Patents by Inventor Masayuki TAKEKAWA

Masayuki TAKEKAWA 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: 10374688
    Abstract: Provided is a technique for efficiently using a channel bandwidth in a wireless communication system provided with a function for dividing a frequency channel into a plurality of segments and performing relay using the segments that differ from relay section to relay section. In a second scheme, an upstream direction of a first relay section is a DL section, and two segments are used. An upstream direction of a second relay section is a UL section, and two segments are used. That is, 2/3 of an area is used in a frequency-axis direction, and 1/2 of the area is used in a time-axis direction similarly to a first scheme. A data area ratio for the second scheme becomes 1/3. A data area ratio for the first scheme is 1/6. Thus, a throughput for the second scheme is twice a throughput for the first scheme.
    Type: Grant
    Filed: February 20, 2015
    Date of Patent: August 6, 2019
    Assignee: HITACHI KOKUSAI ELECTRIC INC.
    Inventors: Kei Yanagisawa, Masayuki Takekawa
  • Patent number: 10070406
    Abstract: A method for adjusting a transmission timing of a terminal station, which is performed at a base station in a Time-Division Duplex communication system, is disclosed. The method includes (a) receiving ranging signals or other reference signals, transmitted from a terminal station; (b) determining whether transmission timing at the terminal station is appropriate or not, by referring to the ranging signals transmitted from the terminal station; and (c) transmitting a value for adjusting the transmission timing at the terminal station. The value of the transmission timing is a value of the integral multiples of the timing offset detection capability of the ranging signal, or a value calculated by referring to the received reference signals, which have assigned with a different interval from an interval of the ranging signals.
    Type: Grant
    Filed: September 20, 2016
    Date of Patent: September 4, 2018
    Assignee: Hitachi Kokusai Electric, Inc.
    Inventors: Masayuki Takekawa, Keigo Hasegawa
  • Publication number: 20180048379
    Abstract: Provided is a technique for efficiently using a channel bandwidth in a wireless communication system provided with a function for dividing a frequency channel into a plurality of segments and performing relay using the segments that differ from relay section to relay section. In a second scheme, an upstream direction of a first relay section is a DL section, and two segments are used. An upstream direction of a second relay section is a UL section, and two segments are used. That is, ? of an area is used in a frequency-axis direction, and ½ of the area is used in a time-axis direction similarly to a first scheme. A data area ratio for the second scheme becomes ?. A data area ratio for the first scheme is ?. Thus, a throughput for the second scheme is twice a throughput for the first scheme.
    Type: Application
    Filed: February 20, 2015
    Publication date: February 15, 2018
    Applicant: HITACHI KOKUSAI ELECTRIC INC.
    Inventors: Kei YANAGISAWA, Masayuki TAKEKAWA
  • Patent number: 9781719
    Abstract: The present invention introduces a multichannel MAC into a white-space-using system. A base station and a terminal station are each configured from a plurality of wireless communication units and centralized control units thereof. Each of the wireless communication units wirelessly transmits/receives for one channel. The base station operates one or more channels according to white-space-channel status, and is assigned to a terminal station. When operating a plurality of channels, it is possible to select a redundancy mode for assigning data by duplicating the terminal-station data in a plurality of channels, and a high-speed mode for dividing the data and distributing the data among the plurality of channels.
    Type: Grant
    Filed: August 29, 2013
    Date of Patent: October 3, 2017
    Assignee: HITACHI KOKUSAI ELECTRIC INC.
    Inventors: Keigo Hasegawa, Keat Beng Toh, Masayuki Takekawa, Kei Yanagisawa, Madoka Tanaka
  • Patent number: 9743412
    Abstract: In the wireless communication system, each of a base station 11 and a terminal station 12 obtains its location information, and upon establishment of synchronization, the terminal station 12 transmits a terminal station free channel list and its location information by extremely low power wireless communication, and the base station 11 compares a base station free channel list created based on information from a database 40 with the terminal station free channel list from the terminal station 12, and determines, when there is a common free channel, the free channel as uplink/downlink channels and determines, when there is no common free channel, an uplink channel and a downlink channel as different channels, calculates a base station-terminal station distance from the location information of the base station 11 and the location information of the terminal station 12, and determines terminal station's uplink transmission power based on the distance.
