Abstract

In this paper, we study algebraic aggregate computations in Sensor Networks. The main contribution is the presentation of an early-stopping protocol that computes the average function under a harsh model of the conditions under which sensor nodes operate. This protocol is shown to be time-optimal in the presence of infrequent failures. The approach followed saves time and energy by the computation relying on a small network of delegate nodes that can be rebuilt fast in case of node failures and communicate using a collision-free schedule. Delegate nodes run two protocols simultaneously, namely, a collection/dissemination tree-based algorithm, which is shown to be optimal, and a mass-distribution algorithm. Both algorithms are analyzed under a model where the frequency of failures is a parameter. Other aggregate computation algorithms can be easily derived from this protocol. To the best of our knowledge, this is the first optimal early-stopping algorithm for aggregate computations in Sensor Networks. (C) 2012 Elsevier Inc. All rights reserved.