Noise-Induced Synchronizationに基づいた実環境信号による無線センサネットワークの同期

摘要

Noise-induced synchronization is a theory of a phenomenon that multiple nonlinear oscillators synchronize with each others only by adding common noise to each. As an application of this synchronization theory, we propose a system that synchronize wireless sensor network devises by using environmental signals obtained from the sensors on each. For wireless sensor network, it is important to develop low-power consumption protocols, and it becomes possible to reduce the power consumption by intermittent communications. Although synchronization among the sensor devises is necessary to realize such a protocol, sending and receiving of the synchronization signals themselves consume electric power of limited battery on each sensor. In this paper, we investigate a novel synchronization scheme, which does not require any signal exchange, by applying the noise-induced synchronization theory. Since the sensing signals obtained at each sensor devise may be different even if they are located in short-distance, the success rate of the synchronization is analyzed with changing the cross-correlation among the sequences added to each sensor devise. T By experiments using the real wireless sensor network devises, it is clarified that sensor devises can be synchronized by the environmental signals autonomously sensed at each sensor node without any signal exchange among the devises, when the sensors are located in short-range communications.%結合のない非線形振動子を共通な入力ノイズのみによって同期させるNoise-Induced Synchronizationが注目されており，その理論研究が進められている．本稿では，この同期理論を応用することで，省電力化が求められる無線センサネットワークの同期を，センサが取得する情報のみで達成させる手法を提案する．無線センサネットワークにおいては，間欠的な信号送受信を行うことで省電力化が可能となるが，そのためにはセンサノード間の同期が必要となる．しかしながら，同期達成のために信号の送受信を行うと，そのために電力を消費してしまう．そこで，本稿では，Noise-Induced Synchronizationを適用することにより，通信を行わずに時刻同期を達成する手法を検討する．実環境信号は完全な共通ノイズ入力とはならないため，同期達成のために必要なノイズ間の相互相関を解析する．さらに，実際のセンサネットワークノードを用いた実験により，各センサノードが取得する実環境信号を振動子に入力することで，近距離であれば通信せずにセンサノード間の同期が達成できることが示された．