Patents by Inventor Akihisa Ushirokawa

Akihisa Ushirokawa 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: 7139284
    Abstract: A spread code allocation method in a CDMA cellular having a first code set including a plurality of first codes and a second code set including one or a plurality of second codes, allocating the second code to the first code set and multiplying the plurality of first codes by the allocated second code to generate a plurality of combined codes, assigning a priority to the combined code for each transmission signal to be transmitted from a base station to a mobile station, allocating the combined code to the transmission signal based on the priority, and diffusing the transmission signal by the allocated combined code to transmit the diffused transmission signal to the mobile station.
    Type: Grant
    Filed: October 31, 2000
    Date of Patent: November 21, 2006
    Assignee: NEC Corporation
    Inventors: Hiroshi Furukawa, Akihisa Ushirokawa
  • Patent number: 7039099
    Abstract: A path timing comparing section compares correlation peak values and their path timings detected from a delay profile with correlation peak values and their path timings assigned to fingers in the previous cycle. If a path timing determining section determines from the comparison result that a path with high intensity level has appeared, it immediately assigns the path to a finger. This enables maintaining good receiving characteristics.
    Type: Grant
    Filed: April 10, 2001
    Date of Patent: May 2, 2006
    Assignee: NEC Corporation
    Inventors: Koichi Tamura, Akihisa Ushirokawa
  • Patent number: 6856608
    Abstract: To prevent degradation of transmission quality due to interference between scramble codes, under such a situation as soft hand over, when the number of mobile stations connected with a base station exceeds the number of the orthogonal codes. The base station decides the priority of the scramble code. The scramble code is allocated to the mobile station, in accordance with the priority. When a mobile station ends its call, or stops temporarily its call, its PN code is re-allocated to the mobile station with lowest priority code.
    Type: Grant
    Filed: March 3, 2000
    Date of Patent: February 15, 2005
    Assignee: NEC Corporation
    Inventors: Hiroshi Furukawa, Kojiro Hamabe, Akihisa Ushirokawa
  • Patent number: 6714584
    Abstract: A CDMA adaptive antenna receiving apparatus is provided with plural receivers of which each is for receiving one or more of desired signal components incoming at the same time. Each of the plural receivers includes plural adaptive receiving units for updating sequentially a directivity in accordance with one desired signal component. The plural adaptive receiving units which are included in the same receiver employ a symbol decision error of the same receiver in common. Each receiver further includes a means for detecting the incoming directions of the plural desired signal components and a means for controlling directivities of the plural adaptive receiving units in accordance with the incoming directions of the plural desired signal components and directivities of the plural adaptive receiving units.
    Type: Grant
    Filed: April 6, 1999
    Date of Patent: March 30, 2004
    Assignee: NEC Corporation
    Inventors: Naoto Ishii, Shousei Yoshida, Akihisa Ushirokawa
  • Patent number: 6665286
    Abstract: The adaptive receiving block 2k for the k-user generates a receiving signal by the k-th user the m-th path inherent antenna directivity pattern respectively, obtains the k-th user demodulation signal by demodulating and adding for each path simultaneously and outputs weight control error signal e′kl˜e′kM for the purpose of forming directivity pattern for each path. The weight control error synthesis circuit 3 optionally synthesizes weight control error signal e′kl˜e′kM and outputs synthesis weight control error signal e′kl˜e′km. Synthesizing weight control error signals with respect to paths whose arrival directions of multi-path of each user are close, performing a control without synthesizing weight control errors with respect to paths whose arrival directions are apart, increasing the information available for adaptive control and enhancing an adaptive control characteristic and an interference suppression ability.
    Type: Grant
    Filed: February 12, 1999
    Date of Patent: December 16, 2003
    Assignee: NEC Corporation
    Inventors: Yasushi Maruta, Shousei Yoshida, Akihisa Ushirokawa
  • Publication number: 20030137957
    Abstract: A radio communication system having a transmitting device and a receiving device is provided which is capable of avoiding occurrence of non-communicable areas even when a number of frequency channels is insufficient or even when base stations cannot be placed among sufficiently short intervals and of improving an average throughput in the base stations and the radio communication system. When channel quality exceeds a predetermined level, radio signals are transmitted and received, according to an orthogonal frequency division multiplexing method. In contrast, when the channel quality becomes degraded, by performing code spreading and despreading by using a spreading rate being predetermined so that, as the channel quality becomes degraded a larger value is selected, information is transmitted and received.
    Type: Application
    Filed: January 23, 2003
    Publication date: July 24, 2003
    Applicant: NEC Corporation
    Inventors: Yoshikazu Kakura, Akihisa Ushirokawa
  • Publication number: 20030118057
    Abstract: In the communication system performing transmission with generating the vacant period in the slotted mode during data transmission in order to perform various process, such as different frequency carrier quality measurement or so forth, the control signal for maintaining a communication quality is inserted even in the vacant period. Therefor, a link quality may not be degraded even if the vacant period is long.
