Patents by Inventor Kei Igarashi

Kei Igarashi 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: 8688130
    Abstract: A disclosed base station includes a communication unit configured to receive from a mobile station a first report signal including base station specification information specifying a base station, reception quality information indicating reception quality of a signal received from the specified base station, and change request information requesting to change communication quality between the mobile station and the specified base station; and an automatic area control unit configured to determine whether the base station is specified by the base station specification information, to obtain location information indicating the location of the mobile station if the base station is specified by the base station specification information, and to change at least one base station parameter based on the reception quality information and the location information to change the reception quality at the location of the mobile station.
    Type: Grant
    Filed: September 14, 2012
    Date of Patent: April 1, 2014
    Assignee: NTT DoCoMo, Inc.
    Inventors: Yuki Inoue, Keizo Cho, Shinichi Mori, Hiroyuki Hosono, Akira Ishii, Kei Igarashi
  • Patent number: 8446855
    Abstract: An access point for establishing wireless connection with one or more wireless communication stations which can perform intermittent reception operation, based on a packet transmission system which allocates wireless bands by CSMA/CA, has: unit for describing, in a same packet or in respective packets, buffering information on a downlink packet addressed to a subordinate wireless communication station currently in an intermittent reception state, and transmission prohibition period information indicating a period where transmission from the subordinate wireless communication station is prohibited; unit for transmitting the instruction described packet, in which the description has been made, to the subordinate wireless communication station; unit for making a state of the access point transit to a Doze state immediately after the instruction described packet is transmitted, or when a predetermined number of downlink packets are transmitted; and unit for making a state of the access point transit to an Awake s
    Type: Grant
    Filed: August 28, 2009
    Date of Patent: May 21, 2013
    Assignee: NTT DoCoMo, Inc.
    Inventors: Kei Igarashi, Akira Yamada
  • Patent number: 8363582
    Abstract: When a wireless communication station, which is about to communicate while intermittently receiving a multicast service, transmits, to an access point, a request packet describing information on the multicast service and an intermittent reception request, the access point describes, in a packet, intermittent reception timing information corresponding to the multicast service information described in this request packet, and replies with this packet to the wireless communication station. The wireless communication station reads the intermittent reception timing information from the received packet, and performs transition to the Awake state or the Doze state according to this intermittent reception timing. The access point, on the other hand, transmits the multicast packet to the wireless communication station according to the intermittent reception timing.
    Type: Grant
    Filed: August 28, 2009
    Date of Patent: January 29, 2013
    Assignee: NTT DoCoMo, Inc.
    Inventors: Kei Igarashi, Akira Yamada
  • Publication number: 20130012225
    Abstract: A disclosed base station includes a communication unit configured to receive from a mobile station a first report signal including base station specification information specifying a base station, reception quality information indicating reception quality of a signal received from the specified base station, and change request information requesting to change communication quality between the mobile station and the specified base station; and an automatic area control unit configured to determine whether the base station is specified by the base station specification information, to obtain location information indicating the location of the mobile station if the base station is specified by the base station specification information, and to change at least one base station parameter based on the reception quality information and the location information to change the reception quality at the location of the mobile station.
    Type: Application
    Filed: September 14, 2012
    Publication date: January 10, 2013
    Applicant: NTT DOCOMO, INC.
    Inventors: Yuki Inoue, Keizo Cho, Shinichi Mori, Hiroyuki Hosono, Akira Ishii, Kei Igarashi
  • Patent number: 8310968
    Abstract: The present invention implements an intermittent reception method with which a portable station that does not receive a multicast service does not enter the Awake state unnecessarily. A packet buffer portion buffers a received packet in such a memory as RAM and recording device, and judges whether the buffered packet is a multicast packet. When the packet buffer unit judges that the packet buffered by the packet buffer unit is a multicast packet, a DTIM beacon generation unit generates a DTIM beacon in which multicast notification data indicating that the multicast packet is buffered is set. A packet transmission unit transmits the DTIM beacon generated by the DTIM beacon generation unit to wireless communication stations or the like.
    Type: Grant
    Filed: September 8, 2009
    Date of Patent: November 13, 2012
    Assignee: NTT DoCoMo, Inc.
    Inventors: Kei Igarashi, Akira Yamada
  • Patent number: 8301152
    Abstract: A disclosed base station includes a communication unit configured to receive from a mobile station a first report signal including base station specification information specifying a base station, reception quality information indicating reception quality of a signal received from the specified base station, and change request information requesting to change communication quality between the mobile station and the specified base station; and an automatic area control unit configured to determine whether the base station is specified by the base station specification information, to obtain location information indicating the location of the mobile station if the base station is specified by the base station specification information, and to change at least one base station parameter based on the reception quality information and the location information to change the reception quality at the location of the mobile station.
    Type: Grant
    Filed: April 25, 2008
    Date of Patent: October 30, 2012
    Assignee: NTT DoCoMo, Inc.
