Abstract
In sensor networks, it is crucial to design and employ energy-efficient communication protocols, since nodes are battery-powered and thus their lifetimes are limited. This paper studies data dissemination in two-tiered networks comprised of stationary sensor nodes and mobile data users who request periodic sensor data updates. We propose a protocol called SAFE (sinks accessing data from environments) which attempts to save energy through data dissemination path sharing among multiple data sinks. Simulation results show that the proposed protocol is energy-efficient as well as scalable to a large data sink population.