論文 - 上原　一浩

Study of signal separation and demodulation techniques considering IQ imbalance by stored data batch signal processing 査読

Yudai Mita, Yuta Hiraoka, Tomofumi Hikasa, Shigeru Tomisato, Satoshi Denno, Kazuhiro Uehara

IEICE Communications Express   14 ( 1 )   30 - 33   2025年1月

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担当区分：最終著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.23919/comex.2024xbl0173

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A study on the effect of water on the received power characteristics of water level gauge antennas installed in underpass 査読

Koichi Yamaguchi, Shuhei Yamamoto, Ryota Ogata, Shigeru Tomisato, Kazuhiro Uehara

IEICE Communications Express   12 ( 12 )   640 - 642   2023年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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A study on continuous phase signal separation and demodulation method using stored data batch signal processing 査読

Tomofumi Hikasa, Takuyuki Hirakawa, Syo Nakaie, Shigeru Tomisato, Satoshi Denno, Kazuhiro Uehara

IEICE Communications Express   11 ( 12 )   734 - 740   2022年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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Evaluation of sensor terminal signal separation performance based on modulation systems in storage-based batch signal processing using STFT 査読

Takuyuki Hirakawa, Toru Nishiyama, Syo Nakaie, Shigeru Tomisato, Satoshi Denno, Kazuhiro Uehara

IEICE Communications Express   11 ( 6 )   319 - 323   2022年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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Receivable signal sequence number increase in LED visible light wireless communications by spatially parallel signal transmission 査読

Ryosuke Okamoto, Shigeru Tomisato, Satoshi Denno, Kazuhiro Uehara

IEICE Communications Express   11 ( 6 )   296 - 301   2022年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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A new scheme of automatic modulation classification using Convolutional Neural Network with constellation diagram 査読 国際誌

Yutao Liu, Toru Nishiyama, Shigeru Tomisato, Kazuhiro Uehara

IEICE Communications Express   10 ( 8 )   492 - 497   2021年8月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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Examination of signal separation/demodulation method of multi-value modulation sensor terminal signal using STFT in storage batch signal processing 査読 国際誌

Toru Nishiyama, Takuyuki Hirakawa, Syo Nakaie, Shigeru Tomisato, Satoshi Denno, Kazuhiro Uehara

IEICE Communications Express   10 ( 8 )   458 - 462   2021年8月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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Inter-system interference reduction of adaptive bandwidth control for multi-band wireless transmission 査読 国際誌

Naoto Takamatsu, Shigeru Tomisato, Kazuhiro Uehara, Satoru Shimizu, Yoshinori Suzuki

IEICE Communications Express   10 ( 6 )   337 - 342   2021年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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Adaptive bandwidth control for multi-band OFDM transmission with spectrum sharing 査読 国際誌

Yoshiki Inuzuka, Shigeru Tomisato, Kazuhiro Uehara, Satoru Shimizu, Yoshinori Suzuki

IEICE Communications Express   9 ( 5 )   131 - 135   2020年5月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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Transmission performance improvement by non-linear distortion noise power control in multi-band systems 査読

Shigeru Tomisato, Jumpei Onji, Kazuhiro Uehara

International Journal of Computer and Software Engineering (IJCSE)   4 ( 143 )   2019年3月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.15344/2456-4451/2019/143

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[招待論文] ソフトウェア無線・コグニティブ無線技術の研究開発 招待 査読

上原一浩

電子情報通信学会論文誌(B)   J100-B ( 9 )   693 - 704   2017年9月

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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High-Capacity Wireless Access Networks Using 920 MHz Band for Wide-Area IoT/M2M Services 招待 査読

Kazunori Akabane, Nobuaki Mochizuki, Shigeru Teruhi, Mamoru Kobayashi, Shuichi Yoshino, Masashi Shimizu, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E99B ( 9 )   1920 - 1929   2016年9月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In the near future, many sensors and terminals will be connected to the public network to provide various convenient IoT/M2M services. In order to connect many sensors to the network efficiently, wireless communication systems in the 920MHz band are seen as attractive solutions. We are focusing on the 920MHz band to research and develop high-capacity protocols that can accommodate many terminals, and low power consumption technologies for battery-driven terminals. In this paper, we describe the following three concrete wireless systems that use our proposals. (1) A physical distribution pallet management system that can handle thousands of pallet-embedded sensors and a wireless module with a battery lifetime of about ten years. (2) Water leakage monitoring system for underground pipes by using sensors and a wireless module in each valve box. (3) A wide-area and high-capacity radio relay system for smart metering services like the reading of gas meters. The radio relay system can accommodate various sensors and terminals and has large potential for providing various IoT/M2M services in conjunction with smart metering services.

DOI： 10.1587/transcom.2016SNI0001

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非対称縦積み線路を用いた準ミリ波帯バランスミキサ 査読

山口陽, 加保貴奈, 豊田一彦, 上原一浩, 中川匡夫, 荒木純道

電子情報通信学会論文誌(C)   J98-C ( 5 )   266 - 275   2016年5月

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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[招待論文] ユーザセントリックな無線通信システム実現に向けたマルチバンド一括送受信フロントエンド 招待 査読

加保貴奈, 山口陽, 芝宏礼, 大島心平, 中川匡夫, 上原一浩

電子情報通信学会論文誌(C)   J99-C ( 5 )   258 - 265   2016年5月

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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Concurrent Multi-Band Mixer with Independent and Linear Gain Control 査読

Takana Kaho, Yo Yamaguchi, Hiroyuki Shiba, Tadao Nakagawa, Kazuhiro Uehara, Kiyomichi Araki

IEICE TRANSACTIONS ON ELECTRONICS   E98C ( 7 )   659 - 668   2015年7月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Novel multi-band mixers that can receive multiple band signals concurrently are proposed and evaluated. The mixers achieve independent gain control through novel relative power control method of the multiple local oscillator (LO) signals. Linear control is also achieved through multiple LO signal input with total LO power control. Theoretical analysis shows that odd-order nonlinearity components of the multiple LO signals support linear conversion gain control. Dual-and triple-band tests are conducted using typical three MOSFET mixers fabricated by a 0.25 mu m SiGe BiCMOS process. Measurements confirm over 40 dB independent control of conversion gain, linear control achieved through LO input power control. The proposed mixers have high input linearity with a 5 dBm output third intercept point. A method is also proposed to reduce interference caused by mixing between multiple LO signals.

