One key issue in wireless sensor networks is energy efficiency. Aggregation techniques attempt to minimize the energy expended in communication by processing the data in the network rather than forwarding it all to a central point for processing. However, the naive application of this technique can result in a net increase in total energy expenditure due to the computational costs of the processing. In this paper, we present a new model for aggregation in wireless sensor networks, incorporating both the amount of data reduction achieved by the aggregation function and its associated computation costs. We then use this model to create a powerful, lightweight, distributed aggregation tree creation protocol, called Tethys, suitable for implementation in wireless sensor networks. We show that our protocol provides significantly lower energy consumption than protocols which do not take the amount of data reduction and computational cost of aggregation into consideration.
Multimedia applications have unique characteristics that can be leveraged to design energy-efficient loss recovery mechanisms. Given their loss tolerance and strict timing requirements, various frame dropping policies can be used to affect both application performance and energy consumption. However, the effects on energy consumption of such frame dropping policies depends on not only high-layer effects, but also the MAC layer underlying them. Therefore, we first present an analysis of an energy-efficient MAC-layer protocol, called Fast Transmit MAC Protocol (FTMP). We then explore three frame dropping policies: proactive, reactive, and opportunistic. We present the EELR (energy-efficient loss recovery) protocol, which uniquely combines all three frame dropping policies to provide both high energy efficiency and high application performance. EELR is implemented in a real system on top of an energysaving MAC layer that exposes information about transmission costs to the transport layer for use in frame dropping decisions. Through analysis and real-world experiments, we show that the combination of an energy-efficient MAC layer with a transport protocol using all three frame-drop policies outperforms any other combination.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.