Patents by Inventor Fukutaro Hamaoka
Fukutaro Hamaoka 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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Publication number: 20240080045Abstract: There is provided an encoding circuit used for coherent digital signal processing, including: a serial-parallel circuit that divides input data into a plurality of pieces of divided data by serial-parallel conversion; a plurality of encoders that adds an error correction code to the divided data and encodes the divided data; and a bit conversion circuit that converts a bit sequence in order to make an amount of noise generated by a communication channel non-uniform among the plurality of pieces of divided data encoded by each of the plurality of encoders.Type: ApplicationFiled: January 8, 2021Publication date: March 7, 2024Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takeshi KAKIZAKI, Masanori NAKAMURA, Fukutaro HAMAOKA
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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: 11799557Abstract: A communication device includes an amplitude conversion unit configured to generate a symbol sequence according to a bit sequence, a distribution matching unit configured to add redundant bits to the symbol sequence through probabilistic amplitude shaping (PAS) coding, an insertion unit configured to insert a pilot symbol into the symbol sequence to which the redundant bits have been added and transmit the symbol sequence into which the pilot symbol has been inserted to a transmission path, and a control unit configured to acquire information on the transmission path and change, according to the information on the transmission path, allocation of the redundancy of the PAS coding and the redundancy of the pilot symbol in a range of redundancy that is able to be allocated depending on a predetermined throughput.Type: GrantFiled: August 26, 2019Date of Patent: October 24, 2023Assignee: Nippon Telegraph and Telephone CorporationInventors: Takeshi Kakizaki, Fukutaro Hamaoka, Masanori Nakamura, Takeo Sasai
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Patent number: 11728889Abstract: An optical reception device includes a coefficient update section which optimizes a dispersion coefficient used in compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and a phase rotation amount used in compensation of a nonlinear optical effect of the received signal, and a transmission characteristic estimation section which estimates a transmission characteristic of a transmission line by using the optimized dispersion coefficient and the optimized phase rotation amount.Type: GrantFiled: December 16, 2019Date of Patent: August 15, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takeo Sasai, Fukutaro Hamaoka, Masanori Nakamura, Seiji Okamoto
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Patent number: 11716149Abstract: An optical reception device includes a nonlinear optical compensation section which performs compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and compensation of a nonlinear optical effect of the received signal N (N is an integer of at least 1) step(s), and a coefficient update section which updates a coefficient so as to optimize the coefficient used in each step of the nonlinear optical compensation section based on a signal having been subjected to the compensation by the nonlinear optical compensation section and a predetermined training signal.Type: GrantFiled: March 2, 2020Date of Patent: August 1, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takeo Sasai, Fukutaro Hamaoka
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Patent number: 11632185Abstract: A receiver convolutes each of a real component and an imaginary component of each polarization of a polarization-multiplexed reception signal with an impulse response for compensating for frequency characteristics of the receiver and a complex impulse response for wavelength dispersion compensation, and generates, as input signals, the convoluted real component and imaginary component of each polarization and phase conjugations thereof, for each polarization.Type: GrantFiled: January 31, 2020Date of Patent: April 18, 2023Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takayuki Kobayashi, Masanori Nakamura, Fukutaro Hamaoka, Yutaka Miyamoto
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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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Publication number: 20220416890Abstract: An optical reception device includes a coefficient update section which optimizes a dispersion coefficient used in compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and a phase rotation amount used in compensation of a nonlinear optical effect of the received signal, and a transmission characteristic estimation section which estimates a transmission characteristic of a transmission line by using the optimized dispersion coefficient and the optimized phase rotation amount.Type: ApplicationFiled: December 16, 2019Publication date: December 29, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takeo SASAI, Fukutaro HAMAOKA, Masanori NAKAMURA, Seiji OKAMOTO
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Patent number: 11463169Abstract: 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: GrantFiled: January 15, 2020Date of Patent: October 4, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo Horikoshi, Masanori Nakamura, Yoshiaki Kisaka, Seiji Okamoto, Fukutaro Hamaoka