DOI： 10.1587/transele.E98.C.659

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Dependency on Beamwidth in an SD Method Utilizing Two-Ray Fading Characteristics 査読

Ken Hiraga, Kazumitsu Sakamoto, Maki Arai, Tomohiro Seki, Hideki Toshinaga, Tadao Nakagawa, Kazuhiro Uehara

IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS   14   56 - 59   2015年

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

Using ray-tracing propagation calculation, we clarify the dependency on antenna element beamwidth of the channel capacity of a spatial division (SD) transmission method utilizing the characteristics of two-ray fading. It was clarified that the SD transmission method can be effectively applied to microstrip antennas or horn antennas with beamwidth of more than 10, but that it is not effective when applied to narrow-beam antennas with less than 10 beamwidth. In such cases, simple parallel transmission is a better way to utilize the narrow beam to increase channel capacity.

DOI： 10.1109/LAWP.2014.2355258

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ホワイトスペース利用実現に向けた広帯域周波数センシングシステムの提案と性能評価 査読

芝宏礼, 山口陽, 山田貴之, 加保貴奈, 中川匡夫, 上原一浩

電子情報通信学会論文誌(B)   J97-B ( 12 )   1224 - 1233   2014年12月

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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Spatial Division Transmission without Signal Processing for MIMO Detection Utilizing Two-Ray Fading 査読

Ken Hiraga, Kazumitsu Sakamoto, Maki Arai, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E97B ( 11 )   2491 - 2501   2014年11月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper presents a spatial division (SD) transmission method based on two-ray fading that dispenses with the high signal processing cost of multiple-input and multiple-output (MIMO) detection and antennas with narrow beamwidth. We show the optimum array geometries as functions of the transmission distance for providing a concrete array design method. Moreover, we clarify achievable channel capacity considering reflection coefficients that depend on the polarization, incident angle, and dielectric constant. When the ground surface is conductive, for two-and three-element arrays, channel capacity is doubled and tripled, respectively, over that of free space propagation. We also clarify the application limit of this method for a dielectric ground by analyzing the channel capacity's dependency on the dielectric constant. With this method, increased channel capacity by SD transmission can be obtained merely by placing antennas of wireless transceiver sets that have only SISO (single-input and single-output) capability in a two-ray propagation environment. By using formulations presented in this paper for the first time and adding discussions on the adoption of polarization multiplexing, we clarify antenna geometries of SD transmission systems using polarization multiplexing for up to six streams.

DOI： 10.1587/transcom.E97.B.2491

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Performance evaluation of a simple decoding method for millimeter-wave short-range MIMO transmission through a wall 査読

Kazumitsu Sakamoto, Ken Hiraga, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEICE Communications Express   3 ( 4 )   131 - 137   2014年4月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1587/comex.3.131

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Study on MIMO transmission using orthogonal directivities obtained from higher order microstrip antenna modes 査読

M. Arai, T. Seki, K. Hiraga, K. Sakamoto, H. Toshinaga, T. Nakagawa, K. Uehara

ELECTRONICS LETTERS   50 ( 7 )   562 - 564   2014年3月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST ENGINEERING TECHNOLOGY-IET  

A simpler MIMO transmission method using orthogonal directivities is proposed. In future wireless communication systems, higher data rates will be required since large amounts of data will be transmitted and received. MIMO technology is useful for achieving higher data rates. However, since MIMO detection becomes complicated when the number of antennas becomes large, a simpler method should be considered. To solve this problem, the present authors proposed a spatial division method using orthogonal directivities. This previously proposed method to N streams is expanded transmission for application to much higher data rate systems. Furthermore, using higher order antenna modes at the same frequency to more easily obtain orthogonal directivities is proposed. To evaluate the proposed method, it is confirmed by numerical analysis that the capacity of the proposed method increases without MIMO detection when the number of antennas becomes large.

DOI： 10.1049/el.2014.0120

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A Study of Short-Range MIMO Transmission Utilizing Polarization Multiplexing for the Simplification of Decoding 査読

Ken Hiraga, Kazumitsu Sakamoto, Kentaro Nishimori, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E97B ( 2 )   459 - 468   2014年2月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

One of the procedures for increasing the number of multi-input and multi-output (MIMO) branches without increasing the computational cost for MIMO detection or multiplexing is to exploit parallel transmissions by using polarization multiplexing. In this paper the effectiveness of using polarization multiplexing is confirmed under the existence of polarization rotation, which is inevitably present in short-range multi-input and multi-output (SR-MIMO) channels with planar array antennas. It is confirmed that 8 x 8 SR-MIMO transmission system with polarization multiplexing has 60 bit/s/Hz of channel capacity. This paper also shows a model for theoretical cross polarization discrimination (XPD) degradation, which is useful to calculate XPD degradations on diagonal paths.

