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: 7760680
    Abstract: In packet communications between a mobile terminal and a base station, the mobile terminal checks a priority level of a traffic and judges a type of the traffic, and transmits a reservation signal for a transmission request to the base station when the type of the traffic is a high priority level or realtime type, and does not transmits it when the type of the traffic is a low priority level or non-realtime type, while the base station determines a resource amount to be reserved for packet transmission according to a resource utilization state and the reservation signal for the traffic of the high priority level or realtime type, or an average transmission interval or transmission rate for the traffic of the low priority level or non-realtime type according to margins in remaining resources, and notifies the resource amount or the average transmission interval or transmission rate to the mobile terminal.
    Type: Grant
    Filed: December 2, 2002
    Date of Patent: July 20, 2010
    Assignee: NTT DoCoMo, Inc.
    Inventors: Lan Chen, Hidetoshi Kayama, Narumi Umeda
  • Patent number: 7733969
    Abstract: A method for generating a cyclic training sequence comprises the following steps: generating randomly the first information block with the length N, copying the last L samples of the first information block to the beginning of the block as the first CP, generating the second information block with the length N by using the first information block of the training symbol in a circle manner in which the last d samples of the first information block are shifted to the position before the rest (N?d) samples and the N samples thus rearranged forms the second information block, copying the last L samples of the second information block to the beginning of the block as the second CP to form the integrated cyclic training sequence.
    Type: Grant
    Filed: May 23, 2006
    Date of Patent: June 8, 2010
    Assignee: NTT Docomo, Inc.
    Inventors: Zhongshan Zhang, Hidetoshi Kayama
  • Patent number: 7729666
    Abstract: Embodiments of the present invention include a system and method of dynamic space-frequency-division multiple-access for the uplink from terminals to a base-station. The system includes a base-station and multiple terminals. According to different spatial mapping modes, the base-station performs an optimization computation using an optimization function in order to obtain control information for controlling terminals; after receiving the control information, the user terminal controls the transmitting mode using this control information. The method includes the following operations: at the base-station, performing an optimization computation using an optimization function according to different spatial mapping modes respectively, in order to obtain control information for controlling terminals; at the user terminal, controlling a transmitting mode using the control information after receiving the above control information.
    Type: Grant
    Filed: December 28, 2006
    Date of Patent: June 1, 2010
    Assignee: NTT DoCoMo, Inc.
    Inventors: Zhan Zhang, Hidetoshi Kayama
  • Patent number: 7710977
    Abstract: A mobile communications base station has a service quality detection unit that monitors and measures communication qualities of wireless terminals currently located in the service area, and a packet classification unit that classifies packets addressed to the wireless terminals into two or more groups based on the measured communication qualities. The base station also has a buffering delay measuring unit that measures buffering delay of the packets for each of the groups. A transmission priority detection unit of the base station determines the order of priority for transmitting the packets based on the measured buffering delay in comparison with a prescribed threshold value. A resource allocation unit of the base station allocates the radio resources to the packets based on the order of priority to transmit the packets to the associated wireless terminals.
    Type: Grant
    Filed: March 5, 2003
    Date of Patent: May 4, 2010
    Assignee: NTT DoCoMo, Inc.
    Inventors: Daisuke Kitazawa, Lan Chen, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20100074117
    Abstract: A method for accessing a hybrid network including a wide area network and a distributed network, a gateway apparatus, a wireless terminal and a gateway communication system are disclosed for reducing the power consumption of the wireless terminal which is an access gateway. The method comprises: sensing by a gateway apparatus a relay request slot on a downlink common control channel of the wide area network; transmitting by a wireless terminal a relay request signal requesting to relay a data packet to be transmitted, in the relay request slot on the downlink common control channel; and if the relay request signal from the wireless terminal is sensed in the relay request slot, establishing by the gateway apparatus a connection with the wireless terminal in a distributed network environment.
    Type: Application
    Filed: September 21, 2009
    Publication date: March 25, 2010
    Inventors: Lei Du, Yong Bai, Lan Chen, Hidetoshi Kayama
  • Patent number: 7634272
    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: Grant
    Filed: October 17, 2003
    Date of Patent: December 15, 2009
    Assignee: NTT DoCoMo, Inc.
    Inventors: Takeshi Yamashita, Hideo Matsuki, Jyunichirou Hagiwara, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20090232073
    Abstract: The present invention discloses a method and apparatus of physical resource allocation as well as a method of data receiving and a receiving end in a wireless communication system. The method of physical resource allocation includes: detecting a pilot signal sent by each user within a designated range; obtaining received power of the pilot signal sent by each user; scheduling each user within the designated range to obtain a user group including at least one user according to the received power; and allocating a same physical resource to each user of the user group. According to the method and the apparatus, it is possible to reuse a physical resource and sequentially decode data packets corresponding to users in a user group occupying the same physical resource according to the Capture Effect and interference cancellation technology, thereby improving the spectrum efficiency and throughput of uplink or downlink greatly.
