Analyzing the Multiple Aggregation Trees Technique for Fault Tolerance in Sensor Networks

The potential gains of deploying sensor networks for large scale applications are being realized. One of the basic operations in sensor networks is in-network aggregation. Among the various approaches to in-network aggregation, such as tree-based aggregation and gossip-based aggregation, the tree-based approaches have better performance and energy-saving characteristics. However, sensor networks are highly prone to failures. Numerous techniques suggested in literature to counteract the effect of failures have not been analyzed in depth. In this paper, we focus on the performance of these tree-based aggregation techniques in the presence of failures. First, we identify a fault model that captures the important failure traits of the system. Then, we analyze the correctness of simple tree aggregation with our fault model. We then use the same fault model to analyze the techniques that utilize redundant trees to improve the variance. We conclude that using multiple trees for tree aggregation do not necessarily result in substantial improvement in fault tolerance.