Patents by Inventor Mamoru Sawahashi

Mamoru Sawahashi 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: 10715375
    Abstract: A modulation device includes a mapping circuit configured to map information bits to signal points on a plurality of concentric rings, when a signal space arrangement in which the number of signal points on all of the plurality of rings is the same is used as a basis, reduce the number of signal points on an innermost ring or a plurality of rings from inner to outer rings from among the plurality of rings, generate a new ring outside the signal space arrangement used as the basis, and arrange, on the generated ring, signal points which achieve the same frequency utilization efficiency as that of the signal space arrangement used as the basis.
    Type: Grant
    Filed: December 21, 2016
    Date of Patent: July 14, 2020
    Assignee: NEC CORPORATION
    Inventors: Norifumi Kamiya, Mamoru Sawahashi
  • Publication number: 20200092155
    Abstract: A modulation device includes a mapping circuit configured to map information bits to signal points on a plurality of concentric rings, when a signal space arrangement in which the number of signal points on all of the plurality of rings is the same is used as a basis, reduce the number of signal points on an innermost ring or a plurality of rings from inner to outer rings from among the plurality of rings, generate a new ring outside the signal space arrangement used as the basis, and arrange, on the generated ring, signal points which achieve the same frequency utilization efficiency as that of the signal space arrangement used as the basis.
    Type: Application
    Filed: December 21, 2016
    Publication date: March 19, 2020
    Applicant: NEC CORPORATION
    Inventors: Norifumi KAMIYA, Mamoru SAWAHASHI
  • Publication number: 20200067753
    Abstract: A base station for transmitting a synchronization signal from N transmission antennas (N>=2) in orthogonal frequency division multiple access includes a signal sequence generation unit configured to generate a synchronization signal sequence to be used for the synchronization signal in a frequency domain; a subcarrier mapping unit configured to divide a transmission band of the synchronization signal into K frequency blocks (K>=2) and map the synchronization signal sequence into one or more subcarriers in the K frequency blocks; a precoding unit configured to generate N precoding vectors to be multiplied by the synchronization signal sequence in the frequency domain and multiply the synchronization signal sequence to be transmitted from an n-th antenna (1<=n<=N) by at least an n-th precoding vector; and a transmission unit configured to transmit the synchronization signal from the N transmission antennas.
    Type: Application
    Filed: December 14, 2017
    Publication date: February 27, 2020
    Applicant: NTT DOCOMO, INC.
    Inventors: Yoshihisa Kishiyama, Satoshi Nagata, Keisuke Saito, Mamoru Sawahashi
  • Patent number: 10256960
    Abstract: A base station apparatus is used in a mobile communication system in which at least a shared data channel is transmitted by an orthogonal modulation scheme using an I-channel and a Q-channel. The base station apparatus includes a providing unit providing Acknowledgement/Non-Acknowledgement information indicating whether retransmission of a signal received in uplink is required; a mapping unit mapping a number of multiplexed users of the Acknowledgement/Non-Acknowledgement information to the I-channel or the Q-channel based on a predetermined mapping table; and a reporting unit reporting the Acknowledgement/Non-Acknowledgement information to the respective users. The mapping table indicates that, when the number of the multiplexed users is equal to or less than a predetermined number, the Acknowledgement/Non-Acknowledgement information is associated with the I-channel or the Q-channel, and otherwise, the Acknowledgement/Non-Acknowledgement information is associated with the I-channel and the Q-channel.
    Type: Grant
    Filed: September 19, 2013
    Date of Patent: April 9, 2019
    Assignee: NTT DOCOMO, INC.
    Inventors: Nobuhiko Miki, Mamoru Sawahashi, Kenichi Higuchi
  • Patent number: 10177887
    Abstract: A radio base station that communicates with a user terminal, and has a control section that executes control so that signals are time-division-multiplexed over a first radio resource region where symbols are multiplexed at a rate equal to or below a Nyquist rate and a second radio resource region where symbols are multiplexed at a faster rate than the Nyquist rate. The radio base station also includes a transmission section that transmits the signals that are time-division-multiplexed in the first radio resource region and the second radio resource region, to the user terminal to reduce the interference against predetermined signals in a radio communication system in which Faster-Than-Nyquist (FTN) is used.
