Distributed Coordination Protocols for Wireless Charging in Sensor Networks

Wireless power transfer is used to fundamentally address energy management problems in Wireless Rechargeable Sensor Networks (WRSNs). In such networks, mobile entities traverse the network and wirelessly replenish the energy of sensor nodes. In recent research on collaborative mobile charging, the mobile entities are also allowed to charge each other. In this chapter, we enhance the collaborative feature by forming a hierarchical charging structure. We distinguish the Chargers in two groups, the hierarchically lower, called Mobile Chargers, that charge sensor nodes and the hierarchically higher, called Special Chargers, that charge Mobile Chargers. We define the Coordination In this chapter, we investigate the problem of efficient wireless power transfer in wireless sensor networks where special mobile entities called Mobile Chargers, traverse the network and wirelessly replenish the energy of sensor nodes. The methods we present are distributed and use limited network information. More specifically, we propose four new protocols for efficient wireless charging while addressing key issues such as the identification of what are good coordination procedures and what are good trajectories for the Mobile Chargers. Two of our protocols (DC, DCLK) perform distributed, limited network knowledge coordination and charging, while two others (CC, CCGK) perform centralized, global network knowledge coordination and charging. As detailed simulations demonstrate, one of our distributed protocols outperforms a known state-of-the-art method, while its performance gets quite close to the performance of the powerful centralized global knowledge method.