Patents by Inventor Yoshiaki Kisaka

Yoshiaki Kisaka 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: 11463169
    Abstract: A wavelength dispersion amount estimation apparatus includes a correlation signal generation unit configured to generate, from a receive signal, a first signal including a main signal of the receive signal and a second signal, which includes an image signal corresponding to the main signal, with a shift by a baud rate of the receive signal relative to the first signal in a frequency domain, a correlation calculation unit configured to calculate a cross correlation of the first signal and the second signal, and a dispersion amount calculation unit configured to calculate a wavelength dispersion amount, based on a position of a peak of the cross correlation.
    Type: Grant
    Filed: January 15, 2020
    Date of Patent: October 4, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kengo Horikoshi, Masanori Nakamura, Yoshiaki Kisaka, Seiji Okamoto, Fukutaro Hamaoka
  • Patent number: 11444694
    Abstract: Provided is an optical transmission system that includes an optical transmitter, and an optical receiver. The optical transmitter includes: a signal coding unit configured to perform nonlinear trellis coding, which corresponds to nonlinear calculation, on a symbol sequence; and a modulator configured to modulate the symbol sequence subjected to the nonlinear trellis coding by the signal coding unit, and transmit the modulated symbol sequence to the optical receiver. The optical receiver includes: a light receiving unit configured to receive an optical signal transmitted from the optical transmitter, and convert the received optical signal into an electrical signal; and a digital signal processing unit configured to perform digital signal processing on the electrical signal to reconstruct the symbol sequence.
    Type: Grant
    Filed: November 6, 2019
    Date of Patent: September 13, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Shuto Yamamoto, Akira Masuda, Hiroki Taniguchi, Yoshiaki Kisaka
  • Patent number: 11444699
    Abstract: There are provided an optical transmission apparatus that subjects a transmission signal including a plurality of sequences to Hadamard transform to obtain a signal in which a predetermined delay is added to one of the sequences, optically modulates the obtained signal, and transmits the modulated signal, and an optical reception apparatus that demodulates a reception signal received from the optical transmission apparatus by subjecting the reception signal to adaptive equalization processing with a predetermined number of taps.
    Type: Grant
    Filed: January 15, 2020
    Date of Patent: September 13, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Akira Masuda, Fukutaro Hamaoka, Shuto Yamamoto, Seiji Okamoto, Kengo Horikoshi, Masanori Nakamura, Asuka Matsushita, Yoshiaki Kisaka
  • Publication number: 20220263645
    Abstract: A synchronization detection device includes: a correction unit configured to correct sampled data of a waveform on which a dither signal is superimposed, for each period of a reference signal in accordance with a period of the dither signal; a multiplication unit configured to multiply the corrected sampled data by a weight coefficient that is different for each level of the reference signal and associated with a timing of the reference signal; and an averaging unit configured to derive, as a detection result, an average of a result of the multiplication of the corrected sampled data by the weight coefficient.
    Type: Application
    Filed: July 25, 2019
    Publication date: August 18, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Hiroto KAWAKAMI, Shoichiro KUWAHARA, Yoshiaki KISAKA
  • Patent number: 11397363
    Abstract: A control processor performs, in a startup sequence of an IQ optical modulator using a nested MZI, a first-stage process of controlling, so that a signal quality of an optical QAM signal output from a monitor port of the IQ optical modulator approaches a target quality, a voltage applied by a Bias_I voltage generator to I-component MZ optical modulator, a voltage applied by a Bias_Q voltage generator to a Q-component MZ optical modulator, and a voltage applied by a Bias_Ph voltage generator to a Bias_Ph phase adjusting means for controlling an optical path length of a parent MZI. After a completion of the first-stage process, the control processor changes a voltage output from the Bias_Ph voltage generator by a predetermined amount.
