研究者詳細 - 山田　寛喜

論文 - 山田　寛喜

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Observation of snow covered urban area using ALOS-2 data

Ryoichi Sato, Shusei Hayashi, Yoshio Yamaguchi, Hiroyoshi Yamada

Proceedings of the European Conference on Synthetic Aperture Radar, EUSAR 2018- 1437 - 1440 2018年

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）出版者・発行元：Institute of Electrical and Electronics Engineers Inc.

We show observation result for snow covered or uncovered urban area using quad-pol ALOS-2/PALSAR-2 data. From the result of the observation for autumn and winter seasons, double bounce scattering contribution decreases and surface scattering contribution increases for the snow covered case, even when radar illumination direction is almost normal to the alignment of urban buildings. To determine the exact cause of the scattering behavior and minutely evaluate the polarimetric features, 'collective' reflected field, which approximately includes all of the multiple reflections inside multi-layered snow, is introduced for additional consideration. By using the collective reflection coefficient, instead of the conventional Fresnel coefficient, one can evaluate the reflection characteristics not only from the surface of the top snow layer but also from all of the internal reflections of each snow layer easily. It is found from the result for the dihedral structure between the three-layered snow plane and vertical concrete wall that the dominant contribution sometimes changes from the double bounce scattering to the surface scattering even when the surface of the top layer of the snow is flat.

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Multi-baseline PolSAR model-based scattering component decomposition by using EM algorithm for ALOS2 data

Hiroyoshi Yamada, Kosuke Miyazaki, Ryoichi Sato, Yoshio Yamaguchi

Proceedings of the European Conference on Synthetic Aperture Radar, EUSAR 2018- 1341 - 1344 2018年

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）出版者・発行元：Institute of Electrical and Electronics Engineers Inc.

The PolSAR scattering component decomposition is one of powerful tools to extract characteristics of terrain for classification and the other applications. Especially, the model-based scattering decomposition technique becomes popular due to their strong relation to actual scattering mechanism. However, several assumptions are required to derive a unique solution. The authors has proposed the model-based decomposition technique with multi-baseline dataset. However, the technique has a limitation when there exist dominant 3 components. In this report we apply generalized inverse problem with the technique to obtain a sub-optimal solution. Performance of the method is demonstrated numerically, and also experimentally by ALOS2 dataset.

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Understanding of MIMP SAR data from rice paddy

Motofumi Arii, Hiroyoshi Yamada, Yuto Kaneshiro

Proceedings of the European Conference on Synthetic Aperture Radar, EUSAR 2018- 322 - 325 2018年

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）出版者・発行元：Institute of Electrical and Electronics Engineers Inc.

Though SAR remote sensing has been expected as an efficient rice crop monitoring tool, there still exist non-negligible mysteries to extract physical parameters. To solve the problems, it is essential to conduct theoretical characterization of experimentally obtained radar backscatter from rice paddies. In this paper, rice paddies in Niigata city, Japan, were observed by an L-band full polarimetric SAR, by systematically varying the incidence angle and polarization. Bragg scattering was obvious in the SAR imagery at L-band, and it was theoretically modeled. Then, backscatter from the rice paddy suppressing the Bragg scattering effect was obtained by utilizing the model.

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Effectiveness of Implicit Beamforming with Large Number of Antennas Using Calibration Technique in Multi-User MIMO System 査読

Nishimori, Kentaro, Hiraguri, Takefumi, Mitsui, Tsutomu, Yamada, Hiroyoshi

ELECTRONICS 6 ( 4 ) 2017年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

This paper examines the effectiveness of implicit beamforming (IBF), which enables transmission without channel state information (CSI) feedback in multi-user multiple-input multiple-output (MU-MIMO) systems with a large number of antennas. First, we explain why CSI feedback from terminal stations to the base station produces a very large overhead. A calibration technique is then introduced, which compensates for the difference between the complex amplitudes of the transmitters and receivers to facilitate CSI-feedback-free beamforming; this technique is called IBF. The efficacy of this calibration technique is demonstrated by measuring the amplitude and phase errors obtained using a 16-element array testbed and by performing a channel capacity evaluation. Finally, the throughput under IEEE802.11ac-based massive MIMO transmission, both with and without CSI feedback, is obtained in terms of the medium access control efficiency.

DOI： 10.3390/electronics6040091

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Theoretical Characterization of X-Band Multiincidence Angle and Multipolarimetric SAR Data From Rice Paddies at Late Vegetative Stage 査読

Motofumi Arii, Hiroyoshi Yamada, Tatsuharu Kobayashi, Shoichiro Kojima, Toshihiko Umehara, Tomomi Komatsu, Takeshi Nishimura

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 55 ( 5 ) 2706 - 2715 2017年5月

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

Various polarimetric decomposition techniques have been proposed and demonstrated for more than 20 years. However, they still have never been operational applications because of insufficient validations. The true composition ratio of scattering mechanisms within a radar backscatter has to be known. To achieve this, a novel comprehensive approach to accurately identify the contribution of each scattering mechanism by a multiincidence angle and multipolarimetric (MIMP) synthetic aperture radar (SAR) observation combined with a theoretical model simulation is introduced. Rice paddies in Niigata City in Japan having a simple vegetation structure without topography were observed by X-band polarimetric and interferometric SAR 2 (Pi-SAR2), by gradually varying the flight path in terms of incidence angle. In addition to the MIMP SAR observation, a dominant scattering mechanism is reliably isolated through the theoretical characterization of the data by a discrete scatterer model. In the case of the rice paddies at a late vegetative stage, a dominant scattering on HH gradually varies from the doublebounce scattering to the volume scattering of rice grains in terms of incidence angle, whereas VV is affected by various volume scatterings of grains, leaves, and stems at the small, medium, and large incidence angles, respectively. HV is simply affected by the volume scattering of grains at the small incidence angle, and then it gradually switches to the volume scattering of the stalks. This brand new approach by the MIMP SAR observation with the theoretical modeling for this specific stage could take forward the polarimetric decomposition studies.

