Takefumi HIRAGURI


Novel Access Control Scheme with Collision Detection Utilizing MIMO Transmission Procedure in WLAN Systems
Takefumi HIRAGURI Kentaro NISHIMORI Yoshiaki MORINO Mamoru UGAJIN Hideaki YOSHINO 
Publication:   
Publication Date: 2018/07/01
Vol. E101-B  No. 7  pp. 1561-1574
Type of Manuscript:  Special Section PAPER (Special Section on Communication Quality in Wireless Networks)
Category: 
Keyword: 
MIMOaccess controlWLANcollision detectionorthogonally polarized antenna
 Summary | Full Text:PDF(2.7MB)

Effect of User Antenna Selection on Block Beamforming Algorithms for Suppressing Inter-User Interference in Multiuser MIMO System
Nobuyoshi KIKUMA Kentaro NISHIMORI Takefumi HIRAGURI 
Publication:   
Publication Date: 2018/07/01
Vol. E101-B  No. 7  pp. 1523-1535
Type of Manuscript:  INVITED PAPER (Special Section on Communication Quality in Wireless Networks)
Category: 
Keyword: 
multiuser MIMOblock beamforminguser antenna selectionachievable bit ratethroughput
 Summary | Full Text:PDF(1.3MB)

Multi-Beam Massive MIMO with Beam-Selection Using Only Amplitude Information in Uplink Channel
Fumiya MURAMATSU Kentaro NISHIMORI Ryotaro TANIGUCHI Takefumi HIRAGURI 
Publication:   
Publication Date: 2018/07/01
Vol. E101-B  No. 7  pp. 1544-1551
Type of Manuscript:  Special Section PAPER (Special Section on Communication Quality in Wireless Networks)
Category: 
Keyword: 
massive MIMOhybrid analog-digital beamformingconstant modulus algorithmbeam-selection method
 Summary | Full Text:PDF(1.7MB)

An (N+N2)-Mixer Architecture for a High-Image-Rejection Wireless Receiver with an N-Phase Active Complex Filter
Mamoru UGAJIN Takuya SHINDO Tsuneo TSUKAHARA Takefumi HIRAGURI 
Publication:   
Publication Date: 2017/04/01
Vol. E100-A  No. 4  pp. 1008-1014
Type of Manuscript:  PAPER
Category: Circuit Theory
Keyword: 
integrated circuitwireless receiverimage rejectionmismatch correction3-phase analog circuitcomplex filter
 Summary | Full Text:PDF(1.6MB)

A Novel Collision Avoidance Scheme Using Optimized Contention Window in Dense Wireless LAN Environments
Yoshiaki MORINO Takefumi HIRAGURI Hideaki YOSHINO Kentaro NISHIMORI Takahiro MATSUDA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2016/11/01
Vol. E99-B  No. 11  pp. 2426-2434
Type of Manuscript:  PAPER
Category: Wireless Communication Technologies
Keyword: 
IEEE802.11 MACcontention windowtransmission efficiency
 Summary | Full Text:PDF(1.5MB)

FFT-Based Block Diagonalization at User Terminal for Implicit Beamforming in Multiuser MIMO System
Hayate KIMOTO Kentaro NISHIMORI Takefumi HIRAGURI Hideo MAKINO 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2016/01/01
Vol. E99-B  No. 1  pp. 115-123
Type of Manuscript:  Special Section PAPER (Special Section on Recent Progress in Antennas, Propagation and Wireless Systems Related to Topics in ISAP2014)
Category: Antennas and Propagation
Keyword: 
multiuser MIMOblock diagonalizationFFTimplicit beamformingIEEE802.11aceigenvalue
 Summary | Full Text:PDF(2.2MB)

Survey of Transmission Methods and Efficiency Using MIMO Technologies for Wireless LAN Systems
Takefumi HIRAGURI Kentaro NISHIMORI 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2015/07/01
Vol. E98-B  No. 7  pp. 1250-1267
Type of Manuscript:  INVITED SURVEY PAPER
Category: 
Keyword: 
MIMOMU-MIMOtransmission efficiencyoverheadaccess controlMAC protocolCSI feedbackimplicit beamformingPHY
 Summary | Full Text:PDF(2.4MB)

