On the Optimality of the Greedy Policy for Battery Limited Energy Harvesting Communications

TL;DR

This paper analyzes when a greedy power control policy maximizes throughput in battery-limited energy harvesting communication systems, providing conditions, bounds, and asymptotic relationships related to battery capacity and energy arrival statistics.

Contribution

It characterizes the exact conditions under which the greedy policy is optimal and derives bounds and asymptotic relationships involving battery capacity and energy arrival mean.

Findings

Greedy policy is optimal if battery capacity is below a specific threshold.

Bounds on the threshold are established.

Asymptotic analysis relates the threshold to the mean energy arrival.

Abstract

Consider a battery limited energy harvesting communication system with online power control. Assuming independent and identically distributed (i.i.d.) energy arrivals and the harvest-store-use architecture, it is shown that the greedy policy achieves the maximum throughput if and only if the battery capacity is below a certain positive threshold that admits a precise characterization. Simple lower and upper bounds on this threshold are established. The asymptotic relationship between the threshold and the mean of the energy arrival process is analyzed for several examples.