    Type: Grant
    Filed: May 15, 2019
    Date of Patent: July 26, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Hiroto Kawakami, Shoichiro Kuwahara, Yoshiaki Kisaka, Masanori Nakamura
  • Publication number: 20220224575
    Abstract: A device generates a symbol sequence by performing adaptive equalization by an estimation inverse transfer function of a transmission line on a reception signal sequence extracted from the transmission line, and performing provisional determination on the symbol sequence generated; generates a plurality of the symbol sequences indicating transmission line states in a range of a provisional determination symbol provisionally determined and nearby symbols of the provisional determination symbol; generates, based on the plurality of the symbol sequences indicating the transmission line states generated and an estimation transfer function of the transmission line, an estimation reception symbol sequence for each of the transmission line states; calculates a metric between the symbol sequence obtained from the reception signal sequence and each of a plurality of the estimation reception symbol sequences; selects a most likelihood estimation reception symbol sequence of the plurality of the estimation reception sym
    Type: Application
    Filed: May 8, 2020
    Publication date: July 14, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Hiroki TANIGUCHI, Masanori NAKAMURA, Shuto YAMAMOTO, Akira MASUDA, Yoshiaki KISAKA
  • Publication number: 20220224415
    Abstract: An electric digital received signal obtained from a received optical signal is segmented into blocks of a certain length with an overlap of a length determined in advance with an adjacent block. Fourier transformation is performed for each of the blocks. The blocks subjected to the Fourier transformation are stored consecutively in time series, a coefficient determined based on a wavelength dispersion compensation amount according to one of frequency positions and a delay amount according to one of the frequency positions and one of time positions is applied to each of frequency component values included in a plurality of the stored blocks, and the blocks to which the coefficient has been applied and which are obtained by adding up the frequency component values to which the coefficient has been applied for each of the frequency positions are generated. Inverse Fourier transformation is performed on the generated blocks to which the coefficient has been applied.
    Type: Application
    Filed: June 6, 2019
    Publication date: July 14, 2022
    Inventors: Masanori NAKAMURA, Seiji Okamoto, Kengo HORIKOSHI, Shuto YAMAMOTO, Takayuki KOBAYASHI, Yoshiaki KISAKA, Masahito TOMIZAWA
  • Publication number: 20220216923
    Abstract: An optical transmission system according to an embodiment includes: an optical transmission unit which modulates an optical signal into which a known signal is inserted and transmits the optical signal; and an optical reception unit which receives the optical signal from the optical transmission unit, wherein the optical reception unit includes: an optical receiver which performs coherent detection of a reception signal of the optical signal received from the optical transmission unit; a receiver transfer function estimation section which estimates a nonlinear response transfer function of the optical receiver based on the known signal included in the reception signal after the detection by the optical receiver; and a receiver compensation section which compensates nonlinear distortion of the reception signal after the detection based on the nonlinear response transfer function which the receiver transfer function estimation section estimates.
    Type: Application
    Filed: May 23, 2019
    Publication date: July 7, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Asuka MATSUSHITA, Masanori NAKAMURA, Kengo HORIKOSHI, Shoichiro KUWAHARA, Yoshiaki KISAKA
  • Patent number: 11381317
    Abstract: An optical receiving device that divides receive signals obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands, matches timing of the receive signals along a time axis between the frequency bands resulting from the division, performs a combining process of combining the receive signals contained in the plurality of frequency bands, and compensates the receive signals for waveform distortion either before or after the combining process, includes: a first wavelength dispersion compensation unit adapted to compensate the receive signals for waveform distortion in each of the frequency bands resulting from the division; a first nonlinear compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and timed with each other in a time domain for a nonlinear optical effect; and a second wavelength dispersion compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and compensate
    Type: Grant
    Filed: January 6, 2020
    Date of Patent: July 5, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Seiji Okamoto, Yoshiaki Kisaka, Masanori Nakamura
  • 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
  • Publication number: 20220158731
    Abstract: A wavelength dispersion amount estimation apparatus includes a correlation signal generation unit configured to generate, from a receive signal, a first signal including a main signal of the receive signal and a second signal, which includes an image signal corresponding to the main signal, with a shift by a baud rate of the receive signal relative to the first signal in a frequency domain, a correlation calculation unit configured to calculate a cross correlation of the first signal and the second signal, and a dispersion amount calculation unit configured to calculate a wavelength dispersion amount, based on a position of a peak of the cross correlation.
