Energy efficient sleep/wake scheduling of stations in wireless networks

A wireless ad hoc network is typically Constrained by battery power, and hence, it is important to conserve battery power in order to keep the network alive for a long time. We consider a wireless network consisting of an access point (AP) and a wireless node, which is limited by energy, and we seek scheduling algorithms that conserve battery power at the wireless node. Since the packet arrivals are stochastic, communication happens only during the time slots when packets are available. Hence, keeping the receiver ON at all times is wasteful of resources. However, when the receiver is turned OFF, a packet, on arrival, is stored in a buffer (at the AP) which incurs a holding cost. We propose sleep/wake scheduling at the wireless node with an objective of minimizing the power spent (at the receive node) and the queuing delay at the AP, while maintaining the stability of the queue. We note here that this energy optimum scheduling is a distributed problem in which the queue-length information at the transmitter is not known at the receiver. We show that the optimum wake process at the receiver follows closely as that of the arrival process of the packets at the AP. We numerically evaluate the optimum scheduler, and discuss the energy and queuing delay performance of our proposed optimum scheduler.