Patents by Inventor Etsushi Yamazaki

Etsushi Yamazaki has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20240048250
    Abstract: An aspect of the present invention is a wireless communication device including a water flow generator that controls a shape of a partial region on a water surface, and an emission unit that emits a wave carrying information toward the region.
    Type: Application
    Filed: December 16, 2020
    Publication date: February 8, 2024
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kazumitsu SAKAMOTO, Kento YOSHIZAWA, Takeshi KINOSHITA, Etsushi YAMAZAKI, Takayuki MIZUNO, Takuya OHARA
  • Publication number: 20230421420
    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.
    Type: Application
    Filed: November 25, 2020
    Publication date: December 28, 2023
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Etsushi YAMAZAKI, Seiji OKAMOTO, Masanori NAKAMURA, Kengo HORIKOSHI, Takeo SASAI, Yoshiaki KISAKA
  • Patent number: 11799547
    Abstract: A signal processing apparatus includes: a coefficient update unit configured to approximate a characteristic of a transmission line of an optical signal by a first tap coefficient vector of which an L0 norm is a predetermined value or less; a zeroing unit configured to generate a second tap coefficient vector by replacing, with 0, a tap coefficient of which an absolute value is less than a threshold among tap coefficients of the first tap coefficient vector; and an adaptive filter configured to perform, based on the second tap coefficient vector, adaptive equalization processing on a digital signal corresponding to an optical signal received via the transmission line.
    Type: Grant
    Filed: September 17, 2019
    Date of Patent: October 24, 2023
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kengo Horikoshi, Masanori Nakamura, Seiji Okamoto, Hideki Nishizawa, Etsushi Yamazaki
  • Publication number: 20230291471
    Abstract: A phase difference distribution estimation method includes: receiving an optical signal via a space and detecting a phase of the optical signal; calculating characteristic values related to characteristics of the atmosphere through which the optical signal propagates from the optical signal received in the receiving; estimating a phase difference distribution of an optical signal received after a certain period of time, on the basis of the characteristic values calculated in the calculating; and controlling a phase of an optical signal in the receiving on the basis of the phase difference distribution estimated in the estimating.
    Type: Application
    Filed: June 23, 2020
    Publication date: September 14, 2023
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yohei KATAYAMA, Kazumitsu SAKAMOTO, Kento YOSHIZAWA, Hiroyuki FUKUMOTO, Takuya OHARA, Takeshi KINOSHITA, Etsushi YAMAZAKI, Takayuki MIZUNO
  • Publication number: 20230291479
    Abstract: A communication device includes: a light output unit for outputting light; a light splitting unit for splitting the light output by the light output unit into a plurality of split beams; and a plurality of spatial optical communication units provided in correspondence to the plurality of split beams, wherein the spatial optical communication units respectively transmit a corresponding split beam which is input from the light splitting unit to a partner communication device across space.
    Type: Application
    Filed: June 24, 2020
    Publication date: September 14, 2023
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Yohei KATAYAMA, Kazumitsu SAKAMOTO, Kento YOSHIZAWA, Hiroyuki FUKUMOTO, Takuya OHARA, Takeshi KINOSHITA, Etsushi YAMAZAKI, Takayuki MIZUNO
  • Publication number: 20230224036
    Abstract: A switching instructor outputs a beacon light selection notification signal when a optical transceiver transmits a optical wireless signal of a beacon light and outputs a signal light selection notification signal when the optical transceiver transmits the optical wireless signal of the signal light. A spatial light modulator controller performs switching of a control signal given to each of the plurality of pixels of a spatial light modulator to: cause a phase delay in light received by each of the plurality of pixels of the spatial light modulator when the switching instructor outputs the beacon light selection notification signal and cause a phase delay in light received by each of the plurality of pixels of the spatial light modulator when the switching instructor outputs the signal light selection notification signal.
