Design and analysis of an adaptive duty-cycling scheme for load balance in wireless sensor networks

The power issue in wireless sensor networks is one of the critical problems since each node has a limited source of power, which is commonly impossible to replenish. The most effective strategy to save the energy is to schedule the nodes to switch between sleeping state and active state. In the prior studies of employing sleep/wakeup protocol, each node follows its cycle of sleep and active state, called schedule period, without considering the network connectivity. Thus, it causes some additional communication delays. To deal with this problem, topology control schemes have been proposed to extend the network lifetime and minimize the communication delays. However, the energy consumption on each node is not well-balanced, in which some nodes deplete their energy and die earlier than the others. It far more reduces the network coverage and prevents seamless communications in the network, and thus reduces the network life time. In this paper, we propose an Adaptive Duty-cycling (ADC) approach. The ADC scheme can enable well-balanced energy consumption among all nodes while minimizing a small additional communication delay by applying a different duty-cycle to each group. Simulation results show that our propose scheme can extend the network lifetime at least 25% compared to the conventional ones. It also guarantees the communication delay under a constant throughout the network lifetime.