An Energy-Efficient Node Activation Scheme for Reconfigurable Sensor Networks

This paper presents an energy-efficient node activation scheme that reduces the cost in recharging energy-depleted sensor nodes in a wireless sensor network. The network operation combined with node activation is modeled as a stochastic decision process, where the activation decisions directly affect the energy efficiency of the network. An analytical model is developed to formulate the network operation as a Semi-Markov Decision Process (SMDP) by assuming exponentially distributed recharging and discharging times. Using this model, an optimal activation policy is obtained that minimizes the recharging rate. To evaluate the developed node activation scheme, simulation was performed for both a correlated and an independent sensor network model. In the correlated model, a 72% reduction of recharging rate has been achieved, compared with no intelligent node activation. The approach presented provides a framework for designing wireless sensor networks where energy efficiency is of critical importance.