DOI： 10.1587/transcom.E97.B.459

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Theoretical and experimental analysis of spatial division using antenna directivities in short-range MIMO transmission 査読

M. Arai, T. Seki, K. Hiraga, T. Nakagawa, K. Uehara

ELECTRONICS LETTERS   50 ( 2 )   65 - 66   2014年1月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST ENGINEERING TECHNOLOGY-IET  

DOI： 10.1049/el.2013.3555

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An SD Method Utilizing Null Dependency on Transmission Distance Due to Two-Ray Fading 査読

Ken Hiraga, Kazumitsu Sakamoto, Maki Arai, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS   13   126 - 129   2014年

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

A spatial division (SD) transmission method utilizing the characteristics of two-ray fading due to ground reflection with linear antenna arrays horizontal to the ground is proposed. Formulations of the optimum array arrangements as functions of the transmission distance and achievable channel capacity are clarified. For two- and three-element arrays, channel capacity is respectively doubled and tripled over that of free-space propagation. The proposed method provides increased capacity without the extra signal processing cost incurred when using conventional multiple-input-multiple-output (MIMO) transmission.

DOI： 10.1109/LAWP.2013.2297379

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Performance Evaluation of Short-Range MIMO Using a Method for Controlling Phase Difference between Each Propagation Channel 査読

Kazumitsu Sakamoto, Ken Hiraga, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E96B ( 10 )   2513 - 2520   2013年10月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A Simple decoding method for short-range MIMO (SR-MIMO) transmission can reduce the power consumption for MIMO decoding, but the distance between the transceivers requires millimeter-order accuracy in order to satisfy the required transmission quality: In this paper, we propose a phase difference control method between each propagation channel to alleviate the requirements for the transmission distance accuracy. In the proposed method, the phase difference between each propagation channel is controlled by changing the transmission (or received) power ratio of each element of sub-array antennas. In millimeter-wave broadband transmission simulation, we clarified that when sub-array antenna spacing is set to 6.6 mm and element spacing of sub-array antenna is set to 2.48 mm, the proposed method can extend the transmission distance range satisfying the required transmission quality, which is that bit error rate (BER) before error correction is less than 10(-2) from 9 similar to 29 mm to 0 similar to 50 mm in QPSK, from 15 similar to 19 mm to 0 similar to 30 mm in 16QAM, and from only 15 mm to 4 similar to 22 mm in 64QAM.

DOI： 10.1587/transcom.E96.B.2513

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Effects of weight errors on capacity in simple decoding of short-range MIMO transmission 査読

Ken Hiraga, Kazumitsu Sakamoto, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEICE Communications Express   2 ( 5 )   193 - 199   2013年5月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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An SDM Method Utilizing Height Pattern Due to Two-Ray Fading Characteristics 査読

Ken Hiraga, Kazumitsu Sakamoto, Maki Arai, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS   12   1622 - 1626   2013年

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

A spatial division multiplexing (SDM) transmission method utilizing the characteristics of two-ray fading without relying on narrow beam of the antennas is introduced. This letter formulates the optimized array antenna arrangements and channel capacity as functions of the transmission distance and shows achievable channel capacity for two-and three-element antenna arrays. The letter also describes bandwidth dependency up to 15% bandwidth based on an assumed application to 60-GHz-band gigabit wireless systems. The proposed method provides increased capacity comparable to multiple-input-multiple-output (MIMO) transmission without the extra signal processing cost incurred when using conventional MIMO.

DOI： 10.1109/LAWP.2013.2294454

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Nonlinear modeling and analysis on concurrent amplification of dual-band gaussian signals 査読

Ikuma Ando, Gia Khanh Tran, Kiyomichi Araki, Takayuki Yamada, Takana Kaho, Yo Yamaguchi, Kazuhiro Uehara

IEICE Transactions on Electronics   E96-C ( 10 )   1254 - 1262   2013年

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Institute of Electronics, Information and Communication, Engineers, IEICE  

In the recently developed Flexible Wireless System (FWS), the same platform needs to deal with different wireless systems. This increases nonlinear distortion in its wideband power amplifier (PA) because the PA needs to concurrently amplify multi-band signals. By taking higher harmonics as well as inter- and cross-modulation distortion into consideration, we have developed a method to analytically evaluate the adjacent channel leakage power ratio (ACPR) and error vector magnitude (EVM) on the basis of the PA's nonlinear characteristics. We devise a novel method for modeling the PA amplifying dual-band signals. The method makes it possible to model it merely by performing a one-tone test, making use of the Volterra series expansion and the generalWiener model. We then use the Mehler formula to derive the closed-form expressions of the PA's output power spectral density (PSD), ACPR, and EVM. The derivations are based on the assumption that the transmitted signals are complex Gaussian distributed in orthogonal frequency division multiplexing (OFDM) transmission systems. We validate the method by comparing measurement and simulation results and confirm it can appropriately predict the ACPR and EVM performance of the nonlinear PA output with OFDM inputs. In short, the method enables correct modeling of a wideband PA that amplifies dualband signals merely by conducting a one-tone test. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.

DOI： 10.1587/transele.E96.C.1254

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Study on short-range MIMO transmission using interference cancellation by antenna directivities 査読

Maki Arai, Tomohiro Seki, Ken Hiraga, Tadao Nakagawa, Kazuhiro Uehara

Asia-Pacific Microwave Conference Proceedings, APMC   395 - 397   2013年

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

In this paper, a simple method for canceling interference by using antenna directivities is proposed for short-range transmission systems. For higher data transmission systems the millimeter-wave frequency bands are useful because of their wide bandwidths. Also, Multiple-Input Multiple-Output (MIMO) technology can be applied to these bands because the application enables channel capacity to be increased by using multiple antennas at the transmitter and receiver without expanding the frequency bandwidth. However, since MIMO transmission schemes are complicated we consider parallel transmission, a simple method for transmitting multiple data streams that is suitable for short-range MIMO transmission. We propose a simple method for canceling interference by using antenna directivities and improving channel capacity in parallel transmission. Numerical analysis shows that the method maximizes channel capacity at the optimal spacing Lopt = 2λ0. It is also found that the channel capacity of the method is 14 % higher than that of Eigenmode beamforming (EM-BF) for two transmission streams and 12 % higher for four streams. © 2013 IEEE.

