Patents by Inventor Mikio Kuwahara

Mikio Kuwahara 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: 7203462
    Abstract: Phase and amplitude deviations, which are generated, for example, by cables connecting an array antenna of a CDMA base station and the base station, are calibrated in the baseband.
    Type: Grant
    Filed: September 29, 2003
    Date of Patent: April 10, 2007
    Inventors: Mikio Kuwahara, Nobukazu Doi, Toshiro Suzuki, Yuji Ishida, Takashi Inoue, Sumaru Niida
  • Publication number: 20070072646
    Abstract: In a wireless base station comprising a center unit, and a remote unit provided with an array antenna and connected to the center unit through an optical fiber, the center unit outputs to the optical fiber a transmission signal in a base band state prior to array processing, the remote unit performs the array processing of transmission signals in accordance with array weights and converts the transmission signals into RF signals, thereby to localize the compensation for transmission signal deviations occurring among the antenna elements on the remote unit side.
    Type: Application
    Filed: February 6, 2006
    Publication date: March 29, 2007
    Inventors: Mikio Kuwahara, Masanori Taira
  • Patent number: 7116992
    Abstract: When a person of holding a mobile station gets near to a previously set target position, application 200 is started and service of utilizing positional information is provided to the person of holding the mobile station or a third party. The mobile station includes a position comparator 103 for comparing a current position of the mobile station calculated by a position calculator 102 by using a signal from an antenna 100 with a target position inputted from means for target position input 104 and an application controller 106 for controlling the application 200 by using a result of position comparison 120. Further, a frequency of position calculation is pertinently controlled in the position calculator 102 by a position calculation controller 107 operated by the result of position comparison 120.
    Type: Grant
    Filed: April 5, 2000
    Date of Patent: October 3, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Mikio Kuwahara, Ayumu Koide, Nobukazu Doi
  • Publication number: 20060217158
    Abstract: A wireless communication which suppresses radio interference between wireless base stations and improves the channel efficiency is implemented. In the wireless communication system including a central base station, a plurality of remote base stations having a direction-variable antenna, and a plurality of mobile stations to communicate with the remote base stations, the central base station performs centralized management of radio-wave beam patterns to be sent to the plurality of mobile stations which will communicate with remote base stations and performs packet scheduling of the mobile stations in such a manner that radio waves sent from the remote base stations will not cause strong interference at the mobile stations.
    Type: Application
    Filed: February 9, 2006
    Publication date: September 28, 2006
    Inventors: Koki Uwano, Masanori Taira, Kenzaburo Fujishima, Mikio Kuwahara
  • Patent number: 7082321
    Abstract: A radio communication system and method having an array antenna and a weighting arrangement that provides a downlink array weight for a downlink on the basis of information about bearings of a plurality of incoming signals received through a plurality of uplinks, and transmission power control information about transmission data to be transmitted through a downlink.
    Type: Grant
    Filed: July 15, 2003
    Date of Patent: July 25, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Mikio Kuwahara, Nobukazu Doi
  • Patent number: 7072673
    Abstract: A radio handset includes: a signal receiver for receiving signals from a plurality of radio stations; a reception timing analyzer for analyzing reception timings of signals received by the signal reception means; a radio station selector for selecting radio stations to be used in a position calculation; and a position calculator for calculating a position of a signal reception point by using the reception timings of the signals from the selected radio stations. The radio station selector selects the radio stations to be used in the position calculation in such a manner that when reception timings of signals from two or more of the radio stations cannot be separated from one another, it is decided to exclude a signal from at least one of these radio stations.
    Type: Grant
    Filed: October 22, 2002
    Date of Patent: July 4, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Kenzaburo Fujishima, Mikio Kuwahara, Koji Watanabe
  • Publication number: 20060128414
    Abstract: In a wireless communication system having a base station and a terminal, it is important to extend the operating life of the terminal in the case of using a battery as the power supply of the terminal. Particularly in the case where a state in which a base station is not present in the range within which the terminal can communicate lasts long, the reduction of the electric power consumption during the standby of the terminal becomes an issue. The terminal monitors the received signal power strength of a signal transmitted by the base station. When the power strength exceeds a prescribed value, it is considered that the base station is present and the base station performs operations for carrying out communication with the base station.