    Type: Grant
    Filed: January 16, 2014
    Date of Patent: August 22, 2017
    Assignee: Hitachi Kokusai Electric, Inc.
    Inventors: Kei Yanagisawa, Keigo Hasegawa, Masayuki Takekawa
  • Patent number: 9713171
    Abstract: Provided is a wireless communication system that is capable of preventing interference between secondary use systems that do not use a database. The wireless communication system uses a white space for opposing communication between a base station and a terminal station. At startup, the base station transmits a preamble over a cycle that is n-times a frame length (where n is an integer 2 or greater), changes a set frequency channel if ranging is not detected from a terminal station within a fixed time interval, and begins normal operation using the set frequency channel if ranging is detected. At startup, the terminal station detects a preamble within a received signal, changes a set frequency channel if a peak is detected at each frame length, and transmits a ranging signal if peaks are detected for cycles that are n-times the frame length and peaks are not detected for other cycles.
    Type: Grant
    Filed: September 5, 2014
    Date of Patent: July 18, 2017
    Assignee: Hitachi Kokusai Electric Inc.
    Inventors: Kei Yanagisawa, Masayuki Takekawa, Keigo Hasegawa
  • Patent number: 9661644
    Abstract: There is provided a wireless communication system that is capable of preventing interference with a primary use system caused by a CPE emitting radio waves at a frequency which is not a transmittable frequency before acquiring a list of transmittable frequencies based on its position information. In a wireless communication system that uses white space, a BS 10 and a CPE 22 store a specific frequency which is guaranteed to not interfere with a primary user. The BS 10 regularly switches between a first period when communication is performed at an operating frequency that uses white space and a second period when communication is performed at the specific frequency.
    Type: Grant
    Filed: March 28, 2014
    Date of Patent: May 23, 2017
    Assignee: Hitachi Kokusai Electric, Inc.
    Inventors: Masayuki Takekawa, Keigo Hasegawa, Kei Yanagisawa
  • Patent number: 9609523
    Abstract: Disclosed is a wireless communication system using white spaces and a base station that does not have its own backhaul, starts wireless communications without radiating radio waves of frequencies causing interference with primary users. A BS being in isolation starts a wireless communication with a CPE, connected to the internet, so as to access a database to acquire a list of frequencies available for transmission. The BS uses a predetermined frequency to perform the wireless communication with the CPE, and acquires, via this wireless communication, the list of frequencies available for transmission. Thereafter, the BS performs wireless communications with the CPE and with another CPE on the basis of the acquired list of frequencies available for transmission. The BS can hold, in advance, information of the predetermined frequency for which it has been estimated that the BS will cause no interference with the wireless communications of the primary users.
    Type: Grant
    Filed: September 10, 2014
    Date of Patent: March 28, 2017
    Assignee: HITACHI KOKUSAI ELECTRIC, INC.
    Inventors: Masayuki Takekawa, Keigo Hasegawa, Kei Yanagisawa, Keat Beng Toh
  • Publication number: 20170013582
    Abstract: A method for adjusting a transmission timing of a terminal station, which is performed at a base station in a Time-Division Duplex communication system, is disclosed. The method includes (a) receiving ranging signals or other reference signals, transmitted from a terminal station; (b) determining whether transmission timing at the terminal station is appropriate or not, by referring to the ranging signals transmitted from the terminal station; and (c) transmitting a value for adjusting the transmission timing at the terminal station. The value of the transmission timing is a value of the integral multiples of the timing offset detection capability of the ranging signal, or a value calculated by referring to the received reference signals, which have assigned with a different interval from an interval of the ranging signals.
    Type: Application
    Filed: September 20, 2016
    Publication date: January 12, 2017
    Inventors: Masayuki TAKEKAWA, Keigo HASEGAWA
  • Patent number: 9467867
    Abstract: To establish a wireless link with a terminal station without interfering with a primary user of a frequency, in a system and method in which a base station accesses a management apparatus for managing the frequency available for wireless communication via the wireless link with the terminal station.
