Optimal Transmission Policy for Cooperative Transmission with Energy Harvesting and Battery Operated Sensor Nodes

TL;DR

This paper develops an optimal transmission policy for cooperative sensor networks with energy harvesting and battery-powered nodes, maximizing throughput under various storage constraints and considering long-term battery effects.

Contribution

It introduces a convex optimization framework for joint power allocation, including cases with finite storage capacity and battery degradation effects.

Findings

Optimal policies can be computed independently for energy harvesting sensors.

Finite storage capacity impacts achievable throughput significantly.

Battery degradation affects long-term network performance.

Abstract

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. First, we address the case in which the storage capacity of the energy harvesting sensor is infinite. In this context, we identify the necessary conditions for such optimal transmission policy. On their basis, we first show that the problem is convex. Then we go one step beyond and prove that (i) the optimal power allocation for the energy harvesting sensor can be computed independently; and (ii) it unequivocally determines (and allows to compute) that of the battery operated one. Finally, we generalize the analysis for the case of finite storage capacity. Performance is assessed by means of computer simulations. Particular attention is paid to the impact of finite storage capacity and long-term battery degradation on the achievable throughput.