Patents by Inventor Masahito Tomizawa
Masahito Tomizawa 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: 9621299Abstract: The estimation of an amount of chromatic dispersion using a training signal sequence is possible. A transmission method includes: a training signal sequence generation step of generating, as training signal sequences, a plurality of signal sequences having power concentrated in a plurality of frequency bands, the power concentrated at different frequency bands; a training signal sequence selection step of selecting at least one training signal sequence from among the plurality of training signal sequences generated in the training signal sequence generation step, a signal multiplexing step of generating a signal sequence obtained by time-division multiplexing the training signal sequence selected in the training signal sequence selection step with a transmission data sequence, and an electrical-to-optical conversion step of transmitting the signal sequence generated in the signal multiplexing step as an optical signal.Type: GrantFiled: January 15, 2014Date of Patent: April 11, 2017Assignee: Nippon Telegraph and Telephone CorporationInventors: Koichi Ishihara, Masato Mizoguchi, Tomoki Murakami, Tomoyoshi Kataoka, Yoshiaki Kisaka, Tadao Nakagawa, Etsushi Yamazaki, Seiji Okamoto, Kengo Horikoshi, Masahito Tomizawa, Riichi Kudo
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Publication number: 20170070296Abstract: An optical signal transmission apparatus includes a modulation unit which modulates a transmission signal, a training signal sequence generation unit which generates a plurality of signal sequences having power concentrated in a plurality of different frequency bands, at least one of an amplitude and a phase of the plurality of signal sequences being modulated, as a training signal sequence, a signal multiplexing unit which appends the training signal sequence to the transmission signal, and an electro-optical conversion unit which converts a signal sequence obtained by appending the training signal sequence to the transmission signal into an optical signal and transmits the optical signal.Type: ApplicationFiled: March 17, 2015Publication date: March 9, 2017Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Seiji OKAMOTO, Koichi ISHIHARA, Etsushi YAMAZAKI, Mitsuteru YOSHIDA, Tomoyoshi KATAOKA, Kazushige YONENAGA, Yoshiaki KISAKA, Masanori NAKAMURA, Masahito TOMIZAWA
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Patent number: 9438365Abstract: A client signal mapping circuit for accommodating a client signal in a transmission frame, including: a buffer unit configured to temporarily store the client signal; a buffer used amount monitoring unit configured to report a used amount of the buffer unit; a stuff processing determination unit configured to compare the used amount of the buffer unit with a predetermined reference value, and a pseudo random sequence signal and the comparison result; an overhead insertion unit configured to add an overhead to the client signal read from the buffer unit to form a transmission frame; and a reading control unit configured to perform control for reading the client signal from the buffer unit based on determination by the stuff processing determination unit.Type: GrantFiled: August 27, 2015Date of Patent: September 6, 2016Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masahiro Suzuki, Takuya Ohara, Takashi Ono, Shigeki Aisawa, Masahito Tomizawa
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Publication number: 20160065326Abstract: An optical transmission and reception system includes a transmitter and receiver. The transmitter differentially encodes control information to generate a differentially coded signal; uses the differentially coded signal to modulate a signal sequence in which electricity concentrates at a particular frequency; applies time-division multiplexing on the modulated signal sequence and a primary signal in one of two polarized wave components, and applies time-division multiplexing on the other polarized wave components and the signal sequence itself; and polarization-multiplexes the both of the time-division multiplexed polarized waves into an optical signal; and transmits the optical signal to the receiver.Type: ApplicationFiled: March 14, 2014Publication date: March 3, 2016Inventors: Yoshiaki KISAKA, Koichi ISHIHARA, Masahito TOMIZAWA, Etsushi YAMAZAKI
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Publication number: 20160006525Abstract: A client signal mapping circuit for accommodating a client signal in a transmission frame, including: a buffer unit configured to temporarily store the client signal; a buffer used amount monitoring unit configured to report a used amount of the buffer unit; a stuff processing determination unit configured to compare the used amount of the buffer unit with a predetermined reference value, and a pseudo random sequence signal and the comparison result; an overhead insertion unit configured to add an overhead to the client signal read from the buffer unit to form a transmission frame; and a reading control unit configured to perform control for reading the client signal from the buffer unit based on determination by the stuff processing determination unit.Type: ApplicationFiled: August 27, 2015Publication date: January 7, 2016Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masahiro SUZUKI, Takuya OHARA, Takashi ONO, Shigeki AlSAWA, Masahito TOMIZAWA
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Publication number: 20150372766Abstract: An increase in circuit scale is suppressed and a phase variation caused in a transmission path or the like is compensated for.Type: ApplicationFiled: February 13, 2014Publication date: December 24, 2015Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Mitsuteru YOSHIDA, Etsushi YAMAZAKI, Seiji OKAMOTO, Hiroyuki UZAWA, Kengo HORIKOSHI, Koichi ISHIHARA, Takayuki KOBAYASHI, Yoshiaki KISAKA, Masahito TOMIZAWA, Naoki FUJIWARA, Tomoyoshi KATAOKA, Kazushige YONENAGA