    Type: Grant
    Filed: November 13, 2014
    Date of Patent: October 11, 2016
    Assignee: HITACHI KOKUSAI ELECTRIC, INC.
    Inventors: Keigo Hasegawa, Masayuki Takekawa
  • Publication number: 20160277938
    Abstract: To establish a wireless link with a terminal station without interfering with a primary user of a frequency, in a system and method in which a base station accesses a management apparatus for managing the frequency available for wireless communication via the wireless link with the terminal station.
    Type: Application
    Filed: November 13, 2014
    Publication date: September 22, 2016
    Inventors: Keigo HASEGAWA, Masayuki TAKEKAWA
  • Patent number: 9438329
    Abstract: A wireless communication terminal includes: an array antenna; a MAC processing section, provided to detect a first order system, that interprets information on a quiet period that the base station has informed of the MAC processing section in advance and generates a quiet period signal; a synthesizing section that weights signals received by antennas of the array antenna by using weighting coefficients, and combines the signals to produce a synthetic signal; and an array antenna control section that optimizes the weighting coefficients so as to reduce an interference signal received from the array antenna, over a period of presence of the quiet period signal. The optimized weighting coefficients are applied while downstream signals from the base station are being received, but are not applied while the primary usage system is being detected.
    Type: Grant
    Filed: November 19, 2013
    Date of Patent: September 6, 2016
    Assignee: Hitachi Kokusai Electric Inc.
    Inventors: Keat Beng Toh, Masayuki Takekawa, Keigo Hasegawa
  • Publication number: 20160227418
    Abstract: Disclosed is a wireless communication system using white spaces and a base station that does not have its own backhaul, starts wireless communications without radiating radio waves of frequencies causing interference with primary users. A BS being in isolation starts a wireless communication with a CPE, connected to the internet, so as to access a database to acquire a list of frequencies available for transmission. The BS uses a predetermined frequency to perform the wireless communication with the CPE, and acquires, via this wireless communication, the list of frequencies available for transmission. Thereafter, the BS performs wireless communications with the CPE and with another CPE on the basis of the acquired list of frequencies available for transmission. The BS can hold, in advance, information of the predetermined frequency for which it has been estimated that the BS will cause no interference with the wireless communications of the primary users.
    Type: Application
    Filed: September 10, 2014
    Publication date: August 4, 2016
    Applicant: HITACHI KOKUSAI ELECTRIC INC.
    Inventors: Masayuki TAKEKAWA, Keigo HASEGAWA, Kei YANAGISAWA, Keat Beng TOH
  • Publication number: 20160227584
    Abstract: Provided is a wireless communication system that is capable of preventing interference between secondary use systems that do not use a database. The wireless communication system uses a white space for opposing communication between a base station and a terminal station. At startup, the base station transmits a preamble over a cycle that is n-times a frame length (where n is an integer 2 or greater), changes a set frequency channel if ranging is not detected from a terminal station within a fixed time interval, and begins normal operation using the set frequency channel if ranging is detected. At startup, the terminal station detects a preamble within a received signal, changes a set frequency channel if a peak is detected at each frame length, and transmits a ranging signal if peaks are detected for cycles that are n-times the frame length and peaks are not detected for other cycles.
    Type: Application
    Filed: September 5, 2014
    Publication date: August 4, 2016
    Inventors: Kei YANAGISAWA, Masayuki TAKEKAWA, Keigo HASEGAWA
  • Publication number: 20160135196
    Abstract: There is provided a wireless communication system that is capable of preventing interference with a primary use system caused by a CPE emitting radio waves at a frequency which is not a transmittable frequency before acquiring a list of transmittable frequencies based on its position information. In a wireless communication system that uses white space, a BS 10 and a CPE 22 store a specific frequency which is guaranteed to not interfere with a primary user. The BS 10 regularly switches between a first period when communication is performed at an operating frequency that uses white space and a second period when communication is performed at the specific frequency.