    Type: Application
    Filed: June 15, 2020
    Publication date: July 13, 2023
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kazumitsu SAKAMOTO, Yohei KATAYAMA, Kento YOSHIZAWA, Takeshi KINOSHITA, Etsushi YAMAZAKI, Takayuki MIZUNO, Takuya OHARA
  • Publication number: 20230208521
    Abstract: In an optical wireless communication system including: an optical wireless communication apparatus that moves along with a first optical wireless station; and a second optical wireless station opposed to the first optical wireless station, the optical wireless communication apparatus includes at least one reference light transmitting unit that transmits reference light to the second optical wireless station with a position in front in a moving direction of the first optical wireless station defined as a transmission position, the second optical wireless station includes a reference light receiving unit that receives the reference light transmitted from the at least one reference light transmitting unit, an estimation unit that estimates an influence of atmospheric air on transmission of signal light based on a reception state of the reference light received by the reference light receiving unit, a compensation unit that performs compensation processing on the signal light based on the influence of the atmosph
    Type: Application
    Filed: June 12, 2020
    Publication date: June 29, 2023
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kazumitsu SAKAMOTO, Yohei KATAYAMA, Kento YOSHIZAWA, Takeshi KINOSHITA, Etsushi YAMAZAKI, Takayuki MIZUNO, Takuya OHARA
  • Patent number: 11671119
    Abstract: A signal processing device includes a distributing unit and a plurality of correcting units with different processing performance, the distributing unit distributes a bit sequence having a first number of bits to the first correcting unit, and a bit sequence having a second number of bits less than the first number of bits to the second correcting unit having lower processing performance than the first correcting unit, the first correcting unit applies error correction processing to the bit sequence having the first number of bits distributed to the first correcting unit, and the second correcting unit applies error correction processing to the bit sequence having the second number of bits distributed to the second correcting unit.
    Type: Grant
    Filed: May 9, 2019
    Date of Patent: June 6, 2023
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Seiji Okamoto, Etsushi Yamazaki, Masanori Nakamura, Yoshiaki Kisaka, Masahito Tomizawa
  • Publication number: 20230097741
    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.
    Type: Application
    Filed: March 11, 2020
    Publication date: March 30, 2023
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kengo HORIKOSHI, Masanori NAKAMURA, Seiji OKAMOTO, Etsushi YAMAZAKI, Asuka MATSUSHITA, Takeo SASAI
  • Publication number: 20220303003
    Abstract: A signal processing apparatus includes: a coefficient update unit configured to approximate a characteristic of a transmission line of an optical signal by a first tap coefficient vector of which an LO norm is a predetermined value or less; a zeroing unit configured to generate a second tap coefficient vector by replacing, with 0, a tap coefficient of which an absolute value is less than a threshold among tap coefficients of the first tap coefficient vector; and an adaptive filter configured to perform, based on the second tap coefficient vector, adaptive equalization processing on a digital signal corresponding to an optical signal received via the transmission line.
    Type: Application
    Filed: September 17, 2019
    Publication date: September 22, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kengo HORIKOSHI, Masanori NAKAMURA, Seiji OKAMOTO, Hideki NISHIZAWA, Etsushi YAMAZAKI
  • Patent number: 11349572
    Abstract: An optical communication system is provided in which a serial/parallel converting unit outputs bit sequences of sequence groups a number of which is determined by a logarithmic value and a bit sequence of a highest-order sequence group, a converting unit converts the bit sequence of the sequence group input to the converting unit into a bit sequence for which a probability of occurrence of 0 or a probability of occurrence of 1 is a predetermined probability of occurrence, a selecting unit acquires a bit sequence for which the probability of occurrence is converted by a converting unit higher in order than the converting unit for the selecting unit, and selects an order of output of a symbol to other selecting units in the sequence groups higher in order than the selecting unit in accordance with the acquired bit sequence, a multiplication unit multiplies a value representing the symbol selected by a highest-order selecting unit, by a number in accordance with the bit sequence of the highest order sequence gro
    Type: Grant
    Filed: May 8, 2019
    Date of Patent: May 31, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Masanori Nakamura, Seiji Okamoto, Etsushi Yamazaki, Yoshiaki Kisaka
  • Patent number: 11329764
    Abstract: An error correction device includes a first correction unit which performs error correction decoding of data by a repetitive operation, having a full operation state in which the error correction decoding is repeated until convergence is obtained and a save operation state in which the number of times of the repetitive operation is restricted to a predetermined number. An error information estimation unit estimates an input error rate or an output error rate of the first correction unit using a decoding result of the first correction unit, and a control unit which controls transition between the full operation state and the save operation state based on at least one piece of information of the input error rate, the output error rate, and an operation time of the first correction unit. It is thus possible to provide an error correction device that can improve a transmission characteristic while suppressing power consumption.