DOI： 10.1109/APMC.2013.6695158

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Signal Separation and Reconstruction Method for Simultaneously Received Multi-System Signals in Flexible Wireless System 査読

Takayuki Yamada, Doohwan Lee, Hiroyuki Shiba, Yo Yamaguchi, Kazunori Akabane, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E95B ( 4 )   1085 - 1092   2012年4月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

We previously proposed a unified wireless system called "Flexible Wireless System". Comprising of flexible access points and a flexible signal processing unit, it collectively receives a wideband spectrum that includes multiple signals from various wireless systems. In cases of simultaneous multiple signal reception, however, reception performance degrades due to the interference among multiple signals. To address this problem, we propose a new signal separation and reconstruction method for spectrally overlapped signals. The method analyzes spectral information obtained by the short-time Fourier transform to extract amplitude and phase values at each center frequency of overlapped signals at a flexible signal processing unit. Using these values enables signals from received radio wave data to be separated and reconstructed for simultaneous multi-system reception. In this paper, the BER performance of the proposed method is evaluated using computer simulations. Also, the performance of the interference suppression is evaluated by analyzing the probability density distribution of the amplitude of the overlapped interference on a symbol of the received signal. Simulation results confirmed the effectiveness of the proposed method.

DOI： 10.1587/transcom.E95.B.1085

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Effectiveness of Short-Range MIMO Using Dual-Polarized Antenna 査読

Ken Hiraga, Tomohiro Seki, Kentaro Nishimori, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E95B ( 1 )   87 - 96   2012年1月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Short-range Multiple-Input-Multiple-Output (SR-MIMO) transmission is an effective technique for achieving high-speed and short-range wireless communication. With this technique, however, the optimum aperture size of array antennas grows when the transmission distance is increased. Thus, antenna miniaturization is an important issue in SR-MIMO. In this paper, we clarify the effectiveness of using dual-polarized planar antennas as a means of miniaturizing SR-MIMO array antennas by measurements and analysis of MIMO transmission characteristics. We found that even in SR-MIMO transmission, the use of dual-polarized transmission enables higher channel capacity. Dual-polarized antennas can reduce by two thirds the array area that is needed to obtain the same channel capacity. For a transmission distance of two wavelengths, the use of a dual-polarized antenna improved the channel capacity by 26 bit/s/Hz while maintaining the same number of transmitters and receivers and the same antenna aperture size. Moreover, dual-polarized SR-MIMO has a further benefit when zero-forcing (ZF) reception without transmit beamforming is adopted, i.e., it effectively simplifies hardware configuration because it can reduce spatial correlation even in narrow element spacing. In this work, we confirmed that the application of dual-polarization to SR-MIMO is an effective way to both increase channel capacity and enhance transceiver simplification.

DOI： 10.1587/transcom.E95.B.87

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Analyses of Antenna Displacement in Short-Range MIMO Transmission over Millimeter-Wave 査読

Ken Hiraga, Tomohiro Seki, Kentaro Nishimori, Kenjiro Nishikawa, Ichihiko Toyoda, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E94B ( 10 )   2891 - 2895   2011年10月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Short-range multiple-input and multiple-output (SR-MIMO) has attracted much attention, because the technique makes it possible to raise channel capacity to several hundred Gbit/s by utilizing the millimeter-wave band (e.g., 60 GHz band). Although the opposed transceiving antennas are assumed to be accurately positioned in previous studies regarding SR-MIMO, a very important issue is to evaluate the performance degradation due to displacement between MIMO transceivers. In SR-MIMO over the millimeter-wave band, any displacement is perceived as significant because the wavelength is small. This paper evaluates the influence on SR-MIMO transmission performance over millimeter-wave caused by displacement between the transmitting and receiving antennas. The channel capacity is found to degrade by 5% when the horizontal displacement is 1 mm and by 2.7% when the rotational displacement is 10 degrees. In addition, comparing performances obtained with a number of antenna array arrangements clarifies that a square pattern arrangement is suitable for short-range wireless transmission.

DOI： 10.1587/transcom.E94.B.2891

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A Low-Noise, High-Gain Quasi-Millimeter-Wave Receiver MMIC with a Very High Degree of Integration Using 3D-MMIC Technology 査読

Takana Kaho, Yo Yamaguchi, Kazuhiro Uehara, Kiyomichi Araki

IEICE TRANSACTIONS ON ELECTRONICS   E94C ( 10 )   1548 - 1556   2011年10月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

We present a highly integrated quasi-millimeter-wave receiver MMIC that integrates 22 circuits in a 3 x 2.3 mm area using three-dimensional MMIC (3D-MMIC) technology. The MMIC achieves low noise (3 dB) and high gain (41 dB) at 26 GHz by using an on-chip image reject filter. It integrates a multiply-by-eight (X8) local oscillator (LO) chain with the IF frequency of the 2.4 GHz band and can use low-cost voltage-controlled oscillators (VCO5) and demodulators in a 2-3 GHz frequency band. Multilayer inductors contribute to the miniaturization especially in a 2-12 GHz frequency band. Furthermore, it achieves a high dynamic range by using two step attenuators with a new built-in inverter using an N-channel depression field-effect transistor (FET). The power consumption of the MMIC is only 450 mW.

