湯 素華
| 情報・ネットワーク工学専攻 | 教授 |
| Ⅰ類（情報系） | 教授 |
| メタネットワーキング研究センター | 教授 |
研究者情報
委員歴
- 2024年04月 - 現在
幹事, 情報処理学会ITS研究会 - 2022年05月 - 現在
Academic editor, Wireless Communications and Mobile Computing - 2022年06月 - 2026年06月
Editor, IEICE Transactions on Communications, 学協会 - 2021年01月 - 2024年12月
Secretary, IEEE ITS Tokyo Chapter, 学協会 - 2020年06月 - 2024年06月
運営委員, 電子通信情報学会SeMI研究会, 学協会 - 2020年04月 - 2024年03月
運営委員, 情報処理学会ITS研究会, 学協会 - 2022年01月 - 2022年12月
Guest editor, MDPI Applied Sciences, Special Issue, 学協会 - 2020年04月 - 2022年03月
代表会員, 情報処理学会, 学協会 - 2019年01月 - 2020年12月
Technical Program Committee Chair, IEEE ITS Society Tokyo Chapter, 学協会 - 2016年04月 - 2020年03月
幹事, 情報処理学会ITS研究会, 学協会 - 2015年06月 - 2019年05月
編集委員, 情報処理学会 論文誌ジャーナル/JIP編集委員会, 学協会 - 2016年10月 - 2018年01月
編集委員会幹事, 2017情報処理学会論文誌「超スマート社会に向けた高度交通システムとモバイル通信」特集号 - 2014年07月01日 - 2016年03月31日
運営委員, 情報処理学会ITS研究会
研究活動情報
受賞
- 受賞日 2022年09月
情報処理学会、マルチメディア、分散、協調とモバイル(DICOMO2022)シンポジウム
角度情報を用いたBLE測位の高精度化に関する検討
優秀論文賞, 山見 悠人;湯 素華 - 受賞日 2022年03月
情報処理学会高度交通システムとスマートコミュニティ(ITS)研究会
C-V2X sidelinkを用いた近距離通信の高信頼スケジューリング法
優秀論文賞, 瀬川 洋介;湯 素華;上野 高明;大岸 智彦;小花 貞夫 - 受賞日 2021年09月
電子情報通信学会通信ソサイエティ
活動功労賞, 湯 素華 - 受賞日 2021年01月
情報処理学会高度交通システムとスマートコミュニティ(ITS)研究会
無線チャネル状態情報の空間・時間変化の併用による歩行者の角度推定及び高精度測位法の提案と評価
優秀論文賞, 駒宮 亘;小花 貞夫;湯 素華
国内学会・会議・シンポジウム等の賞 - 受賞日 2020年09月
情報処理学会、マルチメディア、分散、協調とモバイル(DICOMO2020)シンポジウム
Cellular-V2Xを用いたリアルタイム情報共有と配信のための無線リソースの効率的なスケジューリング法の提案
優秀論文賞, 瀬川 洋介;上野 高明;大岸 智彦;小花 貞夫;湯 素華
国内学会・会議・シンポジウム等の賞 - 受賞日 2019年09月
情報処理学会、マルチメディア、分散、協調とモバイル(DICOMO2019)シンポジウム
車両移動による無線チャネル状態情報の変化を利用した歩行者の角度推定及び高精度測位法の提案と評価
優秀論文賞, 駒宮 亘;小花 貞夫;湯 素華
国内学会・会議・シンポジウム等の賞 - 受賞日 2018年09月
情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2018) シンポジウム
車両からの電波の長期計測による路側機の高精度測位方式の提案
最優秀論文賞, 戸田和宏;湯 素華;小花貞夫
国内学会・会議・シンポジウム等の賞 - 受賞日 2017年07月
IEEE ICME 2017
Finalist of the World’s FIRST 10K Best Paper Award (Top 3%), Junjun Jiang;Yi Yu;Suhua Tang;Yong Ma;Guo-Jun Qi;Kiyoharu Aizawa - 受賞日 2017年07月
APWeb-WAIM 2017
Best Paper Runner Up, Chunlin Zhong;Yi Yu;Suhua Tang;Shin’ichi Satoh;Kai Xing - 受賞日 2013年11月
ACM SIGSPATIAL CUP 2013
Edge-based locality sensitive hashing for efficient geo-fencing application
Geofencing programming contest winner, Yi Yu;Suhua Tang;Roger Zimmermann
国際学会・会議・シンポジウム等の賞 - 受賞日 2011年11月
International Academy, Research, and Industry Association
Association control for throughput maximization and energy efficiency for wireless LANs
Best paper award, Oyunchimeg Shagdar;Suhua Tang;Akio Hasegawa;Tatsuo Shibata;Sadao Obana
国際学会・会議・シンポジウム等の賞
論文
- Efficient V2V Communications by Clustering-Based Collaborative Caching
Hiroki Tokunaga; Suhua Tang
ラスト(シニア)オーサー, Electronics, MDPI AG, 13巻, 5号, 掲載ページ 883-883, 出版日 2024年02月25日, 査読付, Vehicle-to-vehicle (V2V) communication plays an important role in enabling autonomous driving. However, when multiple vehicles request the same content, like road conditions, delivering it individually by V2V communication can significantly increase traffic volume, potentially causing congestion in the wireless channel. To address this issue, Content-Centric Network (CCN) technology is applied to V2V communication, which improves communication efficiency by exploiting content cached at vehicles. However, previous methods faced the following challenges: (i) vehicles could not use content stored in nearby vehicles outside the communication path, and (ii) redundant caching of the same content occurred at nearby vehicles. To tackle these challenges, this paper proposes a collaborative caching method in which vehicles are grouped into clusters and each cluster has a designated head responsible for managing caches across all vehicles within the cluster. In this way, this method enables vehicles to use the content cached at adjacent vehicles that are not directly on a communication path. In addition, it eliminates redundant caches, allowing a more diverse range of content storage. Extensive simulation results demonstrate that the proposed approach effectively reduces content delivery latency by 33% compared to the method using clusters without cooperative caching and by 19% compared to the ECV+ method.
研究論文（学術雑誌） - Enhancing computation offloading by integrating MEC and IRS
Hafiz Hasnain Imtiaz; Suhua Tang
ラスト(シニア)オーサー, Workshop on Autonomous Future Networks for Industry 5.0, IEEE Future Networks World Forum, 出版日 2023年11月, 査読付 - Reliable NR-V2X broadcast transmission by relay
Suhua Tang; Sadao Obana
筆頭著者, IEEE VTC2023-Fall, 出版日 2023年10月, 査読付
研究論文（国際会議プロシーディングス） - Multi-Slot Over-the-Air Computation in Fading Channels
Suhua Tang; Petar Popovski; Chao Zhang; Sadao Obana
筆頭著者, IEEE Transactions on Wireless Communications, Institute of Electrical and Electronics Engineers (IEEE), 22巻, 10号, 掲載ページ 6766-6777, 出版日 2023年10月, 査読付
研究論文（学術雑誌）, 英語 - Relay Selection for Over-the-Air Computation Achieving Both Long Lifetime and High Reliability
Jingyang Zhou; Suhua Tang
責任著者, Sensors, MDPI AG, 23巻, 8号, 掲載ページ 3824-3824, 出版日 2023年04月08日, 査読付, In a general wireless sensor network, a sink node collects data from each node successively and then post-processes the data to obtain useful information. However, conventional methods have a scalability problem: the data collection/processing time increases with the number of nodes, and frequent transmission collisions degrade spectrum efficiency. If only statistical values of the data are needed, using over-the-air computation (AirComp) can efficiently perform data collection and computation. However, AirComp also has its problems: when the channel gain of a node is too low, (i) the transmission power of that node will be high, decreasing the lifetime of that node and the entire network, and (ii) sometimes, the computation error still occurs even though the maximal transmission power is used. To jointly solve these two problems, in this paper we investigate the relay communication for AirComp and study a relay selection protocol. The basic method selects an ordinary node with a good channel condition as a relay node, considering both computation error and power consumption. This method is further enhanced to explicitly consider network lifetime in relay selection. Extensive simulation evaluations confirm that the proposed method helps to prolong the lifetime of the entire network and reduce computation errors as well.
研究論文（学術雑誌）, 英語 - Melody Generation from Lyrics with Local Interpretability
Wei Duan; Yi Yu; Xulong Zhang; Suhua Tang; Wei Li; Keizo Oyama
ACM Transactions on Multimedia Computing, Communications, and Applications, Association for Computing Machinery (ACM), 19巻, 3号, 掲載ページ 1-21, 出版日 2023年02月27日, 査読付, Melody generation aims to learn the distribution of real melodies to generate new melodies conditioned on lyrics, which has been a very interesting topic in the area of artificial intelligence and music. However, a challenging issue still limits the quality and reliability of melody generation conditioned on lyrics: how to enhance the interpretability between the input lyrics and generated melodies so humans can understand their relationships. To solve this issue, in this article, we propose a model for melody generation from lyrics with local interpretability, which contains two significant contributions: (i) Mutual information between input lyrics and generated melody is exploited to instruct the training of the network, which avoids the loss of content consistency during the training stage. (ii) Transformer is explored to efficiently extract semantic features from lyrics sequences, which provides more interpretable correlations between different syllables in lyrics. Experiments on a large-scale dataset with paired lyrics-melodies demonstrate that the proposed approach can generate higher-quality melodies from lyrics compared with existing methods.
研究論文（学術雑誌） - Variational Autoencoder with CCA for Audio–Visual Cross-modal Retrieval
Jiwei Zhang; Yi Yu; Suhua Tang; Jianming Wu; Wei Li
ACM Transactions on Multimedia Computing, Communications, and Applications, Association for Computing Machinery (ACM), 19巻, 3s号, 掲載ページ 1-21, 出版日 2023年02月24日, 査読付, Cross-modal retrieval is to utilize one modality as a query to retrieve data from another modality, which has become a popular topic in information retrieval, machine learning, and databases. Finding a method to effectively measure the similarity between different modality data is the major challenge of cross-modal retrieval. Although several research works have calculated the correlation between different modality data via learning a common subspace representation, the encoder’s ability to extract features from multi-modal information is not satisfactory. In this article, we present a novel variational autoencoder architecture for audio–visual cross-modal retrieval by learning paired audio–visual correlation embedding and category correlation embedding as constraints to reinforce the mutuality of audio–visual information. On the one hand, audio encoder and visual encoder separately encode audio data and visual data into two different latent spaces. Further, two mutual latent spaces are respectively constructed by canonical correlation analysis. On the other hand, probabilistic modeling methods are used to deal with possible noise and missing information in the data. Additionally, in this way, the cross-modal discrepancies from intra-modal and inter-modal information are simultaneously eliminated in the joint embedding subspace. We conduct extensive experiments over two benchmark datasets. The experimental results confirm that the proposed architecture is effective in learning audio–visual correlation and is appreciably better than the existing cross-modal retrieval methods.
研究論文（学術雑誌） - AoA Estimation for High Accuracy BLE positioning
Yuto Yamami; Suhua Tang
IEEE CCNC 2023, 2023巻, 出版日 2023年01月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Multi-Task Partial Offloading with Relay and Adaptive Bandwidth Allocation for the MEC-Assisted IoT
Hafiz Hasnain Imtiaz; Suhua Tang
責任著者, Sensors, MDPI AG, 23巻, 1号, 掲載ページ 190-190, 出版日 2022年12月24日, 査読付, The fifth-generation (5G) wireless network is visualized to offer many types of services with low latency requirements in Internet of Things (IoT) networks. However, the computational capabilities of IoT nodes are not enough to process complex tasks in real time. To solve this problem, multi-access edge computing (MEC) has emerged as an effective solution that will allow IoT nodes to completely or partially offload their computational tasks to MEC servers. However, the large communication delay at a low transmission rate for nodes far from the access point (AP) makes this offloading less meaningful. This paper studies joint multi-task partial offloading from multiple IoT nodes to a common MEC server collocated with an AP, and it uses relay selection to help nodes far from the AP. The computation time of all tasks is minimized by adaptive task division and resource allocation (bandwidth and computation resource), and it is solved with an evolutionary algorithm. The simulation results confirm that the proposed method with both relay selection and adaptive bandwidth allocation outperforms the methods with neither or only one function.
研究論文（学術雑誌） - Deep Attention-Based Alignment Network for Melody Generation from Incomplete Lyrics
Gurunath Reddy M; Zhe Zhang; Yi Yu; Florian Harscoe; Simon Canales; Suhua Tang
IEEE ISM’22, 出版日 2022年12月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Efficient V2V communications by clustering-based collaborative caching
Hiroki Tokunaga; Suhua Tang
IEEE ICVES’22, 出版日 2022年11月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Node Scheduling for AF-based Over-the-Air Computation
Suhua Tang; Hiroyuki Yomo; Chao Zhang; Sadao Obana
筆頭著者, IEEE Wireless Communications Letters, 2022巻, 9号, 掲載ページ 1945-1949, 出版日 2022年09月, 査読付
研究論文（学術雑誌）, 英語 - Exploiting Phase Difference of Arrival of V2X Signals for Pedestrian Positioning
Suhua Tang; Sadao Obana
筆頭著者, Proc. IEEE VTC2022-Fall, 2022巻, 出版日 2022年09月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Unified Performance Analysis of Stochastic Clustered Cooperative Systems with Distance-based Relay Selection
Fangzhou Yu; Chao Zhang; Suhua Tang
IEEE Trans. Wireless Commun., 2022巻, 8号, 掲載ページ 6180-6194, 出版日 2022年08月, 査読付
研究論文（学術雑誌）, 英語 - Cellular V2X Sidelinkにおける高信頼・低遅延なスケジューリング法の提案と評価
瀬川洋介; 上野高明; 大岸智彦; 湯素華; 小花貞夫
責任著者, 情報処理学会論文誌,, 63巻, 4号, 掲載ページ 1029-1041, 出版日 2022年04月, 査読付
研究論文（学術雑誌）, 日本語 - Melody Generation from lyrics using three branch conditional LSTM-GAN
Abhishek Srivastava; Wei Duan; Rajiv Ratn Shah; Yi Yu; Suhua Tang; Wei Li
Proc. MMM’22, 2022巻, 出版日 2022年04月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Improving Performance of C-V2X Sidelink by Interference Prediction and Multi-Interval Extension
Yosuke Segawa; Suhua Tang; Takaaki Ueno; Tomohiko Ogishi; Sadao Obana
責任著者, IEEE Access, 2022巻, 4号, 出版日 2022年04月, 査読付
研究論文（学術雑誌）, 英語 - LSTM-based high precision pedestrian positioning
Masaki Inoue; Suhua Tang; Sadao Obana
Proc. IEEE CCNC’22, 2022巻, 出版日 2022年01月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Enhancing urban road network by combining route planning and dynamic lane reversal
Zuoting Zhang; Suhua Tang
International Conference on Mobile Computing and Ubiquitous Networking (ICMU), 1巻, 出版日 2021年11月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - IMP: Impedance matching enhanced power-delivered-to-load optimization for magnetic MIMO wireless power transfer system
Wangqiu Zhou; Hao Zhou; Wenxiong Hua; Fengyu Zhou; Xiang Cui; Suhua Tang; Zhi Liu; Xiangyang Li
IEEE/ACM International Symposium on Quality of Service (IWQOS), IEEE, 1巻, 出版日 2021年06月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Reliable over-the-air computation by amplify-and-forward based relay
Suhua Tang; Huarui Yin; Chao Zhang; Sadao Obana
IEEE Access, 9巻, 掲載ページ 53333-53342, 出版日 2021年04月, 査読付
研究論文（学術雑誌）, 英語 - Precise angle estimation by jointly using spatial/temporal change of channel state information and its application in pedestrian positioning
Wataru Komamiya; Suhua Tang; Sadao Obana
IEEE Access, Institute of Electrical and Electronics Engineers (IEEE), 9巻, 掲載ページ 59420-59431, 出版日 2021年04月, 査読付
研究論文（学術雑誌）, 英語 - Performance analysis of millimeter wave wireless power transfer with imperfect beam alignment
Man Wang; Chao Zhang; Xiaoming Chen; Suhua Tang
IEEE Transactions on Vehicular Technology, 70巻, 3号, 掲載ページ 2605-2618, 出版日 2021年03月, 査読付
研究論文（学術雑誌）, 英語 - HPNet: A compressed neural network for robust hybrid precoding in multi-user massive MIMO systems
Mingyang Chai; Suhua Tang; Ming Zhao; Wuyang Zhou
IEEE Globecom’20, 2020巻, 出版日 2020年12月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Reliable and efficient dissemination of traffic events among vehicles associated with different operators by using cellular V2X
Yosuke Segawa; Suhua Tang; Takaaki Ueno; Tomohiko Ogishi; Sadao Obana
IEEE VNC’20, 1巻, 出版日 2020年12月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Ensemble super-resolution with a reference dataset
Junjun Jiang; Yi Yu; Zhen Wang; Suhua Tang; Ruimin Hu; Jiayi Ma
IEEE Transactions on Cybernetics, 50巻, 11号, 掲載ページ 4694-4708, 出版日 2020年11月, 査読付
研究論文（学術雑誌）, 英語 - Exploiting large vehicles with high antenna for efficient relay in inter-vehicle communication
Takuya Mori; Suhua Tang; Sadao Obana
Proc. IEEE VTC2020-Spring, 2020巻, 出版日 2020年05月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Dynamic control of transmission interval for efficient pedestrian-to-vehicle communication based on channel utilization rate
Shun Ito; Suhua Tang; Sadao Obana
Proc. IEEE VTC2020-Spring, 2020巻, 出版日 2020年05月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Radiation angle estimation and high-precision pedestrian positioning by tracking change of channel state information
Wataru Komamiya; Suhua Tang; Sadao Obana
Sensors, 20巻, 5号, 出版日 2020年03月, 査読付
研究論文（学術雑誌）, 英語 - CCN-based inter-vehicle communication for efficient collection of road and traffic information
Takanori Nakazawa; Suhua Tang; Sadao Obana
Electronics, MDPI, 9巻, 1号, 出版日 2020年01月, 査読付
研究論文（学術雑誌）, 英語 - Context-Patch Face Hallucination Based on Thresholding Locality-Constrained Representation and Reproducing Learning.