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Publication number: 20150341138Abstract: The estimation of an amount of chromatic dispersion using a training signal sequence is possible. A transmission method includes: a training signal sequence generation step of generating, as training signal sequences, a plurality of signal sequences having power concentrated in a plurality of frequency bands, the power concentrated at different frequency bands; a training signal sequence selection step of selecting at least one training signal sequence from among the plurality of training signal sequences generated in the training signal sequence generation step, a signal multiplexing step of generating a signal sequence obtained by time-division multiplexing the training signal sequence selected in the training signal sequence selection step with a transmission data sequence, and an electrical-to-optical conversion step of transmitting the signal sequence generated in the signal multiplexing step as an optical signal.Type: ApplicationFiled: January 15, 2014Publication date: November 26, 2015Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Koichi ISHIHARA, Masato MIZOGUCHI, Tomoki MURAKAMI, Tomoyoshi KATAOKA, Yoshiaki KISAKA, Tadao NAKAGAWA, Etsushi YAMAZAKI, Seiji OKAMOTO, Kengo HORIKOSHI, Masahito TOMIZAWA, Riichi KUDO
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Publication number: 20150333838Abstract: 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: ApplicationFiled: January 24, 2014Publication date: November 19, 2015Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo HORIKOSHI, Kohki SHIBAHARA, Etsushi YAMAZAKI, Mitsuteru YOSHIDA, Koichi ISHIHARA, Takayuki KOBAYASHI, Yoshiaki KISAKA, Takuya OHARA, Masahito TOMIZAWA, Tomoyoshi KATAOKA
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Patent number: 9178614Abstract: A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path.Type: GrantFiled: January 24, 2012Date of Patent: November 3, 2015Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Etsushi Yamazaki, Takayuki Kobayashi, Masahito Tomizawa, Riichi Kudo, Koichi Ishihara, Tadao Nakagawa, Mitsuteru Ishikawa
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Patent number: 9160479Abstract: A client signal mapping circuit for accommodating a client signal in a transmission frame, including: a buffer unit configured to temporarily store the client signal; a buffer used amount monitoring unit configured to report a used amount of the buffer unit; a stuff processing determination unit configured to compare the used amount of the buffer unit with a predetermined reference value, and a pseudo random sequence signal and the comparison result; an overhead insertion unit configured to add an overhead to the client signal read from the buffer unit to form a transmission frame; and a reading control unit configured to perform control for reading the client signal from the buffer unit based on determination by the stuff processing determination unit.Type: GrantFiled: December 9, 2011Date of Patent: October 13, 2015Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masahiro Suzuki, Takuya Ohara, Takashi Ono, Shigeki Aisawa, Masahito Tomizawa
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Patent number: 8977120Abstract: In an apparatus for accommodating and multiplexing asynchronous client signals in which an idle signal is defined, the transmission side transmits client signals after synchronizing the client signals by inserting or removing, with reference to a specific client signal, an idle signal to/from the same type of another client signal, and in the receiving side, a PLL part is shared by recovering a clock from a client signal and distributing the clock for another client signal.Type: GrantFiled: March 11, 2011Date of Patent: March 10, 2015Assignees: Nippon Telegraph and Telephone Corporation, Fujitsu LimitedInventors: Takuya Ohara, Takashi Ono, Shigeki Aisawa, Masahito Tomizawa, Hiroyuki Honma, Satoru Saitoh, Masahiro Shioda
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Patent number: 8971703Abstract: A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path.Type: GrantFiled: February 1, 2012Date of Patent: March 3, 2015Assignee: Nippon Telegraph and Telephone CorporationInventors: Etsushi Yamazaki, Takayuki Kobayashi, Masahito Tomizawa, Riichi Kudo, Koichi Ishihara, Tadao Nakagawa, Mitsuteru Ishikawa
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Publication number: 20140016929Abstract: A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path.Type: ApplicationFiled: January 24, 2012Publication date: January 16, 2014Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Etsushi Yamazaki, Takayuki Kobayashi, Masahito Tomizawa, Riichi Kudo, Koichi Ishihara, Tadao Nakagawa, Mitsuteru Ishikawa
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Publication number: 20130343749Abstract: A wavelength dispersion amount estimation method, a wavelength dispersion compensation circuit, and a receiving device which rapidly estimate and set a wavelength dispersion amount to compensate with high accuracy at the receiving device which compensates waveform distortion at an optical fiber transmission path.Type: ApplicationFiled: January 2, 2012Publication date: December 26, 2013Inventors: Etsushi Yamazaki, Takayuki Kobayashi, Masahito Tomizawa, Riichi Kudo, Koichi Ishihara, Tadao Nakagawa, Mitsuteru Ishikawa
