Patents by Inventor Asuka MATSUSHITA
Asuka MATSUSHITA 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).
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Patent number: 11901953Abstract: An optical transmission system, in which an optical transmission apparatus and an optical reception apparatus are provided, includes a coefficient determination unit configured to optimize, based on a reception signal received by the optical reception apparatus, a coefficient to be used to compensate for deterioration according to characteristics of each device configuring a transmission path between the optical transmission apparatus and the optical reception apparatus, and a device characteristic estimation unit configured to estimate the characteristics of each device by using the optimized coefficient.Type: GrantFiled: March 31, 2020Date of Patent: February 13, 2024Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takeo Sasai, Masanori Nakamura, Asuka Matsushita, Yoshiaki Kisaka
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Patent number: 11870489Abstract: A tentative decision is made for symbols on the basis of a received signal and a decision threshold, and a tentative decision signal including a sequence of the symbols is output. A scale value indicating a rate of increase or reduction of the received signal or a threshold change rate indicating a degree of change in the decision threshold is updated so that an appearance frequency of each of symbols included in the tentative decision signal matches an appearance frequency of each of symbols in a reference signal obtained by modulating a transmitted signal with a modulation method used in transmission which is shared between a transmitting side and a receiving side, and an SN ratio is calculated using the scale value or the threshold change rate when a degree of agreement between the appearance frequencies is within a predetermined permissible range.Type: GrantFiled: October 9, 2019Date of Patent: January 9, 2024Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masanori Nakamura, Shuto Yamamoto, Asuka Matsushita, Fukutaro Hamaoka, Yoshiaki Kisaka
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Patent number: 11736202Abstract: There are provided an evaluation method and an evaluation device for an optical receiver capable of evaluating only a phase error between optical 90-degree hybrids with high accuracy even when there is a skew between channels in the optical receiver. In the evaluation method and the evaluation device for the optical receiver including optical 90-degree hybrids, a phase error between the optical 90-degree hybrids is calculated by calculation of decomposing a transfer function of the optical receiver into a product of matrixes to evaluate the optical receiver.Type: GrantFiled: March 6, 2020Date of Patent: August 22, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Shogo Yamanaka, Masanori Nakamura, Asuka Matsushita
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Patent number: 11711151Abstract: 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: GrantFiled: May 23, 2019Date of Patent: July 25, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Asuka Matsushita, Masanori Nakamura, Kengo Horikoshi, Shoichiro Kuwahara, Yoshiaki Kisaka
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Publication number: 20230106338Abstract: An optical transmission system, in which an optical transmission apparatus and an optical reception apparatus are provided, includes a coefficient determination unit configured to optimize, based on a reception signal received by the optical reception apparatus, a coefficient to be used to compensate for deterioration according to characteristics of each device configuring a transmission path between the optical transmission apparatus and the optical reception apparatus, and a device characteristic estimation unit configured to estimate the characteristics of each device by using the optimized coefficient.Type: ApplicationFiled: March 31, 2020Publication date: April 6, 2023Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takeo SASAI, Masanori NAKAMURA, Asuka MATSUSHITA, Yoshiaki KISAKA
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Publication number: 20230097741Abstract: 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: ApplicationFiled: March 11, 2020Publication date: March 30, 2023Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Masanori NAKAMURA, Seiji OKAMOTO, Etsushi YAMAZAKI, Asuka MATSUSHITA, Takeo SASAI
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Publication number: 20230097193Abstract: A tentative decision is made for symbols on the basis of a received signal and a decision threshold, and a tentative decision signal including a sequence of the symbols is output. A scale value indicating a rate of increase or reduction of the received signal or a threshold change rate indicating a degree of change in the decision threshold is updated so that an appearance frequency of each of symbols included in the tentative decision signal matches an appearance frequency of each of symbols in a reference signal obtained by modulating a transmitted signal with a modulation method used in transmission which is shared between a transmitting side and a receiving side, and an SN ratio is calculated using the scale value or the threshold change rate when a degree of agreement between the appearance frequencies is within a predetermined permissible range.Type: ApplicationFiled: October 9, 2019Publication date: March 30, 2023Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masanori NAKAMURA, Shuto YAMAMOTO, Asuka MATSUSHITA, Fukutaro HAMAOKA, Yoshiaki KISAKA
