On the fundamental capacity and lifetime limits of energy-constrained wireless sensor networks

Energy constraints on sensor nodes pose significant challenges towards extending operational lifetimes and sustainable capacities of wireless sensor networks. We seek to answer two fundamental questions with respect to energy-constrained sensor networks. First, what is the operational lifetime of a particular wireless sensor network under the control of optimal power management schemes? With an adequate definition of operational lifetimes, our asymptotic analysis shows that, with fixed node densities, operational lifetime of sensor networks decreases in the order of 1/n as the number of initially deployed nodes n grows. Second, what is the impact of constrained energy levels on the maximum sustainable throughput in sensor networks? Even with renewable energy sources on each of the sensors (e.g., solar energy sources), our analysis concludes that the maximum sustainable throughput in energy-constrained sensor networks scales worse than the capacity based on interference among concurrent transmissions as long as the physical network size grows with n in the order greater than log n. In this case, when the number of nodes is sufficiently high, the energy-constrained network capacity dominates.