    Type: Application
    Filed: March 2, 2009
    Publication date: September 17, 2009
    Inventors: Yuan Yan, Anxin Li, Xiangming Li, Hidetoshi Kayama
  • Patent number: 7590085
    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: Grant
    Filed: November 18, 2003
    Date of Patent: September 15, 2009
    Assignee: NTT DoCoMo, Inc.
    Inventors: Masayuki Motegi, Hideki Tobe, Hidetoshi Kayama, Narumi Umeda
  • Patent number: 7580387
    Abstract: A time slot assigning method for assigning a time slot for transmission of a signal between a base station and a mobile station in each frame is provided. The method comprises assigning a first slot group used for transmission of a down signal from the base station to the mobile station; assigning a second slot group used for transmission of an up signal from the mobile station to the base station are assigned; and arranging a third slot group immediately after the first slot group, the third slot group being used giving a priority to transmission of another down signal from the base station to the mobile station.
    Type: Grant
    Filed: July 16, 2002
    Date of Patent: August 25, 2009
    Assignee: NTT DoCoMo, Inc.
    Inventors: Hidetoshi Kayama, Lan Chen, Narumi Umeda
  • Patent number: 7570684
    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: Grant
    Filed: November 22, 2005
    Date of Patent: August 4, 2009
    Assignee: NTT Docomo, Inc.
    Inventors: Zhongshan Zhang, Hidetoshi Kayama
  • Patent number: 7548519
    Abstract: In a mobile communication system for carrying out packet transmission/reception between a mobile terminal having a power saving mode to reduce a power consumption and a radio base station, a packet type of a packet is judged, and a sleep timer value indicating a time duration since a last packet is transmitted/received until the power saving mode starts is set according to a judgement result. Then, at least one sleep timer for measuring an elapsed time since the packet is transmitted/received is activated, and the mobile terminal is controlled to execute the power saving mode at a timing at which the elapsed time measured by the at least one sleep timer exceeded the sleep timer value.
    Type: Grant
    Filed: December 9, 2002
    Date of Patent: June 16, 2009
    Assignee: NTT DoCoMo, Inc.
    Inventors: Masayuki Motegi, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20090131096
    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: November 18, 2008
    Publication date: May 21, 2009
    Applicant: NTT DoCoMo, Inc.
    Inventors: Lan CHEN, Daisuke KITAZAWA, Hidetoshi KAYAMA, Narumi UMEDA
  • Patent number: 7532601
    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: Grant
    Filed: July 23, 2003
    Date of Patent: May 12, 2009
    Assignee: NTT DoCoMo, Inc.
    Inventors: Hidetoshi Kayama, Lan Chen, Narumi Umeda
  • Patent number: 7532572
    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: Grant
    Filed: May 14, 2004
    Date of Patent: May 12, 2009
    Assignee: NTT DoCoMo, Inc.
    Inventors: Lan Chen, Daisuke Kitazawa, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20090073931
    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: November 18, 2008
    Publication date: March 19, 2009
    Applicant: NTT DoCoMo, Inc.
    Inventors: Lan CHEN, Daisuke Kitazawa, Hidetoshi Kayama, Narumi Umeda
  • Patent number: 7496067
    Abstract: Provided is a resource allocating method capable of ensuring QoS according to priority levels and efficiently allocating resources.
    Type: Grant
    Filed: October 3, 2003
    Date of Patent: February 24, 2009
    Assignee: NTT DoCoMo, Inc.
    Inventors: Heng Qiu, Hidetoshi Kayama, Narumi Umeda
  • Publication number: 20090034453
    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: September 29, 2008
    Publication date: February 5, 2009
    Applicant: NTT DoCoMo, Inc.
    Inventors: Masayuki MOTEGI, Takeshi YAMASHITA, Hidetoshi KAYAMA, Narumi UMEDA
  • Patent number: 7483710
    Abstract: 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: Grant
    Filed: September 30, 2003
    Date of Patent: January 27, 2009
    Assignee: NTT DoCoMo, Inc.
    Inventors: Daisuke Kitazawa, Lan Chen, Hidetoshi Kayama, Narumi Umeda
  • Patent number: 7471927
    Abstract: A system is provided in which 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 is improved 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 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: Grant
    Filed: June 6, 2003
    Date of Patent: December 30, 2008
    Assignee: NTT DoCoMo, Inc.
    Inventors: Lan Chen, Daisuke Kitazawa, Hidetoshi Kayama, Narumi Umeda
  • Patent number: 7457622
    Abstract: In a mobile communication system having a plurality of radio base stations and a mobile station, a radio base station selection method in which a radio base station to start communicating with a mobile station is selected from among adjacent radio base stations capable of communicating with the mobile station is provided. The method includes the steps of requiring, by a radio base station in service, a radio channel availability report from each of adjacent radio base stations indicated by the mobile station, in response to a signal for requesting connection to the mobile station; selecting a radio base station to be connected to the mobile station, based on the radio channel availability reports obtained from the adjacent radio base stations; and notifying the mobile station of information necessary for communicating with the selected radio base station.
    Type: Grant
    Filed: July 17, 2002
    Date of Patent: November 25, 2008
    Assignee: NTT DoCoMo, Inc.
    Inventors: Hidetoshi Kayama, Lan Chen, Narumi Umeda