LEB-MAC: Load and energy balancing MAC protocol for energy harvesting powered wireless sensor networks

Ambient energy from solar, vibration, heat and wind provide alternative energy sources to power sensors and extend the lifetime of wireless sensor networks which have traditionally been powered by batteries. This paper aims to enhance the performance of energy harvesting powered wireless sensor networks in three aspects: relaying, scheduling, and medium access control. To better adapt to the characteristics of energy harvesting, an asynchronous receiver-initiated duty-cycling approach is preferred in energy harvesting powered wireless sensor networks. This reduces the duty cycle of senders, and regulates the active and sleep intervals according to the energy levels of sensors. When nodes run out of power and need time to recharge, network holes or voids develop, forcing data packets to be routed via other paths, like detours. The proposed relaying strategy aims to prevent holes by balancing the load across the network according to nodes' energy harvesting characteristics. This is a natural consequence of the asynchronous duty cycling by scheduling transmission based on the receiver's availability. The simulation results show that our scheme outperforms in terms of sender duty cycle, end-to-end delay and delivery ratio, especially in challenged conditions where other protocols fail.