    Type: Application
    Filed: March 28, 2014
    Publication date: May 12, 2016
    Inventors: Masayuki TAKEKAWA, Keigo Hasegawa, Kei YANAGISAWA
  • Patent number: 9319888
    Abstract: A technique for enabling utilization of a one-way link in wireless communication systems of the type using whitespaces is disclosed. A wireless communication system is arranged to include a transmitting station which transmits data by wireless communication and receiving stations which receive data as sent thereto, for performing wireless communication by using a whitespace. The receiving station detects data receivability at a specific frequency and sends communication quality information which is a detection result thereof to the transmitting station. The transmitting station holds this communication quality information. Then, upon startup of data reception by wireless communication, the receiving station sends to the transmitting station a packet indicating required quality which is a condition for the data reception.
    Type: Grant
    Filed: August 6, 2012
    Date of Patent: April 19, 2016
    Assignee: HITACHI KOKUSAI ELECTRIC, INC.
    Inventors: Keigo Hasegawa, Masayuki Takekawa, Keat Beng Toh
  • Publication number: 20160007358
    Abstract: In the wireless communication system, each of a base station 11 and a terminal station 12 obtains its location information, and upon establishment of synchronization, the terminal station 12 transmits a terminal station free channel list and its location information by extremely low power wireless communication, and the base station 11 compares a base station free channel list created based on information from a database 40 with the terminal station free channel list from the terminal station 12, and determines, when there is a common free channel, the free channel as uplink/downlink channels and determines, when there is no common free channel, an uplink channel and a downlink channel as different channels, calculates a base station-terminal station distance from the location information of the base station 11 and the location information of the terminal station 12, and determines terminal station's uplink transmission power based on the distance.
    Type: Application
    Filed: January 16, 2014
    Publication date: January 7, 2016
    Inventors: Kei YANAGISAWA, Keigo HASEGAWA, Masayuki TAKEKAWA
  • Patent number: 9185686
    Abstract: A base station judges whether backup channel of the base station has therein a channel which is not an operating channel of another base station configuring an adjacent cell by the channel management unit, and, if there is at least one channel which is not an operating channel of the another base station, performs fairness processing according to a prescribed etiquette to have one of the channels as an operating channel of the base station, and, if not, determines a base station which requests a release of an operating channel from the another based on the basis of a degree of satisfaction defined as a function of an offered communication traffic within a cell, a transmission rate depending on a propagation environment between the base station and a wireless communication terminal and an actually allocated operating channel number, and performs negotiation processing to cause a release of an operating channel.
    Type: Grant
    Filed: January 10, 2013
    Date of Patent: November 10, 2015
    Assignee: Hitachi Kokusai Electric Inc.
    Inventors: Keigo Hasegawa, Masayuki Takekawa, Keat Beng Toh
  • Publication number: 20150311970
    Abstract: A wireless communication terminal includes: an array antenna; a MAC processing section, provided to detect a first order system, that interprets information on a quiet period that the base station has informed of the MAC processing section in advance and generates a quiet period signal; a synthesizing section that weights signals received by antennas of the array antenna by using weighting coefficients, and combines the signals to produce a synthetic signal; and an array antenna control section that optimizes the weighting coefficients so as to reduce an interference signal received from the array antenna, over a period of presence of the quiet period signal. The optimized weighting coefficients are applied while downstream signals from the base station are being received, but are not applied while the primary usage system is being detected.
    Type: Application
    Filed: November 19, 2013
    Publication date: October 29, 2015
    Inventors: Keat Beng TOH, Masayuki TAKEKAWA, Keigo HASEGAWA
  • Publication number: 20150257152
    Abstract: The present invention introduces a multichannel MAC into a white-space-using system. A base station and a terminal station are each configured from a plurality of wireless communication units and centralized control units thereof. Each of the wireless communication units wirelessly transmits/receives for one channel. The base station operates one or more channels according to white-space-channel status, and is assigned to a terminal station. When operating a plurality of channels, it is possible to select a redundancy mode for assigning data by duplicating the terminal-station data in a plurality of channels, and a high-speed mode for dividing the data and distributing the data among the plurality of channels.
    Type: Application
    Filed: August 29, 2013
    Publication date: September 10, 2015
    Inventors: Keigo Hasegawa, Keat Beng Toh, Masayuki Takekawa, Kei Yanagisawa, Madoka Tanaka