Junjun Jiang; Yi Yu 0001; Suhua Tang; Jiayi Ma 0001; Akiko Aizawa; Kiyoharu Aizawa
IEEE Trans. Cybernetics, 50巻, 1号, 掲載ページ 324-337, 出版日 2020年, 査読付
研究論文（学術雑誌）, 英語 - Lyrics-conditioned neural melody generation
Yi Yu; Florian Harscoet; Simon Canales; Gurunath Reddy; Suhua Tang; Junjun Jiang
International Conference on Multimedia Modeling (MMM’20),, 2020巻, 出版日 2020年01月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Fast and reliable dissemination of road and traffic information by combining cellular V2X and DSRC
Masashi Takakusaki; Suhua Tang; Takaaki Ueno; Tomohiko Ogishi; Sadao Obana
IEEE Globecom 2019 workshop, 2019巻, 出版日 2019年12月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Single antenna precise angle estimation by exploiting Doppler shift and its application in pedestrian positioning
Wataru Komamiya; Sadao Obana; Suhua Tang
IEEE ICVES’19, 2019巻, 出版日 2019年09月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Supervised generative adversarial cross-modal hashing by transferring pairwise similarities for venue discovery
Himanshu Aggarwal; Rajiv Shah; Suhua Tang; Feida Zhu
IEEE BigMM’19, 2019巻, 出版日 2019年09月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Channel estimation and achievable rate of massive MU-MIMO systems with IQ imbalance
Nana Zhang; Huarui Yin; Weidong Wang; Suhua Tang
IEICE Trans. Communications, E102-B巻, 8号, 掲載ページ 1512-1525, 出版日 2019年08月, 査読付
研究論文（学術雑誌）, 英語 - 車両からの電波の長期計測による路側機の高精度測位方式の提案
戸田 和宏; 湯 素華; 小花 貞夫
情報処理学会論文誌, 60巻, 8号, 掲載ページ 1379-1389, 出版日 2019年08月, 査読付
研究論文（学術雑誌）, 日本語 - Reducing false wake-up in contention-based wake-up control of wireless LANs
Suhua Tang; Sadao Obana
Wireless Networks, 25巻, 掲載ページ 2333-2349, 出版日 2019年07月, 査読付
研究論文（学術雑誌）, 英語 - Deep cross-modal correlation learning for audio and lyrics in music retrieval
Yi Yu; Suhua Tang; Francisco Raposo; Lei Chen
ACM Transactions on Multimedia Computing Communications and Applications, 15巻, 1号, 出版日 2019年02月, 査読付
研究論文（学術雑誌）, 英語 - High-precision pedestrian positioning by using radio signals from vehicles and roadside units
Kazuhiro Toda; Suhua Tang; Sadao Obana
Proc. ICEIC’19, 2019巻, 出版日 2019年01月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Face hallucination through differential evolution parameter map learning with facial structure prior.
Junjun Jiang; Jiayi Ma 0001; Suhua Tang; Yi Yu 0001; Kiyoharu Aizawa
Inf. Sci., 481巻, 掲載ページ 174-188, 出版日 2019年, 査読付
研究論文（学術雑誌）, 英語 - Efficient Collection of Road and Traffic Information by CCN-based Inter-Vehicle Communications
Takanori Nakazawa; Sadao Obana; Suhua Tang
Proc. APCC’18, 2018巻, 出版日 2018年11月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Improvement of pedestrian positioning precision by using spatial correlation of mutipath error
Yearlor Patou; Sadao Obana; Suhua Tang
Proc. IEEE ICVES’18, 2018巻, 出版日 2018年09月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Deep CNN denoiser and multi-layer neighbor component embedding for face hallucination
Junjun Jiang; Yi Yu; Jinhui Hu; Suhua Tang; Jiayi Ma
Proc. IJCAI-18, 2018巻, 出版日 2018年07月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Improving performance of pedestrian positioning by using vehicular communication signals
Suhua Tang; Sadao Obana
IET Intelligent Transport Systems, 12巻, 5号, 掲載ページ 366-374, 出版日 2018年05月, 査読付
研究論文（学術雑誌）, 英語 - Energy-efficient data collection method for sensor networks by integrating asymmetric communication and wake-up radio
Masanari Iwata; Suhua Tang; Sadao Obana
Sensors (Switzerland), MDPI AG, 18巻, 4号, 出版日 2018年04月06日, 査読付, In large-scale wireless sensor networks (WSNs), nodes close to sink nodes consume energy more quickly than other nodes due to packet forwarding. A mobile sink is a good solution to this issue, although it causes two new problems to nodes: (i) overhead of updating routing information
and (ii) increased operating time due to aperiodic query. To solve these problems, this paper proposes an energy-efficient data collection method, Sink-based Centralized transmission Scheduling (SC-Sched), by integrating asymmetric communication and wake-up radio. Specifically, each node is equipped with a low-power wake-up receiver. The sink node determines transmission scheduling, and transmits a wake-up message using a large transmission power, directly activating a pair of nodes simultaneously which will communicate with a normal transmission power. This paper further investigates how to deal with frame loss caused by fading and how to mitigate the impact of the wake-up latency of communication modules. Simulation evaluations confirm that using multiple channels effectively reduces data collection time and SC-Sched works well with a mobile sink. Compared with the conventional duty-cycling method, SC-Sched greatly reduces total energy consumption and improves the network lifetime by 7.47 times in a WSN with 4 data collection points and 300 sensor nodes.
研究論文（学術雑誌）, 英語 - Fine-grained integration of priority control and relay selection for fast and reliable inter-vehicle communication
Takuya Mori; Suhua Tang; Sadao Obana
Proc. ICICT 2018, 2018巻, 出版日 2018年02月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - 歩行者事故削減のためのGPSと車両からの電波を用いた歩行者位置の高精度測位方式の提案と評価
山下 遼; 湯 素華; 小花 貞夫
情報処理学会論文誌, 59巻, 1号, 出版日 2018年01月, 査読付
研究論文（学術雑誌）, 日本語 - モバイル端末の消費電力削減のためのBLEを用いたWi-Fiウェイクアップ制御方式の提案と実装
田中 直也; 湯 素華; 小花 貞夫
デジタルプラクティス, 9巻, 1号, 出版日 2018年01月, 査読付
研究論文（学術雑誌）, 日本語 - VenueNet: Fine-Grained Venue Discovery by Deep Correlation Learning
Yi Yu; Suhua Tang; Kiyoharu Aizawa; Akiko Aizawa
Proceedings - 2017 IEEE International Symposium on Multimedia, ISM 2017, Institute of Electrical and Electronics Engineers Inc., 2017-巻, 掲載ページ 288-291, 出版日 2017年12月28日, 査読付, Venue photos, as a new type of multimedia contents, are exploding on the Internet because users like to take photos and share with their friends in which venue they spent time and what impressed them there. Discovering a venue by a social photo is very useful for supplementing venue retrieval and recommendation. However, little research focused on fine-grained venue discovery by leveraging multimodal venue dataset. In this paper, we present the first multimodal dataset specially built for venue discovery, which includes venue photos, descriptions, and categories. Using this dataset, we propose a novel framework for fine-grained venue discovery through correlating venue photos and descriptions, aiming to learn a VenueNet representing a knowledge base and association for venues and their properties in different modalities. In the training phase, visual and textual features of the same venues, by two sub-networks, are respectively mapped to a same semantic space, in which canonical correlation analysis (CCA) is applied to these features to train the two sub-networks. In the query phase, given a photo, its correlation with textual features in the dataset is analyzed to find the most similar venue. Experimental results verify the practicability of the Deep CCA model for fine-grained venue discovery from large-scale multimodal dataset.
研究論文（国際会議プロシーディングス）, 英語 - Compact LBP and WLBP descriptor with magnitude and direction difference for face recognition
Soo-Chang Pei; Mei-Shuo Chen; Yi Yu; SuHua Tang; ChunLin Zhong
Proc. IEEE ICIP 2017, 2017巻, 出版日 2017年09月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Context-patch based face hallucination via thresholding locality-constrained representation and reproducing learning
Junjun Jiang; Yi Yu; Suhua Tang; Jiayi Ma; Guo-Jun Qi; Akiko Aizawa
Proceedings - IEEE International Conference on Multimedia and Expo, IEEE Computer Society, 掲載ページ 469-474, 出版日 2017年08月28日, 査読付, Face hallucination, which refers to predicting a HighResolution (HR) face image from an observed Low-Resolution (LR) one, is a challenging problem. Most state-of-the-arts employ local face structure prior to estimate the optimal representations for each patch by the training patches of the same position, and achieve good reconstruction performance. However, they do not take into account the contextual information of image patch, which is very useful for the expression of human face. Different from position-patch based methods, in this paper we leverage the contextual information and develop a robust and efficient context-patch face hallucination algorithm, called Thresholding Locality-constrained Representation with Reproducing learning (TLcR-RL). In TLcR-RL, we use a thresholding strategy to enhance the stability of patch representation and the reconstruction accuracy. Additionally, we develop a reproducing learning to iteratively enhance the estimated result by adding the estimated HR face to the training set. Experiments demonstrate that the performance of our proposed framework has a substantial increase when compared to state-of-the-arts, including recently proposed deep learning based method.
研究論文（国際会議プロシーディングス）, 英語 - Context-patch based face hallucination via thresholding locality-constrained representation with reproducing learning
Junjun Jiang; Yi Yu; Suhua Tang; Yong Ma; Guo-Jun Qi; Kiyoharu Aizawa
Proc. IEEE ICME 2017, 2017巻, 掲載ページ 1-6, 出版日 2017年07月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Sink-Based Centralized Transmission Scheduling by Using Asymmetric Communication and Wake-up Radio
Masanari Iwata; Suhua Tang; Sadao Obana
2017 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE, 2017巻, 掲載ページ 1-6, 出版日 2017年, 査読付, In large-scale wireless sensor networks (WSNs) for wild environments, nodes once deployed run only on battery. Moreover, nodes close to a sink consume energy more quickly than other nodes due to packet forwarding. Mobile sink is a good solution to this issue, although it causes two new problems to nodes: (i) overhead of updating routing information and (ii) increased operating time due to aperiodic query. To solve these problems, this paper proposes an energy efficient data collection protocol for mobile sink, where sink-based centralized transmission scheduling (SC-Sched) is realized by using asymmetric communication and wake-up radio (WuR). Specifically, nodes do not update routing information. Instead, the sink determines the transmission order. In addition, each node is equipped with a WuR. At the time that a packet transmission between two nodes is scheduled, the sink transmits a wake-up message using a large transmission power, directly activating both nodes simultaneously to communicate. Extensive simulation evaluations confirm that the proposed method is more energy efficient than conventional methods, reducing energy consumption to 1/9 in a WSN with 600 nodes. This method is further enhanced to deal with frame loss caused by multipath fading, improving frame delivery rate meanwhile suppressing energy consumption and data collection time.
研究論文（国際会議プロシーディングス）, 英語 - Deep multi-label hashing for large-scale visual search based on semantic graph
Chunlin Zhong; Yi Yu; Suhua Tang; Shin’ichi Satoh; Kai Xing
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Springer Verlag, 10366巻, 掲載ページ 169-184, 出版日 2017年, 査読付, Huge volumes of images are aggregated over time because many people upload their favorite images to various social websites such as Flickr and share them with their friends. Accordingly, visual search from large scale image databases is getting more and more important. Hashing is an efficient technique to large-scale visual content search, and learning-based hashing approaches have achieved great success due to recent advancements of deep learning. However, most existing deep hashing methods focus on single label images, where hash codes cannot well preserve semantic similarity of images. In this paper, we propose a novel framework, deep multi-label hashing (DMLH) based on a semantic graph, which consists of three key components: (i) Image labels, semantically similar in terms of co-occurrence relationship, are classified in such a way that similar labels are in the same cluster. This helps to provide accurate ground truth for hash learning. (ii) A deep model is trained to simultaneously generate hash code and feature vector of images, based on which multi-label image databases are organized by hash tables. This model has excellent capability in improving retrieval speed meanwhile preserving semantic similarity among images. (iii) A combination of hash code based coarse search and feature vector based fine image ranking is used to provide an efficient and accurate retrieval. Extensive experiments over several large image datasets confirm that the proposed DMLH method outperforms state-of-the-art supervised and unsupervised image retrieval approaches, with a gain ranging from 6.25% to 38.9% in terms of mean average precision.
研究論文（国際会議プロシーディングス）, 英語 - Energy efficient downlink transmission in wireless LANs by using low-power wake-up radio
Suhua Tang; Sadao Obana
Wireless Communications and Mobile Computing, Hindawi Limited, 2017巻, 掲載ページ 1-12, 出版日 2017年, 査読付, In the downlink of a wireless LAN, power-save mode is a typical method to reduce power consumption. However, it usually causes large delay. Recently, remote wake-up control via a low-power wake-up radio (WuR) has been introduced to activate a node to instantly receive packets from an access point (AP). But link quality is not taken into account and protocol overhead of wake-up per node is relatively large. To solve these problems, in this paper, a broadcast-based wake-up control framework is proposed, and a low-power WuR is used to receive traffic indication map from an AP, monitor link quality, and perform carrier sense. Among the nodes which have packets buffered at the AP, only those whose SNR is above a threshold will be activated, contending via a proper contention window to receive packets from the AP. Optimal SNR threshold, deduced by theoretical analysis, helps to reduce transmission collisions and false wake-ups (caused by wake-up latency) and improve transmission rate. Extensive simulations confirm that the proposed method (i) effectively reduces power consumption of nodes compared with other methods, (ii) has less delay than power-save mode in times of light traffic, and (iii) achieves higher throughput than other methods in the saturation state.
研究論文（学術雑誌）, 英語 - Using psychoacoustic models for sound analysis in music
Tim Ziemer; Yi Yu; Suhua Tang
ACM International Conference Proceeding Series, Association for Computing Machinery, 08-10-巻, 掲載ページ 1-7, 出版日 2016年12月08日, 査読付, Overall sound perception of a song is an important attribute of music. Several psychoacoustic models have been studied to extract perceptual sound qualities from audio signals. By means of listening tests, we investigate whether these sound models successfully reflect (inter-)subjective perception of sound resemblance in music. Preliminary results shows that psychoacoustic descriptors are in better accordance with subjective judgments than low-level features. As the psychoacoustic descriptors model auditory perception, we can assume causal relationships and directly draw conclusions on perception from the listening test results. We observed that roughness is the most crucial sound resemblance criteria, followed by sharpness, loudness, spaciousness and tonalness. The findings indicate that these psychoacoustic models may be suitable for music data mining, music browsing, automatic playlist generation and music recommendation tasks.