    Inventors: Yuki Inoue, Keizo Cho, Shinichi Mori, Hiroyuki Hosono, Akira Ishii, Kei Igarashi
  • Patent number: 8165051
    Abstract: A radio terminal includes a radio interface configured to allow radio communication with a radio base station, and a controller configured to control switching between a wake-up state in which the radio interface is turned on and a sleep state in which the radio interface is turned off. The radio terminal acquires a reference wake-up timing scheduled as a wake-up timing for switching from the sleep state to the wake-up state. The controller shifts the wake-up timing from the reference wake-up timing.
    Type: Grant
    Filed: April 15, 2009
    Date of Patent: April 24, 2012
    Assignee: NTT DoCoMo, Inc.
    Inventors: Imad Aad, Luis Loyola, Joerg Widmer, Kei Igarashi, Akira Yamada
  • Patent number: 8149864
    Abstract: A communication terminal used in a mobile communication system complying with a carrier sense multiple access scheme is disclosed. The communication terminal includes: a receiving unit configured to receive a wireless packet transmitted by another communication terminal or a base station; a determination unit configured to determine periodic transmission timing of the communication terminal based on determination criterion information included in the wireless packet; and a transmission unit configured to periodically transmit wireless packets to the base station based on the transmission timing.
    Type: Grant
    Filed: February 19, 2010
    Date of Patent: April 3, 2012
    Assignee: NTT DoCoMo, Inc.
    Inventors: Akira Yamada, Kei Igarashi, Takatoshi Sugiyama
  • Patent number: 8144677
    Abstract: An object of the present invention is to realize a distributed autonomous transmission scheduling by using a terminal without the need to observe packets in relation to communication of other wireless terminals in a cell, such as VoIP, in which a plurality of wireless terminals that periodically transmit packets exist, thereby allowing intermittent reception during the packet observation and enabling to control power consumption of the wireless terminal as well as to reduce the load to thereby improve the communication quality. To attain the object, a VoIP terminal 100 recognizes and retains a scheduling table received by a wireless terminal that is connected to a wireless base station and that is not communicating with other wireless terminals, additionally writes terminal information of the terminal in the scheduling table at the start of communication of the terminal, and broadcasts the scheduling table.
    Type: Grant
    Filed: August 8, 2008
    Date of Patent: March 27, 2012
    Assignee: NTT DoCoMo, Inc.
    Inventors: Kei Igarashi, Akira Yamada
  • Patent number: 8130784
    Abstract: A communication terminal used in a mobile communication system complying with a carrier sense multiple access scheme is disclosed. The communication terminal includes: a receiving unit configured to receive a wireless packet transmitted by another communication terminal or a base station; a determination unit configured to determine periodic transmission timing of the communication terminal based on determination criterion information included in the wireless packet; and a transmission unit configured to periodically transmit wireless packets to the base station based on the transmission timing.
    Type: Grant
    Filed: February 19, 2010
    Date of Patent: March 6, 2012
    Assignee: NTT DoCoMo, Inc
    Inventors: Akira Yamada, Kei Igarashi, Takatoshi Sugiyama
  • Patent number: 8054852
    Abstract: A communication terminal used in a mobile communication system complying with a carrier sense multiple access scheme is disclosed. The communication terminal includes: a receiving unit configured to receive a wireless packet transmitted by another communication terminal or a base station; a determination unit configured to determine periodic transmission timing of the communication terminal based on determination criterion information included in the wireless packet; and a transmission unit configured to periodically transmit wireless packets to the base station based on the transmission timing.
    Type: Grant
    Filed: February 27, 2007
    Date of Patent: November 8, 2011
    Assignee: NTT DoCoMo, Inc.
    Inventors: Akira Yamada, Kei Igarashi, Takatoshi Sugiyama
  • Patent number: 8009599
    Abstract: A wireless communication device that transmits packets, on the basis of a packet transmission scheme for allocating wireless bands with virtual carrier sensing, has: monitoring module for monitoring packets communicated between other wireless communication devices and base stations for a local cell and another cell; determination module for determining whether a possibility exists that a local station receives other-cell interference resulting from communication between the wireless communication device in the other cell and the base station, on the basis of the monitoring result; occupancy period detection module for detecting an occupancy period occupied due to communication between the wireless communication device in the other cell and the base station, on the basis of the monitoring results, when determination is made that receiving the other-cell interference is possible; and timing recognition module for recognizing a timing for avoiding the other-cell interference in a predetermined period on the basi
    Type: Grant
    Filed: March 19, 2007
    Date of Patent: August 30, 2011
    Assignee: NTT DoCoMo, Inc.
    Inventors: Kei Igarashi, Akira Yamada
  • Patent number: 7940692
    Abstract: A wireless communication terminal comprises: a packet receiving unit for receiving a packet from a wireless base station; module for obtaining a transmission rate and a required transmission time from the received packet; module for calculating a time required to perform a packet transmission/reception procedure on the basis of the required transmission time; an analysis unit that functions as module for recognizing the existence of other terminal by decoding a destination MAC address described in the packet when the obtained transmission rate is equal to or lower than a transmission rate used by the wireless communication terminal; and a same-cell terminal list creation unit and band use time period scheduling unit for setting a band use time period that is equal to or greater than the time required to perform the packet transmission/reception procedure, for a time period, within a predetermined period corresponding to a packet generation period, regarding the other terminal and the wireless communication te
    Type: Grant
    Filed: August 20, 2007
    Date of Patent: May 10, 2011
    Assignee: NTT DoCoMo, Inc.