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Publication number: 20220294535Abstract: A communication device includes an amplitude conversion unit configured to generate a symbol sequence according to a bit sequence, a distribution matching unit configured to add redundant bits to the symbol sequence through probabilistic amplitude shaping (PAS) coding, an insertion unit configured to insert a pilot symbol into the symbol sequence to which the redundant bits have been added and transmit the symbol sequence into which the pilot symbol has been inserted to a transmission path, and a control unit configured to acquire information on the transmission path and change, according to the information on the transmission path, allocation of the redundancy of the PAS coding and the redundancy of the pilot symbol in a range of redundancy that is able to be allocated depending on a predetermined throughput.Type: ApplicationFiled: August 26, 2019Publication date: September 15, 2022Inventors: Takeshi Kakizaki, Fukutaro Hamaoka, Masanori NAKAMURA, Takeo Sasai
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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: 20220158731Abstract: 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: ApplicationFiled: January 15, 2020Publication date: May 19, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Masanori NAKAMURA, Yoshiaki KISAKA, Seiji OKAMOTO, Fukutaro HAMAOKA
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Publication number: 20220149974Abstract: A receiver convolutes each of a real component and an imaginary component of each polarization of a polarization-multiplexed reception signal with an impulse response for compensating for frequency characteristics of the receiver and a complex impulse response for wavelength dispersion compensation, and generates, as input signals, the convoluted real component and imaginary component of each polarization and phase conjugations thereof, for each polarization.Type: ApplicationFiled: January 31, 2020Publication date: May 12, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takayuki KOBAYASHI, Masanori NAKAMURA, Fukutaro HAMAOKA, Yutaka MIYAMOTO
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Publication number: 20220131619Abstract: An optical reception device includes a nonlinear optical compensation section which performs compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and compensation of a nonlinear optical effect of the received signal N (N is an integer of at least 1) step(s), and a coefficient update section which updates a coefficient so as to optimize the coefficient used in each step of the nonlinear optical compensation section based on a signal having been subjected to the compensation by the nonlinear optical compensation section and a predetermined training signal.Type: ApplicationFiled: March 2, 2020Publication date: April 28, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takeo SASAI, Fukutaro HAMAOKA
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Patent number: 11303359Abstract: 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; aType: GrantFiled: July 2, 2019Date of Patent: April 12, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiji Okamoto, Fukutaro Hamaoka, Masanori Nakamura, Yoshiaki Kisaka
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Patent number: 11283527Abstract: An optical transmission system includes an optical transmitter and an optical receiver. The optical transmitter includes a low speed signal generation unit configured to generate, based on an input signal of a transmission data sequence and a signal obtained by cyclically shifting a spectrum of the input signal, a plurality of low speed signals, a high speed signal generation unit configured to digital-to-analog convert and synthesize the plurality of low speed signals to generate a high speed signal, and an optical modulation unit configured to transmit an optical signal obtained by modulation of the high speed signal to a transmission path.Type: GrantFiled: December 4, 2019Date of Patent: March 22, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masanori Nakamura, Fukutaro Hamaoka, Hiroshi Yamazaki, Munehiko Nagatani, Takayuki Kobayashi, Yutaka Miyamoto
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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: 11245487Abstract: An optical transmission system includes an optical transmitter, an optical receiver, and a control apparatus. The control apparatus repeatedly performs an adjustment process for adjusting power of an optical signal of a frequency band to be adjusted while switching the frequency band to be adjusted between at least two frequency bands including at least a frequency band where stimulated Raman scattering occurs among frequency bands that are multiplexed in a multiplexed optical signal transmitted by the optical transmission system. In the adjustment process, when power of an optical signal of the frequency band to be adjusted transmitted from the optical transmitter has been changed, the control apparatus determines the power of the optical signal of the frequency band to be adjusted on the basis of a signal quality measured by the optical receiver that has received the optical signal.Type: GrantFiled: May 20, 2019Date of Patent: February 8, 2022Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Fukutaro Hamaoka, Kyo Minoguchi, Seiji Okamoto, Yoshiaki Kisaka
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Publication number: 20220029707Abstract: An optical transmission system includes an optical transmitter and an optical receiver. The optical transmitter includes a low speed signal generation unit configured to generate, based on an input signal of a transmission data sequence and a signal obtained by cyclically shifting a spectrum of the input signal, a plurality of low speed signals, a high speed signal generation unit configured to digital-to-analog convert and synthesize the plurality of low speed signals to generate a high speed signal, and an optical modulation unit configured to transmit an optical signal obtained by modulation of the high speed signal to a transmission path.Type: ApplicationFiled: December 4, 2019Publication date: January 27, 2022Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masanori NAKAMURA, Fukutaro HAMAOKA, Hiroshi YAMAZAKI, Munehiko NAGATANI, Takayuki KOBAYASHI, Yutaka MIYAMOTO