    Type: Grant
    Filed: February 27, 2015
    Date of Patent: January 8, 2019
    Assignee: NTT DOCOMO, INC.
    Inventors: Mamoru Sawahashi, Teruo Kawamura, Yoshihisa Kishiyama
  • Patent number: 10104562
    Abstract: A mobile communications system having a first base station and one or more second base stations is disclosed, wherein the first base station includes a first generator which generates a first known signal for use in common between the first base station and the second base station and a second known signal use specific to each of the first base station and the second base station, and a radio transmitter which wirelessly transmits, to a subordinate terminal apparatus, the first known signal and the second known signal which are generated by the first generator.
    Type: Grant
    Filed: April 18, 2014
    Date of Patent: October 16, 2018
    Assignee: NTT DOCOMO, INC.
    Inventors: Yoshihisa Kishiyama, Motohiro Tanno, Mamoru Sawahashi
  • Publication number: 20180160434
    Abstract: The object is achieved by providing a base station apparatus for performing time and frequency scheduling in uplink packet access with: an interference amount measurement part configured to measure an uplink interference amount for each interference amount measurement unit which comprises a predetermined period and a predetermined number of frequency blocks; an interference amount determination part configured to determine whether the uplink interference amount satisfies a predetermined condition; and an overload indicator reporting part configured to report an overload indicator to a neighboring cell when the predetermined condition is satisfied.
    Type: Application
    Filed: February 2, 2018
    Publication date: June 7, 2018
    Applicant: NEC CORPORATION
    Inventors: Motohiro Tanno, Yoshihisa Kishiyama, Kenichi Higuchi, Mamoru Sawahashi, Toshifumi Sato
  • Patent number: 9924524
    Abstract: The object is achieved by providing a base station apparatus for performing time and frequency scheduling in uplink packet access with: an interference amount measurement part configured to measure an uplink interference amount for each interference amount measurement unit which comprises a predetermined period and a predetermined number of frequency blocks; an interference amount determination part configured to determine whether the uplink interference amount satisfies a predetermined condition; and an overload indicator reporting part configured to report an overload indicator to a neighboring cell when the predetermined condition is satisfied.
    Type: Grant
    Filed: October 14, 2016
    Date of Patent: March 20, 2018
    Assignee: NEC CORPORATION
    Inventors: Motohiro Tanno, Yoshihisa Kishiyama, Kenichi Higuchi, Mamoru Sawahashi, Toshifumi Sato
  • Publication number: 20170078061
    Abstract: A radio base station that communicates with a user terminal, and has a control section that executes control so that signals are time-division-multiplexed over a first radio resource region where symbols are multiplexed at a rate equal to or below a Nyquist rate and a second radio resource region where symbols are multiplexed at a faster rate than the Nyquist rate. The radio base station also includes a transmission section that transmits the signals that are time-division-multiplexed in the first radio resource region and the second radio resource region, to the user terminal to reduce the interference against predetermined signals in a radio communication system in which Faster-Than-Nyquist (FTN) is used.
    Type: Application
    Filed: February 27, 2015
    Publication date: March 16, 2017
    Applicant: NTT DOCOMO, INC.
    Inventors: Mamoru SAWAHASHI, Teruo KAWAMURA, Yoshihisa KISHIYAMA
  • Publication number: 20170070377
    Abstract: A user terminal with a transmission processing section that generates an SC-FDMA (Single Carrier Frequency Division Multiple Access) signal by blocking symbols that are arranged in a given time region at a symbol rate equal to or lower than a Nyquist rate. The transmission processing section converts the blocks into symbols that are multiplexed in a high density, in block units, in the time domain, by allowing an overlap between the symbols in the blocks. The user terminal also includes a transmission section that transmits the SC-FDMA signal to a radio base station to improve uplink throughput.
