マイクロ波無線給電システムにおいて、バッテリレスデバイスに電力と情報を同時に伝送するSWIPTシステムは有用である。しかし、連続波に基づく従来のSWIPTシステムでは情報を伝送する際に電力伝送効率が低下してしまう。この課題に対し、マルチトーン波形を用いる手法が提案されてきた。本研究では、周波数変調されたマルチトーン波形の情報復調を、整流時のピーク対平均電力を測定することで、従来で必要だったFFTによる復調方式に比べて軽量にした。

In microwave wireless power transfer systems, Simultaneous Wireless and Information Transfer (SWIPT) is a useful method for battery-less devices as it transmits power and information to the device simultaneously. However, conventional SWIPT systems, where continuous waves are utilized for realizations, power deteriorations are severe when transmitting information, which confines the working areas of the battery-less devices. To mitigate this problem, multitone-based SWIPT has been proposed. Multitone waveforms consist of multiple waveforms to have high peak to average power, which results in increasing the power conversion efficiencies at the receiver without increasing the transmit power. In contrast to the conventional frequency shifted multitone-based SWIPT method, where FFTs are utilized to decode information, we have proposed the light weight calculation method by measuring peak to average power ratio of the received signal. This enables us to implement mutltone-based SWIPT systems for battery-less devices whose computational resources are too small to leverage FFTs.

Takashi Ikeuchi, Yoshihiro Kawahara

Contact: ikeuchi@akg.t.u-tokyo.ac.jp