    Type: Application
    Filed: January 23, 2003
    Publication date: June 26, 2003
    Applicant: NEC CORPORATION
    Inventors: Akihisa Ushirokawa, Kojiro Hamabe
  • Publication number: 20030096579
    Abstract: It is sought to permit communication distance increase, interference power reduction and hardware scale increase suppression.
    Type: Application
    Filed: November 21, 2002
    Publication date: May 22, 2003
    Applicant: NEC CORPORATION
    Inventors: Takumi Ito, Akihisa Ushirokawa
  • Patent number: 6509872
    Abstract: An adaptive antenna receiving apparatus includes (a) a plurality of antennas, (b) a plurality of adaptive receivers each of which receives signals received in the antennas, in an adaptive antenna pattern in an order in which the signals arrived at the antennas, (c) a plurality of initial receipt weight calculators each of which calculates an initial antenna pattern for each of the signals, and outputs the thus calculated initial antenna pattern to each of the adaptive receivers, (d) an adder which adds output signals transmitted from each of the adaptive receivers, to one another, and (e) a judge which symbol-judges an output signal transmitted from the adder, and transmits an output signal to each of the adaptive receivers.
    Type: Grant
    Filed: August 29, 2001
    Date of Patent: January 21, 2003
    Assignee: NEC Corporation
    Inventors: Naoto Ishii, Shousei Yoshida, Akihisa Ushirokawa
  • Patent number: 6487174
    Abstract: In a transmitting electric power control apparatus, non-linear bias characteristic in S/N measurement is previously obtained by measurement, and a conversion table for realizing this reverse characteristic is created in an S/N measuring circuit 10, and when a measured S/N value is output from the dividing circuit 9, the table conversion circuit 1 receives this S/N value as an input and outputs a corrected S/N value from the above-described conversion table, whereby it is possible to provide the S/N measurement with high accuracy, and this corrected and measured S/N is compared with a target S/N, and a demand for increasing and decreasing transmitting electric power is transmitted to a mobile station 53, and, in the mobile station 53, in accordance with the instruction from the base station 20, the transmitting electric power is determined and a coded information signal is transmitted.
    Type: Grant
    Filed: July 10, 1998
    Date of Patent: November 26, 2002
    Assignee: NEC Corporation
    Inventors: Hironori Mizuguchi, Shousei Yoshida, Akihisa Ushirokawa
  • Publication number: 20020114308
    Abstract: To provide a cellular system for enhancing precision of judgement by rendering the number of code words to be judgement candidates at a base station as small as possible and thus improving the efficiency of using the code words.
    Type: Application
    Filed: February 20, 2002
    Publication date: August 22, 2002
    Applicant: NEC CORPORATION
    Inventors: Nahoko Takano, Kojiro Hamabe, Akihisa Ushirokawa
  • Patent number: 6418320
    Abstract: In a method of controlling transmission power in a mobile station which switches a plurality of base stations from one to another with a hand-off time interposed on switching, an increase of the transmission power is suppressed with reference to reception levels of pilot signals sent from the plurality of the base stations which are divided into a first group of base stations under connection and a second group of base stations under non-connection. Specifically, the transmission power is slowly or gradually increased or kept constant when the reception level of the pilot signal sent from the second group base station exceeds that of the pilot signal sent from the first group base station.
    Type: Grant
    Filed: May 29, 1998
    Date of Patent: July 9, 2002
    Assignee: NEC Corporation
    Inventors: Shousei Yoshida, Akihisa Ushirokawa, Hiroshi Furukawa
  • Patent number: 6373881
    Abstract: A CDMA communication receiver comprises a memory for storing chip samples representing amplitudes of a despreading chip sequence sampled at intervals smaller than chip intervals of the chip sequence. From the memory, sync search and tracking circuitry reads a set of chip samples spaced from each other by the chip intervals and spaced from corresponding chip samples of adjacent sets by the smaller intervals, and detects a match or mismatch between the read chip samples and the incoming data sequence. If they match, it is determined that the read chip samples is a synchronized chip sequence. Otherwise, a next set of chip samples is read from the memory for making a further test between the next set and the incoming data sequence. A despreading filter despreads the incoming data sequence with the synchronized chip sequence.
