  Wireless energy harvesting sensor networks constitute a new paradigm, where
the motes deployed in the field are no longer constrained by the limited
battery resource, but are able to re-charge themselves through directed
electromagnetic energy transfer. The energy sources, which we call actors, are
mobile and move along pre-decided patterns while radiating an appropriate level
of energy, sufficient enough to charge the sensors at an acceptable rate. This
is the first work that investigates the impact of energy transfer, especially
concerning the energy gain in the sensors, the energy spent by the actors, and
the overall lifetime in the resulting mobile sensor-actor networks. We propose
two event-specific mobility models, where the events occur at the centers of a
Voronoi tessellation, and the actors move along either (i)the edges of the
Voronoi cells, or (ii) directly from one event center to another. We undertake
a comprehensive simulation based study using traces obtained from our
experimental energy harvesting circuits powering Mica2 motes. Our results
reveal several non-intuitive outcomes, and provide guidelines on which mobility
model may be adopted based on the distribution of the events and actors.
