NETWRAP: An NDN based real time wireless recharging framework for wireless sensor networks

A mobile vehicle equipped with wireless energy transmission technology can move around a wireless sensor network and recharge nodes over the air, leading to potentially perpetual operation if nodes can always be recharged before energy depletion. When to recharge which nodes, and in what order, critically impact the outcome. So far only a few works have studied this problem and relatively static recharging policies were proposed. However, dynamic changes such as unpredictable energy consumption variations in nodes, and practical issues like scalable and efficient gathering of energy information, are not yet addressed. In this paper, we propose NETWRAP, an NDN based Real Time Wireless Recharging Protocol for dynamic recharging in wireless sensor networks. We leverage concepts and mechanisms from NDN (Named Data Networking) to design a set of protocols that continuously gather and deliver energy information to the mobile vehicle, including unpredictable emergencies, in a scalable and efficient manner. We derive analytic results on energy neutral conditions that give rise to perpetual operation. We also discover that optimal recharging of multiple emergencies is an Orienteering problem with Knapsack approximation. Our extensive simulations demonstrate the effectiveness and efficiency of the proposed framework and validate the theoretical analysis.