Throughput optimal energy neutral management for energy harvesting wireless sensor networks

Energy harvesting techniques have enabled the provisioning of alternative energy sources beside the conventional one which is typically provided by the batteries. Using such harvesting techniques together with proper energy management mechanisms, a Energy Neutral state can be achieved so that desired performance level can be supported perpetually. Existing energy neutral management mechanisms rely on the prediction of the amount of energy that can be harvested in the future. Such mechanisms suffer from the time consuming prediction processes and great fluctuations in the actual implementations. Hence, in this paper we propose real time adaptive energy management policies that enable energy neutral management based solely on observed information in the past instead of predicting the amount of energy that can be harvested in the future. We will show that these policies are throughput optimal in the sense that we are able to ensure that the data queue of each sensor node remain stable when the largest possible data rate is applied under different channel capacity scenarios. We also propose an energy harvest-store(use) method to reduce the energy losses caused by storing energy in non ideal energy buffers. Simulation studies show that our proposed throughput optimal policies and harvest-store(use) method are indeed able to improve the overall throughput as compared to existing schemes.