Patents by Inventor Kohki Shibahara

Kohki Shibahara 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).

  • Patent number: 10985846
    Abstract: A signal receiving apparatus includes at least one signal separating apparatus that separates a specific signal from a plurality of received signals. Each of the at least one signal separating apparatus includes a spatial filtering unit that separates at least one equalized signal and a decision signal outputting unit that generates a first decision signal by deciding the equalized signal and outputs the generated first decision signal. The spatial filtering unit separates the at least one equalized signal by multiplying at least the plurality of received signals among the plurality of received signals and either the first decision signal output from the decision signal outputting unit or a second decision signal output from another signal separating apparatus by predetermined weighting coefficients.
    Type: Grant
    Filed: March 8, 2018
    Date of Patent: April 20, 2021
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kohki Shibahara, Takayuki Mizuno, Akira Isoda, Yutaka Miyamoto
  • Publication number: 20200381888
    Abstract: An optically amplified repeater system includes optical transmission paths, a multi-channel optical amplifier, one or more Raman amplification pumping light sources, and a wavelength multiplexer. The multi-channel optical amplifier includes K simultaneous pumping light sources, N optical amplification media, and one or more optical couplers, and simultaneously amplifies, with the K simultaneous pumping light sources, light intensities of optical signals that pass through the N optical amplification media and propagate through the optical transmission paths. Light intensities of the wavelength band of the optical signals is Raman amplified by the Raman amplification pumping light. A light intensity of the Raman amplification pumping light output from the one or more Raman amplification pumping light sources is determined in accordance with characteristic differences between the optical signals passing through the optical transmission paths.
    Type: Application
    Filed: August 24, 2018
    Publication date: December 3, 2020
    Applicant: Nippon Telegraph and Telephone Corporation
    Inventors: Takayuki MIZUNO, Akira ISODA, Kohki SHIBAHARA, Mitsunori FUKUTOKU, Yutaka MIYAMOTO
  • Patent number: 10536238
    Abstract: An optical transmission system includes an optical transmission apparatus and an optical reception apparatus. The optical transmission apparatus includes a conversion unit that converts multiple binary data sequences into data in a predetermined signal format; a coding unit that generates multiple pieces of coded data by performing predetermined coding on each of the multiple pieces of converted data; an optical signal generation unit that generates multiple optical signals by converting the multiple pieces of coded data into optical signals; and a mode multiplexer that converts the multiple optical signals into different modes, generates a mode-division multiplexed optical signal by mode-division multiplexing the optical signals, and transmits the generated mode-division multiplexed optical signal to the optical reception apparatus.
    Type: Grant
    Filed: January 11, 2017
    Date of Patent: January 14, 2020
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kohki Shibahara, Takayuki Mizuno, Hiroto Kawakami, Yutaka Miyamoto
  • Publication number: 20200014469
    Abstract: A signal receiving apparatus includes at least one signal separating apparatus that separates a specific signal from a plurality of received signals. Each of the at least one signal separating apparatus includes a spatial filtering unit that separates at least one equalized signal and a decision signal outputting unit that generates a first decision signal by deciding the equalized signal and outputs the generated first decision signal. The spatial filtering unit separates the at least one equalized signal by multiplying at least the plurality of received signals among the plurality of received signals and either the first decision signal output from the decision signal outputting unit or a second decision signal output from another signal separating apparatus by predetermined weighting coefficients.
    Type: Application
    Filed: March 8, 2018
    Publication date: January 9, 2020
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kohki SHIBAHARA, Takayuki MIZUNO, Akira ISODA, Yutaka MIYAMOTO
  • Publication number: 20180375607
    Abstract: An optical transmission system includes an optical transmission apparatus and an optical reception apparatus. The optical transmission apparatus includes a conversion unit that converts multiple binary data sequences into data in a predetermined signal format; a coding unit that generates multiple pieces of coded data by performing predetermined coding on each of the multiple pieces of converted data; an optical signal generation unit that generates multiple optical signals by converting the multiple pieces of coded data into optical signals; and a mode multiplexer that converts the multiple optical signals into different modes, generates a mode-division multiplexed optical signal by mode-division multiplexing the optical signals, and transmits the generated mode-division multiplexed optical signal to the optical reception apparatus.
    Type: Application
    Filed: January 11, 2017
    Publication date: December 27, 2018
    Applicant: Nippon Telegraph and Telephone Corporation
    Inventors: Kohki SHIBAHARA, Takayuki MIZUNO, Hiroto KAWAKAMI, Yutaka MIYAMOTO
  • Patent number: 9762982
    Abstract: There is provided a multi-flow optical transceiver that includes (a) a plurality of wavelength-tunable light sources, (b) a plurality of optical modulation units which modulates light with an input signal, (c) an optical multiplexing/demultiplexing switch which couples light from at least one of the wavelength-tunable light sources to at least one of the optical modulation units with any power, (d) an optical coupling unit which couples a plurality of lights, modulated by a plurality of the optical modulation units, to at least one waveguide, (e) at least one multiple carrier generating unit which generates multiple carries, arranged at equal frequency intervals, from light of the wavelength-tunable light source, and (f) a wavelength separation unit which branches the multiple carriers from the multiple carrier generating unit for each wavelength.
