Patents by Inventor Kei Yanagisawa

Kei Yanagisawa 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
  • 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: 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
  • 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
  • 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
  • Patent number: 9049726
    Abstract: A network management unit included in a base station of WRAN, and a heterogeneous-systems coexistence function unit included in a relay station perform communications by taking advantage of the wireless line of WRAN. In this way, the network management unit and the heterogeneous-systems coexistence function unit make the determination and management of a frequency channel to be utilized by WLAN. Concretely, the QP (Quiet Period) of WRAN and that of WLAN are synchronized with each other with respect to the above-described frequency channel. During the synchronized QPs, WRAN and WLAN make the absence confirmation of a primary user.
    Type: Grant
    Filed: February 14, 2013
    Date of Patent: June 2, 2015
    Assignee: HITACHI KOKUSAI ELECTRIC INC.
    Inventors: Keigo Hasegawa, Masayuki Takekawa, Keat Beng Toh, Kei Yanagisawa
  • Publication number: 20130235771
    Abstract: A network management unit included in a base station of WRAN, and a heterogeneous-systems coexistence function unit included in a relay station perform communications by taking advantage of the wireless line of WRAN. In this way, the network management unit and the heterogeneous-systems coexistence function unit make the determination and management of a frequency channel to be utilized by WLAN. Concretely, the QP (Quiet Period) of WRAN and that of WLAN are synchronized with each other with respect to the above-described frequency channel. During the synchronized QPs, WRAN and WLAN make the absence confirmation of a primary user.
    Type: Application
    Filed: February 14, 2013
    Publication date: September 12, 2013
    Applicant: HITACHI KOKUSAI ELECTRIC INC.
    Inventors: Keigo HASEGAWA, Masayuki TAKEKAWA, Keat Beng TOH, Kei YANAGISAWA
  • Patent number: 6860759
    Abstract: A housing (20) of a connector has a front end that can be introduced through a mount hole (H) in a panel (P). A detector (50) is mounted on the front end of the housing (20) is movable between a standby position and a detecting position. Movement of the detector (50) toward the detecting position is prevented by interference with the inner peripheral surface of the mount hole (H) while the housing (20) is being mounted on the panel (P). However, the inner peripheral surface of the mount hole (H) when the male housing (20) is mounted properly on the panel (P). Thus, the detector (50) can be moved to the detecting position.
    Type: Grant
    Filed: December 16, 2002
    Date of Patent: March 1, 2005
    Assignee: Sumitomo Wiring Systems, Ltd.
    Inventors: Hideto Nakamura, Kei Yanagisawa
  • Patent number: 6679720
    Abstract: A connector includes male and female connector housings (10, 20). The male housing (10) has a receptacle (11) and a lock arm (15) projects into the receptacle (11) for locking the female housing (20). A slider (34) is assembled into the female housing (20) and is biased forwardly by coil springs (33). The lock arm (15) is resiliently deformable between an engaging position where it is engageable with the slider (34) and a disengaging position where it is disengaged from the slider (34). If a connecting or separating operation is interrupted halfway, spring forces accumulated in the compression coil springs (33) resiliently compressed by the slider (34) are released. Thus, the lock arm (15) is pushed forward by the slider (34) to separate the housings (10, 20) from each other.
    Type: Grant
    Filed: February 12, 2002
    Date of Patent: January 20, 2004
    Assignee: Sumitomo Wiring Systems, Ltd.
    Inventors: Hideto Nakamura, Kei Yanagisawa
  • Patent number: 6659785
    Abstract: A connector has first and second housings (10, 30). The first housing (10) has male terminal fittings (13) and a shorting terminal (15) that is biased into shorting contact against the male terminal fittings (13). A pushing portion (36) displaces receiving pieces (20) of the shorting terminal (15) toward a bottom wall (12W) during connection of two housings (10, 20). The bottom wall (12W) has an escaping portion (22) for avoiding an interference with the receiving pieces (20). The receiving pieces (20) are displaced toward the bottom wall (12W) by the pushing portion (36) and enter the escaping portion (22). Thus the shorting terminal 15 is deformed to a large degree.
    Type: Grant
    Filed: April 9, 2002
    Date of Patent: December 9, 2003
    Assignee: Sumitomo Wiring Systems, Ltd.
    Inventors: Hideto Nakamura, Kei Yanagisawa
  • Publication number: 20030114044
    Abstract: A housing (20) of a connector has a front end that can be introduced through a mount hole (H) in a panel (P). A detector (50) is mounted on the front end of the housing (20) is movable between a standby position and a detecting position. Movement of the detector (50) toward the detecting position is prevented by interference with the inner peripheral surface of the mount hole (H) while the housing (20) is being mounted on the panel (P). However, the inner peripheral surface of the mount hole (H) when the male housing (20) is mounted properly on the panel (P). Thus, the detector (50) can be moved to the detecting position.
    Type: Application
    Filed: December 16, 2002
    Publication date: June 19, 2003
    Applicant: Sumitomo Wiring Systems, Ltd.
    Inventors: Hideto Nakamura, Kei Yanagisawa
  • Patent number: 6520786
    Abstract: A connector includes first and second housings (10, 30). During connection of the housings (10, 20), a slanted surface (38) of a pushing portion (37) comes into contact with receiving pieces (20) of a shorting terminal (15), which in turn is deformed resiliently by the inclination of the pushing portion (37) and moves away from male terminal fittings (13) to cancel a shorted state of the male terminal fittings (13). The pushing portions (37) are hard to deform and are provided with slanted surface (38) for resiliently deforming the shorting terminal (15). Therefore, the pushing portions (37) can deform the shorting terminal (15) without losing its guiding function even if the pushing portion (37) and the shorting terminal (15) get caught with each other at their contact portions.
    Type: Grant
    Filed: January 18, 2002
    Date of Patent: February 18, 2003
    Assignee: Sumitomo Wiring Systems, Ltd.
    Inventors: Hideto Nakamura, Kei Yanagisawa
  • Publication number: 20030022542
    Abstract: A connector has first and second housings (10, 30). The first housing (10) has male terminal fittings (13) and a shorting terminal (15) that is biased into shorting contact against the male terminal fittings (13). A pushing portion (36) displaces receiving pieces (20) of the shorting terminal (15) toward a bottom wall (12W) during connection of two housings (10, 20). The bottom wall (12W) has an escaping portion (22) for avoiding an interference with the receiving pieces (20). The receiving pieces (20) are displaced toward the bottom wall (12W) by the pushing portion (36) and enter the escaping portion (22). Thus the shorting terminal 15 is deformed to a large degree.
    Type: Application
    Filed: April 9, 2002
    Publication date: January 30, 2003
    Applicant: Sumitomo Wiring Systems, Ltd.
    Inventors: Hideto Nakamura, Kei Yanagisawa