研究論文（国際会議プロシーディングス）, 英語 - Concept-level multimodal ranking of Flickr photo tags via recall based weighting
Rajiv Ratn Shah; Yi Yu; Suhua Tang; Shin'Ichi Satoh; Akshay Verma; Roger Zimmermann
MMCommons 2016 - Proceedings of the 2016 ACM Workshop on the Multimedia COMMONS, co-located with ACM Multimedia 2016, Association for Computing Machinery, Inc, 掲載ページ 19-26, 出版日 2016年10月16日, 査読付, Social media platforms allow users to annotate photos with tags that significantly facilitate an effective semantics understanding, search, and retrieval of photos. However, due to the manual, ambiguous, and personalized nature of user tagging, many tags of a photo are in a random order and even irrelevant to the visual content. Aiming to automatically compute tag relevance for a given photo, we propose a tag ranking scheme based on voting from photo neighbors derived from multimodal information. Specifically, we determine photo neighbors leveraging geo, visual, and semantics concepts derived from spatial information, visual content, and textual metadata, respectively. We leverage high-level features instead traditional low-level features to compute tag relevance. Experimental results on a representative set of 203,840 photos from the YFCC100M dataset confirm that above-mentioned multimodal concepts complement each other in computing tag relevance. Moreover, we explore the fusion of multimodal information to refine tag ranking leveraging recall based weighting. Experimental results on the representative set confirm that the proposed algorithm outperforms state-of-the-arts.
研究論文（国際会議プロシーディングス）, 英語 - Improving positioning precision of pedestrians by using both GPS satellites and vehicles
Ryo Yamashita; Suhua Tang; Sadao Obana
Proc. ITS world congress 2016, 2016巻, 出版日 2016年10月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Leveraging multimodal information for event summarization and concept-level sentiment analysis
Rajiv Ratn Shah; Yi Yu; Akshay Verma; Suhua Tang; Anwar Dilawar Shaikh; Roger Zimmermann
KNOWLEDGE-BASED SYSTEMS, ELSEVIER SCIENCE BV, 108巻, C号, 掲載ページ 102-109, 出版日 2016年09月, 査読付, The rapid growth in the amount of user-generated content (UGCs) online necessitates for social media companies to automatically extract knowledge structures (concepts) from photos and videos to provide diverse multimedia-related services. However, real-world photos and videos are complex and noisy, and extracting semantics and sentics from the multimedia content alone is a very difficult task because suitable concepts may be exhibited in different representations. Hence, it is desirable to analyze UGCs from multiple modalities for a better understanding. To this end, we first present the EventBuilder system that deals with semantics understanding and automatically generates a multimedia summary for a given event in real-time by leveraging different social media such as Wikipedia and Flickr. Subsequently, we present the EventSensor system that aims to address sentics understanding and produces a multimedia summary for a given mood. It extracts concepts and mood tags from visual content and textual metadata of UGCs, and exploits them in supporting several significant multimedia-related services such as a musical multimedia summary. Moreover, EventSensor supports sentics-based event summarization by leveraging EventBuilder as its semantics engine component. Experimental results confirm that both Event Builder and EventSensor outperform their baselines and efficiently summarize knowledge structures on the YFCC100M dataset. (C) 2016 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語 - Energy and spectrum efficient wireless LAN by tightly integrating low-power wake-up radio
Suhua Tang; Chao Zhang; Hiroyuki Yomo; Sadao Obana
Proc. IEEE PIMRC’16, 掲載ページ 1942-1947, 出版日 2016年09月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Predicting user preference based on matrix factorization by exploiting music attributes
Amir Hossein Nabizadeh; Alípio Mário Jorge; Suhua Tang; Yi Yu
ACM International Conference Proceeding Series, Association for Computing Machinery, 20-22-巻, 掲載ページ 61-66, 出版日 2016年07月20日, 査読付, With the emergence of online Music Streaming Services (MSS) such as Pandora and Spotify, listening to music online became very popular. Despite the availability of these services, users face the problem of finding among millions of music tracks the ones that match their music taste. MSS platforms generate interaction data such as users' defined playlists enriched with relevant metadata. These metadata can be used to predict users' preferences and facilitate personalized music recommendation. In this work, we aim to infer music tastes of users by using personal playlist information. Characterizing users' taste is important to generate trustable recommendations when the amount of usage data is limited. Here, we propose to predict the users' preferred music feature's value (e.g. Genre as a feature has different values like P op, Rock, etc.) by modeling, not only usage information, but also music description features. Music attribute information and usage data are typically dealt with separately. Our method FPMF (Feature Prediction based on Matrix Factorization) treats music feature values as virtual users and retrieves the preferred feature values for real target users. Experimental results indicate that our proposal is able to handle the item cold start problem and can retrieve preferred music feature values with limited usage data. Furthermore, our proposal can be useful in recommendation explanation scenarios.
研究論文（国際会議プロシーディングス）, 英語 - Energy and Spectrum Efficient Wireless LAN by Tightly Integrating Low-Power Wake-up Radio
Suhua Tang; Chao Zhang; Hiroyuki Yomo; Sadao Obana
2016 IEEE 27TH ANNUAL INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE, 掲載ページ 1895-1900, 出版日 2016年, 査読付, CSMA is the de facto standard in wireless LANs (WLANs), where one transceiver is used for both the control and data planes. When many nodes contend to access a same channel, the WLAN transceiver performs carrier sense during most time, which wastes much energy. Dynamic adjustment of parameters (contention window) is suggested in previous works for improving network throughput, but this is also realized at the cost of continuously monitoring the channel with large power consumption. To solve these problems, in this paper, we suggest tightly integrating a lower power wake-up radio (WuR) with the power-hungry WLAN module. Specifically, (i) The WuR is used to monitor the channel and conduct carrier sense. It activates the WLAN module for actual transmissions when the channel gets ready. (ii) The WuR is used to measure the inter-frame space, based on which contention window is adjusted accordingly. Extensive simulation evaluations confirm that the proposed scheme (WuR-CSMA) effectively reduces the duty ratio of WLAN modules and improves system throughput, achieving both energy and spectral efficiency compared with the conventional schemes.
研究論文（国際会議プロシーディングス）, 英語 - 狭域交通情報共有のための車車間通信における車両位置情報に基づく効率的な中継転送方式の提案
吉川 潤; 湯 素華; 小花 貞夫
情報処理学会論文誌, 57巻, 1号, 掲載ページ 43-53, 出版日 2016年01月, 査読付, ITS（高度道路交通システム）では，700MHz帯車車間通信により，お互いの位置・速度情報などを頻繁に交換して衝突を防止するシステムの研究開発が行われてきているが，今後は，安全運転だけでなく，エコドライブや運転の快適性や利便性の向上を図る5.8GHz帯車車間通信の実現も強く期待される．本論文では，ドライバが道路や交通の状況に応じて走行できるように，5.8GHz帯車車間通信により渋滞や事故などの狭域な交通情報を周辺車両で効率的に共有させることを目的として，中継車両選択における従来方式の問題点であったほぼ同位置にある複数車両からの同時転送による衝突を防止するための中継転送方式を提案する．提案方式では，700MHz帯車車間通信により共有される位置情報から送信車両との距離の明確な順序付けを行い，遠い車両を待ち時間の少ないSlotに割り当てることにより，MAC（Media Access Control）層のコンテンション機構に基づいて効率的に中継車両を選択する．シミュレーション評価により提案方式が既存方式と比べて，交通情報の拡散率を33%向上させ，また遅延時間を55%低減できることを確認した．In ITS (Intelligent Transport Systems), inter-vehicle communications (IVCs) in the 700MHz band are used to frequently exchange position and speed information between vehicles to avoid collision accidents. Besides this support system for safe driving, new functions like eco-driving, and comfort and convenience of driving by leveraging the 5.8GHz band, are also strongly expected. Relay selection suggested for the latter in previous works, however, faces the packet collision problem caused by the simultaneous forward transmissions from relay vehicles with almost the same distance. To solve this problem, this paper aims at efficient, local diffusion of congestion and accident information in the 5.8GHz band so that drivers can learn road and traffic conditions in time. Specifically, via IVCs in the 700MHz band, vehicles learn the same local map of nearby vehicles. On this basis, potential relay vehicles are sorted according to their distances from the sending vehicle, and farther vehicles are assigned slots with shorter delay. By the MAC (Media Access Control) layer contention mechanism, the farthest and available vehicle is selected as the relay. Extensive simulation evaluations confirm that the proposed scheme improves the reachability by up to 33%, and decreases the latency by up to 55%, compared with state-of-the-art methods.
研究論文（学術雑誌）, 日本語 - Improving Precision of BLE-based Indoor Positioning by Using Multiple Wearable Devices
Naoki Nakajima; Suhua Tang; Tomohiko Ogishi; Sadao Obana
ADJUNCT PROCEEDINGS OF THE 13TH INTERNATIONAL CONFERENCE ON MOBILE AND UBIQUITOUS SYSTEMS: COMPUTING NETWORKING AND SERVICES (MOBIQUITOUS 2016), ASSOC COMPUTING MACHINERY, 2016巻, 掲載ページ 118-123, 出版日 2016年, 査読付, Many kinds of smart (wearable) devices like smartphones are penetrating into our life. With these devices, indoor positioning techniques have been extensively researched. However, the positioning precision, using a single Wi-Fi or BLE (Bluetooth Low Energy) device, is usually limited to several meters. To improve positioning precision, we propose an approach of fingerprinting using multiple wearable BLE devices. In the initial experiments, we noticed that body obstruction leads to different signal strengths when a person with a wearable device turns around. On this basis, we further build directional maps for fingerprinting and study the potential combination of multiple devices in positioning. The experimental results in two indoor scenarios confirm that using multiple devices and directional maps help to greatly improve positioning precision to the decimeter level (more specifically 0.07m). The impact of BLE beacon density is also investigated.
研究論文（国際会議プロシーディングス）, 英語 - Tight Integration of Wake-up Radio in Wireless LANs and the Impact of Wake-up Latency
Suhua Tang; Sadao Obana
2016 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE, 2016巻, 出版日 2016年, 査読付, In wireless LANs (WLANs), a power-hungry transceiver is used for both the control (carrier sense) and data exchanges. As a result, when many nodes contend to access a same channel, the WLAN transceiver performs carrier sense during most time, which wastes much energy. To solve this problem, we study separating the control and data operations in WLANs, by tightly integrating a lower power wake-up radio (WuR) with the WLAN module. Specifically, the WuR is used to monitor the channel and conduct carrier sense. It activates the WLAN module for actual transmissions when the channel gets ready. This is a contention-based self wake-up, which is different from previous schemes where a specific receiver is remotely activated. Due to the hardware constraint, a WLAN module is susceptible to a non-negligible wake-up latency. Our analysis shows that this wake-up latency may break the carrier sense mechanism and lead to false wake-up events. Then, we propose to recover the carrier sense mechanism by resetting the backoff counter of a falsely activated node in a way as if it is frozen in the wake-up period. Simulation evaluations confirm that the proposed scheme effectively mitigates the impact of wake-up latency by reducing the duty time of WLAN modules.
研究論文（国際会議プロシーディングス）, 英語 - PROMPT: Personalized User Tag Recommendation for Social Media Photos Leveraging Personal and Social Contexts
Rajiv Ratn Shah; Anupam Samanta; Deepak Gupta; Yi Yu; Suhua Tang; Roger Zimmermann
PROCEEDINGS OF 2016 IEEE INTERNATIONAL SYMPOSIUM ON MULTIMEDIA (ISM), IEEE, 2016巻, 掲載ページ 486-492, 出版日 2016年, 査読付, 招待, Social media platforms such as Flickr allow users to annotate photos with descriptive keywords, called, tags with the goal of making multimedia content easily understandable, searchable, and discoverable. However, manual annotation is very time-consuming and cumbersome for most users, which makes it difficult to search relevant photos. Moreover, predicted tags for a photo are not necessarily relevant to users' interests. Thus, it necessitates for an automatic tag prediction system that considers users' interests and describes objective aspects of the photo such as visual content and activities. To this end, this paper presents a tag recommendation system, called, PROMPT, that recommends personalized tags for a given photo leveraging personal and social contexts. Specifically, first, we determine a group of users who have similar tagging behavior as the user of the photo, which is very useful in recommending personalized tags. Next, we find candidate tags from visual content, textual metadata, and tags of neighboring photos, and recommends five most suitable tags. We initialize scores of the candidate tags using asymmetric tag co-occurrence probabilities and normalized scores of tags after neighbor voting, and later perform random walk to promote the tags that have many close neighbors and weaken isolated tags. Finally, we recommend top five user tags to the given photo. Experimental results on a Flickr dataset (46,700 photos in the test set and 28 million photos in the train set) with 1,540 unique user tags confirm that the proposed algorithm outperforms state-of-the-arts.
研究論文（国際会議プロシーディングス）, 英語 - Dynamic Threshold Selection for Frame Length-Based Wake-Up Control
Suhua Tang; Hiroyuki Yomo; Sadao Obana
IEEE WIRELESS COMMUNICATIONS LETTERS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 4巻, 6号, 掲載ページ 609-612, 出版日 2015年12月, 査読付, In frame-length based wake-up control, a wake-up receiver smoothens the signal envelope by low-pass-filtering (LPF) before frame length detection. However, the LPF also has a side effect of distorting the rising and falling edges of the envelope. This letter analyzes the effect of LPF on frame length detection, and suggests measuring potential frame lengths with multiple thresholds and from them selecting the correct one. The analysis shows that using thresholds with exponential intervals helps to achieve a good performance with only a small number of thresholds. The effectiveness of the proposed scheme is also confirmed by experimental results.
研究論文（学術雑誌）, 英語 - Cooperative Relative Positioning for Intelligent Transportation System
Suhua Tang; Nobuaki Kubo; Nao Kawanishi; Rei Furukawa; Akio Hasegawa; Yoshio Takeuchi
International Journal of Intelligent Transportation Systems Research, Springer New York LLC, 13巻, 3号, 掲載ページ 131-142, 出版日 2015年09月01日, 査読付, Global navigation satellite system-based positioning plays an important role in support system for safe driving, where relative positions of vehicles are used to prevent collision accidents from happening. In urban areas, however, multipath errors (MPEs) in pseudo-ranges, caused by obstruction and reflection of roadside buildings, greatly degrade the precision of relative positions. On the other hand, simply removing all reflected signals might lead to a shortage of satellites in fixing positions. This dilemma is solved in this paper by exploiting spatial correlation of MPEs. First, by analysis, ray-tracing simulation and testbed experiments, we show that MPEs in pseudo-ranges are spatially correlated in a small area. Then, we suggest a cooperative relative positioning scheme to exploit correlated signals, including reflected ones, in computing relative positions of nearby vehicles. Efficient transmission of pseudo-ranges is also discussed. The proposed scheme, which can be implemented either in a distributed way or via a cloud of intelligent transportation system, helps to improve the precision of relative positions in urban canyons.
研究論文（学術雑誌）, 英語 - Efficient geo-fencing via hybrid hashing: A combination of bucket selection and in-bucket binary search
Suhua Tang; Yi Yu; Roger Zimmermann; Sadao Obana
ACM Transactions on Spatial Algorithms and Systems, 1巻, 2号, 掲載ページ 5:1-5:22, 出版日 2015年07月, 査読付
研究論文（学術雑誌）, 英語 - Optimization of Frame Length Modulation-Based Wake-Up Control for Green WLANs
Suhua Tang; Hiroyuki Yomo; Yoshio Takeuchi
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 64巻, 2号, 掲載ページ 768-780, 出版日 2015年02月, 査読付, In this paper, green wireless local area networks (WLANs), where idle access points (APs) are put into sleep and activated upon the request of mobile nodes, are realized by exploiting WLAN signals to convey wake-up messages. Specifically, wake-up messages, sent by nodes, are modulated onto frame lengths (physical transmission time) of successive WLAN signals and detected by non-WLAN low-cost receivers equipped at APs. This method, however, is susceptible to serious 1) false negative events due to low signal quality or collisions with background WLAN frames and 2) false positive events where background WLAN frames happen to have the same frame lengths as those of wake-up messages. In the proposed scheme, WLAN frames forming a wake-up message are transmitted in a burst and interpreted as an equivalent message. On this basis, false probability is reduced from two aspects: 1) Modulation constellations of frame lengths are optimized to maximize the Hamming distance between equivalent messages, and 2) preamble frame and envelope smoothing are used to mitigate false events. In addition to theoretical analysis and simulation, a prototype test bed is built and experimented on. Extensive evaluations confirm that the proposed scheme helps to greatly improve the reliability of wake-up control compared with state-of-the-art methods.