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Patent number: 11558114Abstract: Part of compensation of the transmission characteristics of the optical transmitter is performed by transmitter compensation circuitry disposed at a stage prior to the optical transmitter. Remaining part of compensation of the transmission characteristics of the optical transmitter and compensation of the transmission characteristics of the optical receiver is performed by a receiver compensation circuitry disposed at a stage subsequent to the optical receiver. Transmitter compensation characteristics of the transmitter compensation circuitry is set so that a peak-to-average-power ratio of an output signal from the transmitter compensation circuitry becomes equal to or smaller than a predetermined value.Type: GrantFiled: May 21, 2020Date of Patent: January 17, 2023Assignees: NTT Electronics Corporation, NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akihiro Yamagishi, Atsushi Hoki, Katsuya Tanaka, Eisuke Tsuchiya, Masanori Nakamura, Asuka Matsushita
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Patent number: 11444699Abstract: 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: GrantFiled: January 15, 2020Date of Patent: September 13, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira Masuda, Fukutaro Hamaoka, Shuto Yamamoto, Seiji Okamoto, Kengo Horikoshi, Masanori Nakamura, Asuka Matsushita, Yoshiaki Kisaka
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Publication number: 20220216923Abstract: 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: ApplicationFiled: May 23, 2019Publication date: July 7, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Asuka MATSUSHITA, Masanori NAKAMURA, Kengo HORIKOSHI, Shoichiro KUWAHARA, Yoshiaki KISAKA
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Publication number: 20220173807Abstract: Part of compensation of the transmission characteristics of the optical transmitter is performed by transmitter compensation circuitry disposed at a stage prior to the optical transmitter. Remaining part of compensation of the transmission characteristics of the optical transmitter and compensation of the transmission characteristics of the optical receiver is performed by a receiver compensation circuitry disposed at a stage subsequent to the optical receiver. Transmitter compensation characteristics of the transmitter compensation circuitry is set so that a peak-to-average-power ratio of an output signal from the transmitter compensation circuitry becomes equal to or smaller than a predetermined value.Type: ApplicationFiled: May 21, 2020Publication date: June 2, 2022Applicants: NTT Electronics Corporation, NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akihiro YAMAGISHI, Atsushi HOKI, Katsuya TANAKA, Eisuke TSUCHIYA, Masanori NAKAMURA, Asuka MATSUSHITA
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Publication number: 20220140913Abstract: There are provided an evaluation method and an evaluation device for an optical receiver capable of evaluating only a phase error between optical 90-degree hybrids with high accuracy even when there is a skew between channels in the optical receiver. In the evaluation method and the evaluation device for the optical receiver including optical 90-degree hybrids, a phase error between the optical 90-degree hybrids is calculated by calculation of decomposing a transfer function of the optical receiver into a product of matrixes to evaluate the optical receiver.Type: ApplicationFiled: March 6, 2020Publication date: May 5, 2022Inventors: Shogo Yamanaka, Masanori Nakamura, Asuka Matsushita
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Patent number: 11283528Abstract: 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 fluctuType: GrantFiled: August 27, 2019Date of Patent: March 22, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira Masuda, Seiji Okamoto, Shuto Yamamoto, Fukutaro Hamaoka, Masanori Nakamura, Asuka Matsushita, Yoshiaki Kisaka
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Publication number: 20220069921Abstract: 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: ApplicationFiled: January 15, 2020Publication date: March 3, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira MASUDA, Fukutaro HAMAOKA, Shuto YAMAMOTO, Seiji OKAMOTO, Kengo HORIKOSHI, Masanori NAKAMURA, Asuka MATSUSHITA, Yoshiaki KISAKA
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Patent number: 11228366Abstract: A process of estimating a transfer function or an inverse transfer function of the optical transmitter from first data obtained by the optical receiver when a first known signal is transmitted from the transmitter to the receiver, and a temporary transfer function or a temporary inverse transfer function of the optical receiver, is performed for multiple frequency offsets between the optical transmitter and the optical receiver. At this time, the transfer function or the inverse transfer function of the optical transmitter is estimated by comparing the first data obtained by compensating at least one or none of a temporary transfer function of the optical receiver and transmission path characteristics detected in the receiver, with a first known signal before transmission to which what is not compensated for the first data between the temporary transfer function of the optical receiver and the transmission path characteristic is added.Type: GrantFiled: February 3, 2020Date of Patent: January 18, 2022Assignees: NTT ELECTRONICS CORPORATION, NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akihiro Yamagishi, Atsushi Hoki, Masayuki Sugasawa, Masanori Nakamura, Asuka Matsushita
