Patents by Inventor Hirotake Wakai

Hirotake Wakai 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).

  • Publication number: 20090034479
    Abstract: To prevent a packet loss during hand over, provided is a network system including: a gateway coupled with a wired network; and at least two base stations coupled with the gateway over the wired network and providing a wireless access method, in which the gateway is configured to: calculate, for each of the at least two base stations, a delay in information transmission between the gateway and each of the at least two base stations; choose a maximum delay from among the calculated delays of each of the at least two base stations; calculate, as a delay difference of each of the at least two base stations, a difference between the chosen maximum delay and the delay of each of the at least two base stations; and notify each of the at least two base stations of the calculated delay difference of each of the at least two base stations.
    Type: Application
    Filed: July 18, 2008
    Publication date: February 5, 2009
    Inventors: Koji Wakayama, Hirotake Wakai
  • Publication number: 20070223505
    Abstract: A data transmission apparatus is disclosed, which includes a first terminal for use with variable-rate data, a second terminal for use with constant-rate data, a processing unit for input of data from the first and second terminals, a modulator unit for modulating the output of the processor unit, a control unit for controlling the modulator, and a transmitter unit. The processor has a first buffer for writing thereinto data from the first terminal, a second buffer for writing therein data from the second terminal, and a selector for reading data from either one of the first and second buffers while switching therebetween at a predetermined rate, thereby allowing the switching of the selector to be performed under the control of the control unit.
    Type: Application
    Filed: February 22, 2007
    Publication date: September 27, 2007
    Inventors: Kimio ITAI, Yoshikuni Ito, Hirotake Wakai
  • Publication number: 20030112810
    Abstract: A wireless bridge selects wireless bridges, each with communication quality at a predetermined level or higher, from other wireless bridges, which are located in a range where the wireless bridge can communicate, as wireless bridges to which a spanning tree protocol (STP) is applied. The wireless bridge adds a MAC header, where a broadcast or multicast address is a forwarding destination address, to a packet to be multicast to a plurality of wireless bridges and transmits the packet from a wireless interface as a multicast-service packet.
    Type: Application
    Filed: December 6, 2002
    Publication date: June 19, 2003
    Inventors: Sumie Nakabayashi, Hirotake Wakai
  • Patent number: 5926065
    Abstract: A digital demodulator which demodulates an analog signal obtained through a quadrature amplitude modulation to produce a digital demodulated signal includes a converter to convert the analog signal into a digital signal and a signal processor to quadrature-demodulating the digital signal from the converter. Assuming that the analog signal has a carrier frequency of f.sub.IF and the signal conversion is accomplished with the sampling frequency fs, the demodulator is set to satisfy fs=4.multidot.f.sub.IF /(2n+1), where n denotes a positive integer. The signal processing section conducts the quadrature demodulation according to a quadrature local oscillation signal having a frequency fc satisfying fc=fs/4.
    Type: Grant
    Filed: October 8, 1997
    Date of Patent: July 20, 1999
    Assignee: Hitachi Denshi Kabushiki Kaisha
    Inventors: Hirotake Wakai, Makoto Ohnishi, Fumihito Tomaru