Patents by Inventor Yutaka Kai

Yutaka Kai 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: 20220147872
    Abstract: A non-transitory computer-readable recording medium storing a calculation processing program for causing a computer to execute processing, the processing including: calculating error gradients of a plurality of layers of a machine learning model that includes an input layer of the machine learning model at the time of machine learning of the machine learning model; selecting a layer of which the error gradient is less than a threshold as a suppression target of the machine learning; and controlling a learning rate and performing the machine learning on the layer selected as the suppression target in a certain period of time before the machine learning is suppressed.
    Type: Application
    Filed: August 30, 2021
    Publication date: May 12, 2022
    Applicant: FUJITSU LIMITED
    Inventors: YUTAKA KAI, Akihiko Kasagi, Yasushi Hara, Takumi Danjo
  • Publication number: 20220147772
    Abstract: A computer-implemented method includes: calculating error gradients with respect to a plurality of layers included in a machine learning model at a time of machine learning of the machine learning model, the plurality of layers including an input layer of the machine learning model; specifying, as a layer to be suppressed, a layer located in a range from a position of the input layer to a predetermined position among the layers in which the error gradient is less than a threshold; and suppressing the machine learning for the layer to be suppressed.
    Type: Application
    Filed: July 15, 2021
    Publication date: May 12, 2022
    Applicant: FUJITSU LIMITED
    Inventors: YUTAKA KAI, Akihiko Kasagi, Yasushi Hara, Takumi Danjo
  • Publication number: 20210406683
    Abstract: A process includes starting a learning process for building a model including multiple layers each including a parameter. The learning process executes iterations, each including calculating output error of the model using training data and updating the parameter value based on the output error. The process also includes selecting two or more candidate layers representing candidates for layers, where the updating is to be suppressed, based on results of a first iteration of the learning process. The process also includes calculating, based on the number of iterations executed up to the first iteration, a ratio value which becomes larger when the number of iterations executed is greater, and determining, amongst the candidate layers, one or more layers, where the updating is to be suppressed at a second iteration following the first iteration. The number of one or more layers is determined according to the ratio value.
    Type: Application
    Filed: April 9, 2021
    Publication date: December 30, 2021
    Applicant: FUJITSU LIMITED
    Inventors: YUTAKA KAI, Akihiko Kasagi
  • Publication number: 20210397948
    Abstract: A memory holds a model including a plurality of layers including their respective parameters and training data. A processor starts learning processing, which repeatedly calculates an error of an output of the model by using the training data, calculates an error gradient, which indicates a gradient of the error with respect to the parameters, for each of the layers, and updates the parameters based on the error gradients. The processor calculates a difference between a first error gradient calculated in a first iteration in the learning processing and a second error gradient calculated in a second iteration after the first iteration for a first layer among the plurality of layers. In a case where the difference is less than a threshold, the processor skips the calculating of the error gradient and the updating of the parameter for the first layer in a third iteration after the second iteration.
    Type: Application
    Filed: March 10, 2021
    Publication date: December 23, 2021
    Applicant: FUJITSU LIMITED
    Inventors: Yasushi Hara, Akihiko Kasagi, Takumi Danjo, YUTAKA KAI
  • Publication number: 20210158212
    Abstract: A first learning rate is set to a first block including a first parameter, and a second learning rate, which is smaller than the first learning rate, is set to a second block including a second parameter. The first block and the second block are included in a model. Learning processing in which updating the first parameter based on a prediction error of the model, the prediction error having been calculated by using training data, and the first learning rate and updating the second parameter based on the prediction error and the second learning rate are performed iteratively is started. An update frequency of the second parameter is controlled such that this update frequency becomes lower than an update frequency of the first parameter by intermittently omitting the updating of the second parameter in the learning processing based on a relationship between the first and second learning rates.
    Type: Application
    Filed: October 8, 2020
    Publication date: May 27, 2021
    Applicant: FUJITSU LIMITED
    Inventors: YUTAKA KAI, Akihiko Kasagi
  • Patent number: 10027408
    Abstract: An optical transmitter transmits to an optical receiver a multi-carrier modulated signal light by driving a light source with a modulated signal modulated with a multi-carrier modulation scheme. The optical receiver monitors reception characteristic of any of subcarrier signals included in the modulated signal and transmits a monitor result to the optical transmitter. The optical transmitter controls drive conditions of the light source based on the monitor result received from the optical receiver.
