Patents by Inventor Hidetoshi Kayama

Hidetoshi Kayama 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: 7076258
    Abstract: A system controlling the traffic balance between the paging of incoming calls and a location registration and including a plurality of base and mobile stations and a management server for location information of each mobile station. A set of cells formed by the base stations constitutes a first area group. Each mobile station shifts to a mode periodically receiving signals from the base stations if no signals are transmitted and received for a predetermine period. Each base station forms second to n-th area groups (n?2), each having an area smaller than that of the first area, to be used when the mobile stations are in idle state. Each mobile station selects the area group to register according to the period in which no packet is received and transmitted, and registers its location while specifying an area within this area group with respect to the server.
    Type: Grant
    Filed: September 9, 2002
    Date of Patent: July 11, 2006
    Assignee: NTT DoCoMo, Inc.
    Inventors: Masayuki Motegi, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20060133526
    Abstract: Embodiments of the present invention include a method for performing joint time synchronization and carrier frequency offset estimation in a wireless communication system, comprising steps of: on a transmitter: performing frequency domain spreading and interleaving on input data by using a predetermined spreading factor (SF) to generate a frequency domain training symbol; performing Inverse Discrete Fourier Transformation (IDFT) on the generated frequency domain training symbol to generate a first time domain training symbol; reversely copying the generated first time domain training symbol to a second time domain training symbol such that a complete training sequence is formed; and on a receiver: detecting an average power of received signals to judge the coming of a training sequence, and performing coarse frame synchronization; performing joint fine frame synchronization and carrier frequency offset estimation based on a received training sequence; and compensating for the carrier frequency offset based on
    Type: Application
    Filed: November 22, 2005
    Publication date: June 22, 2006
    Inventors: Zhongshan Zhang, Hidetoshi Kayama
  • Publication number: 20060126554
    Abstract: A mobile-communications system is disclosed. The system includes a mobile station, a wireless-base station enabled to communicate with the mobile station, and a location-information management apparatus for managing a state of the mobile station in a network layer upper to a link layer for managing wireless-communications resources. The mobile station is provided with wireless-communications means for transmitting and receiving a signal with the wireless-base station in an active state in the link layer for managing the wireless-communications resources, discontinuous-receiving means for discontinuously receiving a control signal from the wireless-base station in the link layer in a state different from the active state, and state-management means for creating a state-transition signal in response to a paging signal included in the control signal.
    Type: Application
    Filed: November 18, 2003
    Publication date: June 15, 2006
    Applicant: NTT DoCoMo, Inc.
    Inventors: Masayuki Motegi, Hideki Tobe, Hidetoshi Kayama, Narumi Umeda
  • Patent number: 7035637
    Abstract: An object of the invention is to make improvement in the configuration of location registration areas. When a base station 13P is newly installed in a location registration area 30A, the base station 13P recognizes a location of its own with GPS or the like and performs communication with a plurality of surrounding base stations 13Q to select a location registration area 30A to which it should belong, based on the belonging status of the surrounding base stations 13Q and the location of its own.
    Type: Grant
    Filed: December 6, 2002
    Date of Patent: April 25, 2006
    Assignee: NTT DoCoMo, Inc.
    Inventors: Masayuki Motegi, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20050186982
    Abstract: The present invention improves a system capacity and satisfaction rate with a quality of service in packet communications performed through a radio link established between a transmitting station and a receiving station by dynamically limiting transmission power of packets in the transmitting station and keeping an increase of an interference level in the receiving station, which belongs to another cell, within a TPC margin. The present invention includes a resource allocator 115 configured to set transmission power of packets in a next step period, by use of transmission power of packets in a preceding step period (slot) and an interference level of the receiving station.
    Type: Application
    Filed: June 6, 2003
    Publication date: August 25, 2005
    Inventors: Lan Chen, Daisuke Kitazawa, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20050099973
    Abstract: In a disclosed mobile communications system wherein packet communication between a base station and its subordinated mobile station is established based on a reservation packet, the packet communication uses controlled transmission power and a radio resource allocated based on reception quality information received from the mobile station.
    Type: Application
    Filed: November 5, 2004
    Publication date: May 12, 2005
    Applicant: NTT DoCoMo, Inc.