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Patent number: 8571037Abstract: An optical digital transmission system of the present invention newly defines one second negative stuff byte in an overhead area for accommodation of the client signals with multiplexing into the OTU frame, newly defines one third positive stuff byte in a corresponding tributary slot in a payload area for accommodation of client signals with multiplexing, newly defines stuff control bits that is used for decision of the use of the second negative stuff byte and the third positive stuff byte in three different places in the overhead area for client signal accommodation with multiplexing, performs control by using the newly defined stuff control bits when accommodation of the client signal with the third positive stuff byte or the second negative stuff byte is required, and performs stuff control without using the newly defined stuff control bits when accommodation of the client signal by the third positive stuff byte and the second negative stuff byte is not required.Type: GrantFiled: November 13, 2009Date of Patent: October 29, 2013Assignees: Nippon Telegraph and Telephone Corporation, NTT Electronics CorporationInventors: Shigeki Aisawa, Masahito Tomizawa, Yutaka Miyamoto, Yoshiaki Kisaka, Yasuyuki Endo, Katsuyoshi Miura, Kazuhito Takei
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Publication number: 20130259481Abstract: A client signal mapping circuit for accommodating a client signal in a transmission frame, including: a buffer unit configured to temporarily store the client signal; a buffer used amount monitoring unit configured to report a used amount of the buffer unit; a stuff processing determination unit configured to compare the used amount of the buffer unit with a predetermined reference value, and a pseudo random sequence signal and the comparison result; an overhead insertion unit configured to add an overhead to the client signal read from the buffer unit to form a transmission frame; and a reading control unit configured to perform control for reading the client signal from the buffer unit based on determination by the stuff processing determination unit.Type: ApplicationFiled: December 9, 2011Publication date: October 3, 2013Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Masahiro Suzuki, Takuya Ohara, Takashi Ono, Shigeki Aisawa, Masahito Tomizawa
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Patent number: 8514881Abstract: A digital transmission system includes at least a client device and a transmission device, and rate-adjusts the client signal transmitted from the client device to the transmission device before accommodating/multiplexing the signal in a frame. The transmission device includes a rate adjusting unit and a frame processing unit. The rate adjusting unit encapsulates the client signal by using a predetermined frame structure, inserts an idle pattern if necessary, and performs rate adjustment into the bit rate which can be contained in the frame. The frame processing unit accommodates/multiplexes the signal after the rate adjustment. The digital transmission system inserts a bit string of the client signal directly in a payload area of the digital frame, or accommodates and multiplexes it. Alternatively, a specific pattern is accommodated in the payload area, or accommodated and multiplexed after performing a reversible digital signal processing.Type: GrantFiled: January 16, 2008Date of Patent: August 20, 2013Assignees: Nippon Telegraph and Telephone Corporation, NTT Electronics CorporationInventors: Yoshiaki Kisaka, Takuya OHara, Shigeki Aisawa, Yutaka Miyamoto, Kazuhito Takei, Yasuyuki Endoh, Katsuyoshi Miura, Tadanobu Nikaido, Masahito Tomizawa
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Publication number: 20130004168Abstract: In an apparatus for accommodating and multiplexing asynchronous client signals in which an idle signal is defined, the transmission side transmits client signals after synchronizing the client signals by inserting or removing, with reference to a specific client signal, an idle signal to/from the same type of another client signal, and in the receiving side, a PLL part is shared by recovering a clock from a client signal and distributing the clock for another client signal.Type: ApplicationFiled: March 11, 2011Publication date: January 3, 2013Applicants: FUJITSU LIMITED, NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Takuya Ohara, Takashi Ono, Shigeki Aisawa, Masahito Tomizawa, Hiroyuki Honma, Satoru Saitoh, Masahiro Shioda
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Patent number: 8254789Abstract: A device and method for adjusting the chromatic dispersion in an optical transmission system includes an optical element having a temperature-dependent chromatic dispersion. The device and method further include a device for adjusting a temperature or a temperature distribution of at least one region of the optical element for providing a predefined chromatic dispersion of the optical element. Therefore, the chromatic dispersion of the optical element may be regulated along an optical transmission path.Type: GrantFiled: September 23, 2003Date of Patent: August 28, 2012Assignees: Deutsche Telekom AG, Nippon Telegraph and Telephone CorporationInventors: Arnold Mattheus, Yutaka Miyamoto, Masahito Tomizawa
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Patent number: 8135285Abstract: An optical transmission system for performing frequency synchronization even with a client signal with low frequency accuracy, and for transmitting thereof by accommodating/multiplexing without causing a bit slip. A new overhead is added to the entire client signal, and the signal including the new overhead being stuffed is transmitted in conjunction with a plurality of stuffing bits as an optical signal wherein a data storing bit for a negative stuffing, a stuffing information notification bit, and a stuff bits inserting bit for a positive stuffing in the payload are defined in plurality as stuffing bits for adjusting clock frequencies of the client signal in this new overhead.Type: GrantFiled: December 21, 2006Date of Patent: March 13, 2012Assignee: NTT Electronics CorporationInventors: Yoshiaki Kisaka, Shigeki Aisawa, Yutaka Miyamoto, Masahito Tomizawa, Yasuyuki Endoh, Kazuhito Takei