On minimum delay duty-cycling protocol in sustainable sensor network

To ensure sustainable operations of wireless sensor networks, environmental energy harvesting has been well recognized as one promising solution for long-term applications. Unlike in battery-powered sensor networks, we are targeting a duty-cycle adjustment to optimize the network performance, e.g., delay minimization, with full harvested energy utilization. In this paper, we introduce a set of duty-cycle adjustment schemes that will minimize cross traffic delay (CTD) in energy-harvesting sensor networks. We first present an offline solution by assuming that the link reliability and traffic distribution are known a priori. Based on the submodular property of the CTD function, we theoretically prove that a simple greedy algorithm can achieve constant approximation. We next propose a class of online algorithms that do not require the knowledge of link reliability and traffic distribution. For each of these algorithms, we give a theoretical bound on the performance. We have evaluated our design with a TelosB-based implementation and experimental results corroborate our theoretical analysis.