研究論文（学術雑誌）, 英語 - Social interactions over location-aware multimedia systems
Yi Yu; Roger Zimmermann; Suhua Tang
Multimedia Data Mining and Analytics: Disruptive Innovation, Springer International Publishing, 掲載ページ 117-146, 出版日 2015年01月01日, 査読付, Advancements in positioning techniques and mobile communications have enabled location-based services with a broad range of location-aware multimedia applications. Accordingly, various social multimedia data, relevant to different aspects of users’ daily life, is aggregated over time on the Internet. Such location-aware multimedia data contains rich context of users and has two implications: individual user interest and geographic-social behaviors. Exploiting these multimedia landscapes helps mine personal preferences, geographic interests and social connections, and brings the opportunities of discovering more interesting topics. In this chapter, we first introduce some examples of location-aware multimedia data and social interaction data. Then, we report some latest methods related to context detection and location-aware multimedia applications. We further present some analysis of geo-social data. Finally, we point out the trend in the integration of social and content delivery networks. In brief, this chapter delivers a picture of emerging geographic-awaremultimedia technologies and applications, with location information as a clue.
論文集(書籍)内論文, 英語 - Support System for Improving Golf Swing by Using Wearable Sensors
Takayuki Mitsui; Suhua Tang; Sadao Obana
2015 EIGHTH INTERNATIONAL CONFERENCE ON MOBILE COMPUTING AND UBIQUITOUS NETWORKING (ICMU), SPRINGER-VERLAG BERLIN, 掲載ページ 100-101, 出版日 2015年, 査読付, This paper proposes a support system for improving golf swing by using wearable sensors, aiming at putting forward proper advice to beginners without requiring a human coach. First, the system framework is introduced. Then, sensor data obtained in the experiments is presented and analyzed. The analysis shows that there are clear differences between beginners and experienced players in their sensor data, which can be used to distinguish the levels of golf players, and help improve the performance of beginners.
研究論文（国際会議プロシーディングス）, 英語 - Exploiting frame length of 802.15.4g signals for wake-up control in sensor networks
Suhua Tang; Hiroyuki Yomo; Shinji Yamaguchi; Akio Hasegawa; Sadao Obana
2015 IEEE WIRELESS COMMUNICATIONS AND NETWORKING CONFERENCE (WCNC), IEEE, 掲載ページ 1578-1583, 出版日 2015年, 査読付, Sensor networks are playing more and more important roles, e.g., accurately monitoring the generation and consumption of electric power for the purpose of smart grid. In these applications, sensor nodes, working with battery, should be put into sleep in the idle state to prolong network lifetime and be activated on demand to ensure real-time response. State-of-the-art schemes merely exploiting duty-cycling cannot simultaneously satisfy these two requirements. In this paper, we exploit frame length of 802.15.4g signals for the wake-up control of sensor nodes. A wake-up ID is modulated onto frame lengths of consecutive signals defined by the mode switch mechanism, transmitted by a sensor node using the standard 802.15.4g protocol, and detected by a non-802.15.4g, low-power wake-up receiver. A prototype wake-up receiver is implemented by using FPGA. It consists of two-stage wake-up control in the sense that duty-cycling is also exploited in the detection of wake-up signals. The proposed scheme achieves a better trade-off between power-consumption and wake-up latency, compared with the conventional duty-cycling schemes. The experimental evaluation confirms that the wake-up control meets the sensitivity requirement of data communications.
研究論文（国際会議プロシーディングス）, 英語 - Refining Mobile Web Design for Reducing Energy Consumption of Mobile Terminals
Takuya Ihara; Suguru Doki; Tomohiko Ogishi; Suhua Tang; Sadao Obana
2015 9th International Conference on Next Generation Mobile Applications, Services and Technologies (NGMAST 2015), IEEE, 掲載ページ 13-18, 出版日 2015年, 査読付, Recent years have seen an increasing demand of web applications on mobile terminals. However, web pages, conventionally designed for PCs with stable power supply and large screen, do not lead to the same user experience when directly running on mobile terminals with limited battery and small screen. There have been some initial efforts on mobile-enabled web design, but the energy consumption of web pages on mobile terminals is seldom taken into account. In this paper, we discuss how to refine mobile web design for reducing energy consumption of web browsing on mobile terminals. First, based on experiments, we analyze energy consumption of different computing resources on each mobile terminal during web page browsing. We reveal that besides CPU, Wi-Fi and display, scrolling operations also lead to a large energy consumption, which, however, is not seriously considered in previous works. Then, based on the fact that web contents have different access popularity, we propose a content rearrangement method: listing contents in the decreasing order of their access popularity so as to reduce the average number of scrolling operations required to reach target contents. The proposed method is evaluated, by both theoretical analysis and experiments on actual web pages. E.g., in a scenario with 100 contents where the top 10 are already in order, applying the proposed method to the rest 90 less popular contents still reduces the energy consumption of web browsing by 26% according to the theoretical analysis.
研究論文（国際会議プロシーディングス）, 英語 - Transmission Control for Reliable Pedestrian-to-Vehicle Communication by Using Context of Pedestrians
Suhua Tang; Kiyoshi Saito; Sadao Obana
2015 IEEE INTERNATIONAL CONFERENCE ON VEHICULAR ELECTRONICS AND SAFETY (ICVES), IEEE, 掲載ページ 41-47, 出版日 2015年, 査読付, Pedestrian-to-vehicle communication is an effective method to reducing pedestrian accidents, but its performance is greatly degraded when many pedestrians contend to transmit frequently on the same channel. In this paper, we propose to solve this problem from three aspects, (i) defining accident models for intersections and straight roads where pedestrian accidents frequently occur, (ii) estimating the degree of risk by exploiting pedestrian context information, and (iii) differentiating pedestrian transmissions with different transmission intervals and channel access priorities so that messages from pedestrians in high risk can be quickly and reliably sent to potentially colliding vehicles. The proposed scheme is implemented via network simulator and extensively evaluated. Experimental results confirm that in dense scenarios with a large number of pedestrians, the proposed scheme can greatly improve packet delivery rate of pedestrians in high risk compared with the conventional schemes.
研究論文（国際会議プロシーディングス）, 英語 - Iterative receiver for amplify-and-forward relay networks with unknown noise correlation
Chao Zhang; Suhua Tang; Pinyi Ren
WIRELESS COMMUNICATIONS & MOBILE COMPUTING, WILEY-BLACKWELL, 14巻, 17号, 掲載ページ 1601-1612, 出版日 2014年12月, 査読付, For amplify-and-forward relay networks, we propose an iterative scheme to estimate channel and detect information symbols for the multi-antenna destination in spatially correlated noise. The equivalent channel coefficients and noise covariance are estimated by expectation-maximization algorithm. In addition, we discuss the initialization of iteration and analyze the modified Cramer-Rao bound to show the performance of the proposed iterative estimation. Moreover, on the basis of the structure of the proposed iterative estimator, a joint channel estimation and detection receiver is also provided. Finally, simulation results show that the proposed channel estimator and receiver can achieve the optimal performances in amplify-and-forward relay networks with unknown noise correlation. Copyright (c) 2012 John Wiley & Sons, Ltd.
研究論文（学術雑誌）, 英語 - ATLAS: Automatic temporal segmentation and annotation of lecture videos based on modelling transition time
Rajiv Ratn Shah; Yi Yu; Anwar Dilawar Shaikh; Suhua Tang; Roger Zimmermann
MM 2014 - Proceedings of the 2014 ACM Conference on Multimedia, Association for Computing Machinery, Inc, 1巻, 掲載ページ 209-212, 出版日 2014年11月03日, 査読付, The number of lecture videos available is increasing rapidly, though there is still insufficient accessibility and traceability of lecture video contents. Specifically, it is very desirable to enable people to navigate and access specific slides or topics within lecture videos. To this end, this paper presents the ATLAS system for the VideoLectures.NET challenge (MediaMixer, transLectures) to automatically perform the temporal segmentation and annotation of lecture videos. ATLAS has two main novelties: (i) a SVMHMM model is proposed to learn temporal transition cues and (ii) a fusion scheme is suggested to combine transition cues extracted from heterogeneous information of lecture videos. According to our initial experiments on videos provided by VideoLectures.NET, the proposed algorithm is able to segment and annotate knowledge structures based on fusing temporal transition cues and the evaluation results are very encouraging, which confirms the effectiveness of our ATLAS system.
研究論文（国際会議プロシーディングス）, 英語 - Large-scale aerial image categorization by multi-task discriminative topologies discovery
Yingjie Xia; Luming Zhang; Suhua Tang
First International Workshop on Internet-Scale Multimedia Management, 1巻, 出版日 2014年11月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Distributed Multiuser Scheduling for Improving Throughput of Wireless LAN
Suhua Tang
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 13巻, 5号, 掲載ページ 2770-2781, 出版日 2014年05月, 査読付, In wireless LANs, the performance of CSMA/CA might be degraded by several problems: (i) severe collisions in the uplink, (ii) head-of-line problem caused by fading in the downlink, and (iii) serious unfairness between uplink and downlink. In this paper, a distributed multiuser scheduling (DMUS) scheme is proposed to simultaneously address these problems. In DMUS, a node (i) computes its normalized SNR (signal to noise ratio) as the ratio of its instantaneous SNR to its average SNR, and (ii) contends via a contention window (CW) for the channel to initiate its uplink or downlink transmission when its normalized SNR is greater than a threshold. The contribution is threefold: (i) All three problems are solved in a unified framework by applying multiuser diversity in both uplink and downlink. Fresh SNR is exploited for distributed scheduling meanwhile airtime fairness is retained. (ii) SNR threshold and CW are jointly optimized to maximize throughput, taking into account time-variant link quality, collision probability and protocol overhead. (iii) Network performance is theoretically analyzed. Extensive simulations confirm that DMUS greatly improves total throughput under almost all scenarios compared with both the contention-based CSMA/CA scheme and the contention-free PCF scheme.
研究論文（学術雑誌）, 英語 - Joint Transmit Power Control and Rate Adaptation for Wireless LANs
Suhua Tang; Hiroyuki Yomo; Akio Hasegawa; Tatsuo Shibata; Masayoshi Ohashi
WIRELESS PERSONAL COMMUNICATIONS, SPRINGER, 74巻, 2号, 掲載ページ 469-486, 出版日 2014年01月, 査読付, Wireless local area networks (WLANs) are widely deployed recently. But many basic service sets (BSSs) nearby have to share a common channel due to the limitation in the spectrum resource. To get higher throughput with newly deployed access points (APs), it is necessary to improve spatial reuse of the channels by transmit power control (TPC). The achievable throughput, however, heavily depends on other factors such as rate adaptation (RA). Moreover, TPC without careful design may lead to asymmetric links and degrade fairness. In this paper, we jointly design TPC and RA to further improve total throughput of WLANs, and suggest (i) choosing power for each BSS by maximizing throughput which takes tradeoff between transmit rate and spatial reuse of channels, and, (ii) avoiding potential asymmetric links by explicit coordination among APs: each BSS uses almost the same power as its co-channel neighbors while BSSs far from each other may use different power levels as required. Extensive simulation evaluations confirm that the proposed scheme can greatly improve total throughput of dense WLANs, meanwhile fairness is retained.
研究論文（学術雑誌）, 英語 - Simulation Evaluations of Cooperative Relative Positioning around Intersections
Nao Kawanishi; Rei Furukawa; Suhua Tang; Akio Hasegawa; Ryu Miura; Yoshio Takeuchi
2013 13TH INTERNATIONAL CONFERENCE ON ITS TELECOMMUNICATIONS (ITST), IEEE, 掲載ページ 372-377, 出版日 2013年, 査読付, Position information plays an important role in support system for safe driving, where inter-vehicle distance is used to prevent collision accidents from happening. In urban areas, however, multipath propagation of GPS signals degrades the accuracy of absolute positions and the deduced relative position. On the other hand, simply removing reflected signals might lead to a shortage of satellites in fixing positions. In our previous work, we suggested cooperative relative positioning to improve the accuracy of relative positions of adjacent vehicles so as to prevent collision accidents from happening. In this paper, we focus on intersections, which are risky areas for vehicles where accidents occur with a higher probability than other areas, then investigate whether our scheme can help to improve the accuracy of relative positions at intersections. More specifically, we evaluate multipath errors due to reflection/diffraction and analyze their correlation between receivers around intersections. We find that (i) Our system helps to improve the accuracy of relative positions of vehicles running on the same road, (ii) The spatial correlation of positioning signals decreases as vehicles get nearer to intersections. As a result of the initial step to focus on intersections, only relying on our scheme is insufficient and other measures become necessary as well in order to get accurate relative positions.
研究論文（国際会議プロシーディングス）, 英語 - Edge-based locality sensitive hashing for efficient geo-fencing application
Yi Yu; Suhua Tang; Roger Zimmermann
GIS: Proceedings of the ACM International Symposium on Advances in Geographic Information Systems, 掲載ページ 566-569, 出版日 2013年, 査読付, Geo-fencing is a promising technique for emerging location-based services. Its two basic spatial predicates, INSIDE and WITHIN pairings between points and polygons, can be addressed by state-of-the-art methods such as the crossing number algorithm. In the era of big-data, however, geo-fencing has to process millions of points and hundreds of polygons or even more in real-time. In this paper, we propose an efficient algorithm to improve the scalability of geo-fencing, which consists of two main stages. At the first stage, an R-tree is used to quickly detect whether a point is inside the minimum bounding rectangle of a polygon. In the second stage, instead of an exhaustive search, we design an edge-based locality sensitive hashing scheme adapted to the crossing number algorithm. As for the case of WITHIN detection, a probing scheme is suggested to locate adjacent buckets so as to check all edges near to a target point. By further exploiting batch processing and multi-threading programming, our algorithm can achieve a fast speed while retaining 100% accuracy over all training datasets provided by the GIS Cup 2013 organizers. © 2013 Authors.
研究論文（国際会議プロシーディングス）, 英語 - Association control for wireless LANs: Pursuing throughput maximization and energy efficiency
Oyunchimeg Shagdar; Suhua Tang; Akio Hasegawa; Tatsuo Shibata; Masayoshi Ohashi; Sadao Obana
IARIA International Journal on Advances in Networks and Services, 5巻, 3&4号, 出版日 2012年12月, 査読付
研究論文（学術雑誌）, 英語 - Energy-efficient WLAN with on-demand AP wake-up using IEEE 802.11 frame length modulation
Yoshihisa Kondo; Hiroyuki Yomo; Suhua Tang; Masahito Iwai; Toshiyasu Tanaka; Hideo Tsutsui; Sadao Obana
COMPUTER COMMUNICATIONS, ELSEVIER SCIENCE BV, 35巻, 14号, 掲載ページ 1725-1735, 出版日 2012年08月, 査読付, This paper considers a radio-on-demand (ROD) wireless LAN (WLAN) in which access points (APs) are put into a sleep mode during idle periods and woken up by stations (STAs) upon communications demands. The on-demand wake-up is realized by a wake-up receiver which is equipped with each AP and is used to detect a wake-up signal transmitted by STA. In order to reduce the hardware installation cost at STA, we advocate to utilizing wireless LAN frames transmitted by each STA as a wake-up signal. We generate a wake-up signal based on frame length modulation (FLM) where each STA creates a series of WLAN frames with different length to which the information on wake-up ID is embedded. The simple and low-power wake-up receiver extracts the wake-up ID from the received frames. In this paper, we design and develop a prototype of the wake-up receiver and propose a wake-up protocol which defines a procedure to realize the on-demand AP wake-up in ROD WLAN. We evaluate system-level performance of ROD WLAN based on our prototype and our proposed wake-up protocol, and investigate appropriate settings of parameters for our proposed FLM to achieve the required system-level performance. Our numerical results confirm that the proposed wake-up protocol with FLM achieves smaller delay than a conventional AP employing passive scanning while maintaining small probability to be falsely woken up by continuous interference. (C) 2012 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語 - Wake-up receiver for radio-on-demand wireless LANs
Suhua Tang; Hiroyuki Yomo; Yoshihisa Kondo; Sadao Obana
EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING, SPRINGER INTERNATIONAL PUBLISHING AG, 2012:42巻, doi:10.1186/1687-1499-2012-42号, 掲載ページ 1-13, 出版日 2012年, 査読付, Recent investigations show that access points (APs) of wireless local area networks (WLANs) are idle during much of the time and that an AP in its idle state still consumes a large percentage of power. Wake-up receivers can be used to realize radio-on-demand WLANs, activating APs from the sleep mode only in times of active data communications. A wake-up receiver, sharing the antenna (and the same ISM band) with its co-located WLAN module and exploiting RF energy detection, can be implemented at low cost and run with low power consumption. In this article, we evaluate the effect of an imperfect RF band pass filter (BPF), and suggest a new soft decision method to (i) resist adjacent channel interference leaked by BPF, and, (ii) distinguish wake-up signals from WLAN signals. Extensive simulation and testbed experimental results confirm that the proposed scheme, at a moderate cost, has good performance in delivering wake-up signals and controlling false wake-up events caused by WLAN signals.