DOI： 10.1109/TGRS.2017.2652447

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MIMO Doppler Radar Using Khatri-Rao Product Virtual Array for Indoor Human Detection 査読

Yosuke Wakamatsu, Hiroyoshi Yamada, Yoshio Yamaguchi

IEICE TRANSACTIONS ON COMMUNICATIONS E99B ( 1 ) 124 - 133 2016年1月

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

The MIMO technique can improve system performance of not only communication system but also of radar systems. In this paper, we apply the MIMO radar with enhanced angular resolution to the indoor location estimation of humans. The Khatri-Rao (KR) matrix product is also adopted for further angular resolution enhancement. We show that the MIMO radar with the KR matrix product processing can increase the number of virtual elements effectively with suitable element arrangement, hence higher angular resolution can be realized. In general, the KR matrix product processing is not suitable for coherent radar because of signal correlation. However, when targets signals have enough Doppler frequency differential against each other, this approach works well because the signals are decorrelated. In addition, Doppler filtering is introduced to remove unwanted responses of stationary objects which make human detection difficult with conventional methods. Computer simulation and experimental results are provided to show performance of the proposed method.

DOI： 10.1587/transcom.2015ISP0029

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Experimental Study on MW-SAR imaging in Outdoor Environment 査読

J. Minotani, H. Yamada, Y. Yamaguchi

2015 International Workshop on Electromagnetics and R&S Student Competition (iWEM2015), 2015年11月

Polarimetric Scattering Properties of Landslides in Forested Areas and the Dependence on the Local Incidence Angle 査読

Takashi Shibayama, Yoshio Yamaguchi, Hiroyoshi Yamada

REMOTE SENSING 7 ( 11 ) 15424 - 15442 2015年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

This paper addresses the local incidence angle dependence of several polarimetric indices corresponding to landslides in forested areas. Landslide is deeply related to the loss of human lives and their property. Various kinds of remote sensing techniques, including aerial photography, high-resolution optical satellite imagery, LiDAR and SAR interferometry (InSAR), have been available for landslide investigations. SAR polarimetry is potentially an effective measure to investigate landslides because fully-polarimetric SAR (PolSAR) data contain more information compared to conventional single- or dual-polarization SAR data. However, research on landslide recognition utilizing polarimetric SAR (PolSAR) is quite limited. Polarimetric properties of landslides have not been examined quantitatively so far. Accordingly, we examined the polarimetric scattering properties of landslides by an assessment of how the decomposed scattering power components and the polarimetric correlation coefficient change with the local incidence angle. In the assessment, PolSAR data acquired from different directions with both spaceborne and airborne SARs were utilized. It was found that the surface scattering power and the polarimetric correlation coefficient of landslides significantly decrease with the local incidence angle, while these indices of surrounding forest do not. This fact leads to establishing a method of effective detection of landslide area by polarimetric information.

DOI： 10.3390/rs71115424

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マルチビームMassive MIMOのビーム選択に関する検討

亀山航平, 西森健太郎, 平栗健史, 山田寛喜, 牧野秀夫

電子情報通信学会技術研究報告 2015年11月

航空機搭載リピートパスPOLSARデータを用いた偏波散乱成分分解法に関する検討

山田寛喜, 浦澤文美規, 山口芳雄, 佐藤亮一

電子情報通信学会技術研究報告 2015年11月

全偏波SARデータを用いた土砂災害の調査 (宇宙・航行エレクトロニクス)

柴山卓史, 山口芳雄, 山田寛喜

電子情報通信学会技術研究報告 = IEICE technical report : 信学技報 115 ( 282 ) 7 - 12 2015年10月

PolSARデータを利用した被災橋梁の状態把握のための偏波散乱解析

佐藤亮一, 矢嶋俊樹, 真坂元貴, 山口芳雄, 山田寛喜

電子情報通信学会技術研究報告 2015年10月

マルチベースラインSAR Tomographyのためのレジストレーションに関する検討

浦澤文美規, 山田寛喜, 山口芳雄

電子情報通信学会信越支部大会 2015年10月

ミリ波レーダを用いたSARイメージングに関する実験的検討

美濃谷潤, 山田寛喜, 山口芳雄

電子情報通信学会信越支部大会 2015年10月

Kinect を利用した自由走査式レーダにおける位置推定誤差の影響の検討

服部恵介, 山田寛喜, 山口芳雄, 小林弘一

電子情報通信学会信越支部大会 2015年10月

レンジ・ドップラレーダを用いた複数の人物の動作検出に関する実験的検討

福島真也, 山田寛喜, 小林弘一, 山口芳雄

電子情報通信学会信越支部大会 2015年10月

Khatri-Rao 積仮想アレーを用いたMIMOドップラレーダによる複数の人物を対象とした屋内位置推定に関する検討

若松洋介, 山田寛喜, 山口芳雄

電子情報通信学会信越支部大会 2015年10月

KR変換と圧縮センシングを用いた広帯域DOA推定における相関波到来時の推定誤差に関する検討

石山優, 山田寛喜, 山口芳雄

電子情報通信学会信越支部大会 2015年10月

圧縮センシングを用いた到来方向推定手法に関する基礎検討

石山優, 山田寛喜, 山口芳雄

電子情報通信学会技術研究報告 2015年10月

Kinectを利用したハンドヘルド走査式イメージングレーダシステムの実験的検討

服部恵介, 山田寛喜, 山口芳雄, 小林弘一

電子情報通信学会技術研究報告 2015年10月

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