    Inventors: Kei Igarashi, Akira Yamada
  • Publication number: 20100150074
    Abstract: A communication terminal used in a mobile communication system complying with a carrier sense multiple access scheme is disclosed. The communication terminal includes: a receiving unit configured to receive a wireless packet transmitted by another communication terminal or a base station; a determination unit configured to determine periodic transmission timing of the communication terminal based on determination criterion information included in the wireless packet; and a transmission unit configured to periodically transmit wireless packets to the base station based on the transmission timing.
    Type: Application
    Filed: February 19, 2010
    Publication date: June 17, 2010
    Applicant: NTT DoCoMo, Inc.
    Inventors: Akira YAMADA, Kei Igarashi, Takatoshi Sugiyama
  • Patent number: 7738481
    Abstract: A wireless communication device that performs packet transmission in accordance with a packet transmission system that performs wireless bandwidth allocation by virtual carrier sensing has a time-point management section that manages the time-point and outputs current time-point information, and a parameter management section that manages a parameter relating to packet transmission right acquisition priority.
    Type: Grant
    Filed: February 5, 2007
    Date of Patent: June 15, 2010
    Assignee: NTT DoCoMo, Inc.
    Inventors: Kei Igarashi, Akira Yamada, Atsushi Fujiwara, Takatoshi Sugiyama
  • Publication number: 20100142451
    Abstract: A communication terminal used in a mobile communication system complying with a carrier sense multiple access scheme is disclosed. The communication terminal includes: a receiving unit configured to receive a wireless packet transmitted by another communication terminal or a base station; a determination unit configured to determine periodic transmission timing of the communication terminal based on determination criterion information included in the wireless packet; and a transmission unit configured to periodically transmit wireless packets to the base station based on the transmission timing.
    Type: Application
    Filed: February 19, 2010
    Publication date: June 10, 2010
    Applicant: NTT DoCoMo, Inc.
    Inventors: Akira YAMADA, Kei IGARASHI, Takatoshi SUGIYAMA
  • Publication number: 20100136985
    Abstract: A disclosed base station includes a communication unit configured to receive from a mobile station a first report signal including base station specification information specifying a base station, reception quality information indicating reception quality of a signal received from the specified base station, and change request information requesting to change communication quality between the mobile station and the specified base station; and an automatic area control unit configured to determine whether the base station is specified by the base station specification information, to obtain location information indicating the location of the mobile station if the base station is specified by the base station specification information, and to change at least one base station parameter based on the reception quality information and the location information to change the reception quality at the location of the mobile station.
    Type: Application
    Filed: April 25, 2008
    Publication date: June 3, 2010
    Applicant: NTT DoCoMo, Inc.
    Inventors: Yuki Inoue, Keizo Cho, Shinichi Mori, Hiroyuki Hosono, Akira Ishii, Kei Igarashi
  • Publication number: 20100128620
    Abstract: A mobile communications system is disclosed. The mobile communications system includes a unit which causes a mobile station apparatus residing within a communication area of an arbitrary base station apparatus to measure a propagation state of a wireless signal from a surrounding base station apparatus and which collects the measurement results; and a unit which obtains location information of the mobile station apparatus.
    Type: Application
    Filed: April 25, 2008
    Publication date: May 27, 2010
    Applicant: NTT DOCOMO, INC.
    Inventors: Yuki Inoue, Keizo Cho, Shinichi Mori, Hiroyuki Hosono, Akira Ishii, Kei Igarashi
  • Publication number: 20100110962
    Abstract: The present invention implements an intermittent reception method with which a portable station that does not receive a multicast service does not enter the Awake state unnecessarily. A packet buffer portion buffers a received packet in such a memory as RAM and recording device, and judges whether the buffered packet is a multicast packet. When the packet buffer unit judges that the packet buffered by the packet buffer unit is a multicast packet, a DTIM beacon generation unit generates a DTIM beacon in which multicast notification data indicating that the multicast packet is buffered is set. A packet transmission unit transmits the DTIM beacon generated by the DTIM beacon generation unit to wireless communication stations or the like.
    Type: Application
    Filed: September 8, 2009
    Publication date: May 6, 2010
    Applicant: NTT DoCoMo, Inc.
    Inventors: Kei IGARASHI, Akira Yamada
  • Patent number: 7697457
    Abstract: A wireless communication apparatus comprises a transmission buffer configured to store packets addressed to one or more communication nodes in the network until a transmission timing; a requesting interval determination unit configured to determine a listen interval for each of the communication nodes based on the amount and/or the priority of packets accumulated in the transmission buffer; and a transmission unit configured to transmit a request frame to each of the communication nodes to request the communication nodes to receive a beacon from the wireless communication apparatus at the determined listen interval.
    Type: Grant
    Filed: September 18, 2006
    Date of Patent: April 13, 2010
    Assignee: NTT DoCoMo, Inc.
    Inventors: Kei Igarashi, Akira Yamada, Atsushi Fujiwara