DOI： 10.1587/transele.E94.C.1548

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Combined Nyquist and Compressed Sampling Method for Radio Wave Data Compression of a Heterogeneous Network System 査読

Doohwan Lee, Takayuki Yamada, Hiroyuki Shiba, Yo Yamaguchi, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E93B ( 12 )   3238 - 3247   2010年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

To satisfy the requirement of a unified platform which can flexibly deal with various wireless radio systems we proposed and implemented a heterogeneous network system composed of distributed flexible access points and a protocol free signal processing unit Distributed flexible access points are remote RF devices which perform the reception of multiple types of radio wave data and transfer the received data to the protocol free signal processing unit through wired access network The protocol free signal processing unit performs multiple types of signal analysis by software To realize a highly flexible and efficient radio wave data reception and transfer we employ the recently developed compressed sensing technology Moreover we propose a combined Nyquist and corn pressed sampling method for the decoding signals to be sampled at the Nyquist rate and for the sensing signals to be sampled at the compressed rate For this purpose the decoding signals and the sensing signals are converted into the intermediate band frequency (IF) and mixed In the IF band the decoding signals are set at lower center frequencies than those of the sensing signals The down converted signals are sampled at the rate of four times of the whole bandwidth of the decoding signals plus two times of the whole bandwidth of the sensing signals The purpose of above setting is to simultaneously conduct Nyquist rate and compressed rate sampling in a single ADC Then all of odd (or even) samples are preserved and some of even (or odd) samples are randomly discarded This method reduces the data transfer burden in dealing with the sensing signals while guarantee ing the realization of Nyquist rate decoding performance Simulation and experiment results validate the efficiency of the proposed method

DOI： 10.1587/transcom.E93.B.3238

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An Analysis of Multi-Layer Inductors for Miniaturizing of GaAs MMIC 査読

Yo Yamaguchi, Takana Kaho, Motoharu Sasaki, Kenjiro Nishikawa, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara, Kiyomichi Araki

IEICE TRANSACTIONS ON ELECTRONICS   E93C ( 7 )   1119 - 1125   2010年7月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Newly developed multi-layer inductors on GaAs three-dimensional MMICs are presented. We analyzed single-, double-, triple-, and quadruple-layer stacked-type inductors in what may be the first report on inductors on a GaAs MMIC with three or more layers. The performance of single- and multi-layer inductors was measured and calculated by electromagnetic field simulation. The multi-layer inductors produce 2-11 times higher inductance than that of conventional inductors on 2D-MMICs although they are the same size. This means that the proposed multi-layer inductors have smaller areas with the same inductances than those of conventional inductors. We also conducted the first-ever investigation of how performance factors such as parasitic capacitance, Q-factor, and self-resonant frequency are degraded in multi-layer inductors vis-a-vis those of conventional inductors. A microwave amplifier using multi-layer inductors was demonstrated and found to reduce circuit size by 20%.

DOI： 10.1587/transele.E93.C.1119

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A Very Low Spurious X-Band Frequency Quadrupler with Very High Integration Using 3D-MMIC Technology 査読

Yo Yamaguchi, Takana Kaho, Kazuhiro Uehara

IEICE TRANSACTIONS ON ELECTRONICS   E91C ( 11 )   1744 - 1750   2008年11月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A highly integrated frequency quadrupler MMIC that uses three-dimensional MMIC (3D-MMIC) technology is presented. It consists of four driver amplifiers, two doublers, and a 2-band elimination filter. These seven circuits are integrated in only a 2.36 mm(2) area. The filter sufficiently suppresses spurious output components. The third and fifth harmonic components, which are the spurious components nearest to the desired component, are well suppressed. The desired/undesired ratio is about 40 dB. The driver amplifiers make the quadrupler output a constant power of the desired multiplied signal under low input power. The MMIC supplies +5 dBm of the fourth harmonic component in the input power range from -10 dBm to +5 dBm. The power dissipation of the MMIC is only 160 mW.

DOI： 10.1093/ietele/e91-c.11.1744

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Performance evaluation of an autonomous adaptive base station that supports multiple wireless network systems 査読

Kazunori Akabane, Hiroyuki Shiba, Munehiro Matsui, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS   E91B ( 1 )   22 - 28   2008年1月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Various wireless systems are being developed to meet users' needs, and the rapid increase in frequency demand that accompanies the increasing popularity of wireless services means that more effective use of frequency resources is urgently needed. However, existing base stations are making no effort to use frequency resources effectively, and cooperation among wireless system base stations is needed to use frequency resources more effectively. Base stations can cooperate more efficiently if they are able to use multiple channels of many wireless systems simultaneously. We propose an autonomous adaptive base station (AABS) that can switch among various wireless systems the way software defined radio (SDR) base stations do. AABS can autonomously select and use the most suitable wireless system on the basis of user traffic and its hardware resources. Moreover, frequency resources are used effectively because AABS prevents unnecessary radio wave transmission when the number of users in the wireless systems decreases. AABS is also suitable for "multi-link communication" because it can use multiple channels of multiple wireless systems simultaneously. We developed AABS prototype and evaluated its performance. Our experimental and computer simulation results show the performance of AABS and its efficiency.