研究論文（学術雑誌）, 英語 - Exploiting Burst Transmission and Partial Correlation for Reliable Wake-up Signaling in Radio-On-Demand WLANs
Suhua Tang; Hiroyuki Yomo; Yoshihisa Kondo; Sadao Obana
2012 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE, 掲載ページ 6476-6481, 出版日 2012年, 査読付, Recent investigations show that (i) access points (APs) of wireless local area networks (WLANs) are idle during much of the time, and, (ii) an AP in its idle state without forwarding any packets still consumes a large percentage of power. Therefore, it is necessary to put idle APs into sleep so as to realize green WLANs. The problem, however, is how to quickly and reliably activate APs from sleep when nodes initiate new data flows. Aiming at realizing Radio-On-Demand WLANs, in this paper, we suggest exploiting burst transmission of WLAN frames to convey wake-up IDs from nodes to APs. Our contribution is two-fold: (i) The burst transmission prevents interfering WLAN signals from breaking in, and, (ii) We re-interpret the sequence of WLAN frames for wake-up signaling as an equivalent ID. Based on the analysis of hamming distance among equivalent IDs, we further suggest using partial correlation to reduce the error rate of wake-up signals. The effectiveness of the proposed scheme is confirmed by both theoretical analysis and simulation evaluations.
研究論文（国際会議プロシーディングス）, 英語 - EM Algorithm based Channel Estimation for Amplify-and-Forward Relay Networks with Unknown Noise Correlation
Chao Zhang; Suhua Tang; Pinyi Ren
2012 IEEE VEHICULAR TECHNOLOGY CONFERENCE (VTC FALL), IEEE, 掲載ページ 1-5, 出版日 2012年, 査読付, Due to common interference or noise propagation, noise correlation between relays could occur in Amplify-and-Forward relay networks. To estimate channel coefficient, the noise covariance is required in traditional channel estimations. On the other hand, we also need channel coefficient to estimate the noise covariance. Therefore, traditional channel estimators can not be utilized when noise correlation is unknown. In this paper, we propose an Expectation-Maximization algorithm based iterative channel estimator to solve this problem. Moreover, we analyze the modified Cramer-Rao bound to show the performance of the proposed channel estimation. Finally, simulation results show that the proposed channel estimator can work well in Amplify-and-Forward relay networks with unknown noise correlation.
研究論文（国際会議プロシーディングス）, 英語 - Wake-up ID and Protocol Design for Radio-On-Demand Wireless LAN
Hiroyuki Yomo; Yoshihisa Kondo; Kosuke Namba; Suhua Tang; Takatoshi Kimura; Tetsuya Ito
2012 IEEE 23RD INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE, 掲載ページ 419-424, 出版日 2012年, 査読付, This paper investigates wake-up ID and protocol design for radio-on-demand (ROD) wireless LAN (WLAN) where wake-up radio is applied to access point (AP) in order to save energy consumed by WLAN. Each AP in ROD WLAN is transited to a sleep state when there is no associated user. A wake-up receiver installed into each AP is used to detect a wake-up signal transmitted by a station (STA) upon communications demands. Each STA specifies an AP to wake up by embedding ID of the target AP into the wake-up signal. In this paper, we propose a wake-up ID assignment and ID matching which can reduce the probability of false wake-up caused by bit errors over wireless channels. The proposed scheme generates wake-up ID of each AP based on ESSID in such a way that certain number of hamming distances is maintained among different wake-up IDs. The AP wakes up when the hamming distance between the received ID, possibly containing bit errors, and its assigned ID is less than a predetermined value. The numerical results obtained by theoretical analysis and computer simulation show that the proposed scheme can effectively reduce the false wake-up probabilities with short ID length and very simple operations at wake-up receivers. We also propose a wake-up protocol for ROD WLAN to reduce energy wastefully consumed by APs which are redundantly woken up with the proposed ID assignment/matching. Our simulation results show that ROD WLAN with the proposed protocol achieves much better energy-efficiency than ROD WLAN without the proposed protocol and WLAN without applying ROD technologies.
研究論文（国際会議プロシーディングス）, 英語 - Cooperative Relative Positioning for Intelligent Transportation System
Suhua Tang; Nobuaki Kubo; Masayoshi Ohashi
2012 12TH INTERNATIONAL CONFERENCE ON ITS TELECOMMUNICATIONS (ITST-2012), IEEE, 掲載ページ 500-505, 出版日 2012年, 査読付, In an intelligent transportation system, preventing collision accidents from happening requires to maintain a safe distance between vehicles, which is usually computed from position information. In urban areas, however, non-correlated errors due to multipath propagation in absolute positions degrade the accuracy of relative position. On the other hand, simply removing reflected signals might lead to a shortage of satellites in fixing positions. In this paper, we suggest a cooperative relative positioning (CoRelPos) scheme. Vehicles learn measured information of nearby vehicles by inter-vehicle communications. Correlated information, including that of reflected signals, is used to compute relative position. Statistical analysis of experimental logs verifies that information measured by nearby vehicles is highly correlated under most cases. But exceptions do exist, which require correlation detection. Simulation evaluation and initial experimental results confirm that the proposed scheme can effectively improve the accuracy of relative position compared with the state-of-the-art schemes.
研究論文（国際会議プロシーディングス）, 英語 - Receiver Design for Realizing On-Demand WiFi Wake-up using WLAN Signals
Hiroyuki Yomo; Yoshihisa Kondo; Noboru Miyamoto; Suhua Tang; Masahito Iwai; Tetsuya Ito
2012 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE, 掲載ページ 5206-5211, 出版日 2012年, 査読付, In this paper, we design a simple, low-cost, and low-power wake-up receiver which can be used for an IEEE 802.11-compliant device to remotely wake up the other devices by utilizing its own wireless LAN (WLAN) signals. A typical usage scenario of such a wake-up receiver is energy management of WiFi device: a device equipped with the wake-up receiver turns WiFi interface off when there is no communication demand, which is powered-on only when the wake-up receiver detects a wake-up signal transmitted by the other WiFi device. The employed wake-up mechanism utilizes the length of 802.11 data frame generated by a WiFi transmitter to differentiate the information conveyed to the wake-up receiver. The wake-up receiver is designed to reliably detect the length of transmitted data frame only with simple envelope detection and limited signal processing. We develop a prototype of the wake-up receiver and investigate the detection performance of the envelope of 802.11 signals. Based on the obtained experimental results, we select appropriate parameters employed by the wake-up receiver to improve the detection performance. Our numerical results show that the proposed wake-up receiver achieves much larger detection range than the off-the-shelf, commercial receiver having the similar functionality.
研究論文（国際会議プロシーディングス）, 英語 - Cooperative Relative Positioning for Intelligent Transportation System
Suhua Tang; Nobuaki Kubo; Masayoshi Ohashi
2012 12TH INTERNATIONAL CONFERENCE ON ITS TELECOMMUNICATIONS (ITST-2012), IEEE, 2014巻, 掲載ページ 500-505, 出版日 2012年, 査読付, In an intelligent transportation system, preventing collision accidents from happening requires to maintain a safe distance between vehicles, which is usually computed from position information. In urban areas, however, non-correlated errors due to multipath propagation in absolute positions degrade the accuracy of relative position. On the other hand, simply removing reflected signals might lead to a shortage of satellites in fixing positions. In this paper, we suggest a cooperative relative positioning (CoRelPos) scheme. Vehicles learn measured information of nearby vehicles by inter-vehicle communications. Correlated information, including that of reflected signals, is used to compute relative position. Statistical analysis of experimental logs verifies that information measured by nearby vehicles is highly correlated under most cases. But exceptions do exist, which require correlation detection. Simulation evaluation and initial experimental results confirm that the proposed scheme can effectively improve the accuracy of relative position compared with the state-of-the-art schemes.
研究論文（国際会議プロシーディングス）, 英語 - Association control for throughput maximization and energy efficiency for wireless LANs
Oyunchimeg Shagdar; Suhua Tang; Akio Hasegawa; Tatsuo Shibata; Sadao Obana
2011 The Third International Conference on Emerging Network Intelligence, 掲載ページ 112-117, 出版日 2011年11月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Full Rate Network Coding via Nesting Modulation Constellations
Suhua Tang; Hiroyuki Yomo; Tetsuro Ueda; Ryu Miura; Sadao Obana
EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING, SPRINGER, doi:10.1155/2011/780632号, 出版日 2011年, 査読付, Network coding is an effective method to improving relay efficiency, by reducing the number of transmissions required to deliver data from source(s) to destination(s). However, its performance may be greatly degraded by rate mismatch, which is seldom touched in previous works and remains a challenge. In this paper, we reinterpret network coding as a mapping of modulation constellation. On this basis, we extend the mapping to support full rate network coding (FRNC), enabling simultaneous use of different modulations by nesting the low level constellation as a subset of the high level constellation. When relay links have different qualities, the messages of different flows are combined via network coding in such a way that for each relay link, its desired message is transmitted at its own highest rate. The limit in constellation size is also addressed. Compared with the state-of-the-art solutions to rate mismatch, the proposed scheme achieves the full rate of all relay links on the broadcast channel.
研究論文（学術雑誌）, 英語 - Improving Throughput of Wireless LANs with Transmit Power Control and Slotted Channel Access
Suhua Tang; Akio Hasegawa; Riichiro Nagareda; Akito Kitaura; Tatsuo Shibata; Sadao Obana
2011 IEEE 22ND INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE, 掲載ページ 834-838, 出版日 2011年, 査読付, Throughput of wireless LANs is interference-limited. Newly deployed access points (APs) can hardly bring throughput gain without careful design. Although transmit power control (TPC) can improve spatial reuse of the channels, the achievable throughput also heavily depends on other factors, such as rate adaptation, which are seldom touched in previous works. In addition, TPC protocols, designed with the assumption that all nodes have the same capability, do not work well when legacy nodes not supporting TPC coexist. In this paper, (i) we exploit joint rate adaptation and TPC to improve system performance and suggest choosing power to maximize throughput after taking tradeoff between transmit rate and spatial reuse of channels, and, (ii) we suggest using the NAV (network allocation vector) mechanism to create virtual slots in the scenario where legacy nodes coexist with new nodes running TPC. Simulation results show that (i) the proposed TPC scheme can effectively improve both total throughput and fairness, and, (ii) the slotted channel access scheme ensures that throughput gain can be achieved by nodes running TPC while the performance of legacy nodes not supporting TPC is not degraded.
研究論文（国際会議プロシーディングス）, 英語 - Wake-up Radio using IEEE 802.11 Frame Length Modulation for Radio-On-Demand Wireless LAN
Yoshihisa Kondo; Hiroyuki Yomo; Suhua Tang; Masahito Iwai; Toshiyasu Tanaka; Hideo Tsutsui; Sadao Obana
2011 IEEE 22ND INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE, 掲載ページ 869-873, 出版日 2011年, 査読付, In this paper, we introduce Radio-On-Demand (ROD) wireless LAN (WLAN) in which access points (APs) are put into a sleep mode during idle periods and woken up by stations (STAs) upon communications demands. The on-demand wake-up is realized by a wake-up receiver which is equipped with each AP and is used to detect a wake-up signal transmitted by STA. In this paper, in order to reduce the hardware installation cost at STA, we advocate to utilize wireless LAN frames transmitted by each STA as a wake-up signal to awake the target AP. The STA generates a wake-up signal by devising WLAN signal: each STA creates a series of WLAN frames with different length to which the information on wake-up ID is embedded. The wake-up receiver extracts the wake-up ID from the received frames with a simple detector which ensures its low-power operation. We evaluate false negative (STA fails to wake up the target AP) and false positive (AP falsely wakes up without an intended wake-up signal) probabilities of our proposed on-demand wake-up scheme with computer simulations. The numerical results show that the proposed scheme achieves the false negative probability of about 10(-2) when the detection error ratio of '1' is less than 10(-3). We also show that the false positive probability can be largely reduced by employing long WLAN frames to generate each wake-up signal. These results confirm that the proposed wake-up scheme is a promising approach to reducing wasteful energy consumed by idle APs in WLAN.
研究論文（国際会議プロシーディングス）, 英語 - Wakeup Receiver for Radio-On-Demand Wireless LANs
Suhua Tang; Hiroyuki Yomo; Yoshihisa Kondo; Sadao Obana
2011 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE (GLOBECOM 2011), IEEE, 掲載ページ 1-6, 出版日 2011年, 査読付, Access points (APs) of wireless LANs (WLANs), always powered on and ready to serve mobile nodes, consume a large amount of power in total, but are idle during much of the time. Previous protocol-based sleep-wakeup scheduling schemes partially solve this problem, but the large wakeup delay remains a problem. Aiming at realizing Radio-On-Demand WLANs, in this paper, we suggest using an additional wakeup transceiver to convey wakeup signals from nodes to APs. APs in the sleep mode are activated by nodes when new data flows are initiated, where the wakeup delay is very low. The proposed wakeup transceiver works on the 2.4GHz ISM band and shares antenna with a co-located WLAN module to reduce hardware cost. The wakeup receiver is designed to be simple but very reliable, and consume a very low power. The contribution of this paper is two-fold: (i) Wakeup signals are designed to co-exist with WLAN signals by exploiting the carrier sense mechanism of WLAN devices, and, (ii), explicit signal recognition is used to achieve an extremely low false wakeup probability in an environment where the number of WLAN signals is overwhelming. Testbed experiments confirm that the proposed scheme, besides its simplicity, has good performance in both frame error rate and false wakeup probability.
研究論文（国際会議プロシーディングス）, 英語 - Potential Throughput Based Access Point Selection
Suhua Tang; Noriyuki Taniguchi; Oyunchimeg Shagdar; Morihiko Tamai; Hiroyuki Yomo; Akio Hasegawa; Tetsuro Ueda; Ryu Miura; Sadao Obana
2010 16TH ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS (APCC 2010), IEEE, 掲載ページ 470-475, 出版日 2010年, 査読付, Mobile nodes in wireless LANs connect themselves to the Internet via their associated access points (AP). Although more and more APs are being deployed, nodes tend to gather around some common hotspots, contending for few APs and leaving other APs idle. The traffic unbalance affects both per-node throughput and network throughput. In this paper, we aim to solve this problem by AP selection. We jointly consider the two key factors--channel availability and link quality--that determine the achievable throughput of a node, and suggest the potential throughput (PT) metric for AP selection. The PT metric is defined as the maximal throughput that can be achieved by a node if it exclusively occupies the remaining idle channel. In this way, a node can achieve higher throughput by associating with a farther but less used AP and the congestion of the network can be alleviated. The simulation results show that the PT metric can greatly improve the total throughput when nodes are unevenly distributed around APs. The testbed experiments with the offthe- shelf WLAN cards also confirm that the per-node throughput can be effectively improved with the proposed method.
研究論文（国際会議プロシーディングス）, 英語 - Achieving Full Rate Network Coding with Constellation Compatible Modulation and Coding
Suhua Tang; Hiroyuki Yomo; Tetsuro Ueda; Ryu Miura; Sadao Obana
2010 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE GLOBECOM 2010, IEEE, 掲載ページ 1-6, 出版日 2010年, 査読付, Network coding is an effective method to improving relay efficiency by reducing the number of transmissions. However, its performance is limited by several factors such as packet length mismatch and rate mismatch. Although the former may be solved by re-framing, the latter remains a challenge and is likely to greatly degrade the efficiency of network coding. In this paper, we re-interpret network coding as a mapping of modulation constellation. On this basis, we extend such mapping to enable simultaneous use of different modulations by nesting the low-level constellation as a subset of the high level constellation. When relay links have different qualities, the messages of different flows are combined together in such a way that for each relay link its desired message is transmitted at its own highest rate. Compared with previous solutions to rate mismatch, the proposed scheme achieves the full rate of all relay links on the broadcast channel.
