Patents by Inventor Tomoaki Ishifuji

Tomoaki Ishifuji 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: 8310995
    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: Grant
    Filed: May 2, 2007
    Date of Patent: November 13, 2012
    Assignee: Hitachi, Ltd.
    Inventors: Shinji Murai, Tomoaki Ishifuji, Takashi Yano, Masaaki Shida, Shigenori Hayase
  • Patent number: 7969347
    Abstract: By using the delay profile created by delay profile creating section 102 and the first threshold value 330 received from the first threshold value calculation 105, the first threshold value timing detection section 103 selects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold value 331 received from the second threshold value calculation section 107, reference timing calculation section 106 selects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation section 108 as the receive timing 113 of the incoming wave of the minimum propagation delay time.
    Type: Grant
    Filed: January 4, 2010
    Date of Patent: June 28, 2011
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Nobukazu Doi, Mikio Kuwahara, Tomoaki Ishifuji
  • Patent number: 7711376
    Abstract: At least three base stations transmit a specific signal pattern at given intervals. This allows a mobile station that received this signal pattern to locate itself by using the positional information about the base stations, sending timing (or information on phase shift from the reference time) of each signal pattern from the base stations, and signal pattern receiving time information. At least one of the above base stations changes the sending timing of the signal pattern. On this occasion, the mobile terminal or station is notified of the altered reference time offset (or information on phase shift from the reference time) of the sending timing or updated sending timing of the signal pattern.
    Type: Grant
    Filed: February 13, 2001
    Date of Patent: May 4, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Atsushi Ogino, Mikio Kuwahara, Tomoaki Ishifuji
  • Publication number: 20100103047
    Abstract: By using the delay profile created by delay profile creating section 102 and the first threshold value 330 received from the first threshold value calculation 105, the first threshold value timing detection section 103 selects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold value 331 received from the second threshold value calculation section 107, reference timing calculation section 106 selects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation section 108 as the receive timing 113 of the incoming wave of the minimum propagation delay time.
    Type: Application
    Filed: January 4, 2010
    Publication date: April 29, 2010
    Applicant: HITACHI, LTD.
    Inventors: Katsuhiko Tsunehara, Nobukazu Doi, Mikio Kuwahara, Tomoaki Ishifuji
  • Patent number: 7663532
    Abstract: By using the delay profile created by delay profile creating section 102 and the first threshold value 330 received from the first threshold value calculation 105, the first threshold value timing detection section 103 selects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold value 331 received from the second threshold value calculation section 107, reference timing calculation section 106 selects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation section 108 as the receive timing 113 of the incoming wave of the minimum propagation delay time.
    Type: Grant
    Filed: October 30, 2007
    Date of Patent: February 16, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Nobukazu Doi, Mikio Kuwahara, Tomoaki Ishifuji
  • Patent number: 7660288
    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: Grant
    Filed: July 27, 2006
    Date of Patent: February 9, 2010
    Assignee: Hitachi, Ltd.
    Inventors: Masaaki Shida, Shigenori Hayase, Tomoaki Ishifuji
  • Publication number: 20090285184
    Abstract: The mobile station has a monitor for monitoring the communication qualities of plural wireless interfaces and selecting one of the wireless interfaces to communicate, and a memory for storing the correspondence between the address unique to the selected wireless interface and the network address unique to the mobile station. The mobile station notifies the gateway of the correspondence. The mobile station supplies power to a not operating wireless interface at constant intervals and during a constant time to monitor the communication quality.
    Type: Application
    Filed: July 23, 2009
    Publication date: November 19, 2009
    Inventors: Koji Watanabe, Tomoaki Ishifuji
  • Patent number: 7609197
    Abstract: By using the delay profile created by delay profile creating section 102 and the first threshold value 330 received from the first threshold value calculation 105, the first threshold value timing detection section 103 selects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold value 331 received from the second threshold value calculation section 107, reference timing calculation section 106 selects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation section 108 as the receive timing 113 of the incoming wave of the minimum propagation delay time.
    Type: Grant
    Filed: February 17, 2005
    Date of Patent: October 27, 2009
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Nobukazu Doi, Mikio Kuwahara, Tomoaki Ishifuji
  • Publication number: 20080068254
    Abstract: By using the delay profile created by delay profile creating section 102 and the first threshold value 330 received from the first threshold value calculation 105, the first threshold value timing detection section 103 selects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold value 331 received from the second threshold value calculation section 107, reference timing calculation section 106 selects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation section 108 as the receive timing 113 of the incoming wave of the minimum propagation delay time.
    Type: Application
    Filed: October 30, 2007
    Publication date: March 20, 2008
    Inventors: Katsuhiko Tsunehara, Nobukazu Doi, Mikio Kuwahara, Tomoaki Ishifuji
  • Patent number: 7319684
    Abstract: A system and method are provided for wireless communication. In one example, a wireless communication system that enhances total system throughput is provided. The system performs parallel data transmission from a plurality of access points to a plurality of user terminals. On terminals with power control function, their transmit power can be set to minimize interference. The wireless communication system comprises a management server which performs centralized management of time of access-point-to-terminal packet transmission, access points, and user terminals that perform data transmission, according to transmission time control information from the management server. Transmit queues for measuring downlink traffic and receive queues for measuring uplink traffic are provided on the access points or the management server. The system determines uplink and downlink periods from the transmit and receive queue lengths.