DOI： 10.1093/ietcom/e9l-b.1.22

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A miniaturized in-phase power divider with a DC block function 査読

Hitoshi Hayashi, Tadao Nakagawa, Kazuhiro Uehara, Yoshihiro Takigawa

IEICE TRANSACTIONS ON ELECTRONICS   E90C ( 10 )   2022 - 2029   2007年10月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper describes a miniaturized in-phase power divider with a DC block function. We first propose three types of miniaturized in-phase power dividers composed of two distributed transmission lines, a resistor, and three capacitors to function as a DC block. Then, we use a simulation to compare the dividers. The simulation results show that. by properly selecting circuit configuration, we both achieve broadband frequency characteristics and miniaturize circuitry as compared to the conventional Wilkinson power divider with two DC block capacitors. Finally, an experimental UHF power divider fabricated to test the design concept is presented. Over the frequency range from 0.44 to 0.66 GHz, the experimental power divider exhibits power splits of -3.2 +/- 0.2 dB, return losses greater than 20 dB. and isolation between output ports greater than 20 dB.

DOI： 10.1093/ietele/e90-c.10.2022

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Miniaturized broadbland lumped-element in-phase power dividers 査読

Hitoshi Hayashi, Tadao Nakagawa, Kazuhiro Uehara, Yoshihiro Takigawa

IEICE TRANSACTIONS ON ELECTRONICS   E90C ( 6 )   1222 - 1227   2007年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper describes miniaturized broadband lumped-element in-phase power dividers. We first propose two types of miniaturized broadband lumped-element in-phase power dividers composed of two inductors, a resistor, and two capacitors. Next, we use a simulation to compare these dividers with conventional power dividers. The simulation results reveal that the proposed lumped-element in-phase power dividers can help miniaturize circuits (by decreasing inductances by about 30%, reducing the number of necessary capacitors by half, and decreasing necessary capacitances by about 30% as compared to conventional lumped-element dividers) and attain broadband frequency characteristics (by increasing normalized operating frequency bandwidths (f/fo) by about 80% as compared to conventional lumped-element dividers).

DOI： 10.1093/ietele/e90-c.6.1222

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An active terminal circuit and its application to a distributed amplifier 査読

Hitoshi Hayashi, Munenari Kawashima, Tadao Nakagawa, Kazuhiro Uehara, Yoshihiro Takigawa

IEICE TRANSACTIONS ON ELECTRONICS   E90C ( 6 )   1203 - 1208   2007年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper describes a broadband active terminal circuit and its application to a distributed amplifier. In this study, we first analyzed and compared three types of active terminal circuits using representative circuit configurations, namely, an active terminal circuit with a common-emitter BJT, an active terminal circuit with a Darlington BJT pair, and an active terminal circuit with cascode-connected BJTs. The simulation results showed that the active terminal circuit with cascode-connected BJTs kept the matching condition up to high frequency. After the simulation, we fabricated a distributed amplifier that used an active terminal circuit with cascode-connected BJTs. The RF amplifier achieved a flat gain of 9.7 +/- 1.0 dB over a range of 3-15 GHz.

DOI： 10.1093/ietele/e90-c.6.1203

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Trends in broadband wireless communication systems and software defined radios 招待 査読

Kazuhiro Uehara

Interdisciplinary Information Sciences Journal   12 ( 2 )   163 - 172   2006年9月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.4036/iis.2006.163

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IEEE 802.11 wireless LAN implemented on software defined radio with hybrid programmable architecture 査読

Takashi Shono, Yushi Shirato, Hiroyuki Shiba, Kazuhiro Uehara, Katsuhiko Araki, Masahiro Umehira

IEEE Transactions on Wireless Communications   4 ( 5 )   2299 - 2308   2005年9月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

This paper describes a prototype software defined radio (SDR) transceiver on a distributed and heterogeneous hybrid programmable architecture; it consists of a central processing unit (CPU), digital signal processors (DSPs), and pre/postprocessors (PPPs), and supports both Personal Handy Phone System (PHS), and IEEE 802.11 wireless local area network (WLAN). It also supports system switching between PHS and WLAN and over-the-air (OTA) software downloading. In this paper, we design an IFEE 802.11 WLAN around the SDR; we show the software architecture of the SDR prototype and describe how it handles the IEEE 802.11 WLAN protocol. The medium access control (MAC) sublayer functions are executed on the CPU, while the physical layer (PHY) functions such as modulation/demodulation are processed by the DSPs; higher speed digital signal processes are run on the PPP implemented on a field-programmable gate array (FPGA). The most difficult problem in implementing the WLAN in this way is meeting the short interframe space (SIFS) requirement of the IEEE 802.11 standard; we elucidate the potential weakness of the current configuration and specify a way of implementing the IEEE 802.11 protocol that avoids this problem. This paper also describes an experimental evaluation of the prototype for WLAN use, the results of which agree well with computer-simulation results.

DOI： 10.1109/TWC.2005.853967

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PHSを用いたワイヤレスAO/DIシステムの提案と性能評価 査読

芝宏礼, 上原一浩, 久保田周治

電子情報通信学会論文誌(B)   J87-B ( 5 )   629 - 637   2004年5月

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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Adaptability check during software installation in software defined radio 査読

Yasuo Suzuki, Hiroshi Harada, Kazuhiro Uehara, Teruya Fujii, Yukio Yokoyama, Koji Oda, Ryoichi Hidaka

IEICE Transactions on Communications   E86B ( 12 )   3401 - 3407   2003年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper presents the summarized achievements of "Study Group on Software Technology for Radio Equipment" held at TELEC from April 2000 to March 2003. The Study Group specified the essential issues on Software Defined Radio (SDR), and discussed desirable methods to evaluate conformity to technical regulations in radios that can change RF characteristics only by changing software. The biggest objective in SDR is to build the architecture to allow users to install software exclusively in the combination of hardware and software that have passed the certification test. The Study Group has reached a solution by introducing the idea of "tally." This paper explains the concept of tally, and proposes two types of systems to use tallies in checking adaptability in combinations of hardware and software.