    Type: Grant
    Filed: July 30, 1998
    Date of Patent: April 16, 2002
    Assignee: NEC Corporation
    Inventors: Hironori Mizuguchi, Shousei Yoshida, Akihisa Ushirokawa
  • Publication number: 20020041253
    Abstract: An adaptive antenna receiving apparatus includes (a) a plurality of antennas, (b) a plurality of adaptive receivers each of which receives signals received in the antennas, in an adaptive antenna pattern in an order in which the signals arrived at the antennas, (c) a plurality of initial receipt weight calculators each of which calculates an initial antenna pattern for each of the signals, and outputs the thus calculated initial antenna pattern to each of the adaptive receivers, (d) an adder which adds output signals transmitted from each of the adaptive receivers, to one another, and (e) a judge which symbol-judges an output signal transmitted from the adder, and transmits an output signal to each of the adaptive receivers.
    Type: Application
    Filed: August 29, 2001
    Publication date: April 11, 2002
    Inventors: Naoto Ishii, Shousei Yoshida, Akihisa Ushirokawa
  • Patent number: 6359864
    Abstract: An FDD/CDMA transmission/reception system includes a CDMA transmitter and a CDMA receiver. The CDMA transmitter includes a plurality of transmission antennas, signal transmission units for transmitting transmission signals weighted by different values to the respective transmission antennas, and pilot signal transmission units for transmitting a plurality of different pilot signals to the respective transmission antennas. The CDMA receiver includes a reception unit for obtaining one received signal from the transmission signals from the plurality of transmission antennas of the CDMA transmitter in consideration of reception quality, and a unit for transmitting antenna control signals corresponding to reception power values of the received pilot signals to the CDMA transmitter.
    Type: Grant
    Filed: December 10, 1998
    Date of Patent: March 19, 2002
    Assignee: NEC Corporation
    Inventors: Shousei Yoshida, Akihisa Ushirokawa
  • Publication number: 20020012333
    Abstract: An FDD/CDMA transmission/reception system includes a CDMA transmitter and a CDMA receiver. The CDMA transmitter includes a plurality of transmission antennas, signal transmission units for transmitting transmission signals weighted by different values to the respective transmission antennas, and pilot signal transmission units for transmitting a plurality of different pilot signals to the respective transmission antennas. The CDMA receiver includes a reception unit for obtaining one received signal from the transmission signals from the plurality of transmission antennas of the CDMA transmitter in consideration of reception quality, and a unit for transmitting antenna control signals corresponding to reception power values of the received pilot signals to the CDMA transmitter.
    Type: Application
    Filed: September 21, 2001
    Publication date: January 31, 2002
    Applicant: NEC Corporation
    Inventors: Shousei Yoshida, Akihisa Ushirokawa
  • Publication number: 20010055968
    Abstract: In a method of controlling transmission power in a mobile station which switches a plurality of base stations from one to another with a hand-off time interposed on switching, an increase of the transmission power is suppressed with reference to reception levels of pilot signals sent from the plurality of the base stations which are divided into a first group of base stations under connection and a second group of base stations under non-connection. Specifically, the transmission power is slowly or gradually increased or kept constant when the reception level of the pilot signal sent from the second group base station exceeds that of the pilot signal sent from the first group base station.
    Type: Application
    Filed: May 29, 1998
    Publication date: December 27, 2001
    Inventors: SHOUSEI YOSHIDA, HIROSHI FURUKAWA, AKIHISA USHIROKAWA
  • Publication number: 20010033609
    Abstract: Good receiving characteristics are achieved by receiving a path immediately after the path appears.
    Type: Application
    Filed: April 10, 2001
    Publication date: October 25, 2001
    Applicant: NEC CORPORATION
    Inventors: Koichi Tamura, Akihisa Ushirokawa
  • Publication number: 20010014607
    Abstract: A mobile communications system allowing high-speed setup and release of connection is disclosed. A primary group of base stations and a secondary group included in the primary group are set and a base station included in the secondary group is connected to a mobile station by a corresponding individual wireless link. Further, two common control channels PCCCH and SCCCH are provided to transfer control information and the PCCCH has a shorter control period. The setup control is performed only for a limited number of individual wireless links between the mobile station and the secondary group of base stations.
    Type: Application
    Filed: December 27, 2000
    Publication date: August 16, 2001
    Applicant: NEC Corporation
    Inventors: Hiroshi Furukawa, Akihisa Ushirokawa
  • Patent number: 6222498
    Abstract: In order to effectively reduce a size of CDMA multiuser receiver while maintaining an excellent interference cancellation, an array antenna is combined with a multiuser receiver. The multiuser receiver includes signal processing means which is supplied with incoming signals received at the array antenna. The signal processing means estimates interfering signals with respecting to each of the antenna elements and with respect to each of simultaneously accessing users.
    Type: Grant
    Filed: January 8, 1999
    Date of Patent: April 24, 2001
    Assignee: NEC Corporation
    Inventors: Naoto Ishii, Yasushi Maruta, Shousei Yoshida, Akihisa Ushirokawa