    Type: Grant
    Filed: December 20, 2018
    Date of Patent: May 10, 2022
    Assignees: NTT ELECTRONICS CORPORATION, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Fumiaki Nakagawa, Yasuharu Onuma, Katsuichi Oyama, Yasuyuki Endoh, Etsushi Yamazaki, Yoshiaki Kisaka, Masahito Tomizawa
  • Patent number: 11323238
    Abstract: A frame synchronization apparatus (10) according to this invention includes a multiplication unit (11) configured to multiply a received signal by an inverse complex number of a predetermined synchronization pattern with respect to a predetermined signal point on a complex space diagram for each of a plurality of symbols of the received signal, an addition average unit (12) configured to perform addition averaging of outputs from the multiplication unit for the plurality of symbols of the received signal, and a synchronization determination unit (13) configured to perform coincidence determination of whether an output from the addition average unit (12) falls within a predetermined coincidence determination range of the predetermined signal point, and determine a synchronization state of the frame synchronization based on a result of the coincidence determination.
    Type: Grant
    Filed: June 6, 2019
    Date of Patent: May 3, 2022
    Assignees: NTT ELECTRONICS CORPORATION, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Mitsuteru Yoshida, Yasuyuki Endoh, Katsuichi Oyama, Masayuki Ikeda, Tsutomu Takeya, Etsushi Yamazaki, Yoshiaki Kisaka, Masahito Tomizawa
  • Patent number: 11316588
    Abstract: Provided is a chromatic dispersion compensation method including: dividing a reception signal obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands; adjusting a timing on a time axis of the reception signal for each of the divided frequency bands; performing combination processing for combining the reception signals included in the plurality of frequency bands; performing chromatic dispersion compensation on the reception signal at any timing before or after the combination processing; selecting, before the combination processing, sections in which overlapping parts determined based on lengths of overlap parts are generated; outputting the reception signal for each of the selected sections as a division processing block; and removing the overlap parts from both ends of a processing block generated by combination of the division processing blocks in the combination processing so as to be continuous on a frequency axis.
    Type: Grant
    Filed: August 27, 2019
    Date of Patent: April 26, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kyo Minoguchi, Etsushi Yamazaki, Seiji Okamoto, Yoshiaki Kisaka
  • Patent number: 11251870
    Abstract: An optical transmission system includes an optical transmitter configured to generate a plurality of optical signals encoded and modulated with the same client data being carriers with the same wavelength, and having different carrier phases, and output the plurality of generated optical signals using a plurality of optical transmitter output ports, each of the optical transmitter output ports corresponding to one of the plurality of optical signals, and one or a plurality of first directional couplers including a plurality of first input ports, each of the first input port connected to a corresponding one of the plurality of optical transmitter output ports.
    Type: Grant
    Filed: April 9, 2019
    Date of Patent: February 15, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Etsushi Yamazaki, Yoshiaki Kisaka
  • Publication number: 20220038180
    Abstract: Provided is a chromatic dispersion compensation method including: dividing a reception signal obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands; adjusting a timing on a time axis of the reception signal for each of the divided frequency bands; performing combination processing for combining the reception signals included in the plurality of frequency bands; performing chromatic dispersion compensation on the reception signal at any timing before or after the combination processing; selecting, before the combination processing, sections in which overlapping parts determined based on lengths of overlap parts are generated; outputting the reception signal for each of the selected sections as a division processing block; and removing the overlap parts from both ends of a processing block generated by combination of the division processing blocks in the combination processing so as to be continuous on a frequency axis.
