Patents by Inventor Shigenori Hayase

Shigenori Hayase 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: 7391974
    Abstract: Optical signal transmission is improved by reducing the variance in light output level and OSNR by adjusting optical signal intensity and gain tilt, taking SRS influence into consideration.
    Type: Grant
    Filed: February 27, 2007
    Date of Patent: June 24, 2008
    Assignee: Hitachi, Ltd.
    Inventors: Tetsuya Uda, Shigehiro Takashima, Shigenori Hayase, Yoshimasa Kusano, Satoshi Asamizu, Hirofumi Nakano
  • Publication number: 20080056140
    Abstract: A MIMO wireless data transmission system including a data arrangement in which data to be sent is divided for each transmission stream of MIMO with adding an error detection code thereto and thereby resending a subframe's worth of data when an error occurred at the time of resending. It therefore becomes to avoid the same frame being sent again at the time of resending.
    Type: Application
    Filed: April 11, 2007
    Publication date: March 6, 2008
    Inventors: Masaaki Shida, Shigenori Hayase, Keisuke Yamamoto
  • Publication number: 20070286149
    Abstract: In a system in which a host and a plurality of terminals simultaneously communicate with each other under the SDMA scheme, transmission parameters to be used for generating frames for SDMA transmission to the respective terminals are adjusted in consideration of the transmission time durations necessary for transmission of other frames to be transmitted simultaneously with the first-mentioned frames, so that differences between the frame transmission time durations are reduced.
    Type: Application
    Filed: May 1, 2007
    Publication date: December 13, 2007
    Inventors: Keisuke Yamamoto, Shigenori Hayase, Masaaki Shida
  • Publication number: 20070274256
    Abstract: In a wireless communication system for communicating with a plurality of stations at the same point of time with the same frequency using a Space Division Multiple Access (SDMA), wireless resources are allocated by a first decision unit which evaluates performance of each station obtained when the SDMA is used and which determines periods of time to be allocated to groups of stations formed according to the SDMA technique. Using a first evaluation unit and a second evaluation unit to evaluate performance required by each station and each application, the first decision unit allocates the wireless resources to the stations. It is therefore possible that the wireless resources are efficiently allocated to the stations while preventing an event in which the wireless resources are excessive or insufficient for required quality of service.
    Type: Application
    Filed: May 2, 2007
    Publication date: November 29, 2007
    Inventors: Shinji Murai, Tomoaki Ishifuji, Takashi Yano, Masaaki Shida, Shigenori Hayase
  • Publication number: 20070263745
    Abstract: In a MIMO wireless communication system, the transformation process synthesizes the eigenmodes having a large singular value (i.e. a high effective SNR) and the eigenmodes having a small singular value (i.e. a low effective SNR). Thereby, the former eigenmodes are converted into modes having suppressed effective SNR which do not require a large number of levels of modulation, and the latter eigenmodes are converted into modes having increased effective SNR instead. In a MIMO wireless communication system for eigenmode transmission, a large communication capacity is realized without increasing the number of levels of modulation even in a communication environment capable of achieving a high SNR.
    Type: Application
    Filed: April 17, 2007
    Publication date: November 15, 2007
    Inventors: Shigenori Hayase, Masaaki Shida, Keisuke Yamamoto
  • Publication number: 20070166052
    Abstract: Optical signal transmission is improved by reducing the variance in light output level and OSNR by adjusting optical signal intensity and gain tilt, taking SRS influence into consideration.
    Type: Application
    Filed: February 27, 2007
    Publication date: July 19, 2007
    Applicant: Hitachi, Ltd.
    Inventors: Tetsuya Uda, Shigehiro Takashima, Shigenori Hayase, Yoshimasa Kusano, Satoshi Asamizu, Hirofumi Nakano
  • Patent number: 7209765
    Abstract: A wireless communication system has no limitation in the number of AP antennas and UT antennas, and determines the parallel-communication data units to be a maximum value of MIMO communication, such that it provides a MIMO-SDMA wireless data communication system having superior transmission characteristics. The MIMO-SDMA wireless data communication system includes a single AP (Access Point) and U UTs (User Terminals) communicating with the AP using the same frequency signal at the same time. The UT includes the SDMA reception (Rx) processor, and synthesizes Rx signals of antennas, such that it controls the number of Rx data units. By the control of the number of Rx data units, the communication system controls the number of parallel-communication data units to be equal to a maximum value capable of being implemented by the MIMO-SDMA wireless data communication. The AP informs the UTs of a coefficient matrix required for the SDMA Rx process, prior to transmitting actual data.
    Type: Grant
    Filed: July 27, 2006
    Date of Patent: April 24, 2007
    Assignee: Hitachi, Ltd.