    Type: Application
    Filed: December 7, 2005
    Publication date: June 15, 2006
    Inventors: Masaaki Shida, Kei Suzuki, Mikio Kuwahara
  • Patent number: 7016653
    Abstract: A radio terminal that receives signals from a plurality of radio stations to calculate its current position has: interference canceling means for canceling each interference signal from the plurality of received signals; a plurality of delay profile generating means for generating delay profiles of the plurality of interference-canceled received signals with use of respective corresponding codes; and position calculating means for calculating its current position, which is a signal receiving point, with use of the plurality of delay profiles, whereby advantageously reducing the capacity of a memory mounted in the mobile terminal while the position calculation is speeded up
    Type: Grant
    Filed: June 27, 2002
    Date of Patent: March 21, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Mikio Kuwahara
  • Patent number: 7013111
    Abstract: The disclosed invention provides a wireless communications terminal apparatus that calculates its accurate position, eliminating the influence of a repeater on the calculation without using complicated processing. The terminal apparatus receives signals transmitted from a plurality of radio stations and calculates its position, using the received signals. The terminal apparatus comprises repeater detection means for detecting a signal from a repeater which transmits signals that are generated on the basis of signals transmitted from one of the radio stations and indistinguishable from the signals transmitted from that radio station from among the received signals and position calculation means for calculating its position. When the repeater detection means has detected a signal from a repeater, the position calculation means ignores the detected signal from the repeater and calculates the terminal position, using the received signals from other radio stations.
    Type: Grant
    Filed: July 29, 2002
    Date of Patent: March 14, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Mikio Kuwahara, Kenichi Mizugaki, Atsushi Ogino, Kenzaburo Fujishima
  • Patent number: 7013147
    Abstract: The invention intends to solve a problem that an S/I ratio of a signal from a target base station deteriorates when there is a terminal near another base station. For this purpose, a signal replica of the signal from the nearby base station is generated and the replica is subtracted from a receiving signal. A signal of the target base station is detected from the resultant receiving signal. The signal from the nearby base station is deleted from the denominator of the S/I ratio, thereby increasing the S/I ratio.
    Type: Grant
    Filed: July 17, 2000
    Date of Patent: March 14, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Mikio Kuwahara, Nobukazu Doi
  • Patent number: 6990351
    Abstract: Even in areas where signals from only two or less base stations are available for position calculation, the mobile handset position can be calculated, expanding the position information service area and improving the usefulness. When the number of base stations available for position calculation is three or more, the position calculation is performed based on trilateration. When the number of available base stations is two or one, the position calculation is performed by using a two-station-based position calculation method or a one-station-based position calculation method according to the number of available base stations.
    Type: Grant
    Filed: February 19, 2002
    Date of Patent: January 24, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Mikio Kuwahara
  • Patent number: 6990345
    Abstract: In a method for locating a position of a terminal with use of weak signals, a combined weight to be used to separate a path from others through correlation calculation is obtained from a plurality of delay profiles measured in course of time. The obtained weight is used to combine the delay profiles and a path detection is carried out on the combined delay profiles.
    Type: Grant
    Filed: January 16, 2003
    Date of Patent: January 24, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Mikio Kuwahara, Kenzaburo Fujishima
  • Publication number: 20060002421
    Abstract: To reduce power consumption of a mobile station, this invention provides a wireless communication method for communicating between a base station and a plurality of terminals using a plurality of channels, the channels being slots obtained by dividing frequency-divided carriers by time, in which the base station allocates a set of the channels which is composed of a plurality of neighboring carriers and/or a plurality of successive slots for the each terminal, and the base station allocates at least one of the channels included in the channel sets for packet transmission the terminals.
