: H04L25/03

CPC classification number: H04L25/03159 ,  H04L25/03834

Abstract: A frequency domain conversion unit converts an input signal of oversampling of a first predetermined multiple into a signal in a frequency domain. A rate conversion unit converts a signal being multiplied by a coefficient by a frequency domain filter into a signal of oversampling of a second predetermined multiple. A time domain conversion unit converts the converted signal into a signal in a time domain. A gradient calculation unit calculates a gradient of a loss function for a filter coefficient by using an error back propagation method using, as the loss function, magnitude of a difference between a signal of oversampling of the second predetermined multiple being converted into a signal in the time domain, and a predetermined value determined by oversampling of the second predetermined multiple. A coefficient updating unit updates the coefficient of the frequency domain filter, based on the calculated gradient.

公开(公告)号：US20240007193A1

公开(公告)日：2024-01-04

申请号：US18032647

申请日：2021-04-20

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA

IPC: H04B10/61 ,  H04B10/2507 ,  H04J14/06

CPC classification number: H04B10/61 ,  H04J14/06 ,  H04B10/2507

Abstract: A coherent receiving circuit coherently receives a signal transmitted via a transmission line. A filter group includes a first WL filter, a filter layer, and a second WL filter being connected in tandem. A coefficient updating means adaptively controls filter coefficients of the first WL filter and the second WL filter by using an error back propagation method, based on a difference between an output signal being output from the filter group and a predetermined value thereof. A first distortion detection means detects in-receiver distortion, based on a filter coefficient of the first WL filter. A second distortion detection means detects in-transmitter distortion, based on a filter coefficient of the second WL filter.

公开(公告)号：US20220224418A1

公开(公告)日：2022-07-14

申请号：US17613149

申请日：2020-05-13

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA ,  Toshiharu ITO

IPC: H04B10/61 ,  H04B10/118

Abstract: A receiving optical system control device according to the present invention has: a light intensity calculation means for calculating, from a reception signal acquired by receiving, for each of plurality of mode light beams which are of the incident optical beams and which have been coupled to a plurality of propagation modes of the optical transmission medium by an optical system provided with a variable mechanism, the light intensity of each of the mode light beams; an optical phase calculation means for calculating the optical phase of each of the mode light beams from the reception signal; a relative phase calculation means for calculating the relative phase between the plurality of mode light beams from the optical phases; and a control amount calculation means for calculating the control amount of the variable mechanism from the light intensity and the relative phase.

公开(公告)号：US20210159976A1

公开(公告)日：2021-05-27

申请号：US17044213

申请日：2019-03-22

Applicant: NEC CORPORATION

Inventor： Manabu ARIKAWA ,  Toshiharu ITO

IPC: H04B10/11 ,  H04J14/06

Abstract: An optical reception terminal includes a plurality of matrix filters (40, 41) respectively provided for a plurality of modes and configured to perform polarization separation and equalization on a coherently received signal in a corresponding mode, and two combining filters (50,51) respectively provided for two polarizations and configured to combine signals in corresponding polarization among signals output from the plurality of matrix filters (40, 41) after weighting the signals. Filter coefficients of the plurality of matrix filters (40, 41) and weighting coefficients of the two combining filters (50,51) are controlled based on a deviation from a desired state of both signals in two polarizations after combining by the two combining filters (50,51), so as to minimize a sum of deviations.

公开(公告)号：US20190353768A1

公开(公告)日：2019-11-21

申请号：US16472940

申请日：2016-12-26

Applicant: NEC Corporation

Inventor： Osamu HOSHUYAMA ,  Manabu ARIKAWA

IPC: G01S13/28 ,  G01S7/292 ,  G01S13/90 ,  G01S7/40

Abstract: The present invention is a signal processing device that efficiently removes multiple types of interference waves mixed in with a received signal. This signal processing device is provided with: a first extraction unit that performs deconvolution with respect to a cross-correlation of a reference signal and a received signal and to an autocorrelation of the reference signal, and extracts a channel response to the reference signal; a second extraction unit that extracts a main channel response corresponding to the reference signal from the channel response; and a removal unit that restores a signal by performing convolution with respect to the reference signal and the main channel response, and removes the restored signal from the received signal.

公开(公告)号：US20170264365A1

公开(公告)日：2017-09-14

申请号：US15529145

申请日：2015-11-18

Applicant: NEC Corporation

Inventor： Seigo TAKAHASHI ,  Toshiharu ITO ,  Akihiro TANAKA ,  Kohei HOSOKAWA ,  Manabu ARIKAWA

IPC: H04B10/118 ,  H04B10/548 ,  H04B10/112 ,  H04B10/2581 ,  H04B10/67

CPC classification number: H04B10/118 ,  H04B10/112 ,  H04B10/2581 ,  H04B10/548 ,  H04B10/676

Abstract: It is difficult in a free space optical receiver to satisfy both of the stable receiving and the highly sensitive receiving; therefore, a free space optical receiver according to an exemplary aspect of the present invention includes a light collecting means for collecting laser light having propagated through a free space transmission path; a multimode light generating means for receiving input of the laser light collected by the light collecting means, exciting multimode light, and outputting multimode propagation light including a plurality of propagation mode light beams with a number smaller than a number of multimode light beams possible to be excited; and a mode separating means for separating the multimode propagation light into the plurality of propagation mode light beams and outputting the plurality of propagation mode light beams.