    Type: Grant
    Filed: June 10, 2016
    Date of Patent: July 17, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Masato Nishihara, Toshiki Tanaka, Yutaka Kai, Tomoo Takahara
  • Patent number: 9998230
    Abstract: An optical transmitter includes an optical modulator to modulate light having a predetermined wavelength into an optical signal based on a data signal, a memory, and a processor coupled to the memory and the processor configured to modulate an input signal into a multi-carrier signal so as to generate the data signal, the multi-carrier signal including a plurality of subcarriers each to which a transmission capacity is allocated, acquire a first frequency distribution of an intensity of the multi-carrier signal, acquire a second frequency distribution of an intensity of the optical signal, control the modulating of the input signal into the multi-carrier signal to change a number of subcarriers of the multi-carrier signal, and control the optical modulator to adjust a modulation characteristic of the optical modulator so that a divergence between the first frequency distribution and the second frequency distribution is equal to or less than a predetermined value.
    Type: Grant
    Filed: July 20, 2017
    Date of Patent: June 12, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Masato Nishihara, Toshiki Tanaka, Tomoo Takahara, Ryou Okabe, Yutaka Kai
  • Patent number: 9998233
    Abstract: An optical reception apparatus may include a receiver, a monitor, and a controller. The optical reception apparatus receives multi-carrier modulated signal light modulated by a multi-carrier modulation scheme. The multi-carrier modulation scheme is available to allocate different transmission conditions for each of a plurality of subcarriers in accordance with transmission characteristics of the subcarriers. The receiver may receive from an optical transmission line a training signal light allocated with the same transmission conditions for each of the subcarriers. The monitor may monitor the transmission characteristics of the training signal light to detect a frequency at which a dip of the transmission characteristics occurs. The controller may control, based on the frequency detected by the monitor, a dispersion compensation for the multi-carrier modulated signal light having received a dispersion from the optical transmission line.
    Type: Grant
    Filed: January 11, 2016
    Date of Patent: June 12, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Ryou Okabe, Masato Nishihara, Toshiki Tanaka, Yutaka Kai, Tomoo Takahara
  • Patent number: 9973276
    Abstract: An apparatus includes a receiver configured to receive a signal that has traveled an optical transmission line without returning output from an optical transmitting device and synchronize with the optical transmitting device in order to demodulate the signal; a dispersion compensator configured to compensate for wavelength dispersion caused by transmission of the signal; an acquisition circuit configured to acquire a transmitting timing at which the signal has been transmitted from the optical transmitting device; a calculation circuit configured to calculate a transmission time period from the optical transmitting device to the receiver from the transmitting timing and a receiving timing at which the signal has been received with the receiver; and an amount setting circuit configured to adjust a dispersion compensation amount of the dispersion compensator in accordance with the transmission time period.
    Type: Grant
    Filed: January 24, 2017
    Date of Patent: May 15, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Yutaka Kai, Tomoo Takahara, Toshiki Tanaka, Masato Nishihara, Ryou Okabe
  • Publication number: 20180034551
    Abstract: An optical transmitter includes an optical modulator to modulate light having a predetermined wavelength into an optical signal based on a data signal, a memory, and a processor coupled to the memory and the processor configured to modulate an input signal into a multi-carrier signal so as to generate the data signal, the multi-carrier signal including a plurality of subcarriers each to which a transmission capacity is allocated, acquire a first frequency distribution of an intensity of the multi-carrier signal, acquire a second frequency distribution of an intensity of the optical signal, control the modulating of the input signal into the multi-carrier signal to change a number of subcarriers of the multi-carrier signal, and control the optical modulator to adjust a modulation characteristic of the optical modulator so that a divergence between the first frequency distribution and the second frequency distribution is equal to or less than a predetermined value.
    Type: Application
    Filed: July 20, 2017
    Publication date: February 1, 2018
    Applicant: FUJITSU LIMITED
    Inventors: MASATO NISHIHARA, Toshiki Tanaka, Tomoo Takahara, Ryou Okabe, YUTAKA KAI
  • Patent number: 9876601
    Abstract: There is proved an optical transmission system including: a transmitter configured to transmit an optical signal modulated with a discrete multi-tone (DMT) drive signal; a filter capable of changing a wavelength of the optical signal input from the transmitter; a monitor configured to monitor a power of the optical signal passed through the filter; and at least one processor configured to: set a center wavelength of the filter, shift the center wavelength, detect a change in the power monitored by the monitor, identify a carrier component of the optical signal based on the change in the power, and control a relative relationship between a transmission characteristic of the filter and a wavelength of the carrier component so that the carrier component is included in the optical signal and one of an upper sideband and a lower sideband of the optical signal is at least partially removed by the filter.