Multicast Transmission Access Control Methods for Various Wireless LAN Applications
Toshiyuki OGAWA Takefumi HIRAGURI Kentaro NISHIMORI Hideaki YOSHINO Kenya JIN'NO 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2014/11/01
Vol. E97-B  No. 11  pp. 2534-2542
Type of Manuscript:  PAPER
Category: Terrestrial Wireless Communication/Broadcasting Technologies
Keyword: 
Interference wavemulticast transmissionpacket collisionpacket lossWLAN
 Summary | Full Text:PDF(2.2MB)

Transmission Rate by User Antenna Selection for Block Diagonalization Based Multiuser MIMO System
Kentaro NISHIMORI Takefumi HIRAGURI Hideo MAKINO 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2014/10/01
Vol. E97-B  No. 10  pp. 2118-2126
Type of Manuscript:  Special Section PAPER (Special Section on Recent Progress in Measurement and Design Techniques on Antennas, Propagation and Wireless Systems)
Category: 
Keyword: 
multiuser MIMOblock diagonalizationuser antenna selectionIEEE802.11aceigenvalue
 Summary | Full Text:PDF(1.8MB)

Analog Decoding Method for Simplified Short-Range MIMO Transmission
Ryochi KATAOKA Kentaro NISHIMORI Takefumi HIRAGURI Naoki HONMA Tomohiro SEKI Ken HIRAGA Hideo MAKINO 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2014/03/01
Vol. E97-B  No. 3  pp. 620-630
Type of Manuscript:  PAPER
Category: Antennas and Propagation
Keyword: 
short-range MIMO transmissionzero forcingunitary matrix90-degree phase shifteroptimal element spacing
 Summary | Full Text:PDF(2.4MB)

Non-iterative Algorithm of MIMO Adaptive Array Based on Correlation Matrix Including Parasitic Antennas
Naoki HONMA Kentaro NISHIMORI Takefumi HIRAGURI Yoshitaka TSUNEKAWA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2013/07/01
Vol. E96-B  No. 7  pp. 1945-1952
Type of Manuscript:  PAPER
Category: Antennas and Propagation
Keyword: 
adaptive arraytunable reactance deviceMIMOcorrelation matrix
 Summary | Full Text:PDF(1.5MB)

User-Oriented QoS Control Method Based on CSMA/CA for IEEE802.11 Wireless LAN System
Akira KISHIDA Masashi IWABUCHI Toshiyuki SHINTAKU Tetsu SAKATA Takefumi HIRAGURI Kentaro NISHIMORI 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2013/02/01
Vol. E96-B  No. 2  pp. 419-429
Type of Manuscript:  Special Section PAPER (Special Section on Quality of Communication Services Improving Quality of Life)
Category: 
Keyword: 
user-orientedQoSfixed backoffCSMA/CAIEEE802.11
 Summary | Full Text:PDF(3.1MB)

Development of Multi Channel Ad-Hoc Network System
Kentaro NISHIMORI Takefumi HIRAGURI Masakatsu OGAWA Naoki HONMA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2011/03/01
Vol. E94-B  No. 3  pp. 667-675
Type of Manuscript:  Special Section PAPER (Special Section on Information and Communication Technologies for Next-generation Mobile Multimedia Life)
Category: 
Keyword: 
ad-hoc networksvertical antenna arrangementdistributed channel allocationmulti channels
 Summary | Full Text:PDF(1.4MB)

Power Saving Control Method for Battery-Powered Portable Wireless LAN Access Points in an Overlapping BSS Environment
Masakatsu OGAWA Takefumi HIRAGURI Kentaro NISHIMORI Naoki HONMA Kazuhiro TAKAYA Kazuo MURAKAWA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2011/03/01
Vol. E94-B  No. 3  pp. 658-666
Type of Manuscript:  Special Section PAPER (Special Section on Information and Communication Technologies for Next-generation Mobile Multimedia Life)
Category: 
Keyword: 
IEEE802.11power savingportable access pointoverlapping BSS
 Summary | Full Text:PDF(2.2MB)

A Stochastic Approach to Design MIMO Antenna with Parasitic Elements Based on Propagation Characteristics
Naoki HONMA Kentaro NISHIMORI Riichi KUDO Yasushi TAKATORI Takefumi HIRAGURI Masato MIZOGUCHI 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2010/10/01
Vol. E93-B  No. 10  pp. 2578-2585
Type of Manuscript:  Special Section PAPER (Special Section on Advanced Technologies in Antennas and Propagation in Conjunction with Main Topics of ISAP2009)
Category: Antennas
Keyword: 
MIMOparasitic antennasmobile antennasYagi-Uda arrays
 Summary | Full Text:PDF(1.9MB)

