Interactive Wireless Charging for Energy Balance

Wireless energy transfer is an emerging technology that is used in networks of battery-powered devices in order to deliver energy and keep the network functional. Existing state-of-the-art studies have mainly focused on applying this technology on networks of relatively strong computational and communicational capabilities (wireless sensor networks, ad-hoc networks), also they assume one-directional energy transfer from special chargers to the network nodes. Different from these works, we here study (for the first time in the state-of-theart) interactive, "peer-to-peer" wireless charging in populations of much more resource-limited, mobile agents that abstract distributed portable devices. In this new model for interactive wireless charging, we assume that the agents are capable of achieving bi-directional wireless energy transfer acting both as energy transmitters and harvesters. We consider the cases of both loss-less and lossy energy transfer and provide an upper bound on the time needed to reach a balanced energy distribution in the population. We investigate the delicate impact of the diversity of energy levels on eventual energy balance achieved and highlight some key elements of the charging procedure. In the light of the above, we design and evaluate three interaction protocols that achieve different tradeoffs between energy balance, time and energy efficiency.