Operating frequency selection for low-power magnetic induction-based wireless underground sensor networks

The possibility of employing sensor nodes that wireless communicate under the ground, through concrete, or under-the-debris (disaster scenario) has been recently highlighted at the Wireless Underground Sensor Networks (WUSN) literature. Nonetheless, the best operating frequency for such systems is still an open research aspect. In this work, we address this question for mid-range distances (e.g., 15..30m) by proposing a soil path attenuation model for an underground magnetic induction (MI)-based system involving a pair of nodes. The model is empirically validated and based on simulation results it is possible to conclude that for mid-range MI systems it is strategic to adopt a dynamic frequency selection scheme where audio frequencies are chosen whenever high soil moisture levels are detected.