    Type: Application
    Filed: February 27, 2015
    Publication date: March 9, 2017
    Applicant: NTT DOCOMO, INC.
    Inventors: Mamoru Sawahashi, Teruo Kawamura, Yoshihisa Kishiyama
  • Publication number: 20170034836
    Abstract: The object is achieved by providing a base station apparatus for performing time and frequency scheduling in uplink packet access with: an interference amount measurement part configured to measure an uplink interference amount for each interference amount measurement unit which comprises a predetermined period and a predetermined number of frequency blocks; an interference amount determination part configured to determine whether the uplink interference amount satisfies a predetermined condition; and an overload indicator reporting part configured to report an overload indicator to a neighboring cell when the predetermined condition is satisfied.
    Type: Application
    Filed: October 14, 2016
    Publication date: February 2, 2017
    Applicant: NEC CORPORATION
    Inventors: Motohiro TANNO, Yoshihisa KISHIYAMA, Kenichi HIGUCHI, Mamoru SAWAHASHI, Toshifumi SATO
  • Publication number: 20170012687
    Abstract: A radio base station with a transmission processing section that converts a symbol allocated at a higher symbol rate than a Nyquist rate in a given time domain and/or frequency domain into a symbol allocated at a symbol rate of the Nyquist rate or less in the given time domain and/or frequency domain to generate an OFDMA (Orthogonal Frequency Division Multiple Access) signal for each of a plurality of antennas. The radio base station also includes a transmission section that transmits the 01-DMA signal of each of the plurality of antennas to a user terminal, where the transmission processing section applies transmit diversity with the plurality of antennas to the symbol allocated at the higher symbol rate to improve throughput in a radio communication system using transmit diversity.
    Type: Application
    Filed: February 27, 2015
    Publication date: January 12, 2017
    Applicant: NTT DOCOMO, INC.
    Inventors: Mamoru Sawahashi, Teruo Kawamura, Yoshihisa Kishiyama
  • Publication number: 20160381583
    Abstract: The present invention is designed to reduce the overhead of reference signals for measuring CSI in high-order MIMO multiplexing technique. A radio base station is used in a radio communications system of a frequency division duplexing (FDD) scheme, and has a receiving section that receives reference signals for measuring time division duplex (TDD) channel state information, transmitted from a plurality of antennas provided in a user terminal, a measurement section that measures the channel state information, in a plurality of receiving antennas, by using the reference signals, a generation/selection section that generates an optimal precoding vector from the channel state information measured in each receiving antenna, or selects the optimal precoding vector from a set of precoding vectors that is defined in advance, and a transmission section that transmits a physical downlink shared channel, in MIMO multiplexing transmission, by using the precoding vector selected in the generation/selection section.
    Type: Application
    Filed: February 27, 2015
    Publication date: December 29, 2016
    Applicant: NTT DOCOMO, INC.
    Inventors: Mamoru Sawahashi, Teruo Kawamura, Yoshihisa Kishiyama
  • Patent number: 9525528
    Abstract: A transmission apparatus is provided with radio resource assignment means that assigns radio resources to each physical channel according to a type of the physical channel; and transmission means that transmits information to be transmitted by each physical channel using the assigned radio resources.
    Type: Grant
    Filed: October 15, 2014
    Date of Patent: December 20, 2016
    Assignee: NTT DOCOMO, INC.
    Inventors: Nobuhiko Miki, Motohiro Tanno, Kenichi Higuchi, Mamoru Sawahashi, Hiroyuki Atarashi
  • Patent number: 9491775
    Abstract: To improve the frequency diversity effect and enhance reception quality characteristics in a mobile terminal apparatus even when the system bandwidth is extended, provided are a base station apparatus which maps transmission data to each user to a single or plurality of group bands among group bands configured by dividing a system band into a plurality of bands, and transmits the mapped transmission data on downlink, and a mobile terminal apparatus which receives the transmission data mapped to the group bands and demaps the transmission data.
    Type: Grant
    Filed: January 6, 2010
    Date of Patent: November 8, 2016
    Assignee: NTT DOCOMO, INC.
