Relay Scheduling for Cooperative Communications in Sensor Networks with Energy Harvesting

This paper considers wireless sensor networks (WSNs) with energy harvesting and cooperative communications and develops energy efficient scheduling strategies for such networks. In order to maximize the long-term utility of the network, the scheduling problem considered in this paper addresses the following question: given an estimate of the current network state, should a source transmit its data directly to the destination or use a relay to help with the transmission? We first develop an upper bound on the performance of any arbitrary scheduler. Next, the optimal scheduling problem is formulated and solved as a Markov Decision Process (MDP), assuming that complete state information about the relays is available at the source nodes. We then relax the assumption of the availability of full state information, and formulate the scheduling problem as a Partially Observable Markov Decision Process (POMDP) and show that it can be decomposed into an equivalent MDP problem. Simulation results are used to show the performance of the schedulers.