A Novel Interference Avoidance Technique on Mobile Wireless Routers Using IEEE802.11n PSMP
Akira KISHIDA Takefumi HIRAGURI Masakatsu OGAWA Kentaro NISHIMORI Naoki HONMA Tetsu SAKATA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2010/08/01
Vol. E93-B  No. 8  pp. 2053-2062
Type of Manuscript:  Special Section PAPER (Special Section on Implementation, Experiments, and Practice for Ad Hoc and Mesh Networks)
Category: 
Keyword: 
IEEE802.11nIEEE802.16emutual system interferencePSMPwireless relay
 Summary | Full Text:PDF(2.2MB)

Transmission History Based Distributed Adaptive Contention Window Adjustment Algorithm Cooperating with Automatic Rate Fallback for Wireless LANs
Masakatsu OGAWA Takefumi HIRAGURI Kentaro NISHIMORI Kazuhiro TAKAYA Kazuo MURAKAWA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2010/08/01
Vol. E93-B  No. 8  pp. 2063-2072
Type of Manuscript:  Special Section PAPER (Special Section on Implementation, Experiments, and Practice for Ad Hoc and Mesh Networks)
Category: 
Keyword: 
IEEE 802.11CSMA/CAcontention window adjustmentautomatic rate fallback
 Summary | Full Text:PDF(1.2MB)

Frame Resource Allocation Schemes that Improve System Capacity and Latency Performance of Time-Division Duplex Multihop Relay Systems
Youhei OHNO Tatsuya SHIMIZU Takefumi HIRAGURI Masashi NAKATSUGAWA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2010/08/01
Vol. E93-B  No. 8  pp. 2035-2042
Type of Manuscript:  Special Section PAPER (Special Section on Implementation, Experiments, and Practice for Ad Hoc and Mesh Networks)
Category: 
Keyword: 
multihop relayframe resource allocationsystem capacitylatency
 Summary | Full Text:PDF(1.6MB)

Power Saving Control for Battery-Powered Portable WLAN APs
Masakatsu OGAWA Takefumi HIRAGURI 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2009/09/01
Vol. E92-A  No. 9  pp. 2253-2256
Type of Manuscript:  Special Section LETTER (Special Section on Multi-dimensional Mobile Information Networks)
Category: 
Keyword: 
IEEE802.11power savingportable access point
 Summary | Full Text:PDF(539.7KB)

Power Saving Scheme Suitable for Wireless LAN in Multimedia Communications
Takefumi HIRAGURI Masakatsu OGAWA Makoto UMEUCHI Tetsu SAKATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2009/09/01
Vol. E92-A  No. 9  pp. 2184-2190
Type of Manuscript:  Special Section PAPER (Special Section on Multi-dimensional Mobile Information Networks)
Category: Wireless LAN System
Keyword: 
wireless LANpower savingquality of servicemulticastingbroadcasting
 Summary | Full Text:PDF(971.7KB)

Proposal of Wireless Traffic Control Schemes for Wireless LANs
Takefumi HIRAGURI Takeo ICHIKAWA Masataka IIZUKA Shuji KUBOTA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2008/05/01
Vol. E91-B  No. 5  pp. 1340-1348
Type of Manuscript:  Special Section PAPER (Special Section on Communication Quality)
Category: QoS Control Mechanism and System
Keyword: 
wireless LANIEEE802.11traffic controlload barancingQoS
 Summary | Full Text:PDF(1.1MB)

Novel Multiple Access Protocol for Voice over IP in Wireless LAN
Takefumi HIRAGURI Takeo ICHIKAWA Masataka IIZUKA Masahiro MORIKURA 
Publication:   IEICE TRANSACTIONS on Communications
Publication Date: 2002/10/01
Vol. E85-B  No. 10  pp. 2145-2152
Type of Manuscript:  Special Section PAPER (Special Issue on Mobile Multimedia Communications)
Category: 
Keyword: 
wireless LANCSMA/CAVoIPH.323
 Summary | Full Text:PDF(825KB)