Duty-Cycle Optimization for Machine-to-Machine Area Networks Based on Frame Slotted-ALOHA with Energy Harvesting Capabilities

We propose in this paper a simple method to optimize the duty-cycle of a Machine-to-Machine (M2M) area network equipped with energy harvesters so that the Energy Neutral Operation (ENO) can be achieved and thus devices can operate autonomously forever, as far as the communication part is regarded. We use an exponentially weighted moving-average (EWMA) filter to predict the energy harvested in a complete duty-cycle, and adjust the duty-cycle according to the energy required during the active periods. As a case study, we consider the use of the Frame Slotted-ALOHA (FSA) Medium Access Control (MAC) protocol in a data collection application where a central coordinator interrogates a group of end-devices equipped with solar panels. We evaluate the performance of the proposed mechanism by means of computer-based simulations and show that an optimal configuration of the prediction filter can help to reach the ENO condition and ensure the unlimited lifetime of the network.