On Optimal Scheduling and Power Control for Uncoordinated Multiple Access by Energy Harvesting Nodes

The goal in this paper is to design an optimal scheduling and power control policy that maximizes the long-term time-averaged sum throughput of a Gaussian multiple access channel (MAC) with energy harvesting (EH) nodes, and facilitates uncoordinated operation of the nodes. In order to benchmark the performance of any policy, we derive an upper bound on the sum throughput by considering a genie-aided system where the nodes have infinite capacity batteries and can freely share the available energy between them. Next, we design a time-sharing based power control policy for the EH MAC, which operates in an uncoordinated fashion. We show that, surprisingly, the sum throughput obtained by the proposed policy achieves the genie-aided upper bound asymptotically in the battery size at each node. Simulation results validate the theoretical findings and illustrate the relative impact of various system parameters (e.g., the battery size required to achieve the upper bound) on the number of nodes and the variation in the harvesting rates across the nodes