公开(公告)号：US11277758B2

公开(公告)日：2022-03-15

申请号：US16483083

申请日：2018-02-14

Applicant: NEC Corporation

Inventor： Yasunori Futatsugi ,  Toshiharu Ito ,  Manabu Arikawa

IPC: H04W24/02 ,  H04L1/08 ,  H04L12/26 ,  H04W40/12 ,  H04L43/0888

Abstract: It is difficult in related communication apparatuses to avoid degradation of communication quality due to fading and achieve sufficient throughput performance; therefore, a communication apparatus according to an exemplary aspect of the present invention includes fade avoidance rate calculation means for calculating, from a time variation in communication quality information and a transmission pattern in transmitting a communication packet repeatedly, a fade avoidance rate of a probability that the communication packet lies outside a fade duration, with respect to each transmission pattern; throughput calculation means for calculating, from the transmission pattern and the fade avoidance rate, a throughput of the communication packet with respect to each transmission pattern; and transmission pattern determination means for determining an optimum transmission pattern, of the transmission pattern, by which the throughput is maximized.

公开(公告)号：US10313011B2

公开(公告)日：2019-06-04

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 ,  H04B10/112 ,  H04B10/2581 ,  H04B10/548 ,  H04B10/67

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.

公开(公告)号：US10122447B2

公开(公告)日：2018-11-06

申请号：US15123103

申请日：2014-03-13

Applicant: NEC Corporation

Inventor： Seigo Takahashi ,  Toshiharu Ito ,  Kohei Hosokawa

IPC: H04B10/11 ,  H04B10/112 ,  H04B10/60 ,  H04J14/02

Abstract: It is impossible to prevent the deterioration of the coupling efficiency between received light and a single mode fiber, and difficult to achieve a higher transmission rate, with respect to a free space optical communication receiver; therefore, a free space optical receiver according to an exemplary aspect of the present invention includes light collecting means for collecting laser light having propagated through a free space transmission path; mode controlling means for separating the laser light collected by the light collecting means into a plurality of propagation mode beams depending on a wave-front fluctuation of the laser light and outputting the propagation mode beams; a plurality of single mode transmission media for guiding the plurality of propagation mode beams, respectively; and a plurality of light receiving means for receiving the plurality of propagation mode beams respectively through the plurality of single mode transmission media.

公开(公告)号：US11849348B2

公开(公告)日：2023-12-19

申请号：US17616231

申请日：2020-02-05

Applicant: NEC Corporation

Inventor： Yohei Hasegawa ,  Toshiharu Ito

IPC: H04W28/04 ,  H04L1/00 ,  H04L1/20

CPC classification number: H04W28/04 ,  H04L1/0003 ,  H04L1/203

Abstract: A communication system includes: a transmitting-side terminal; a transmitting-side communication apparatus configured to receive data transmitted by the transmitting-side terminal and transmit the received data by radio transmission to a receiving-side communication apparatus; and the receiving-side communication apparatus configured to transmit the data received by radio transmission from the transmitting-side communication apparatus to a receiving-side terminal. The transmitting-side terminal includes a control unit configured to control a transmission speed of the data addressed to the receiving-side terminal based on a first error rate that is an error rate of radio transmission from the transmitting-side communication apparatus to the receiving-side communication apparatus and a second error rate that is an error rate of transmission from the transmitting-side terminal to the receiving-side terminal.

公开(公告)号：US11139896B2

公开(公告)日：2021-10-05

申请号：US16498138

申请日：2018-03-22

Applicant: NEC CORPORATION

Inventor： Manabu Arikawa ,  Yasunori Futatsugi ,  Toshiharu Ito

IPC: H04B10/06 ,  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：US10735093B2

公开(公告)日：2020-08-04

申请号：US16466702

申请日：2017-12-11

Applicant: NEC Corporation

Inventor： Yoshimasa Ono ,  Toshiharu Ito

IPC: H04B10/079 ,  H04B10/118

Abstract: An optical space communication device includes first and second optical antennas that transmit first and second transmission light and receive first and second reception light, first and second delay circuits that provide a delay to transmission data included in the first and second transmission light, third and fourth delay circuits that provide a delay to reception data included in the first and second reception light, and a receiver that sets a delay of at least one of the first delay circuit and the second delay circuit and sets a delay of at least one of the third delay circuit and the fourth delay circuit, based on delays between the first and third delay circuits and the first optical antenna, delays between the second and fourth delay circuits and a fourth optical antenna, and delays between a communication destination and the third and fourth delay circuits.

公开(公告)号：US10454577B2

公开(公告)日：2019-10-22

申请号：US15751369

申请日：2016-08-17

Applicant: NEC CORPORATION

Inventor： Seigo Takahashi ,  Toshiharu Ito ,  Kohei Hosokawa ,  Manabu Arikawa ,  Yoshimasa Ono ,  Takashi Ishikawa

IPC: H04B10/118 ,  H04B10/112 ,  H04B10/116 ,  H04B10/50 ,  H04B10/61

Abstract: It is difficult in a free space optical transmitter to transmit a beacon beam stably at low cost, and that it is impossible to maintain stable tracking; therefore, a free space optical transmitter according to an exemplary aspect of the present invention includes a laser beam transmitting means for transmitting a plurality of laser beams capable of interfering with each other and differing in one of an optical frequency and a time variation in a phase difference; and a wavefront control beam transmitting means for transmitting, to a free space, a plurality of wavefront control beams obtained by making each of the plurality of laser beams have a different wavefront.

公开(公告)号：US10256904B2

公开(公告)日：2019-04-09

申请号：US15327862

申请日：2015-07-17

Applicant: NEC Corporation

Inventor： Seigo Takahashi ,  Toshiharu Ito ,  Kohei Hosokawa

IPC: H04B10/112 ,  H04B10/60

Abstract: The circuit size of a signal processing circuit increases in a free space optical receiver, which increases in cost, because the signal processing becomes complex attempting to improve the coupling efficiency between received light and a fiber; 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 multi-mode transmission medium for receiving input of the laser light and outputting multi-mode light; a multi-mode signal processing means for outputting a plurality of received electrical signals based on part of the multi-mode light; a monitor means for monitoring signal information based on the multi-mode light; a control means for controlling an operation of the multi-mode signal processing means based on the signal information; and a signal processing means for performing signal processing on the plurality of received electrical signals and outputting an output signal synthesized from the plurality of received electrical signals.

公开(公告)号：US11728888B2

公开(公告)日：2023-08-15

申请号：US17431504

申请日：2020-02-19

Applicant: NEC Corporation

Inventor： Manabu Arikawa ,  Toshiharu Ito

IPC: H04B10/11

CPC classification number: 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：US10511409B2

公开(公告)日：2019-12-17

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 ,  H04B10/118 ,  H04B10/61 ,  H04L27/00

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.