    Type: Application
    Filed: August 27, 2019
    Publication date: February 3, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kyo MINOGUCHI, Etsushi YAMAZAKI, Seiji OKAMOTO, Yoshiaki KISAKA
  • Patent number: 11201721
    Abstract: A frame synchronization apparatus (10) according to this invention includes a multiplication unit (11) configured to multiply a received signal by an inverse complex number of a predetermined synchronization pattern with respect to a predetermined signal point on a complex space diagram for each of a plurality of symbols of the received signal, an addition average unit (12) configured to perform addition averaging of outputs from the multiplication unit for the plurality of symbols of the received signal, and a synchronization determination unit (13) configured to perform coincidence determination of whether an output from the addition average unit (12) falls within a predetermined coincidence determination range of the predetermined signal point, and determine a synchronization state of the frame synchronization based on a result of the coincidence determination.
    Type: Grant
    Filed: February 12, 2021
    Date of Patent: December 14, 2021
    Assignees: NTT ELECTRONICS CORPORATION, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Mitsuteru Yoshida, Yasuyuki Endoh, Katsuichi Oyama, Masayuki Ikeda, Tsutomu Takeya, Etsushi Yamazaki, Yoshiaki Kisaka, Masahito Tomizawa
  • Publication number: 20210367675
    Abstract: An optical communication system is provided in which a serial/parallel converting unit outputs bit sequences of sequence groups a number of which is determined by a logarithmic value and a bit sequence of a highest-order sequence group, a converting unit converts the bit sequence of the sequence group input to the converting unit into a bit sequence for which a probability of occurrence of 0 or a probability of occurrence of 1 is a predetermined probability of occurrence, a selecting unit acquires a bit sequence for which the probability of occurrence is converted by a converting unit higher in order than the converting unit for the selecting unit, and selects an order of output of a symbol to other selecting units in the sequence groups higher in order than the selecting unit in accordance with the acquired bit sequence, a multiplication unit multiplies a value representing the symbol selected by a highest-order selecting unit, by a number in accordance with the bit sequence of the highest order sequence gro
    Type: Application
    Filed: May 8, 2019
    Publication date: November 25, 2021
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Masanori NAKAMURA, Seiji OKAMOTO, Etsushi YAMAZAKI, Yoshiaki KISAKA
  • Publication number: 20210273777
    Abstract: A frame synchronization apparatus (10) according to this invention includes a multiplication unit (11) configured to multiply a received signal by an inverse complex number of a predetermined synchronization pattern with respect to a predetermined signal point on a complex space diagram for each of a plurality of symbols of the received signal, an addition average unit (12) configured to perform addition averaging of outputs from the multiplication unit for the plurality of symbols of the received signal, and a synchronization determination unit (13) configured to perform coincidence determination of whether an output from the addition average unit (12) falls within a predetermined coincidence determination range of the predetermined signal point, and determine a synchronization state of the frame synchronization based on a result of the coincidence determination.
    Type: Application
    Filed: June 6, 2019
    Publication date: September 2, 2021
    Inventors: Mitsuteru YOSHIDA, Yasuyuki ENDOH, Katsuichi OYAMA, Masayuki IKEDA, Tsutomu TAKEYA, Etsushi YAMAZAKI, Yoshiaki KISAKA, Masahito TOMIZAWA
  • Publication number: 20210242942
    Abstract: An optical transmission system includes an optical transmitter configured to generate a plurality of optical signals encoded and modulated with the same client data being carriers with the same wavelength, and having different carrier phases, and output the plurality of generated optical signals using a plurality of optical transmitter output ports, each of the optical transmitter output ports corresponding to one of the plurality of optical signals, and one or a plurality of first directional couplers including a plurality of first input ports, each of the first input port connected to a corresponding one of the plurality of optical transmitter output ports.
    Type: Application
    Filed: April 9, 2019
    Publication date: August 5, 2021
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Etsushi YAMAZAKI, Yoshiaki KISAKA