Dynamic Spectrum Sensing For Energy Harvesting Wireless Sensor

Energy harvesting wireless sensors are driven by electric power extracted from hidden environmental source of energy, such as imperceptible vibrations of walls and floors. It has been shown that radio transmitter system can be powered by energy harvesters with substituting ring for crystal oscillators, which, however, causes frequency instability in oscillator. In order to receive message from such sensors, a receiver must be able to accurately detect transmitted frequencies that may differ among respective sensors. Fast wideband radio frequency sensing schemes using filter-based energy detectors were proposed. These schemes were designed to detect radio devices operating according to known specifications; this paper proposes a dynamic spectrum sensing scheme using a fast fourier transform (FFT) based energy detector for radio devices without knowing radio frequencies. The experimental and theoretical results of this study demonstrate that dynamic spectrum sensing with an FFT-based energy detector can retrieve signal frequencies faster than traditional schemes. It is also shown that it is possible to calculate a suitable set of parameters for minimizing the total sensing time associated with any given pairing of frequency missing rate and resolution.