公开(公告)号：US20240056195A1

公开(公告)日：2024-02-15

申请号：US17766296

申请日：2020-09-11

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA

IPC: H04B10/61

CPC classification number: H04B10/612 ,  H04B10/6165

Abstract: In order to suppress wrong convergence of a filter coefficient without reducing data communication speed, this filter coefficient update amount output device is provided with: a first output unit which outputs a first coefficient update amount derived from a difference between a temporary determination result regarding a processed reception sample value that is the reception sample value on which filter processing by a digital filter has been performed and the processed reception sample value; a second output unit which outputs a second coefficient update amount derived from a gradient with respect to the filter coefficient such that the magnitude of a difference between statistical information on the processed reception sample value during some duration of time, and a set value regarding the statistical information is minimized; and a third output unit which outputs the coefficient update amount derived from the first coefficient update amount and the second coefficient update amount.

公开(公告)号：US20240283546A1

公开(公告)日：2024-08-22

申请号：US18430846

申请日：2024-02-02

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA

IPC: H04B10/69 ,  H04B10/2513

CPC classification number: H04B10/6971 ,  H04B10/2513

Abstract: A frequency domain filter receives an input signal in a frequency domain being blocked by an overlap-save method. The frequency domain filter multiplies the input signal in the frequency domain by a coefficient for each frequency. A coefficient updating unit adaptively updates a filter coefficient of the frequency domain filter. A constraint operation unit performs an operation of a constraint on a filter coefficient of the frequency domain filter in such a way as not to be affected by distortion caused by wraparound from both ends of a block to the output signal. A frequency at which the constraint operation unit performs the operation of the constraint is lower than a frequency at which the coefficient updating unit adaptively updates the filter coefficient of the frequency domain filter.

公开(公告)号：US20200044737A1

公开(公告)日：2020-02-06

申请号：US16605321

申请日：2018-04-18

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA ,  Toshiharu ITO

IPC: H04B10/118 ,  H04B10/61 ,  H04B17/336

Abstract: The signal combining device includes: a plurality of first filters to subject each of a plurality of reception signals to processing with first filter coefficients, the plurality of reception signals being generated by subjecting optical signals to coherent detection; a plurality of second filters to subject outputs of the first filters to processing with second filter coefficients; a combiner to output combined signals acquired by combining outputs of the second filters; and a controller to perform adaptive control for each of the first filter coefficients and each of the second filter coefficients with different step sizes in each other, so that the combined signals are in a predetermined state, based on the reception signals input to the first filters and the combined signals, and to switch an update state of a filter coefficient of each of the first filters, based on magnitudes of the second filter coefficients.

公开(公告)号：US20200015099A1

公开(公告)日：2020-01-09

申请号：US16483083

申请日：2018-02-14

Applicant: NEC Corporation

Inventor： Yasunori FUTATSUGI ,  Toshiharu ITO ,  Manabu ARIKAWA

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

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：US20220385374A1

公开(公告)日：2022-12-01

申请号：US17726870

申请日：2022-04-22

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA

IPC: H04B10/61 ,  H04L25/03 ,  H04B10/58

Abstract: A detector coherent-receives a signal being transmitted from a transmitter. A filter group includes a plurality of filters connected in series along a signal path of a reception signal. The plurality of filters include a plurality of non-linear distortion compensation filters and one or more linear distortion compensation filters. A coefficient updating unit controls a filter coefficient of the plurality of non-linear distortion compensation filters and a filter coefficient of at least some of the linear distortion compensation filters. The coefficient updating unit adaptively controls the filter coefficient, 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 of the output signal.

公开(公告)号：US20200304213A1

公开(公告)日：2020-09-24

申请号：US16088328

申请日：2017-03-17

Applicant: NEC Corporation

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

IPC: H04B10/69 ,  H04B10/11 ,  H04B17/336

Abstract: The objective of the present invention is to reduce the size of a receiving device circuit in an optical space communication system while maintaining communication stability. A data receiving device which decodes one item of data from a plurality of input signals includes: two or more digital signal processing means for subjecting the plurality of input signals to signal processing; a first recording means for temporarily recording the plurality of input signals; a SN ratio estimating means for estimating S/N ratios of each of the plurality of input signals and determining the number of the plurality of input signals to be combined, and the signals to be combined; and a scheduling means for carrying out overall control on the basis of the results from the SN ratio estimating means.

公开(公告)号：US20190013875A1

公开(公告)日：2019-01-10

申请号：US16066854

申请日：2017-01-10

Applicant: NEC CORPORATION

Inventor： Manabu ARIKAWA ,  Toshiharu ITO

IPC: H04B10/61

CPC classification number: H04B10/6165 ,  H04B10/1121 ,  H04B10/118 ,  H04L27/063 ,  H04L27/22

Abstract: In order to increase a compensation range for Doppler shift compensation, this digital signal processing circuit is provided with a Doppler shift compensation unit which, on the basis of a sample sequence signal which is oversampled at N (where N is an integer at least equal to 2) times a symbol rate and includes a central sample corresponding to the timing at a symbol center, and a transition sample corresponding to the timing of a symbol transition, finds a Doppler shift amount included in the sample sequence signal and performs Doppler shift compensation. The Doppler shift compensation unit includes a symbol determining unit which performs a symbol determination with respect to the central sample and a determination with respect to the transition sample. The Doppler shift compensation unit switches between these determinations for each corresponding sample and performs said determinations in order to obtain a phase difference and thereby detect the Doppler shift amount.

公开(公告)号：US20180234180A1

公开(公告)日：2018-08-16

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: H04B10/116 ,  H04B10/50 ,  H04B10/61

CPC classification number: H04B10/116 ,  H04B10/1121 ,  H04B10/118 ,  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：US20180212681A1

公开(公告)日：2018-07-26

申请号：US15745254

申请日：2016-07-15

Applicant: NEC CORPORATION

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

IPC: H04B10/118 ,  H04B10/00

CPC classification number: H04B10/118 ,  H04B10/112 ,  H04B10/12 ,  H04B10/40 ,  H04B10/50 ,  H04B10/60

Abstract: A receiving-side splitter 4 that constitutes part of an optical communication device 1 splits a receiving-side signal light into a plurality of lights at a splitting ratio according to the intensity distribution of mutually different propagation modes included in the receiving-side signal light passed through a transmission medium 3. A transmission-side splitter 10 splits a transmission-side signal light into a plurality of-lights. A signal processing device 5 detects the light intensity and/or the phase of the receiving-side signal light, and sets a control target value for the light intensity and/or the phase of the transmission-side signal light to a value according to the result of the detection. A modulator 9 adjusts the light intensity or the phase of a the transmission-side signal light so that the light intensity or phase equals the set value. A multiplexer 8 multiplexes the plurality of transmission-side signal lights.

公开(公告)号：US20230130197A1

公开(公告)日：2023-04-27

申请号：US17918179

申请日：2021-02-15

Applicant: NEC Corporation

Inventor： Manabu ARIKAWA

IPC: H04B10/61

Abstract: In order to reduce the amount of calculation for signal distortion compensation, this filter coefficient updating device for updating the filter coefficients of a plurality of filters in a filter layer comprising the plurality of filters, which are connected in a first plurality of stages with respect to received data, is provided with: a deriving unit for deriving the respective filter coefficients of the plurality of filters in one or a plurality of stages included in the first plurality of stages, by means of output data output from the last stage of the first plurality of stages; and an updating unit for updating each of the filter coefficients.