    Inventors: Heng Qiu, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20050099972
    Abstract: A scramble code allocation method used by mobile communications systems, and a base station and a mobile station that use the method are disclosed. The scramble code allocation method autonomously and optimally sets up a scramble code unique to a target base station. The method includes a step of generating a collection packet for collecting unique information of surrounding base stations, the unique information being used for setting up respective identifiers of the surrounding base stations; a step of broadcasting the collection packet to the surrounding base stations through a network; a step of receiving response packets from the surrounding base stations in response to the collection packet; a step of extracting the unique information of the surrounding base stations inserted in the response packets that are received; a step of storing the extracted unique information; and a step of setting up an identifier of the target base station based on the stored unique information.
    Type: Application
    Filed: November 5, 2004
    Publication date: May 12, 2005
    Applicant: NTT DoCoMo, Inc.
    Inventors: Masayuki Motegi, Takeshi Yamashita, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20050037798
    Abstract: In mobile communication system 100 according to the present invention, mobile station 1 is camped on cell C10 established by base station B10. In the cell C10, there exist indoor cells C11-C13 and outdoor cells C21, C22 as neighboring cells. Mobile station 1 measures received levels of cells C10-C13, C21, C22 and determines cell types of the respective cells, i.e., whether each cell is an indoor cell or not, based on broadcast information M1. Mobile station 1 selects a cell as a reselection target on the basis of the received levels and cell types.
    Type: Application
    Filed: October 17, 2003
    Publication date: February 17, 2005
    Applicant: NTT DoCoMo, Inc.
    Inventors: Takeshi Yamashita, Hideo Matsuki, Jyunichirou Hagiwara, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20050030918
    Abstract: In a mobile communication system 1 having a radio base station 2, and mobile stations 5, 6 configured to communicate with the base station 2 and segmented into a plurality of mobile station groups, the base station 5 provides a broadcast channel with first instruction information to notify the mobile station 5 of whether or not to receive the broadcast channel, provides a paging channel with second instruction information to notify the mobile station 5 of the presence/absence of paging information, and performs such a channel transmission control as to intermittently transmit the broadcast channel and the paging channel on a control channel.
    Type: Application
    Filed: July 1, 2004
    Publication date: February 10, 2005
    Applicant: NTT DoCoMo, Inc.
    Inventors: Masayuki Motegi, Hideki Tobe, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20050025056
    Abstract: In a packet communications method of performing packet communications between a mobile station and a base station, the base station manages an amount of packets stored in a transmission buffer of the mobile station. The mobile station notifies a changed result of an amount of packets stored in the transmission buffer of the mobile station, when the amount of packets stored in the transmission buffer of the mobile station changes. The base station changes a managed amount in accordance with the changed result notified from the mobile station.
    Type: Application
    Filed: May 14, 2004
    Publication date: February 3, 2005
    Applicant: NTT DoCoMo, Inc.
    Inventors: Lan Chen, Daisuke Kitazawa, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20040254980
    Abstract: An object is to implement smooth execution of management of location information of a mobile station according to states of the mobile station varying with time. Based on a notification of transition into a sleep state from the mobile station, transmitted upon a timeout of a sleep state determination timer with neither packet transmission nor reception at the mobile station, it is determined that the mobile station has moved into the sleep state, and control processing in the link layer is executed (S12) (the control processing in the link layer carried out when the mobile station moves between cells).
    Type: Application
    Filed: June 30, 2004
    Publication date: December 16, 2004
    Inventors: Masayuki Motegi, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20040204101
    Abstract: An object of the present invention is to reduce the volume of a control signal and shorten a delay of processing in a system comprising a base station configured to transmit a pilot signal at a predetermined transmission power and a mobile station configured to transmit a preamble prior to transmission/reception of data.
    Type: Application
    Filed: April 8, 2004
    Publication date: October 14, 2004
    Applicant: NTT DoCoMo, Inc.
    Inventors: Heng Qiu, Hidetoshi Kayama, Jyunichirou Hagiwara, Narumi Umeda
  • Publication number: 20040184417
    Abstract: Base station (100) includes a channel quality detecting unit (120) that detects channel quality between the base station and a mobile station (200), a buffered data amount monitoring unit (130), and a modulation and coding set determination unit (150). The modulation and coding set determination unit determines a modulation and coding set, as a downlink modulation scheme for packet communications, such that a prescribed communication condition corresponding to the channel quality is satisfied, and that padding added to the data buffered in a transmission buffer (140) for subsequent transmission to the mobile station becomes the minimum.