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Software defined radio prototype for PHS and IEEE 802.11 wireless LAN 査読

Hiroyuki Shiba, Takashi Shono, Yushi Shirato, Ichihiko Toyoda, Kazuhiro Uehara, Masahiro Umehira

IEICE Transactions on Communications   E85B ( 12 )   2694 - 2702   2002年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A software defined radio (SDR) prototype based on a multiprocessor architecture (MPA) is developed. Software for Japanese personal handy phone system (PHS) of a 2G mobile system, and IEEE 802.11 wireless LAN, which has much wider bandwidth than the 2G systems, is successfully implemented. Newly developed flexible-rate pre-/post-processor (FR-PPP) achieves the flexibility and wideband performance that the platform needs. This paper shows the design of the SDR prototype and evaluates its performance by experiments that include PHS processor load and wireless LAN throughput characteristics and processor load.

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Proposal for system diversity on software-defined radio 査読

Takashi Shono, Kazuhiro Uehara, Shuji Kubota

IEICE Transactions on Fundamentals   E84-A ( 9 )   2346 - 2358   2001年9月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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マルチプロセッサ・アーキテクチャを用いたソフトウェア無線機における全二重リアルタイム通信を実現するためのソフトウェアの設計と評価 査読

上原一浩, 鈴木康夫, 芝宏礼, 田中裕之, 淺井裕介, 庄納崇, 久保田周治

電子情報通信学会論文誌(B)   J84-B ( 7 )   1208 - 1215   2001年7月

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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Software radio base and personal station prototypes 査読

Yasuo Suzuki, Kazuhiro Uehara, Masashi Nakatsugawa, Yushi Shirato, Shuji Kubota

IEICE Transactions on Communications   E83B ( 6 )   1261 - 1268   2000年6月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Software radio base and personal station prototypes are proposed and implemented. The prototypes are composed of RF/IF, A/D and D/A, pre- and post-processors. CPU, and DSP parts. System software is partitioned into CPU program and DSP program to use processor resources effectively. They support various air interfaces. some of which are equivalent to the 384 kbit/s transmission rate PHS (personal handy phone system) and a 96 kbit/s transmission rate system. The base station can also be used as a communication bridge between two systems. In order to ease IF Filter requirements, the zero-stuff method is employed. Basic transmission and receiving performances are evaluated in an experiment and their results agree well with those expected.

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Proposal for a novel beam combination method for indoor high-speed wireless communication systems 査読

Kazuhiro Uehara, Yasushi Takatori, Kenichi Kagoshima

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY   48 ( 5 )   1511 - 1517   1999年9月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

A novel beam combination method for wide-band digital indoor communication systems such as wireless LAN's and,wireless ATR l's is proposed. Crossed fan beams are used at the base station (BS) and personal stations (PS's), The beam combination method provides better transmission quality than the traditional pencil-beam combination and eliminates complex beam control in the BS, Maximum dispersion distributions in a transmission frequency bandwidth are calculated by a three-dimensional (3-D) indoor propagation delay simulation algorithm. A prototype fan-beam antenna for the PS is fabricated and measured at 20 GHz.

DOI： 10.1109/25.790526

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Rigorous analysis of transient radiation mechanism of small Multi Sector Monopole Yagi-Uda array antenna using FDTD method 査読

Tamami Maruyama, Kazuhiro Uehara, Toshikazu Hori, Kenichi Kagoshima

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS   12 ( 4 )   341 - 351   1999年7月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

The Multi Sector Monopole Yagi-Uda Antenna (MS-MPYA) can be used to realize low profile, multisector antennas. The MS-MPYA has an interesting feature; we can sharpen the beams by using the adjacent array effect if we set metallic fins between the arrays so as to hide the exciters. Otherwise, without the fins, undesired radiation from the adjacent arrays causes beam division. This paper shows the radiation mechanism by using transient solutions in the time domain calculated by the FDTD method to examine how electromagnetic waves interact with the directors, adjacent arrays, and fins in real time. We introduce the transient solutions for three types of MS-MPYA: with adjacent array and with fins, without adjacent array but with fins, and with adjacent arrays but without fins. The transient solutions show that the adjacent array's action is changed by the existence of the fins and caused beam division. Without fins, the adjacent arrays act as directors of the active array and cause beam division. With fins, the adjacent arrays reflect the wave coming from the main array and sharpen the beam. Copyright (C) 1999 John Wiley & Sons, Ltd.

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モノポール八木・宇田アレーアンテナを用いた無線LAN用小型マルチセクタアンテナの解析と設計 査読

丸山珠美, 上原一浩, 鹿子嶋憲一

電子情報通信学会論文誌(B-II)   J80-B-II ( 5 )   424 - 433   1997年5月

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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30-GHz multibeam antenna using bi-layer Butler matrix circuits 査読

Tomohiro Seki, Kazuhiro Uehara, Kenichi Kagoshima

IEICE Transactions on Communications   E79B ( 12 )   1778 - 1783   1996年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

We propose a novel feeding circuit for a 30 GHz planar multibeam antenna applied to high-speed wireless communication systems. The feeding circuit is a bi-layer 8-port Butler matrix constructed with phase adjusted slot-coupled hybrids and branch-line hybrids. The new circuit configuration eliminates troublesome vias and line crossings, so it can be manufactured by traditional photolithograph. The feeding circuit is designed by using the spectral domain moment method considering bonding film effects. A prototype of a multibeam antenna which has seven pencil-beams with 10 degrees beamwidths is manufactured and tested. the beam scan angle error is less than 3 degrees at 30 GHz.

