Joint design of solar energy harvesting with wireless charging

Although wireless charging delivers energy reliably, it still faces regulatory challenges to provide high power density without incurring health risks. In clusteredWireless Sensor Networks (WSNs), relatively low energy supplies from wireless chargers cannot meet the rising energy demands from cluster heads. Fortunately, solar energy harvesting provides high power density without health risks whereas its energy supply is subject to weather dynamics. This chapter introduces a new framework with hybrid energy sources-cluster heads can use solar panels to scavenge solar energy and the rest of nodes are powered by wireless charging. The network is divided into three hierarchical levels. On the first level, we study a discrete placement problem of where to deploy solar-powered cluster heads that can minimize overall cost. Then the discrete problem is extended into continuous space for better solutions using the Weiszfeld algorithm. On the second level, we establish an energy balance in the network. A distributed cluster head reselection algorithm is proposed to regain energy balance when sunlight is unavailable. On the third level, we first consider the tour planning problem by combining wireless charging with mobile data gathering in a joint tour.We then propose a polynomial-time scheduling algorithm to find appropriate hitting points on sensors’ transmission boundaries for data gathering. Our simulation results demonstrate that network with hybrid sources can reduce battery depletion by 20% and save operating cost by 25% compared to previous works.