    Type: Application
    Filed: December 17, 2003
    Publication date: September 23, 2004
    Applicant: NTT DoCoMo, Inc
    Inventors: Lan Chen, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20040166900
    Abstract: A base station includes an adjacent cell interference amount calculator and an adjacent cell interference amount notifier. The adjacent cell interference amount calculator calculates an adjacent cell interference amount caused by an adjacent cell adjacent to an original cell managed by the base station. The adjacent cell interference amount notifier notifies the mobile station of the adjacent cell interference amount. A mobile station includes radio resource associators, a selector, a propagation loss calculator, and a radio resource assigner. The radio resource associators associate a radio resource with a propagation loss in the radio packet communication. The selector selects a radio resource associator in accordance with the adjacent cell interference amount. The propagation loss calculator calculates a propagation loss in the radio packet communication.
    Type: Application
    Filed: February 24, 2004
    Publication date: August 26, 2004
    Applicant: NTT DoCoMo, Inc.
    Inventors: Heng Qiu, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20040131029
    Abstract: Provided is a mobile communication system capable of reducing interference in uplinks and downlinks to achieve excellent communication quality. A mobile station receives cell selection reference signals from a first base station and a second base station to connect before and after a handover, and measures received power values of the cell selection reference signals. The mobile station acquires uplink transmitted power values from the mobile station to the first base station and to the second base station. The first base station and the second base station control a power of the cell selection reference signal so that the uplink transmitted power values from the mobile station to the first base station and to the second base station become substantially equal and so that a received power value at the mobile station of the cell selection reference signal becomes substantially equal to a predetermined reference power value.
    Type: Application
    Filed: October 3, 2003
    Publication date: July 8, 2004
    Applicant: NTT DoCoMo, Inc
    Inventors: Hideki Tobe, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20040132405
    Abstract: An object of the present invention is to support various QoSs and to use resources effectively in a radio communication system. In a radio communication system where, concerning the maximum allowable delay and the reception error rate as required values for QoS, a first mobile station group of which the maximum allowable delay is less than a reference value and the reception error rate is a reference value or more, and a second mobile station group of which the maximum allowable delay is a reference value or more and the reception error rate is less than a reference value coexist, the base station sets the transmission power margin for a mobile station of the first mobile station group to be higher than the transmission power margin for a mobile station of the second mobile station group, and a mobile station of the first mobile station group sets the transmission power margin to be higher than the transmission power margin of a mobile station of the second mobile station group.
    Type: Application
    Filed: September 30, 2003
    Publication date: July 8, 2004
    Applicant: NTT DoCoMo, Inc
    Inventors: Daisuke Kitazawa, Lan Chen, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20040127225
    Abstract: Provided is a resource allocating method capable of ensuring QoS according to priority levels and efficiently allocating resources.
    Type: Application
    Filed: October 3, 2003
    Publication date: July 1, 2004
    Applicant: NTT DoCoMo, Inc
    Inventors: Heng Qiu, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20040105406
    Abstract: The object of the present invention is to provide a transmission power control method which enables the resolution of problems in a first control method for keeping the received power of packet signals in upstream radio channels constant and a second control method for keeping the SIR constant. The present invention relates to the transmission power control method for controlling the transmission power control of packet signals transmitted from a mobile station 30 via an upstream radio channel. The method comprises a step of measuring the traffic volume of the packet signals and a step of switching between the first control method and the second control method.
    Type: Application
    Filed: July 23, 2003
    Publication date: June 3, 2004
    Applicant: NTT DoCoMo, Inc.
    Inventors: Hidetoshi Kayama, Lan Chen, Narumi Umeda
  • Publication number: 20040097240
    Abstract: A method is disclosed that is capable of appropriately assigning radio resource even when a propagation quality changes. After receiving the required communication rate from the mobile station, the base station measures the maximum used radio resource, and multiplies the maximum used radio resource by a factor &agr;. Next, the base station subtracts the above result from the total radio resource and obtains the maximum assignable radio resource. Then, the base station calculates an admissible communication rate based on the maximum assignable radio resources. Then, if the required communication rate is less than or equal to the admissible communication rate, the base station admits the request.
    Type: Application
    Filed: November 18, 2003
    Publication date: May 20, 2004
    Applicant: NTT DoCoMo, Inc.
    Inventors: Lan Chen, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20040082364
    Abstract: A base station comprises a packet classification unit configured to classify packets received/transmitted from/to a plurality of mobile stations into a quantitative guarantee type packet having a request value for communication quality or a relative guarantee type packet not having the request value, and a transmission order controller configured to control a transmission order of the packets for every classified quantitative guarantee type packet and every classified relative guarantee type packet.
    Type: Application
    Filed: October 16, 2003
    Publication date: April 29, 2004
    Applicant: NTT DoCoMo, Inc.
    Inventors: Daisuke Kitazawa, Lan Chen, Hidetoshi Kayama, Narumi Umeda