    Inventors: Shigenori Hayase, Shinji Murai, Tomoaki Ishifuji
  • Publication number: 20070086400
    Abstract: Disclosed is a wireless communication system capable of performing demodulation at the receiving side without substantially deteriorating BER characteristics, regardless of carrier frequency error existing among plural wireless communication systems in SDMA of uplink. The wireless communication system includes plural antennas; a MIMO processor that decomposes a reception signal the plural antennas received from plural transmitters into transmission signals transmitted from the respective transmitters; a FFT processor that carries out OFDM demodulation; and a demapping unit that obtains data from signals which were previously converted into sub-carrier signals by the FFT processor, in which the MIMO processor is installed ahead of the FFT processor for sake of the processing sequence of a receive signal, and even though a carrier frequency offset exists in the reception signal MIMO processing is performed prior to OFDM demodulation to split the reception signal from plural transmitters.
    Type: Application
    Filed: July 27, 2006
    Publication date: April 19, 2007
    Inventors: Masaaki Shida, Shigenori Hayase, Tomoaki Ishifuji
  • Publication number: 20070081450
    Abstract: A wireless communication system has no limitation in the number of AP antennas and UT antennas, and determines the parallel-communication data units to be a maximum value of MIMO communication, such that it provides a MIMO-SDMA wireless data communication system having superior transmission characteristics. The MIMO-SDMA wireless data communication system includes a single AP (Access Point) and U UTs (User Terminals) communicating with the AP using the same frequency signal at the same time. The UT includes the SDMA reception (Rx) processor, and synthesizes Rx signals of antennas, such that it controls the number of Rx data units. By the control of the number of Rx data units, the communication system controls the number of parallel-communication data units to be equal to a maximum value capable of being implemented by the MIMO-SDMA wireless data communication. The AP informs the UTs of a coefficient matrix required for the SDMA Rx process, prior to transmitting actual data.
    Type: Application
    Filed: July 27, 2006
    Publication date: April 12, 2007
    Inventors: Shigenori Hayase, Shinji Murai, Tomoaki Ishifuji
  • Patent number: 7194210
    Abstract: Optical signal transmission is improved by reducing the variance in light output level and OSNR by adjusting optical signal intensity and gain tilt, taking SRS influence into consideration.
    Type: Grant
    Filed: January 17, 2002
    Date of Patent: March 20, 2007
    Assignee: Hitachi, Ltd.
    Inventors: Tetsuya Uda, Shigehiro Takashima, Shigenori Hayase, Yoshimasa Kusano, Satoshi Asamizu, Hirofumi Nakano
  • Publication number: 20060198461
    Abstract: In MIMO transmission which executes quadrature modulation of M transmission antennas and N reception antennas, a transmission signal vector will be set as a vector having the element number of 2M that comprises the in-phase components and quadrature components of M complex signals, a reception signal vector will be set as a vector having the element number of 2N that comprises the in-phase components and quadrature components of N complex signals, and a transfer matrix will be set as a real matrix comprising 2N rows and 2M columns. Then, a transfer matrix containing IQ mismatch is obtained based on a training signal, thereby executing MIMO encoding and decoding. For learning of the transfer matrix, a training signal which has two linearly-independent signal points on a constellation for each of the transmission antennas is used.
    Type: Application
    Filed: August 26, 2005
    Publication date: September 7, 2006
    Inventor: Shigenori Hayase
  • Publication number: 20060056546
    Abstract: To detect phase mismatches between in-phase and quadrature signals of a quadrature demodulator. The phase mismatches can be detected using the signals obtained by removing high frequency components of output of a multiplier by a low pass filter, the output being the product of the in-phase signals of which low frequency components are removed by a first high pass filter by the quadrature signals of which low frequency components are removed by a second high pass filter.
    Type: Application
    Filed: December 7, 2004
    Publication date: March 16, 2006
    Inventors: Shigenori Hayase, Kazuyuki Hori
  • Publication number: 20040208428
    Abstract: Objects of the present invention are to reduce the number of optical filters, and to improve crosstalk characteristics of periodic optical filters. WDM signals are converted into vestigial-side-band signals collectively using a periodic optical filter. As an example, light signals having odd number wavelengths (wavelengths &lgr;1, &lgr;3, &lgr;5) and light signals having even number wavelengths (wavelengths &lgr;2, &lgr;4, &lgr;6) are wavelength-multiplexed in the first optical wavelength multiplexer, and are then filtered by a periodic narrow band-pass optical filter to convert the light signals into vestigial-side-band (VSB) signals. Then, the vestigial-side-band signals are combined by the second optical wavelength multiplexer. Such an interleave configuration enables suppression of crosstalk caused by adjacent channels.
    Type: Application
    Filed: February 27, 2002
    Publication date: October 21, 2004
    Inventors: Nobuhiko Kikuchi, Shigenori Hayase, Ryoji Takeyari
  • Publication number: 20020181061
    Abstract: Optical signal transmission is improved by reducing the variance in light output level and OSNR by adjusting optical signal intensity and gain tilt, taking SRS influence into consideration.
    Type: Application
    Filed: January 17, 2002
    Publication date: December 5, 2002
    Applicant: Hitachi, Ltd.
    Inventors: Tetsuya Uda, Shigehiro Takashima, Shigenori Hayase, Yoshimasa Kusano, Satoshi Asamizu, Hirofumi Nakano