Faculty Profiles - YAMAZATO Takaya

Papers - YAMAZATO Takaya

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A Study on Cluster Lifetime in Multi-Hop Wireless Sensor Networks with Cooperative MISO Scheme Reviewed

Z. Huang, H. Okada, K. Kobayashi, M. Katayama

Journal of Communications and Networks Vol. 14 ( no.4 ) page： pp.443-450 2012.8

Language：English

As for cluster-based wireless sensor networks (WSNs), cluster lifetime is one of the most important subjects in recent researches. Besides reducing the energy consumptions of the clusters, it is necessary to make the clusters achieve equal lifetimes so that the whole network can survive longer. In this paper, we focus on the cluster lifetimes in multi-hop WSNs with cooperative multi-input single-output scheme. With a simplified model of multi-hop WSNs, we change the transmission schemes, the sizes and transmission distances ofclusters to investigate their effects on the cluster lifetimes. Furthermore, linear and uniform data aggregations are considered in our model. As a result, we analyze the cluster lifetimes in different situations and discuss the requirements on the sizes and transmission distances of clusters for equal lifetimes.

DOI： 10.1109/JCN.2012.6292251

A-2-1 Stochastic Resonance BFSK Receiver using Schmitt Trigger Reviewed

CHIGA Keita, TANAKA Hiroya, YAMAZATO Takaya, ARAI Shintaro

Proceedings of the Society Conference of IEICE Vol. 2012 page： 24 2012.8

A-2-2 Performance Evaluation of 2 users BFSK Receiver using Stochastic Resonance Reviewed

TANAKA Hiroya, YAMAZATO Takaya, ARAI Shintaro

Proceedings of the Society Conference of IEICE Vol. 2012 page： 25 2012.8

Demand of Teaching Material Development and OCW

T. Yamazato

60th JSEE Anual Conference Proceedings ( 8-331 ) page： - 2012.8

Interference Comparison of BFDM and Wavelet Based OFDM in Frequency Dispersive Channels Reviewed

GOTO Daisuke, YAMAZATO Takaya, MONGOL Bayarpurev

The transactions of the Institute of Electronics, Information and Communication Engineers. B Vol. 95 ( 8 ) page： 971 - 975 2012.8

Evbaluation of Error-Correcting Method Using Separation of Chaotic Dynamics for Noncoherent Chaos Communications

S. Arai, Y. Nishio and T. Yamazato

page： pp. 261-266 2012.7

Improvement Method of Data Rate for Overlay Hierarchical Coding for Road-to-Vehicle Visible Light Communication Using LED Array and High-Speed Camera

S. Nishimoto, T. Yamazato, H. Okada, T. Fujii, T. Yendo, S. Arai

Technical Report of IEICE Vol. no.148 ( ITS2012-9 ) page： pp.19-24 2012.7

Language：Japanese

This paper aims to improve the data rate for the visible light communication system using LED array and high-speed camera. Previously, we have proposed the decoding algorithm using inverted signals for driving situation. However, using this method the data rate become a half, because we transmit original signals and inverted signals alternately for LED array tracking. In this paper, we propose the data rate improving method for overlay coding which is coding method that overlay two data. We confirm that we can improve data rate as compared with the previous method.

Improvement Method of Data Rate for Overlay Hierarchical Coding for Road-to-Vehicle Visible Light Communication Using LED Array and High-Speed Camera Reviewed

NISHIMOTO Sayaka, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Vol. 112 ( 148 ) page： 19 - 24 2012.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Driver Assistant System using Visible Light Communications : Road-to-Vehicle Visible Light Communications usign LED Array and On-Vehicle High-Speed Camera Reviewed

YAMAZATO Takaya

IEICE technical report. WBS, Wideband System Vol. 112 ( 147 ) page： 25 - 30 2012.7

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

We are conducting a study on visible light communications (VLC) using an LED traffic light and a high-speed camera equipped in a vehicle. Since we use the camera, we can capture and record surround images of the vehicle while receiving the data transmitted from the LED traffic light. This paper introduces the VLC system we are working on. Especially, this paper describes the advantages of road-to-vehicle VLC when the reception device is composed of high-speed camera.

[Poster Presentation] Road-to-Vehicle Communication and Distance Estimation System using Visible Light Communication

A.Ohmura,T.Yamazato,H.Okada,T.Fujii,T.Yendo,S.Arai

Technical Report of IEICE ( USN2012-9 ) page： pp.63-68 2012.5

Road-to-Vehicle Communication and Distance Estimation System using Visible Light Communication Reviewed

OHMURA Akihiro, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

IEICE technical report Vol. 112 ( 31 ) page： 63 - 68 2012.5

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In road-to-vehicle visible light communication data is transmitted toward moving vehicles from the LED array installed on roads. Robust data reception and fast communication are possible by using a high-speed camera as it can reduce the vibration of vehicles. In this road-to-vehicle visible light communication, we propose an integrated system of communication and distance estimation by sending a known data pattern from the LED array.

