Dynamic timeout for data aggregation in wireless sensor networks

In-network data aggregation is a cross-layer routing technique which is essential for wireless sensor networks with a large number of nodes. Although the technique enhances energy efficiency by reducing packet transmissions, it may require routing-layer waiting time which introduces additional delays in packet delivery. This implies that there exists an energy-delay tradeoff which can be controlled depending on the delay level an application can tolerate. In this work, we first perform an in-depth analysis of the data aggregation process and validate the strong relationship between the amount of currently accumulated data in a node and the data aggregation timeout to achieve energy efficiency with little delay overhead. Then, we propose a novel timeout control scheme which dynamically changes timeout according to the amount of currently accumulated data in a node. Our scheme is based on local information without involving control messages so that it is not only robust but also light-weight. Evaluation results based on an implementation of the wireless sensor network show that our scheme facilitates efficient tradeoff between energy and delay. Thus, high energy efficiency can be achieved with little overhead in delay, and vice versa.