    Inventors: Satoshi Nagata, Kazuaki Takeda, Nobuhiko Miki, Yoshihisa Kishiyama, Mamoru Sawahashi
  • Patent number: 9479313
    Abstract: A base station apparatus is used in a mobile communication system in which at least a shared data channel is transmitted by an orthogonal modulation scheme using an I-channel and a Q-channel. The base station apparatus includes a providing unit providing Acknowledgement/Non-Acknowledgement information indicating whether retransmission of a signal received in uplink is required; a mapping unit mapping a number of multiplexed users of the Acknowledgement/Non-Acknowledgement information to the I-channel or the Q-channel based on a predetermined mapping table; and a reporting unit reporting the Acknowledgement/Non-Acknowledgement information to the respective users. The mapping table indicates that, when the number of the multiplexed users is equal to or less than a predetermined number, the Acknowledgement/Non-Acknowledgement information is associated with the I-channel or the Q-channel, and otherwise, the Acknowledgement/Non-Acknowledgement information is associated with the I-channel and the Q-channel.
    Type: Grant
    Filed: September 19, 2013
    Date of Patent: October 25, 2016
    Assignee: NTT DOCOMO, INC.
    Inventors: Nobuhiko Miki, Mamoru Sawahashi, Kenichi Higuchi
  • Patent number: 9474079
    Abstract: The object is achieved by providing a base station apparatus for performing time and frequency scheduling in uplink packet access with: an interference amount measurement part configured to measure an uplink interference amount for each interference amount measurement unit which comprises a predetermined period and a predetermined number of frequency blocks; an interference amount determination part configured to determine whether the uplink interference amount satisfies a predetermined condition; and an overload indicator reporting part configured to report an overload indicator to a neighboring cell when the predetermined condition is satisfied.
    Type: Grant
    Filed: April 9, 2013
    Date of Patent: October 18, 2016
    Assignee: NEC CORPORATION
    Inventors: Motohiro Tanno, Yoshihisa Kishiyama, Kenichi Higuchi, Mamoru Sawahashi, Toshifumi Sato
  • Patent number: 9391750
    Abstract: A transmission apparatus is provided with radio resource assignment means that assigns radio resources to each physical channel according to a type of the physical channel; and transmission means that transmits information to be transmitted by each physical channel using the assigned radio resources.
    Type: Grant
    Filed: March 20, 2006
    Date of Patent: July 12, 2016
    Assignee: NTT DOCOMO, INC.
    Inventors: Nobuhiko Miki, Motohiro Tanno, Kenichi Higuchi, Mamoru Sawahashi, Hiroyuki Atarashi
  • Patent number: 9370014
    Abstract: In a radio communication system, a downlink frequency band includes a plurality of frequency blocks including one or more carrier frequencies, and one or more frequency blocks are used for data transmission to a single user. A radio communication apparatus for use in the communication system has an evaluation unit evaluating the quality of a received signal for each frequency block and storing plurality of stored quality evaluations of the received signal, a comparison unit comparing the plural quality evaluations of the received signal, and a transmission unit transmitting a predetermined number of the quality evaluations of the received signal over an uplink control channel.
    Type: Grant
    Filed: May 9, 2013
    Date of Patent: June 14, 2016
    Assignee: NTT DOCOMO, INC.
    Inventors: Motohiro Tanno, Hiroyuki Atarashi, Kenichi Higuchi, Mamoru Sawahashi
  • Patent number: 9369996
    Abstract: A base station apparatus in a radio communication system where transmit diversity is applied in uplinks includes a reference signal measurement unit configured to measure a receive level of the reference signal, a switch pitch determination unit configured to determine the antenna switch pitch of transmitting the reference signal based on the receive level measured by the reference signal measurement unit, and a transmitting unit configured to transmit the antenna switch pitch determined by the switch pitch determination unit.
    Type: Grant
    Filed: April 15, 2013
    Date of Patent: June 14, 2016
    Assignee: NTT DOCOMO, INC.
    Inventors: Kenichi Higuchi, Mamoru Sawahashi