Opportunistic Power Allocation schemes for the maximization of network lifetime in wireless sensor networks

In this paper, we propose and analyze two opportunistic power allocation (OPA) schemes suitable for decentralized parameter estimation in wireless sensor networks. In these schemes, only sensors for which some locally obtained quality measure exceeds a threshold computed and then broadcasted by the FC, can actually participate in the estimation process. Subsequently, the sensors adjust their transmit power in such a way that the prescribed estimation quality target can be met at the FC. In particular, we consider two different criteria to design the reporting threshold: (1) to minimize the transmit power, which merely requires partial channel state information (CSI); and, (2) to maximize network lifetime which additionally requires residual energy information (REI). For each design, we first define the local decision rule and then we derive closed-form expressions of the global reporting threshold. Then, we assess the performance of the proposed OPA schemes by means of computer simulations, and we carry out a comparison with the optimal water-filling (WF) solution. Results are given in terms of transmit power and average network lifetime.