A Study on Cluster Partitioning with Cooperative MISO Scheme in Wireless Sensor Networks Reviewed

Z. Huang, H. Okada, M. Katayama, T. Yamazato

International Journal of Distributed Sensor Networks page： - 2012.4

Language：English Publishing type：Research paper (scientific journal)

This paper addresses the cluster partitioning problem in wireless sensor networks deployed in a continuous area. We present the model of the network and describe its operational details firstly. Both single-hop and multi-hop transmissions with cooperative Multi-Input Single-Output (MISO) scheme are considered for the inter-cluster communications. Besides, uniform and linear data fusions are discussed. Then the calculations of energy consumptions are derived. Different from other researches, the energy consumptions of intra-cluster communication in each cluster are included and modeled as functions of the cluster size. Finally, we simulate all possible cluster partitions by changing the numbers of clusters and cooperative transmitting nodes, and find the maximal network lifetimes. As a result, the relationships between cluster partitions and network lifetimes are clarified in different situations.

A Distance Estimation Scheme between the LED Array and On-Vihicle High-Speed Camera Using Visible Light

A.Ohmura,T.Yamazato,H.Okada,T.Fujii,T.Yendo,S.Arai

IEICE General Conference Vol. B-10B page： CD-ROM 2012.3

Preliminary Study on Bi-Polar Pulse Receiver using Stochastic Resonance

H. Tanaka, T. Yamazato, S. Arai

IEICE General Conference Vol. A-2 page： CD-ROM 2012.3

A-2-34 Preliminary Study on Bi-Polar Pulse Receiver using Stochastic Resonance Reviewed

TANAKA Hiroya, YAMAZATO Takaya, ARAI Shintaro

Proceedings of the IEICE General Conference Vol. 2012 page： 79 2012.3

A-2-35 State Analysis of Stochastic Resonance in Quadruple-Well Potential Reviewed

Ozaki Shota, Arai Shintaro, Yamazato Takaya, Nishio Yoshifumi

Proceedings of the IEICE General Conference Vol. 2012 page： 80 2012.3

Relay Selection Scheme with Harvested Solar Energy Prediction for Solar-Powered Wireless Sensor Networks Reviewed

OTA KENTARO, KOBAYASHI KENTARO, YAMAZATO TAKAYA, KATAYAMA MASAAKI

IEICE technical report Vol. 111 ( 476 ) page： 85 - 92 2012.3

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

Our goal is to make efficient use of the energy and therefore achieve network operation with a high packet delivery ratio, regardless of day, night and weather variations, in solar powered wireless sensor networks. One method to optimize the consumption energy in the entire network is to employ a cooperative transmission scheme in which a node uses another node as a relay, when sending its data. If we do not consider the changes in the harvested energy in the network, the packet delivery ratio declines during nights and cloudy days. In this paper, however, we propose a new relay selection scheme with harvested solar energy prediction to maintain the required high packet delivery ratio by reducing the effect of the weather variations.

Preliminary Study on BPSK Receiver using Stochastic Resonance Reviewed

H.Tanaka, T.Yamazato, S.Arai

2012 RISP International Workshop on Nonlinear Circuits, Communications and Signal Processing page： CD-ROM 2012.3

Language：Japanese

Stochastic Resonance (SR), known as a noise-enhanced phenomenon, can improve the performance of commutation systems. In this paper, we present a preliminary study on SR and its application to BPSK receiver. We discuss a basic question arises from a receiver using SR that shall we perform SR process in a radio-frequency (RF) band or in a baseband (BB)? As results, we found that SR process in RF band shows better Bit Error Rate (BER) performance. This comes from the fact that a down conversion process that reduces the signal amplitude causes weak noise suppression by SR. While a double frequency term obtained also by the down conversion process do not affect much to the noise reduction performance.

Cancellation Method for Intersymbol Interference on Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

KASASHIMA Tatsuya, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Vol. 111 ( 441 ) page： 129 - 134 2012.2

Publishing type：Research paper (scientific journal) Publisher：The Institute of Electronics, Information and Communication Engineers

In this paper, we discuss on visible light communications using an LED array as the transmitter and a highspeed camera as the receiver. LED array , composed of many LEDs, transmits information by flashing LEDs, unfortunately an LED light diffuses around and affects neighboring LEDs. This problem causes degradation in error rate performance. We treat this ploblem as intersymbol interference (ISI) and try to cancel. In this paper, we first propose an area average quantization for the reduction of ISI. Next, we propose a new ISI cancellation method for overlay decoding and evaluate this method.

Cancellation Method for Intersymbol Interference on Road-to-Vehicle Visible Light Communication using LED Array and High-Speed Camera Reviewed

KASASHIMA Tatsuya, YAMAZATO Takaya, OKADA Hiraku, FUJII Toshiaki, YENDO Tomohiro, ARAI Shintaro

Vol. 111 ( 441 ) page： 129 - 134 2012.2

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Papers - YAMAZATO Takaya