研究論文（国際会議プロシーディングス）, 英語 - Joint Channel and Network Decoding for XOR-Based Relay in Multi-Access Channel
Suhua Tang; Jun Cheng; Chen Sun; Ryu Miura; Sadao Obana
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E92B巻, 11号, 掲載ページ 3470-3477, 出版日 2009年11月, 査読付, In this paper network coding based relay for multi-access channel is studied. In the system, two nodes send messages to a common access point (AP). A relay assists the two nodes by forwarding a network coded version of the messages. The AP performs joint channel and network decoding to recover the two original messages from three received signals. Two schemes, soft network coding (SoftNC) and turbo network coding (TurboNC), both focusing on bitwise exclusive or (XOR) based network coding, are proposed to salvage messages from erroneous signals. SoftNC is simple and backward compatible with existing protocol stack of wireless networks, and reduces packet errors by maximal ratio combining (MRC). TurboNC improves channel efficiency by letting the relay node transmit only parity check bits of the interleaved XORed message, where reliability is retained by iterative decoding. Simulation results show that compared with the network-layer path diversity scheme [8], both SoftNC and TurboNC greatly improve the reliability, and TurboNC also achieves a much higher throughput. The proposed schemes are suitable for improving the performance of wireless local area networks (WLAN).
研究論文（学術雑誌）, 英語 - 無線マルチホップネットワークにおける分散型クロスレイヤ負荷制御
シャグダル・オユーンチメグ; マハダッド・ヌリシラジ; 湯 素華; 鈴木 龍太郎; 小花 貞夫
情報処理学会論文誌, 情報処理学会, 50巻, 2号, 掲載ページ 814-828, 出版日 2009年02月, 査読付
研究論文（学術雑誌）, 日本語 - Distributed multi-user scheduling for improving throughput of wireless LAN
Suhua Tang; Ryu Miura; Sadao Obana
IEEE International Conference on Communications, 出版日 2009年, 査読付, Carrier Sense Multi-Access (CSMA) is a typical method to share the common channel in a Wireless LAN (WLAN). It works fairly well in times of light traffic. However as the number of nodes in a WLAN increases quickly, severe collision greatly degrades network performance. In this paper we propose a Distributed Multi-User Scheduling (DMUS) scheme to solve this problem, taking time-variant link quality and rate adaptation into account. Instead of all nodes, only nodes with high instantaneous link quality are allowed to contend for the channel. By setting a suitable SNR threshold, at any instance only a small percentage of nodes join the contention. As a result, collision is mitigated, fairness is retained by independent fading, and the total throughput is increased since transmissions are finished at higher rates. Simulation results show when there are 40 nodes in a WLAN, the DMUS scheme improves total throughput by up to 49.6% compared with the Contention-Free scheme, and by up to 194.6% compared with the CSMA/CA scheme. ©2009 IEEE.
研究論文（国際会議プロシーディングス）, 英語 - Message Dissemination in Inter-Vehicle CDMA Networks for Safety Driving Support
O. Shagdar; T. Ohyama; M. N. Shirazi; S. Tang; R. Suzuki; R. Miura; S. Obana
2009 IEEE VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-5, IEEE, 掲載ページ 2104-2108, 出版日 2009年, 査読付, Although the near-far effect has been considered to be the major issue preventing CDMA from being used in ad-hoc networks, in this paper, we show that the near-far effect is not a severe issue in inter-vehicle networks for safety driving support, where packet transmissions are performed in the broadcast manner. Indeed, the near-far effect provides extremely reliable transmissions between near nodes, regardless of node density, which can not be achieved by CSMA/CA. However, CDMA can not be directly applied in realistic traffic accident scenarios, where highly reliable transmissions are required between far nodes as well. This paper proposes to apply packet forwarding and transmission scheduling methods that try to expand the area, where reliable transmissions are achievable. Simulation results show that the proposed scheme achieves approximately 100% of delivery ratio and 4 milliseconds of delay in a realistic traffic accident scenario, where CSMA/CA achieves approximately 60% of delivery ratio and 80 milliseconds of delay.
研究論文（国際会議プロシーディングス）, 英語 - Distributed Multi-User Scheduling for Improving Throughput of Wireless LAN
Suhua Tang; Ryu Miura; Sadao Obana
2009 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-8, IEEE, 掲載ページ 5257-5262, 出版日 2009年, 査読付, Carrier Sense Multi-Access (CSMA) is a typical method to share the common channel in a Wireless LAN (WLAN). It works fairly well in times of light traffic. However as the number of nodes in a WLAN increases quickly, severe collision greatly degrades network performance. In this paper we propose a Distributed Multi-User Scheduling (DMUS) scheme to solve this problem, taking time-variant link quality and rate adaptation into account. Instead of all nodes, only nodes with high instantaneous link quality are allowed to contend for the channel. By setting a suitable SNR threshold, at any instance only a small percentage of nodes join the contention. As a result, collision is mitigated, fairness is retained by independent fading, and the total throughput is increased since transmissions are finished at higher rates. Simulation results show when there are 40 nodes in a WLAN, the DMUS scheme improves total throughput by up to 49.6% compared with the Contention-Free scheme, and by up to 194.6% compared with the CSMA/CA scheme.
研究論文（国際会議プロシーディングス）, 英語 - Exploiting Network Coding for Pseudo Bidirectional Relay in Wireless LAN
Suhua Tang; Hiroyuki Yomo; Mehdad N. Shirazi; Tetsuro Ueda; Ryu Miura; Sadao Obana
2009 IEEE 20TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, IEEE, 掲載ページ 706-711, 出版日 2009年, 査読付, Network coding is an effective method to improve forwarding efficiency in multi-hop wireless networks. Previous network coding schemes proposed for unicast transmissions focus on scheduling where paths are already established, and assume a fixed rate for all links, neglecting link rate heterogeneity. In this paper we study a network coding based pseudo bidirectional relay scheme for wireless LAN, taking link quality into account. We first show when network coding based relay improves channel efficiency and how to select such a relay in a distributed way. Then we enhance network coding based transmissions from three aspects: (i) Coordinated rate adaptation is adopted to reduce the probability with which a priori packet is missing in times of network decoding. (ii) The retransmission scheduling completely solves the lack-of-a-priori problem. (iii) Piggybacking receiving status in ACK/NAK further enables opportunistic reception and avoids unnecessary transmissions. Simulation results confirm that compared with direct transmissions, the proposed relay scheme can reduce per-packet transmission time by up to 39% in Rayleigh fading environment.
研究論文（国際会議プロシーディングス）, 英語 - An Opportunistic Forwarding Scheme Exploiting both Long Progress and Adaptive Rate in Wireless Networks
Suhua Tang; Mehdad N. Shirazi; Oyunchimeg Shagdar; Ryutaro Suzuki; Sadao Obana
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E91B巻, 10号, 掲載ページ 3241-3250, 出版日 2008年10月, 査読付, In Mobile Ad hoc Networks (MANET) geographic routing is characterized by local forwarding decision. Links with a long progress are preferred under the greedy forwarding rule. However in a real system long links tend to have a high packet loss rate due to multipath fading. A sub-optimal solution may separately exploit path diversity or rate adaptation. In this paper we study channel efficiency of multi-hop forwarding and try to jointly optimize rate adaptation and forwarder selection in geographic routing by the tradeoff between progress and instantaneous rate. we define a new metric - Bit Transfer Speed (BTS) - as the ratio of the progress made towards the destination to the equivalent time taken to transfer a payload bit. This metric takes overhead, rate and progress into account. Then we propose a packet forwarding scheme that Opportunistically exploits both Ion, Progress and Adaptive Rate (OPAR.) by a cross-layer design of routing and MAC. In OPAR each node selects for a packet the forwarder with the highest BTS. The forwarder changes as local topology (progress), packet size (overhead ratio) or channel state (data rate) varies. Simulation results show that compared with the normalized advance (NADV) [7] scheme and contention-based forwarding (CBF) [17] scheme, OPAR has lower packet loss and can effectively reduce channel occupation time by over 30% in the scenario with moderate mobility speeds.
研究論文（学術雑誌）, 英語 - Reliable cut-through forwarding for inter-vehicle networks
Oyunchimeg Shagdar; Mehdad. N. Shirazi; Suhua Tang; Ryutaro Suzuki; Sadao Obana
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E91B巻, 9号, 掲載ページ 2864-2872, 出版日 2008年09月, 査読付, In inter-vehicle networks, it is required that collision warning messages be distributed over multiple hops with significantly short delay. Cut-through packet forwarding is known to be an effective method to reduce forwarding latency. However. it suffers from the reliability issue. which is especially severe in highly mobile scenario, due to multi-path fading. This paper tries to establish a reliable cut-through forwarding scheme by applying diversity combining, method to Collision warning messages. By exploiting the nature of the multi-hop forwarding of a broadcast packet in CDMA wireless networks, the diversity combinig scheme does not incur any additional communication overhead or delay. The simulation results show that diversity combining schemes, especially Maximal Ratio Combining (MRC), can effectively, reduce BER by orders of magnitude.
研究論文（学術雑誌）, 英語 - Mobility Prediction Progressive Routing (MP2R), a cross-layer design for inter-vehicle communication
Suhua Tang; Naoto Kadowaki; Sadao Obana
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E91B巻, 1号, 掲載ページ 221-231, 出版日 2008年01月, 査読付, In this paper we analyze the characteristics of vehicle mobility and propose a novel Mobility Prediction Progressive Routing (MP2R) protocol for Inter-Vehicle Communication (IVC) that is based on cross-layer design. MP2R utilizes the additional gain provided by the directional antennas to improve link quality and connectivity; interference is reduced by the directional transmission. Each node learns its own position and speed and that of other nodes, and per-forms position prediction. (i) With the predicted progress and link quality, the forwarding decision of a packet is locally made, just before the packet is actually transmitted. In addition the load at the forwarder is considered in order to avoid congestion. (ii) The predicted geographic direction is used to control the beam of the directional antenna. The proposed MP2R protocol is especially suitable for forwarding burst traffic in highly mobile environments. Simulation results show that MP2R effectively reduces Packet Error Ratio (PER) compared with both topology-based routing (AODV [1], FSR [2]) and normal progressive routing (NADV [18]) in the IVC scenarios.
研究論文（学術雑誌）, 英語 - Reliable cut-through forwarding in CDMA inter-vehicle networks
Oyunchimeg Shagdar; Suhua Tang; Mehdad N. Shirazi; Ryutaro Suzuki; Sadao Obana
Proceedings of the 2nd International Conference on Ubiquitous Information Management and Communication, ICUIMC-2008, 掲載ページ 491-495, 出版日 2008年, 査読付, In inter-vehicle networks, it is required that collision warning messages be forwarded over multiple hops with significantly short delay. Cut-through packet forwarding is known to effectively reduce forwarding latency. However, it suffers from reliability issue, which can be severe in wireless networks, due to fading, users' mobility, and so on. This paper tries to establish a reliable cut-through forwarding method by applying diversity combining scheme for collision warning messages. By exploiting the nature of the multi-hop forwarding of a broadcast packet in an CDMA network, the diversity combining scheme does not incur any additional communication overhead or delay. The simulation results show that proposed scheme can reduce BER of the conventional scheme by at least 2 orders of magnitude. © 2008 ACM.
研究論文（国際会議プロシーディングス）, 英語 - Opportunistic Cooperation and Selective Forwarding, a Virtual MIMO Scheme for Wireless Networks
Suhua Tang; Oyunchimeg Shagdar; Mehdad N. Shirazi; Ryutaro Suzuki; Sadao Obana
2008 IEEE 19TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS, IEEE, 掲載ページ 881-886, 出版日 2008年, 査読付, Multipath fading greatly degrades system performance of wireless networks. Conventionally diversity is introduced to mitigate fading. In this paper we study space diversity in multi-hop wireless networks under power constraints. Point-to-point links are extended to group-to-group virtual MIMO links. Then we propose a cross-layer design of MAC and routing that exploits Opportunistic Cooperation and Selective Forwarding (OCSF). Packets are forwarded around the pre-calculated anchor route and the proposed OCSF scheme enables local post selection of both transmitter and forwarder according to channel state information. Simulation results confirm that OCSF outperforms existing schemes that utilize distributed space-time coding or selection diversity.
研究論文（国際会議プロシーディングス）, 英語 - Layer-2 Retransmission and Combining for Network Coding-Based Forwarding in Wireless Networks
Suhua Tang; Oyunchimeg Shagdar; Hiroyuki Yomo; Mehdad N. Shirazi; Ryutaro Suzuki; Sadao Obana
2008 11TH IEEE SINGAPORE INTERNATIONAL CONFERENCE ON COMMUNICATION SYSTEMS (ICCS), VOLS 1-3, IEEE, 掲載ページ 1597-1602, 出版日 2008年, 査読付, Network coding is an effective method to improve channel efficiency by reducing the number of transmissions. However, most existing network coding schemes are based on network layer broadcast. As a result packets become vulnerable to channel errors due to lack of retransmissions. In this paper we present a cross-layer signal processing technique and show that network coded signal mixed from different flows can be separated in the physical layer by exploiting a priori knowledge. Then we propose the soft network coding framework for multi-hop forwarding. This framework enables layer-2 retransmission and further reduces packet errors by combining retransmitted copies. It supports both conventional unicast and the proposed network coding based bi-cast. Simulation results show that compared with plain Decode-and-Forward (DF), the proposed scheme can reduce air-time by about 30% for Poisson arrival traffic while retaining almost the same packet error rate as DF with frame combining.
研究論文（国際会議プロシーディングス）, 英語 - Turbo Network Coding for Efficient and Reliable Relay
Suhua Tang; Jun Cheng; Chen Sun; Ryutaro Suzuki; Sadao Obana
2008 11TH IEEE SINGAPORE INTERNATIONAL CONFERENCE ON COMMUNICATION SYSTEMS (ICCS), VOLS 1-3, IEEE, 掲載ページ 1603-1608, 出版日 2008年, 査読付, A turbo network coding based relay model and its decoding method are proposed for the quasi-static fading multi-access up-link channel. In the model a relay assists two mobile nodes simultaneously by forwarding a network coded version of the two interleaved messages. Access Point (AP) performs joint channel and network decoding with signals received from two mobile nodes and the relay. Compared with existing schemes, the proposed turbo network coding scheme has two main contributions: (I) Only parity check bits of two messages are forwarded by relay and they are further XORed together to improve relay efficiency. (ii) The iterative decoding is used in joint network and channel decoding to salvage packets from erroneous signals in the absence of a priori knowledge. Simulation results indicate that the proposed scheme provides up to 1.8dB gain to the existing scheme in the case of mutual cooperation among mobile nodes.
研究論文（国際会議プロシーディングス）, 英語 - Delay-based priority control over multi-hop wireless mesh networks
Bing Zhang; Oyunchimeg Shagdar; Suhua Tang; Youiti Kado; Masanori Nozaki; Mehdad N. Shirazi
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90B巻, 11号, 掲載ページ 3124-3132, 出版日 2007年11月, 査読付, Wireless mesh networks are attracting more and more attention as a promising technology for the next generation access infrastructure. QoS support is a unavoidable task given the rising popularity of multimedia applications, and also a challenging task for multi-hop wireless mesh networks. Among the numerous QoS factors, end-to-end delay is one of the most critical and important issues, especially for the real time applications. Over multi-hop wireless mesh networks, end-to-end delay of a flow is highly dependant on the number of hops as well as congestion condition of the hop nodes that the flow traverses through. In this paper, we propose QoS priority control schemes based on the end-to-end QoS delay metrics in order to increase traffic accommodation, i.e., the numbers of real-time flows which satisfy the requirements of end-to-end delay and packet delivery ratio over multi-hop wireless mesh networks. The first scheme enables source and forwarding nodes to perform priority control based on the number of hops of routes. The second scheme enables nodes to perform priority control based on the congestion condition of the hop nodes, where the flow traverses through. The effectiveness of the proposed schemes is investigated with NS-2 network simulator for voice and video traffics over multi-hop wireless mesh networks. Simulation results show that the scheme greatly improves the traffic accommodation for voice and video applications in multi-hop wireless mesh networks.