    Type: Application
    Filed: January 15, 2020
    Publication date: May 19, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kengo HORIKOSHI, Masanori NAKAMURA, Yoshiaki KISAKA, Seiji OKAMOTO, Fukutaro HAMAOKA
  • 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: 11303359
    Abstract: There is provided a communication system, wherein: an optical transmission apparatus has: a first storage unit that stores amplitude distribution information, which is information representing a distribution of occurrence probabilities of symbols of an optical signal, in association with a modulation rate of an optical signal; a control unit that selects the modulation rate based on a signal band that is a band determined by the modulation rate and a device band that is a band in which a transmission path and the like allow passage of an optical signal, and controls an occurrence probability of a symbol of an optical signal based on the amplitude distribution information; and an optical transmitter that transmits an optical signal of a symbol of which the occurrence probability is controlled; and an optical reception apparatus has: an optical receiver that receives an optical signal of a symbol; a second storage unit that stores the amplitude distribution information in association with the modulation rate; a
    Type: Grant
    Filed: July 2, 2019
    Date of Patent: April 12, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Seiji Okamoto, Fukutaro Hamaoka, Masanori Nakamura, Yoshiaki Kisaka
  • Publication number: 20220094440
    Abstract: An optical receiving device that divides receive signals obtained by receiving an optical signal using a coherent detection scheme into a plurality of frequency bands, matches timing of the receive signals along a time axis between the frequency bands resulting from the division, performs a combining process of combining the receive signals contained in the plurality of frequency bands, and compensates the receive signals for waveform distortion either before or after the combining process, includes: a first wavelength dispersion compensation unit adapted to compensate the receive signals for waveform distortion in each of the frequency bands resulting from the division; a first nonlinear compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and timed with each other in a time domain for a nonlinear optical effect; and a second wavelength dispersion compensation unit adapted to compensate the receive signals belonging to each of the frequency bands and compensate
    Type: Application
    Filed: January 6, 2020
    Publication date: March 24, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Seiji OKAMOTO, Yoshiaki KISAKA, Masanori NAKAMURA
  • Patent number: 11283528
    Abstract: A digital coherent receiver includes: an adaptive equalizer configured to execute, using a first tap coefficient, adaptive equalization processing on a digital signal that corresponds to a signal; a first coefficient updating unit configured to update the first tap coefficient based on the digital signal on which the adaptive equalization processing has not been executed, the digital signal on which the adaptive equalization processing has been executed, and a first step size; a second coefficient updating unit configured to update a second tap coefficient based on the digital signal on which the adaptive equalization processing has not been executed, the digital signal on which the adaptive equalization processing has been executed, and a second step size; and a control unit configured to detect a fluctuation speed of a state of polarization of the digital signal based on the second tap coefficient, and change the first tap coefficient to the updated second tap coefficient if it is determined that the fluctu
    Type: Grant
    Filed: August 27, 2019
    Date of Patent: March 22, 2022
    Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Akira Masuda, Seiji Okamoto, Shuto Yamamoto, Fukutaro Hamaoka, Masanori Nakamura, Asuka Matsushita, Yoshiaki Kisaka
  • Publication number: 20220069921
    Abstract: There are provided an optical transmission apparatus that subjects a transmission signal including a plurality of sequences to Hadamard transform to obtain a signal in which a predetermined delay is added to one of the sequences, optically modulates the obtained signal, and transmits the modulated signal, and an optical reception apparatus that demodulates a reception signal received from the optical transmission apparatus by subjecting the reception signal to adaptive equalization processing with a predetermined number of taps.
    Type: Application
    Filed: January 15, 2020
    Publication date: March 3, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Akira MASUDA, Fukutaro HAMAOKA, Shuto YAMAMOTO, Seiji OKAMOTO, Kengo HORIKOSHI, Masanori NAKAMURA, Asuka MATSUSHITA, 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: 20220043320
    Abstract: A control processor performs, in a startup sequence of an IQ optical modulator using a nested MZI, a first-stage process of controlling, so that a signal quality of an optical QAM signal output from a monitor port of the IQ optical modulator approaches a target quality, a voltage applied by a Bias_I voltage generator to I-component MZ optical modulator, a voltage applied by a Bias_Q voltage generator to a Q-component MZ optical modulator, and a voltage applied by a Bias_Ph voltage generator to a Bias_Ph phase adjusting means for controlling an optical path length of a parent MZI. After a completion of the first-stage process, the control processor changes a voltage output from the Bias_Ph voltage generator by a predetermined amount.
    Type: Application
    Filed: May 15, 2019
    Publication date: February 10, 2022
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Hiroto KAWAKAMI, Shoichiro KUWAHARA, Yoshiaki KISAKA, Masanori NAKAMURA