Joint Device Charging and Fresh Data Retrieval With Mobile Edge Device in Wireless-Powered IoT Systems

Introducing mobile edge devices in IoT systems for real-time data retrieval can reduce energy consumption and human interaction, and thus has attracted significant research attentions in recent years. In the meanwhile, leveraging mobile edge device(s) to charge the sensor devices in proximity through RF-based Wireless Energy Transfer (WET) technologies can provide controllable and stable energy supply, and is being increasingly deployed in the field. Based on these two recent trends, this work aims to formulate and solve the joint device charging and fresh data retrieval problem where a speed-adjustable mobile edge device judiciously powers a set of sensor devices in emergent energy shortage through WET while retrieving designated data items through multi-hop transmissions. To this end, an efficient 3-phase method for Joint Charging and Retrieving (3JCR) is proposed. 3JCR first identifies the sensor devices to be charged and develops the moving trajectory of the mobile edge device. It then applies a max-flow min-cost based clustering scheme to determine the routing path of the required data items to be transmitted to the mobile edge device, and finally constructs the data retrieval schedule and adjusts the speed of the mobile edge device in the run time. Our extensive experimental results show that 3JCR outperforms all state-of-the-art methods in terms of the number of feasibly retrieved data items, while achieving similar node survival rate.