研究論文（学術雑誌）, 英語 - A reservation-based enhancement of IEEE 802.11 DCF protocol
Mehdad N. Shirazi; Oyunchimeg Shagdar; Suhua Tang; Masanori Nozaki; Youiti Kado; Bing Zhang
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90B巻, 3号, 掲載ページ 538-548, 出版日 2007年03月, 査読付, IEEE 802.11 DCF is an asynchronous and distributed MAC protocol which does not require the existence of a central controller for medium access coordination. This flexibility, which is due to DCF's contention-based nature, comes at the expense of the overhead associated with contention resolution. The overhead consists of frame collision time and channel idle time, which is particularly severe when channel is saturated. In this paper, we present an enhancement of DCF which aims at reducing its contention resolution overhead by equipping it with a distributed reservation mechanism. The proposed reservation mechanism enhances collision avoidance mechanism of DCF by enforcing a partially ordered medium access through an implicit agreement between neighboring nodes. Simulation results, using ns-2 network simulator, show that the added reservation scheme 1) effectively reduces DCF's overhead and improves channel utilization particularly when node density and traffic load is high, 2) significantly enhance DCF's fairness.
研究論文（学術雑誌）, 英語 - Improving routing performance under the fading environment by utilizing position information
Suhua Tang; Masahiro Watanabe; Naoto Kadowaki; Sadao Obana
2007 IEEE WIRELESS COMMUNICATIONS & NETWORKING CONFERENCE, VOLS 1-9, IEEE, 掲載ページ 4253-4258, 出版日 2007年, 査読付, Performance of Mobile Ad hoc Networks (MANET) routing protocols may be greatly degraded due to involvement of weak links in the routes. One solution is to use directional antenna to improve link quality. The other is to less prefer weak links. In the experiments we found that even with the two methods the system performance is still limited in the presence of mobility and multipath fading due to the following facts: (1) beam scanning overhead and frequent beam variations, (2) route instability due to metric variation and false link breaks. Then we improve it by three schemes: (i) Calculate the antenna beam by position information. (ii) Calculate a stable link metric from the expectation value of Received Signal Strength Indication (RSSI). (iii) Avoid false link breaks. These schemes are suitable for the scenarios where both line of sight path and multipath fading exist. The experiment and simulation results indicate that the schemes can effectively reduces PER and improve throughput of AODV in the Rician fading situations.
研究論文（国際会議プロシーディングス）, 英語 - An Opportunistic Progressive Routing (OPR) protocol maximizing channel efficiency
Suhua Tang; Ryutaro Suzuki; Sadao Obana
GLOBECOM 2007: 2007 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-11, IEEE, 掲載ページ 1285-1290, 出版日 2007年, 査読付, In this paper we study the channel efficiency of Mobile Ad hoc Networks (MANET) and try to trade off between the progress and the instantaneous rate when forwarding packets in the fading environment. We define a new metric-bit transfer speed (BTS)-as the ratio of the progress made towards the destination to the equivalent time taken to transfer a payload bit. This metric takes the overhead, rate and progress into account. Then we propose an Opportunistic Progressive Routing (OPR) protocol, jointly optimizing routing and MAC by the cross-layer design. In OPR, a node selects the forwarder with the biggest BTs for a packet and the forwarder changes as the packet size or channel status varies. The extensive simulation shows that OPR greatly reduces channel occupation time and packet loss compared with the normalized advance (NADV) [7] scheme and contention-based forwarding (CBF) [17] scheme.
研究論文（国際会議プロシーディングス）, 英語 - 位置情報に基づきマルチパスフェージングを考慮した移動体向けアドホックルーティングプロトコルの特性評価
渡辺 正浩; 湯 素華; 小花 貞夫
情報処理学会論文誌, 47巻, 12号, 掲載ページ 3214-3224, 出版日 2006年12月, 査読付
研究論文（学術雑誌）, 日本語 - Modulation recognition at low signal-to-noise ratio situations
Suhua Tang; Xuchu Dai; Peixia Xu
Journal of Circuits and Systems, 11巻, 6号, 掲載ページ 114-119, 出版日 2006年12月, 査読付
研究論文（学術雑誌）, 中国語 - Improving Performance of On-demand Routing under Multipath Fading
Suhua Tang; Masahiro Watanabe; Naoto Kadowaki; Sadao Obana
2006 IEEE 63RD VEHICULAR TECHNOLOGY CONFERENCE, VOLS 1-6, IEEE, 掲載ページ 916-920, 出版日 2006年, 査読付, Despite many routing protocols proposed for mobile ad hoc networks few have considered link quality and route stability. Weak links contained in the routes often lead to route breaks. Multipath fading and mobility make link quality time-variant. When the link metric is associated with link quality the routes may change frequently. In times of transmission failure due to collision or fading, the routing packets are susceptible to loss owing to the lack of retransmission mechanism for the broadcast packets. For these reasons, the routes become unstable. In this paper, we investigate the long-term link quality and route stability in the on-demand routing protocols. We compare the link metric policies, optimize the route discovery and use the soft detection scheme to avoid false link breaks. The simulation results show that both Packet Error Ratio (PER) and throughput in the enhanced on-demand routing protocol can be greatly improved under the Rayleigh fading environment.
研究論文（国際会議プロシーディングス）, 英語 - A link heterogeneity-aware on-demand routing (LHAOR) protocol utilizing local update and RSSI information
SH Tang; B Zhang; M Watanabe; S Tanaka
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E88B巻, 9号, 掲載ページ 3588-3597, 出版日 2005年09月, 査読付, Many routing protocols have been proposed for mobile ad hoc networks. Among these protocols, the on-demand routing protocols are very attractive because they have low routing overhead. However, few of the existing on-demand routing protocols have considered the link heterogeneity, such as the different communication rate, different Packet Error Ratio (PER). As a result, the routes tend to have the shortest hop count and contain weak links, which usually provide low performance and are susceptible to breaks in the presence of mobility. In this paper, we analyze the existing on-demand routing protocols and propose a Link Heterogeneity Aware On-demand Routing (LHAOR) protocol, where the link quality and mobility are considered. Specifically, the Local Update (LU) is proposed and the link metric is inversely related with the Received Signal Strength Indicator (RSSI). By using the LU method and RSSI information, the routes adapt to the topology variation and link quality changes, and reach the local optimum quickly, which contains strong links and has a small metric. Simulation and experiment results show that our LHAOR protocol achieves much higher performance than the classical on-demand routing protocols.
研究論文（学術雑誌）, 英語 - Wide-banded wireless signal processing platform and algorithms
Suhua Tang; Xuchu Dai; Peixia Xu
Journal of Data Acquisition and Processing, 20巻, 1号, 掲載ページ 75-82, 出版日 2005年03月, 査読付
研究論文（学術雑誌）, 中国語 - Cyclostationarity-based symbol rate estimation
Suhua Tang; Xuchu Dai; Peixia Xu; Xiaoqing Fang
Acta Armamentarii, 26巻, 2号, 掲載ページ 251-255, 出版日 2005年03月, 査読付
研究論文（学術雑誌）, 中国語 - Trigger update based local optimization for on-demand routing Protocols
S Tang; M Watanabe; N Kadowaki; S Obana
LCN 2005: 30TH CONFERENCE ON LOCAL COMPUTER NETWORKS, PROCEEDINGS, IEEE COMPUTER SOC, 掲載ページ 703-710, 出版日 2005年, 査読付, In mobile ad hoc networks on-demand routing protocols are very attractive due to low overhead In these protocols, however, (1) the routes tend to contain weak links that have a low rate and high packet error ratio; (2) the routes are susceptible to breaks in the presence of mobility. Our major concern in this paper is to locally optimize the routes in the on-demand routing protocols in terms of link quality and mobility. The local optimization is realized by two main techniques: relating link metric with received signal strength and preferring the route with a shorter metric through Trigger Update (TU). In this manner the initial routes converge to the local optimum in the static case, and adapt to topology variations and link quality changes caused by mobility. Also, the routing overhead is controlled Simulation results show that AODV with the application of local optimization (AODV-TU) achieves a much higher performance than the original AODV.
研究論文（国際会議プロシーディングス）, 英語 - A robust AODV protocol with local update
SH Tang; B Zhang
2004 JOINT CONFERENCE OF THE 10TH ASIA-PACIFIC CONFERENCE ON COMMUNICATIONS AND THE 5TH INTERNATIONAL SYMPOSIUM ON MULTI-DIMENSIONAL MOBILE COMMUNICATIONS, VOLS 1 AND 2, PROCEEDINGS, IEEE, 掲載ページ 418-422, 出版日 2004年, 査読付, These days ad hoe networks have found many applications. Multiple ad hoc routing protocols have been proposed, of which on-demand routing protocols are very popular because they are easy to realize and have low routing overhead. However, on-demand routing protocols are not robust against topology variations and routes break often in the case of high mobility, which degrades the communication performance. In this paper, we analyze the Ad-hoe On-demand Distance Vector (AODV) routing protocol. Then we propose a Robust AODV protocol, where the route is built on demand and maintained by locally updating route information. Multiple backup routes are built around the active route and the highest priority backup route will be switched to become the new active route when the current active route breaks or is less preferred. In our Robust AODV protocol, routes adapt to fast topology variations and reach local optimum quickly. Simulation results show that our Robust AODV protocol acquires higher performance than the original AODV.
研究論文（国際会議プロシーディングス）, 英語 - A method to modulation recognition with combined parameters
Suhua Tang; Huarui Yin; Peixia Xu
Journal of Data Acquisition and Processing, 18巻, 1号, 掲載ページ 27-31, 出版日 2003年03月, 査読付
研究論文（学術雑誌）, 中国語
書籍等出版物
- ネットワークシステム : 高等学校用
湯 素華; 能城 茂雄; 早藤 素史; 山際 基; 湯澤 一
日本語, 共編者(共編著者), 219p, 実教出版, 出版日 2023年01月, ISBN 9784407206753 - Radio-on-demand wireless LAN
Suhua Tang; Zhi Liu
英語, 共著, Springer, 出版日 2019年 - Precise pedestrian positioning by using vehicles as mobile anchors
Suhua Tang; Sadao Obana
英語, 共著, CRC Press, 出版日 2019年 - Social interactions over location-aware multimedia systems
Yi Yu; Roger Zimmermann; Suhua Tang
学術書, 英語, 共著, Chapter 5 in the book ``Multimedia data mining and analytics--disruptive innovation,’’, Springer, 出版日 2015年
講演・口頭発表等
- CCNを利用した車車間通信における強化学習によるキャッシュ制御
溝尻 航希; 湯 素華
情報処理学会第86回全国大会
発表日 2024年03月 - NR-V2X サイドリンクブロードキャストの中継による高信頼化
青木 紫朗; 湯 素華
情報処理学会第86回全国大会
発表日 2024年03月 - OFDM信号の位相情報を用いた疑似距離の計測と高精度測位
青木 一馬; 湯 素華
情報処理学会第86回全国大会
発表日 2024年03月 - 空中計算による連合機械学習の性能改善に関する検討
肖 唯巍; 湯 素華
情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2023) シンポジウム
発表日 2023年07月 - オンライン学習を用いた環境変化に対応する測位方式の検討
吉澤 玲; 湯 素華
情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2023) シンポジウム
発表日 2023年07月 - OFDM信号の位相情報を用いた高精度測距に関する評価
劉 経緯; 菊池 典恭; 久保 信明; 湯 素華
口頭発表（一般）, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2023) シンポジウム
発表日 2023年07月 - 中継制御を用いた高信頼空中計算
周 靖陽; 湯 素華
口頭発表（一般）, 情報処理学会第85回全国大会
発表日 2023年03月 - OFDM信号の位相情報を用いた高精度歩行者測位に関する検討
劉 経緯; 湯 素華
口頭発表（一般）, 情報処理学会第85回全国大会
発表日 2023年03月 - オンライン学習を用いた環境変化に対応する測位方式の検討
吉澤 玲; 湯 素華
口頭発表（一般）, 情報処理学会第85回全国大会
発表日 2023年03月 - LSTMを用いたマルチパス誤差の予測及び歩行者測位精度向上に関する検討
陳 子強; 湯 素華
口頭発表（一般）, 情報処理学会第85回全国大会
発表日 2023年03月 - LSTMを用いた高精度歩行者測位方法に関する検討
井上 真樹; 湯 素華
口頭発表（一般）, 情報処理学会高度交通システムとスマートコミュニティ(ITS)研究会
発表日 2023年03月 - 位相情報を用いた歩行者測位のシミュレーション評価
湯 素華; 久保 信明; 菊池 典恭; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会高度交通システムとスマートコミュニティ(ITS)研究会
発表日 2022年09月 - クラスタリングに基づくキャッシュ配置を用いた車車間通信の効率化に関する検討
徳永 大貴; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2022) シンポジウム
発表日 2022年07月 - 角度情報を用いたBLE測位の高精度化に関する検討
山見 悠人; 湯 素華
口頭発表（一般）, 日本語, 分散，協調とモバイル (DICOMO2022) シンポジウム
発表日 2022年07月 - クラスタリングに基づくキャッシュ配置を用いた車車間通信の効率化に関する検討
德永 大貴; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第84回全国大会
