Optimal transmission policy for distributed beamforming with energy harvesting and battery operated sensor nodes

In this paper, we consider a scenario where one energy harvesting and one battery operated sensor cooperatively transmit a common message to a distant base station. The goal is to find the jointly optimal transmission (power allocation) policy which maximizes the total throughput for a given deadline. To that aim, we identify the necessary conditions for such optimal transmission policy. On their basis, we pose an optimization problem that we show to be convex. Performance is assessed by means of computer simulations. As benchmarks, we consider a system with a single energy harvesting sensor and, also, a scenario where the optimal transmission policy for the single-sensor case is adopted by both sensors.