    Type: Grant
    Filed: March 24, 2016
    Date of Patent: September 12, 2017
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Kazushige Yonenaga, Hidehiko Takara, Masahiko Jinno, Kohki Shibahara, Takashi Goh
  • Patent number: 9667350
    Abstract: The optical receiving device with phase compensation apparatus uses coherent opto-electric conversion and is designed for receiving phase- or quadrature-amplitude-modulated optical signals. The phase compensation apparatus includes following elements: a carrier-phase estimation unit that estimates carrier phase errors in a received symbol string; a gain adjustment unit that adjusts weighting of each symbols in phase error evaluation performed in the carrier-phase adjustment unit; a phase-cycle-slip reduction unit with a phase-cycle-slip detector using statistical processing performed on the output symbols from the carrier-phase estimation unit; and a phase compensation circuit that compensates carrier phase errors of the received signal using an output from the carrier phase estimation unit.
    Type: Grant
    Filed: January 24, 2014
    Date of Patent: May 30, 2017
    Assignee: Nippon Telegraph And Telephone Corporation
    Inventors: Kengo Horikoshi, Kohki Shibahara, Etsushi Yamazaki, Mitsuteru Yoshida, Koichi Ishihara, Takayuki Kobayashi, Yoshiaki Kisaka, Takuya Ohara, Masahito Tomizawa, Tomoyoshi Kataoka
  • Publication number: 20160205451
    Abstract: There is provided a multi-flow optical transceiver that includes (a) a plurality of wavelength-tunable light sources, (b) a plurality of optical modulation units which modulates light with an input signal, (c) an optical multiplexing/demultiplexing switch which couples light from at least one of the wavelength-tunable light sources to at least one of the optical modulation units with any power, (d) an optical coupling unit which couples a plurality of lights, modulated by a plurality of the optical modulation units, to at least one waveguide, (e) at least one multiple carrier generating unit which generates multiple carries, arranged at equal frequency intervals, from light of the wavelength-tunable light source, and (f) a wavelength separation unit which branches the multiple carriers from the multiple carrier generating unit for each wavelength.
    Type: Application
    Filed: March 24, 2016
    Publication date: July 14, 2016
    Inventors: Kazushige YONENAGA, Hidehiko TAKARA, Masahiko JINNO, Kohki SHIBAHARA, Takashi GOH
  • Patent number: 9326049
    Abstract: A multi-flow optical transceiver provided with a plurality of wavelength-tunable light sources, a plurality of optical modulation units which modulates light with an input signal, an optical multiplexing/demultiplexing switch which couples light from at least one of the wavelength-tunable light sources to at least one of the optical modulation units with any power, and an optical coupling unit which couples a plurality of lights, modulated by a plurality of the optical modulation units, to at least one waveguide.
    Type: Grant
    Filed: July 18, 2012
    Date of Patent: April 26, 2016
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kazushige Yonenaga, Hidehiko Takara, Masahiko Jinno, Kohki Shibahara, Takashi Goh
  • Publication number: 20150333838
    Abstract: An optical receiving device receives an optical signal that has been modulated by means of phase modulation or quadrature amplitude modulation, converts the received optical signal into an electrical signal using coherent detection, and performs phase compensation on the converted received signal, and includes: a carrier phase estimation unit that estimates carrier phase errors in a received symbol string obtained from the received signal; a gain adjustment unit that performs gain adjustment on symbols input into the carrier phase adjustment unit; a phase cycle slip reduction unit that, by performing statistical processing on an output from the carrier phase estimation unit, detects general noise that causes a phase cycle slip, and reduces the phase cycle slip; and a phase compensation circuit that compensates carrier phase errors contained in the received signal using an output from the carrier phase estimation unit.
    Type: Application
    Filed: January 24, 2014
    Publication date: November 19, 2015
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kengo HORIKOSHI, Kohki SHIBAHARA, Etsushi YAMAZAKI, Mitsuteru YOSHIDA, Koichi ISHIHARA, Takayuki KOBAYASHI, Yoshiaki KISAKA, Takuya OHARA, Masahito TOMIZAWA, Tomoyoshi KATAOKA
  • Publication number: 20140126905
    Abstract: A multi-flow optical transceiver provided with a plurality of wavelength-tunable light sources, a plurality of optical modulation units which modulates light with an input signal, an optical multiplexing/demultiplexing switch which couples light from at least one of the wavelength-tunable light sources to at least one of the optical modulation units with any power, and an optical coupling unit which couples a plurality of lights, modulated by a plurality of the optical modulation units, to at least one waveguide.
    Type: Application
    Filed: July 18, 2012
    Publication date: May 8, 2014
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kazushige Yonenaga, Hidehiko Takara, Masahiko Jinno, Kohki Shibahara, Takashi Goh