Abstract
Energy-efficiency is one of the major concerns in wireless sensor networks since it impacts the network lifetime. In this paper, we investigate the relationship between sensor networks performance, particularly its lifetime, and the number of reporting nodes N by using both analytical and simulation approaches. We first show that the network lifetime and the number of correctly received reports increase when N decreases. Moreover, we demonstrate that the average time required to report all event is a convex function of N. Based on these results, and as a main contribution, we prove that the optimal number of reporting nodes minimizing the energy consumption in the network does not correspond to the optimal number of reporting nodes allowing the fastest way to report an event. The tradeoff between these two requirements is therefore specific to each sensor application, depending on its particular needs. In this paper, we provide a simple methodology to achieve this tradeoff. (C) 2007 Elsevier B.V. All rights reserved.