    Type: Application
    Filed: February 25, 2005
    Publication date: January 5, 2006
    Inventors: Mikio Kuwahara, Kenzaburo Fujishima, Masanori Taira
  • Publication number: 20060002287
    Abstract: To provide a wireless base station comprising an array antenna which transmits packets to terminals, a packet scheduler which determines transmission sequence of the packets, a modulator which generates modulated signals based on the packets, and a beam former for transmission signal which multiplies the packets with array weights for transmission signal and outputs the transmission signal to the array antenna the beam former for transmission signal comprises a memory which stores the array weights for transmission signal associated with the terminals' IDs. The beam former for transmission signal receives the IDs of selected terminals from the packet scheduler, refers to the memory, and selects the array weights for transmission signal by the IDs of the terminals.
    Type: Application
    Filed: February 25, 2005
    Publication date: January 5, 2006
    Inventors: Mikio Kuwahara, Kenzaburo Fujishima, Masanori Taira, Koji Meguro, Toru Okamoto
  • Patent number: 6950661
    Abstract: A location calculation method for calculating, by using propagation delay time of signals received from wireless transmitters, a location of a reception point of the signals to thereby reduce errors in the distance measurement due to an erroneous detection of a path of a received signal includes first step of measuring reception timing of signals received from the wireless transmitters, second step of estimating, according to results of measurement of the reception timing obtained by the first step, an erroneous result of measurement, and third step of removing the results of measurement estimated as the erroneous results by the second step from the results of measurement of the reception timing obtained by the first step, and thereby calculating the location of the reception point.
    Type: Grant
    Filed: January 8, 2002
    Date of Patent: September 27, 2005
    Assignee: Hitachi, Ltd.
    Inventors: Koji Watanabe, Mikio Kuwahara, Katsuhiko Tsunehara, Kenzaburo Fujishima
  • Publication number: 20050197162
    Abstract: A radio communication apparatus enhances cell throughput by adaptive selection of spatially multiplexed channels in consideration of interferences in a local cell and reducing load for calculation of array weights by storing them in advance as fixed values and outputting fixed beams. To reduce the calculation load for the adaptive selection of spatially multiplexed channels that takes interferences within the local cell into consideration, the radio communication apparatus adopts a packet scheduling method that selects a combination of fixed beams and determines the number of spatially multiplexed channels, based on the fixed beams for mobile apparatuses with packets waiting to be transmitted and pre-calculated correlative quantities of inter-beam interferences between these fixed beams.
    Type: Application
    Filed: February 4, 2005
    Publication date: September 8, 2005
    Inventors: Kenzaburo Fujishima, Mikio Kuwahara, Masanori Taira, Koji Meguro, Toru Okamoto
  • Patent number: 6928292
    Abstract: To extend the areas where a mobile handset can determine its position using radio waves, the present invention provides a mobile handset that is equipped with both position calculation means using radio waves from GPS satellites and position calculation means using RF carriers from cellular base stations. Positioning results obtained from both of these position calculation means are combined and weighted with GPS positioning reliability and cellular positioning reliability, respectively. A weighted mean of these results is then output as a final position calculation result.
    Type: Grant
    Filed: March 12, 2002
    Date of Patent: August 9, 2005
    Assignee: Hitachi, Ltd.
    Inventors: Katsuhiko Tsunehara, Mikio Kuwahara
  • 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
  • Patent number: 6889051
    Abstract: An offset measuring method according to the present invention accurately measures a transmitting time offset of a base station. The offset measuring method for receiving signals from the radio base station and measuring the transmitting time offset of the radio base station includes the steps of calculating estimated values of transmitting time offset based on signals received at a plurality of observation points and selecting a minimum from the estimated offsets to determine the selected minimum value as transmitting time offset of the radio base station.
    Type: Grant
    Filed: January 16, 2002
    Date of Patent: May 3, 2005
    Assignee: Hitachi, Ltd.
    Inventors: Atsushi Ogino, Mikio Kuwahara, Tomoaki Ishifuji, Kenzaburo Fujishima