On time-out driven power management policies in wireless networks

Switching the devices to low-power states in prolonged periods of inactivity is a widely used technique to conserve energy for battery-powered wireless devices. In this paper, we present a mathematical abstraction of time-out driven power management policies together with different wakeup mechanisms in wireless networks to characterize the energy-performance trade-offs. The time-out driven power management is modeled as a M/G/1/K queue with multiple vacations and an attention span. We then derive the steady state behaviors of such systems, and present a closed-form solution for systems with large buffers. The analysis reveals that the "best" power management policy to minimize the energy-delay product exhibits a threshold structure, i.e., when the traffic load is below a certain threshold, a node should switch to the low-power state whenever possible and always remain active otherwise, and suggests a threshold-based power management protocol.