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A planar sector antenna for indoor high-speed wireless communication systems 査読

Kazuhiro Uehara, Tomohiro Seki, Kenichi Kagoshima

IEICE Transactions on Communications   E79B ( 12 )   1773 - 1777   1996年12月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

For quasi millimeter-wave and millimeter-wave high-speed wireless communications over wireless LANs and wireless ATMs, narrow beam antennas have been shown to provide high transmission quality by suppressing the troublesome multipath effect. However, the diameter of sector antennas needed to create the narrow beams rapidly increases with the sector number. In addition, the cylindrical shape of typical sector antennas does not suit portable terminals. This paper shows a methodology for designing planar sector antennas that overcomes these problems. The proposed antenna uses two kinds of beams and the antenna gains are equalized in all sectors. The antenna is developed as a 4-beam subarray Fed by a planar Butler matrix circuit. The design method of the subarray and an evaluation of its characteristics in the 20 GHz band are discussed.

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幾何光学的手法による任意指向性アンテナに対する屋内伝搬特性解析 査読

上原一浩, 関智弘, 鹿子嶋憲一

電子情報通信学会論文誌(B-II)   J78-B-II ( 9 )   593 - 601   1995年9月

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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Rigorous analysis of microstrip phased array antennas using a new FDTD method 査読

Kazuhiro Uehara, Kenichi Kagoshima

Electronics Letters   30 ( 2 )   100 - 101   1994年1月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INST ENGINEERING TECHNOLOGY-IET  

A finite-difference time-domain (FDTD) algorithm for radiating antennas that involve multiple, phased excitation sources is presented. The algorithm has the potential to analyse phased array antennas in the time domain. The authors apply it to a two-element microstrip antenna (MSA) phased array on a finite substrate, and compare the results as gained with an existing method and experiments.

DOI： 10.1049/el:19940109

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FDTD method analysis of mutual coupling between microstrip antennas 査読

Kazuhiro Uehara, Kenichi Kagoshima

IEICE Transactions on Communications   E76B ( 7 )   762 - 764   1993年7月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

We analyze the mutual coupling between two microstrip antennas (MSAs) with the finite-difference time-domain (FDTD) method. It is suitable for substrates which have a complex configuration or include feed line structures. The mutual coupling between two MSAs on discontinuous orthogonal substrates is successfully calculated.

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ミリ波帯イメージングアレイ用光学系の設計とプラズマ計測への適用 査読

上原一浩, 米倉丈司, 西村宏, 宮下和仁, 水野皓司

電子情報通信学会論文誌(B-II)   J76-B-II ( 1 )   28 - 36   1993年1月

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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ミリ波帯イメージングアレイ用八木・宇田アンテナの最適設計 査読

上原一浩, 西村宏, 米倉丈司, 夏目健一郎, 水野皓司

電子情報通信学会論文誌(B-II)   J75-B-II ( 7 )   472 - 479   1992年7月

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担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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Lens-coupled imaging arrays for the millimeter- and submillimeter-wave regions 査読

Kazuhiro Uehara, Kazuhito Miyashita, Ken-Ichiro Natsume, Kouki Hatakeyama, Koji Mizuno

IEEE Transactions on Microwave Theory and Techniques   40 ( 5 )   806 - 811   1992年5月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

We have been developing four kinds of lens-coupled antenna imaging arrays for operation at millimeter- and submillimeter-wave frequencies. The comparison between dipole antennas, Yagi-Uda's, trap-loaded antennas, and microstrip patches will be discussed from the viewpoint of the matching with the detectors and optical systems. The radiation patterns and input impedance of each antenna have been calculated and measured to attain the optimum matching using model experiments. The trap-loaded antenna arrays have been successfully applied to plasma diagnostics at the Tsukuba GAMMA 10 tandem mirror.

DOI： 10.1109/22.137382

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Millimeter-wave phase-imagign interferometer for the GAMMA10 tandem mirror 査読

Kunihiko Hattori, Atsushi Mase, Akiyoshi Itakura, Masaaki Inutake, Shoichi Miyoshi, Kazuhiro Uehara, Takeshi Yonekura, Hiroshi Nishimura, Kazuhito Miyashita, Koji Mizuno

Review of Scientific Instruments   62 ( 12 )   2857 - 2861   1991年12月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER INST PHYSICS  

A millimeter-wave phase-imaging interferometer has been developed for the study of density profiles of the GAMMA 10 tandem mirror. The interferometer uses a 70-GHz klystron oscillator and a quasi-optical transmission system. The probe beam is expanded so as to fill an orthogonal view of a plasma cross section. The view is imaged onto a detector array. The detector array consists of beam-lead GaAs Schottky barrier diodes bonded to antennas fabricated using photolithographic techniques on a fused-quartz substrate. Two types of antennas, bow-tie and Yagi-Uda antennas have been used in order to provide an effective matching to millimeter-wave beams, and compared for the performance of an imaging system. The interferometers have been applied to the central-cell and plug-cell plasmas of GAMMA 10.

DOI： 10.1063/1.1142172

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Yagi-Uda array for millimeter-wave imaging 査読

Koji Mizuno, Kazuhiro Uehara, Hiroshi Nishimura, Takeshi Yonekura, Tetsu Suzuki

Electronics Letters   27 ( 2 )   108 - 109   1991年1月

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEE-INST ELEC ENG  

An imaging array consisting of five Yagi-Uda antennas in a dielectric has been constructed for 50 GHz that has antenna patterns suitable for millimetre-wave applications. Crosstalk levels of less than -30 dB between adjacent antennas in an f/1.0 imaging array have been measured in 5 GHz model experiments.

DOI： 10.1049/el:19910072

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