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Publication number: 20210328666Abstract: A process of estimating a transfer function or an inverse transfer function of the optical transmitter from first data obtained by the optical receiver when a first known signal is transmitted from the transmitter to the receiver, and a temporary transfer function or a temporary inverse transfer function of the optical receiver, is performed for multiple frequency offsets between the optical transmitter and the optical receiver. At this time, the transfer function or the inverse transfer function of the optical transmitter is estimated by comparing the first data obtained by compensating at least one or none of a temporary transfer function of the optical receiver and transmission path characteristics detected in the receiver, with a first known signal before transmission to which what is not compensated for the first data between the temporary transfer function of the optical receiver and the transmission path characteristic is added.Type: ApplicationFiled: February 3, 2020Publication date: October 21, 2021Applicants: NTT Electronics Corporation, NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akihiro YAMAGISHI, Atsushi HOKI, Masayuki SUGASAWA, Masanori NAKAMURA, Asuka MATSUSHITA
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Publication number: 20210218476Abstract: 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 fluctuType: ApplicationFiled: August 27, 2019Publication date: July 15, 2021Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akira MASUDA, Seiji OKAMOTO, Shuto YAMAMOTO, Fukutaro HAMAOKA, Masanori NAKAMURA, Asuka MATSUSHITA, Yoshiaki KISAKA
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Patent number: 10651944Abstract: An optical transmitter of an optical data transmission system transmitting data through an optical fiber transmission path includes a main signal generator that converts first transmission data into a predetermined signal format to generate a first signal, a DCSK modulator that DCSK-modulates second transmission data to generate a second signal, a signal-multiplexer that performs time-division multiplexing of the first signal and the second signal, and an electro-optical converter that converts a multiplexed signal obtained by the time-division multiplexing of the signal-multiplexer from an electric signal into an optical signal, and outputs the optical signal to the optical fiber transmission path.Type: GrantFiled: July 26, 2017Date of Patent: May 12, 2020Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo Horikoshi, Seiji Okamoto, Asuka Matsushita, Mitsuteru Yoshida, Fukutaro Hamaoka, Yoshiaki Yamada, Yoshiaki Kisaka
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Patent number: 10637569Abstract: A method estimating transmission characteristics of an optical transmitter of a transmission unit and an optical receiver of a reception unit, including: estimating a temporary transfer or inverse transfer function of the optical receiver; estimating a transfer or inverse transfer function of the optical transmitter from first data acquired by the reception unit when a first known signal is transmitted from the transmission unit, and the estimated temporary transfer or inverse transfer function of the optical receiver, a difference between the first known signal and an original first known signal is minimized; and estimating a transfer or inverse transfer function of the optical receiver from second data acquired by the reception unit when a second known signal is transmitted from the transmission unit, and the estimated transfer or inverse transfer function of the optical transmitter, a difference between the second known signal and an original second known signal is minimized.Type: GrantFiled: November 8, 2017Date of Patent: April 28, 2020Assignees: NTT ELECTRONICS CORPORATION, NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akihiro Yamagishi, Tetsuya Maruyama, Masanori Nakamura, Asuka Matsushita, Shogo Yamanaka
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Publication number: 20200036440Abstract: A method estimating transmission characteristics of an optical transmitter of a transmission unit and an optical receiver of a reception unit, including: estimating a temporary transfer or inverse transfer function of the optical receiver; estimating a transfer or inverse transfer function of the optical transmitter from first data acquired by the reception unit when a first known signal is transmitted from the transmission unit, and the estimated temporary transfer or inverse transfer function of the optical receiver, a difference between the first known signal and an original first known signal is minimized; and estimating a transfer or inverse transfer function of the optical receiver from second data acquired by the reception unit when a second known signal is transmitted from the transmission unit, and the estimated transfer or inverse transfer function of the optical transmitter, a difference between the second known signal and an original second known signal is minimized.Type: ApplicationFiled: November 8, 2017Publication date: January 30, 2020Applicants: NTT Electronics Corporation, NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Akihiro YAMAGISHI, Tetsuya MARUYAMA, Masanori NAKAMURA, Asuka MATSUSHITA, Shogo YAMANAKA