    Type: Grant
    Filed: September 14, 2016
    Date of Patent: January 23, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Toshiki Tanaka, Ryou Okabe, Tomoo Takahara, Masato Nishihara, Yutaka Kai
  • Patent number: 9853728
    Abstract: A bit allocation method is used in an optical transmission system that transmits multicarrier signals of different wavelengths in wavelength division multiplexing. Frequency characteristics of subcarriers included in the multicarrier signals are different between the respective multicarrier signals. The method includes: measuring transmission characteristics of the subcarriers included in corresponding multicarrier signals at different subcarrier frequencies; and determining a number of bits to be allocated to each of the subcarriers included in each of the multicarrier signals based on the transmission characteristics measured at the different subcarrier frequencies.
    Type: Grant
    Filed: August 31, 2016
    Date of Patent: December 26, 2017
    Assignee: FUJITSU LIMITED
    Inventors: Masato Nishihara, Toshiki Tanaka, Yutaka Kai, Ryou Okabe, Tomoo Takahara
  • Publication number: 20170272161
    Abstract: An apparatus includes a receiver configured to receive a signal that has traveled an optical transmission line without returning output from an optical transmitting device and synchronize with the optical transmitting device in order to demodulate the signal; a dispersion compensator configured to compensate for wavelength dispersion caused by transmission of the signal; an acquisition circuit configured to acquire a transmitting timing at which the signal has been transmitted from the optical transmitting device; a calculation circuit configured to calculate a transmission time period from the optical transmitting device to the receiver from the transmitting timing and a receiving timing at which the signal has been received with the receiver; and an amount setting circuit configured to adjust a dispersion compensation amount of the dispersion compensator in accordance with the transmission time period.
    Type: Application
    Filed: January 24, 2017
    Publication date: September 21, 2017
    Applicant: FUJITSU LIMITED
    Inventors: Yutaka Kai, Tomoo Takahara, Toshiki Tanaka, Masato Nishihara, Ryou Okabe
  • Publication number: 20170093515
    Abstract: There is proved an optical transmission system including: a transmitter configured to transmit an optical signal modulated with a discrete multi-tone (DMT) drive signal; a filter capable of changing a wavelength of the optical signal input from the transmitter; a monitor configured to monitor a power of the optical signal passed through the filter; and at least one processor configured to: set a center wavelength of the filter, shift the center wavelength, detect a change in the power monitored by the monitor, identify a carrier component of the optical signal based on the change in the power, and control a relative relationship between a transmission characteristic of the filter and a wavelength of the carrier component so that the carrier component is included in the optical signal and one of an upper sideband and a lower sideband of the optical signal is at least partially removed by the filter.
    Type: Application
    Filed: September 14, 2016
    Publication date: March 30, 2017
    Applicant: FUJITSU LIMITED
    Inventors: Toshiki Tanaka, Ryou Okabe, Tomoo Takahara, MASATO NISHIHARA, YUTAKA KAI
  • Publication number: 20170070286
    Abstract: A bit allocation method is used in an optical transmission system that transmits multicarrier signals of different wavelengths in wavelength division multiplexing. Frequency characteristics of subcarriers included in the multicarrier signals are different between the respective multicarrier signals. The method includes: measuring transmission characteristics of the subcarriers included in corresponding multicarrier signals at different subcarrier frequencies; and determining a number of bits to be allocated to each of the subcarriers included in each of the multicarrier signals based on the transmission characteristics measured at the different subcarrier frequencies.