発表日 2022年03月 - 角度情報を用いたBLE測位の高精度化に関する検討
山見 悠人; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第84回全国大会
発表日 2022年03月 - C-V2X sidelinkを用いた近距離通信の高信頼スケジューリング法
瀬川 洋介; 湯 素華; 上野 高明; 大岸 智彦; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会高度交通システムとスマートコミュニティ(ITS)研究会
発表日 2022年03月 - OFDM信号の位相情報を用いた歩行者測位に関する検討
湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会高度交通システムとスマートコミュニティ（ITS）研究会
発表日 2021年09月 - LSTMを用いた高精度歩行者測位方法に関する検討
井上 真樹; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2021) シンポジウム
発表日 2021年06月 - 都市部における歩行者測位の取り組み
湯 素華; 小花 貞夫
口頭発表（招待・特別）, 日本語, 電気情報通信学会高信頼制御通信（RCC）研究会, 招待
発表日 2021年05月 - 無線センサネットワークにおける空中計算のためのウェイクアップ制御と中継制御に関する検討
周 靖陽; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第83回全国大会
発表日 2021年03月 - マルチパス誤差の空間・時間相関性を用いた歩行者測位精度向上に関する検討
陳 子強; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第83回全国大会, 国内会議
発表日 2021年03月 - オンライン学習を用いた電波伝搬距離推定および高精度歩行者測位方式
井上真樹; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会第83回全国大会, 国内会議
発表日 2021年03月 - 車線数の動的変更と経路計画の組み合わせによる渋滞緩和方式の提案・評価
張 作庭; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第83回全国大会, 国内会議
発表日 2021年03月 - 無線チャネル状態情報の空間・時間変化の併用による歩行者の角度推定及び高精度測位法の提案と評価
駒宮 亘; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第97回MBL・第83回ITS合同研究発表会, 国内会議
発表日 2020年11月 - 無線センサネットワークのための空中計算方式の信頼性に関する検討・評価
湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会第97回MBL・第83回ITS合同研究発表会, 国内会議
発表日 2020年11月 - 車両からの電波のチャネル状態情報を用いた歩行者測位
湯 素華; 小花 貞夫
口頭発表（招待・特別）, 日本語, 電子情報通信学会ソサイエティ大会, 招待, 国内会議
発表日 2020年09月 - 車両からの電波のチャネル状態情報を用いた歩行者測位
湯 素華; 小花 貞夫
口頭発表（招待・特別）, 日本語, 電子情報通信学会ソサイエティ大会, 招待, 国内会議
発表日 2020年09月 - Cellular-V2Xを用いたリアルタイム情報共有と配信のための無線リソースの効率的なスケジューリング法の提案
瀬川 洋介; 上野 高明; 大岸 智彦; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2020) シンポジウム, 国内会議
発表日 2020年06月 - Cellular-V2Xにおける自律分散制御を用いた低遅延・高信頼なスケジューリング法
瀬川洋介; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第82回全国大会, 国内会議
発表日 2020年03月 - 歩車間通信における無線チャネル使用率に基づく動的送信頻度制御
伊藤 舜; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会高度交通システムとスマートコミュニティ(ITS)研究会
発表日 2019年09月 - 車両移動による無線チャネル状態情報の変化を利用した歩行者の角度推定及び高精度測位法の提案と評価
駒宮 亘; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2019) シンポジウム, 国内会議
発表日 2019年07月 - セルラV2XとDSRCを併用した車車間通信による狭域道路・交通情報の効率的な配信方式の提案と評価
高草木 政史; 湯 素華; 上野 高明; 大岸 智彦; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2019) シンポジウム
発表日 2019年07月 - 異種アプリケーション混在環境におけるユーザ満足度を考慮した無線LANの周波数帯域幅割り当て制御
童 雋; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第81 回全国大会, 招待
発表日 2019年03月 - IEEE802.11ahの省電力化のための端末グループ化と通信制御方式の検討
井波健太; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会第81 回全国大会
発表日 2019年03月 - 車両移動による無線チャネル状態情報の変化を利用した高精度な歩行者測位法
駒宮 亘; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第81 回全国大会
発表日 2019年03月 - 車両ネットワークにおけるセルラV2XとDSRCの性能比較検証
高草木 政史; 湯 素華; 上野 高明; 大岸 智彦; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会第81 回全国大会
発表日 2019年03月 - LoRaWANにおけるネットワーク効率化のためのノードのグループ構成法と通信制御方式
手柴 瑞基; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会モバイルコンピューティングとパーベイシブシステム(MBL)研究会
発表日 2018年11月 - CCNにおけるコンテンツ配信者移動環境のための移動管理とキャッシュ配置法
夏川 清; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会モバイルコンピューティングとパーベイシブシステム(MBL)研究会
発表日 2018年11月 - 普通車と大型車の混在を考慮した車車間通信による狭域道路・交通情報の効率的な中継配信方式の提案と評価
高草木政史; 森拓也; 湯 素華; 大岸智彦; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2018) シンポジウム
発表日 2018年07月 - 歩車間通信における無線チャネル使用率に基づく動的送信頻度制御
伊藤舜; 小花貞夫; 湯 素華
口頭発表（一般）, 日本語, 分散，協調とモバイル (DICOMO2018) シンポジウム
発表日 2018年07月 - CCNに基づく車車間通信による狭域道路・交通情報の効率的な収集方式の提案
中沢隆紀; 小花貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2018) シンポジウム
発表日 2018年07月 - 車両からの電波の長期計測による路側機の高精度測位方式の提案
戸田和宏; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2018) シンポジウム
発表日 2018年07月 - マルチパス誤差の空間相関性を利用した歩行者測位手法と性能評価
パトウイヤロ; 小花貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2018) シンポジウム
発表日 2018年07月 - 車両からの電波の長期計測による路側機の高精度測位方式
戸田和宏; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第80 回全国大会, 国内会議
発表日 2018年03月 - マルチパス誤差の空間相関性を利用した歩行者の位置測定精度向上
イヤロ パトウ; 小花貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第80 回全国大会, 国内会議
発表日 2018年03月 - コンテンツ指向ネットワーク(CCN)におけるコンテンツ配信者の移動に伴う経路管理とキャッシュ管理の方式提案
夏川 清; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第80 回全国大会, 国内会議
発表日 2018年03月 - 普通車と大型車の混在を考慮した車車間通信による狭域交通情報の効率的な中継配信方式の提案
高草木政史; 森 拓也; 湯 素華; 鈴木理基; 堀 賢治; 大岸智彦; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第80 回全国大会, 国内会議
発表日 2018年03月 - CCNに基づく車車間通信による狭域道路・交通情報の効率的な収集方式
中沢隆紀; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第80 回全国大会, 国内会議
発表日 2018年03月 - 歩車間通信における無線チャネル使用率に基づく動的送信頻度制御
伊藤 舜; 小花貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第80 回全国大会, 国内会議
発表日 2018年03月 - 磁気共振を用いた非接触給電における複数端末への高効率な給電手法
関 邦洋; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会モバイルコンピューティングとパーベイシブシステム(MBL) 研究会, 招待
発表日 2017年08月 - 狭域交通情報を周辺車両で効率的に共有するための中継車両選択制御と優先送信制御を両立する車車間通信方式の提案
森 拓也; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2017) シンポジウム
発表日 2017年06月 - 車両からの電波到来角度を利用した歩行者測位精度向上方式の提案と評価
戸田 和宏; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2017) シンポジウム
発表日 2017年06月 - Wi-Fi電波を用いた呼吸等のバイタル情報測定と姿勢変化認識
HaoChen Cui; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2017) シンポジウム
発表日 2017年06月 - 車両からの電波到来角度を利用した歩行者測位精度向上のための方式提案
戸田和宏; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第79 回全国大会
発表日 2017年03月 - WiFi電波を用いた呼吸数等のバイタル情報測定と姿勢変化認識の検討
HaoChen Cui; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第79 回全国大会
発表日 2017年03月 - 狭域交通情報を効率的に共有するための中継車両選択制御と優先送信制御を両立する車車間通信方式
森 拓也; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第79 回全国大会
発表日 2017年03月 - モバイル端末の消費電力削減のためのBLEを用いたWi-Fiウェイクアップ制御方式の実装
田中直也; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会MBL研究会
発表日 2016年12月 - GPSと車両からの電波を併用した歩行者測位方式の改良と性能評価
山下 遼; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会ITS研究会
発表日 2016年12月 - 大規模無線センサネットワークにおける中継ノードの省電力化のための非対称通信とWake-up Radio を併用したモバイルシンク通信方式の提案と評価
岩田将成; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2016) シンポジウム, 国内会議
発表日 2016年07月 - 複数ウェアラブルデバイスの併用によるBLE を用いた室内位置測位精度向上手法の検討と評価
中島尚紀; 湯 素華; 大岸智彦; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2016) シンポジウム, 国内会議
発表日 2016年07月 - 磁気共振方式を用いた非接触給電における複数端末に対する効率と公平性の検討
関 邦洋; 小花貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第78 回全国大会, 国内会議
発表日 2016年03月 - 自動走行システムにおける典型的な車車間通信向けユースケースの成立性の一検討
田代祥真; 小花貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第78 回全国大会, 国内会議
発表日 2016年03月 - 複数のウェアラブルデバイスを併用したBLE による室内位置測位精度向上手法の検討
中島尚紀; 湯 素華; 土岐 卓; 大岸 智彦; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会第78 回全国大会, 国内会議
発表日 2016年03月 - 歩車間通信における最適な通信制御のためのコンテクストに基づく歩行者の危険度判定手法の検討
角野カノン; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第78 回全国大会, 国内会議
発表日 2016年03月 - 大規模無線センサネットワークにおける中継ノードの省電力化のための非対称通信とWake-up Radio を併用したモバイルシンク通信方式の提案
岩田将成; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会第78回全国大会, 国内会議
発表日 2016年03月 - 異種アプリケーションが混在する無線LANにおける周波数割り当て制御方式の提案
越川 徹; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会モバイルコンピューティングとパーベイシブシステム(MBL)研究会, 国内会議
発表日 2015年12月 - ウェアラブルセンサを用いた初心者向けテニス上達支援システムにおけるスウィングフォーム分析手法の改善と評価
増田 大輝; 湯 素華; 大岸 智彦; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会モバイルコンピューティングとパーベイシブシステム(MBL)研究会, 国内会議
発表日 2015年12月 - モバイル端末の消費電力削減のためのBluetooth4.0(BLE)を用いたWi-Fiウェイクアップ制御方式の提案
田中 直也; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2015) シンポジウム, 国内会議
発表日 2015年07月 - GPSと車両からの電波を用いた歩行者測位精度向上のための方式提案
山下 遼; 湯 素華; 小花 貞夫
口頭発表（一般）, 日本語, 情報処理学会マルチメディア，分散，協調とモバイル (DICOMO2015) シンポジウム, 国内会議
発表日 2015年07月 - 狭域交通情報共有のための車車間通信における車両位置情報に基づく効率的な中継転送方式の提案
吉川 潤; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会 高度交通システム(ITS)研究会
発表日 2015年03月 - 歩車間通信における歩行者端末のコンテクストに基づく送信優先度制御方式の提案
齋藤 淑; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会 高度交通システム(ITS)研究会
発表日 2015年03月 - MANETにおける周期ブロードキャストによる広域動画配信のためのマルチホップ中継再配信方式の提案と評価
桂 健太; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会 モバイルコンピューティングとユビキタス通信(MBL)研究会
発表日 2015年03月 - 歩行者事故削減のためのGPS と車両からの電波を用いた歩行者位置精度向上の提案
山下 遼; 湯 素華; 小花貞夫
口頭発表（一般）, 日本語, 情報処理学会第77回全国大会
発表日 2015年03月 - モバイル端末の消費電力削減のためのBluetooth4.0(BLE)を用いたWi-Fi ウェイクアップ制御方式
田中 直也; 小花 貞夫; 湯 素華
口頭発表（一般）, 日本語, 情報処理学会第77回全国大会
発表日 2015年03月 - 車両間の協調による高精度相対測位の研究開発
湯 素華; 古川 玲; 川西 直; 長谷川 晃朗; 三浦 龍; 武内 良男
口頭発表（招待・特別）, 日本語, IEICE ITS研究会, 国内会議
発表日 2013年07月
担当経験のある科目_授業
共同研究・競争的資金等の研究課題
- 通信・計算の融合によるセマンティックIoTネットワークに関する研究
湯 素華
テレコム先端技術研究支援センター
研究期間 2024年04月 - 2027年03月 - V2X信号の位相情報を用いた高精度歩行者測位に関する研究開発
湯 素華; 菊池 典恭; 久保 信明
日本学術振興会, 科学研究費助成事業, 電気通信大学, 基盤研究(B), 22H03576
研究期間 2022年04月 - 2025年03月 - センサネットワークにおける高信頼・低消費電力の空中計算技術に関する研究
湯 素華
テレコム先端技術研究支援センター, 研究代表者
研究期間 2021年04月 - 2023年03月 - クラウドに基づく歩行者測位システムの研究開発
湯 素華; 小花 貞夫
日本学術振興会, 科学研究費助成事業, 電気通信大学, 基盤研究(C), 都市部では、建物の遮蔽・反射の影響で、歩行者の測位精度が大幅に劣化しうる。本研究では、（１）衛星から直接波を受信できず、代わりに反射波を測位に使用する際、マルチパス誤差の時間・空間相関性を利用して、歩行者でのマルチパス誤差を推測・補正する。（２）衛星数不足の場合、周辺車両を測位アンカーとし、複数アンテナで、異なる受信時間の複数箇所から連続してCSIを取得して、空間軸・時間軸の二次元の要素を持つ擬似アンテナアレイを構成し、各CSIの位相差から歩車間の角度情報を推測し、2アンテナを利用したときの角度推定・測位誤差を、大きく削減できることを確認した。, 19K11937
研究期間 2019年04月 - 2022年03月 - 多センサ融合により歩行者の位置情報・危険度合を高精度に導出する技術の研究開発
湯 素華; 小花 貞夫
日本学術振興会, 科学研究費助成事業, 電気通信大学, 基盤研究(C), 歩行者がGPS衛星に加え、周辺車両・路側機をアンカーとし、自端末の位置を算出する手法を検討した。 車両・路側機と歩行者の間のチャネル状態情報を利用して、機械学習で非線形再帰関数を学習させ、距離を推定する手法と、距離の誤差特性を考慮し、測位演算中重みづけを行う方式を提案・評価した。また、受信機の時間分解能が測位精度への影響を評価した。さらに、歩行者自身の移動速度、車両・路側機・衛星との距離をKalman filterで融合して測位する手法を提案した。レイ・トレーシング・シミュレーションにより、都市部環境では、GPS衛星測位手法と比べて、測位誤差を大幅に低減できることを確認した。, 16K00120
研究期間 2016年04月 - 2019年03月 - JSTさくらサイエンスプラン
研究代表者
研究期間 2018年10月 - 2018年12月 - ウェイクアップ受信機を用いた省電力無線通信技術についての研究
(公財)電気通信普及財団, 研究代表者
研究期間 2016年04月 - 2017年03月
産業財産権
- 通信方法、端末及び通信プログラム
特許権, 湯 素華, 小花 貞夫, 特願2023-172571, 出願日: 2023年10月04日, 国立大学法人電気通信大学 - 測位システムおよび測位方法
特許権, 湯 素華, 小花 貞夫, 特願PCT/JP2022/032376, 出願日: 2022年08月29日 - 車載装置、通信方法および車載装置プログラム
特許権, 瀬川 洋介, 湯 素華, 小花 貞夫, 特願2022-029178, 出願日: 2022年02月28日 - センサネットワークシステム、シンク、ノード、データ通信処理方法およびプログラム
特許権, 湯 素華, 小花 貞夫, 特願2020-150975, 出願日: 2020年09月09日 - 位置測定装置、位置測定方法、プログラム、および位置測定システム
特許権, 湯 素華, 山下 寮, 小花 貞夫, 特願2015-048549, 出願日: 2015年03月11日, 特開2016-169974, 公開日: 2016年09月23日, 特許6551969, 発行日: 2019年07月12日 - バイタル情報推定装置及びバイタル情報推定プログラム
特許権, 崔 皓琛, 小花 貞夫, 湯 素華, 2019-018120, 出願日: 2019年02月04日 - 無線ネットワーク,それに用いられる無線装置およびその無線装置を備えた移動体
特許権, 2007-294079, 出願日: 2007年11月13日, 湯素華, オユーンチメグ・シャグダル, マハダド・ヌリ・シラジ, 鈴木龍太郎, 小花貞夫, 5194296, 発行日: 2013年02月15日 - 無線基地局およびそれを用いた無線通信システム
特許権, 2011-037031, 出願日: 2011年02月23日, 四方博之, 近藤良久, 湯素華, 小花貞夫, 伊藤哲也, 松本晃, 吉村紘一, 5190568, 発行日: 2013年02月08日 - 端末装置,それと無線通信を行う無線基地局およびそれらを用いた無線通信システム
特許権, 2011-037306, 出願日: 2011年02月23日, 近藤良久, 四方博之, 湯素華, 小花貞夫, 伊藤哲也, 吉村紘一, 岩井優仁, 田中利康, 飯塚宏之, 5190569, 発行日: 2013年02月08日 - 無線装置およびそれを備えた無線ネットワーク
特許権, 2008-229546, 出願日: 2008年09月08日, 湯素華, マハダド・ヌリ・シラジ, 四方博之, オユーンチメグ・シャグダ, 鈴木龍太郎, 小花貞夫, 5168692, 発行日: 2013年01月11日 - 無線装置およびそれを備えた無線ネットワーク
特許権, 2010-521587, 出願日: 2009年04月24日, シャグダル・オユーンチメグ,マハダド・ヌリ・シラジ, 大山卓, 湯素華, 鈴木龍太郎, 小花貞夫, 5163968, 発行日: 2012年12月28日 - 無線ネットワーク
特許権, 2008-290869, 出願日: 2008年11月13日, 湯素華, 植田哲郎, 三浦龍, 小花貞夫, 5119413, 発行日: 2012年11月02日 - 無線装置およびそれを備えた無線ネットワーク
特許権, 2007-318043, 出願日: 2007年12月10日, 湯素華, 程俊, スン・チェン, 鈴木龍太郎, 小花貞夫, 5070439, 発行日: 2012年08月31日 - 無線装置およびそれを備えた無線通信ネットワーク
特許権, 2006-301024, 出願日: 2006年11月07日, 湯素華, 門脇直人, 小花貞夫, 4877778, 発行日: 2011年12月09日 - 無線装置およびそれを備えた無線ネットワークシステム
特許権, 2005-208387, 出願日: 2005年07月19日, 張兵, マハダド・ヌリ・シラジ, 猪木誠二, 湯素華, 門脇直人, 小花貞夫, 4827049, 発行日: 2011年09月22日 - 無線装置およびそれを備えた無線ネットワークシステム
特許権, 2005-328527, 出願日: 2005年11月14日, 湯素華, 渡辺正浩, 門脇直人, 小花貞夫, 4696314, 発行日: 2011年03月11日
学術貢献活動
- IEEE Transactions on Cognitive Communications and Networking
査読, 実施期間 2024年02月 - 2024年03月 - IEEE IV'24
査読, Associate Editor, 実施期間 2024年01月 - 2024年03月 - IEEE Internet of Things Journal
査読, 実施期間 2024年01月 - 2024年02月 - IEEE Transactions on Wireless Communications
査読, 実施期間 2023年12月 - 2024年01月 - IEEE ICC'24
査読, TPC member, 実施期間 2023年10月 - 2024年01月 - IEEE Globecom'23
査読, 実施期間 2023年12月 - IEEE Internet of Things Journal
査読, 実施期間 2023年08月 - IEEE Open Journal of Vehicular Technology
査読, 実施期間 2023年08月 - マルチメディア、分散、協調とモバイル DICOMO 2023 シンポジウム
企画立案・運営等, 情報処理学会, 実施期間 2023年07月 - IEEE Communications Magazine
査読, 実施期間 2023年06月 - IEEE Transactions on Network Science and Engineering
査読, 実施期間 2023年06月 - IEEE ICC'23
査読, IEEE, 実施期間 2023年05月 - IEEE Journal on Selected Areas in Communications
査読, 実施期間 2023年03月