    Type: Grant
    Filed: June 2, 2003
    Date of Patent: January 15, 2008
    Assignee: Hitachi, Ltd.
    Inventors: Tsuyoshi Tamaki, Takashi Yano, Takaki Uta, Tomoaki Ishifuji
  • 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
  • Patent number: 7233581
    Abstract: A time slot for a connection request sent from a mobile station includes the mobile station ID and the application discrimination word of the object application for which the mobile station requests the connection. By referring to the database, a base station assigns a MDC preferentially to a mobile station issuing a connection request for calling a high priority application. The base station monitors the MDCs used for ongoing communications. If a MDC assigned to a mobile station does not satisfy a predetermined radio communication quality, other MDCs for lower priority application are freed and reassigned to the mobile station. A plurality of MDCs including the reassigned MDCs into which the same contents are encapsulated are transmitted to the mobile station.
    Type: Grant
    Filed: March 19, 2001
    Date of Patent: June 19, 2007
    Assignee: Hitachi, Ltd.
    Inventors: Hideya Suzuki, Nobukazu Doi, Tomoaki Ishifuji
  • 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: 7116709
    Abstract: The code system is realized by that a plurality of waveforms A and B each having duty ratios of 50% in which only any one of a rising edge and a falling edge is present are combined with each other, and “1” and “0” are allocated to the combined waveform. In accordance with the present invention, both a clock and data can be transmitted at the same time, and can be readily demodulated without using a complex PLL circuit. As a trial manufacture according to the present invention, the demodulator could be realized which could allow variations contained in an input frequency by more than 1 digit under operating voltage of 2 V. The effectiveness of this patent could be confirmed.
    Type: Grant
    Filed: June 4, 2004
    Date of Patent: October 3, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Satoshi Tanaka, Tomoaki Ishifuji, Kenji Nagai, Katsuhiro Furukawa
  • Patent number: 7016665
    Abstract: A charging system for use in a network composed of wireless terminals with a repeater function. As each terminal with a repeater function receives a communication session start request from a user terminal, it searches for a destination user terminal; when it finds the destination user terminal, it transfers the signal sent from the requesting user terminal to the destination user terminal without the mediation of base stations. The information about the amount of data thus transferred or communication time for transferring data is sent to the charging system which is under the control of the communications service provider concerned.
    Type: Grant
    Filed: May 30, 2002
    Date of Patent: March 21, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Tsuyoshi Tamaki, Masaaki Shida, Tomoaki Ishifuji, Nobukazu Doi, Kazuko Hamaguchi
  • Patent number: 6963269
    Abstract: A contactless IC card having an antenna, a transmit/receive circuit for recovering data (clock) and electric power from a carrier signal received by the antenna, a logic circuit operated with the electric power supplied thereto from the transmit/receive circuit, and a memory. The transmit/receive circuit has a rectifier circuit for outputting data (clock) and rectifier circuits for electric power in such a manner that the carrier signal is inputted to each of the rectifier circuit for outputting data (clock) and the rectifier circuit for electric power. With this configuration, high frequency matching can be optimized separately for the rectifier circuit for outputting data (clock) and the rectifier circuit for electric power. It is also possible to separately optimize adjustments to a voltage of recovered data (clock) and a recovered supply voltage.
    Type: Grant
    Filed: April 1, 2003
    Date of Patent: November 8, 2005
    Assignee: Hitachi, Ltd.
    Inventors: Takeshi Saitoh, Masaaki Shida, Tomoaki Ishifuji
  • Publication number: 20050140543
    Abstract: By using the delay profile created by delay profile creating section 102 and the first threshold value 330 received from the first threshold value calculation 105, the first threshold value timing detection section 103 selects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold value 331 received from the second threshold value calculation section 107, reference timing calculation section 106 selects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation section 108 as the receive timing 113 of the incoming wave of the minimum propagation delay time.
    Type: Application
    Filed: February 17, 2005
    Publication date: June 30, 2005
    Inventors: Katsuhiko Tsunehara, Nobukazu Doi, Mikio Kuwahara, Tomoaki Ishifuji
  • Patent number: 6900753
    Abstract: By using the delay profile created by delay profile creating section 102 and the first threshold value 330 received from the first threshold value calculation section 105, the first threshold value timing detection section 103 selects only the earliest receive timing exceeding the first threshold value, from all the timing that the correlation value in the delay profile becomes a maximum. By using the receive timing and the second threshold value 331 received from the second threshold value calculation section 107, reference timing calculation section 106 selects the reference timing required for calculating the receive timing for the incoming wave of the minimum propagation delay time. The timing delayed by previously set timing behind said reference timing is sent from receive timing calculation section 108 as the receive timing 113 of the incoming wave of the minimum propagation delay time.
    Type: Grant
    Filed: October 8, 2003
    Date of Patent: May 31, 2005
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Nobukazu Doi, Mikio Kuwahara, Tomoaki Ishifuji