    Type: Application
    Filed: August 31, 2016
    Publication date: March 9, 2017
    Applicant: FUJITSU LIMITED
    Inventors: MASATO NISHIHARA, Toshiki Tanaka, YUTAKA KAI, Ryou Okabe, Tomoo Takahara
  • Patent number: 9467229
    Abstract: A multilevel-intensity modulation and demodulation system includes: a digital-to-analog conversion unit to convert an output level value of a digital signal into an analog signal; a multilevel-intensity-modulated light transmission unit to transmit an optical signal multilevel-intensity modulated based on the analog signal; a multilevel-intensity-modulated light reception unit to receive the optical signal multilevel-intensity modulated, and convert the received optical signal into an analog reception electrical signal; an analog-to-digital conversion unit to convert the analog reception electrical signal into a reception level value; and a controller to convert a transmission multiple gradation level being one of a plurality of multiple gradation levels of multilevel-intensity modulation to which the digital signal is mapped, into the output level value so as to cause the reception level value to be in a desired reception state, and to receive a digital signal corresponding to a reception multiple-gradation-
    Type: Grant
    Filed: January 22, 2015
    Date of Patent: October 11, 2016
    Assignee: FUJITSU LIMITED
    Inventors: Yutaka Kai, Masato Nishihara, Toshiki Tanaka, Tomoo Takahara
  • Publication number: 20160285548
    Abstract: An optical transmitter transmits to an optical receiver a multi-carrier modulated signal light by driving a light source with a modulated signal modulated with a multi-carrier modulation scheme. The optical receiver monitors reception characteristic of any of subcarrier signals included in the modulated signal and transmits a monitor result to the optical transmitter. The optical transmitter controls drive conditions of the light source based on the monitor result received from the optical receiver.
    Type: Application
    Filed: June 10, 2016
    Publication date: September 29, 2016
    Applicant: FUJITSU LIMITED
    Inventors: MASATO NISHIHARA, Toshiki Tanaka, YUTAKA KAI, Tomoo Takahara
  • Patent number: 9425897
    Abstract: A transmission apparatus includes: an assigning unit that assigns an information signal to a subcarrier with a frequency different from a frequency of a received radio signal; a creating unit that creates a multi-carrier signal, in which information signals are multiplexed, each of the information signals being assigned to one subcarrier by the assigning unit; and a multiplexing unit that frequency-multiplexes the received radio signal to the multi-carrier signal created by the creating unit and outputs a resulting frequency-multiplexed signal.
    Type: Grant
    Filed: October 6, 2014
    Date of Patent: August 23, 2016
    Assignee: FUJITSU LIMITED
    Inventors: Masato Nishihara, Toshiki Tanaka, Tomoo Takahara, Yutaka Kai
  • Publication number: 20160218812
    Abstract: An optical reception apparatus may include a receiver, a monitor, and a controller. The optical reception apparatus receives multi-carrier modulated signal light modulated by a multi-carrier modulation scheme. The multi-carrier modulation scheme is available to allocate different transmission conditions for each of a plurality of subcarriers in accordance with transmission characteristics of the subcarriers. The receiver may receive from an optical transmission line a training signal light allocated with the same transmission conditions for each of the subcarriers. The monitor may monitor the transmission characteristics of the training signal light to detect a frequency at which a dip of the transmission characteristics occurs. The controller may control, based on the frequency detected by the monitor, a dispersion compensation for the multi-carrier modulated signal light having received a dispersion from the optical transmission line.
    Type: Application
    Filed: January 11, 2016
    Publication date: July 28, 2016
    Applicant: FUJITSU LIMITED
    Inventors: Ryou Okabe, Masato Nishihara, Toshiki Tanaka, Yutaka Kai, Tomoo Takahara
  • Publication number: 20150222359
    Abstract: A multilevel-intensity modulation and demodulation system includes: a digital-to-analog conversion unit to convert an output level value of a digital signal into an analog signal; a multilevel-intensity-modulated light transmission unit to transmit an optical signal multilevel-intensity modulated based on the analog signal; a multilevel-intensity-modulated light reception unit to receive the optical signal multilevel-intensity modulated, and convert the received optical signal into an analog reception electrical signal; an analog-to-digital conversion unit to convert the analog reception electrical signal into a reception level value; and a controller to convert a transmission multiple gradation level being one of a plurality of multiple gradation levels of multilevel-intensity modulation to which the digital signal is mapped, into the output level value so as to cause the reception level value to be in a desired reception state, and to receive a digital signal corresponding to a reception multiple-gradation-
    Type: Application
    Filed: January 22, 2015
    Publication date: August 6, 2015
    Inventors: Yutaka KAI, Masato NISHIHARA, Toshiki TANAKA, Tomoo TAKAHARA