On Linear Power Control Policies for Energy Harvesting Communications

A comprehensive analysis of linear power control polices, which include the well-known greedy policy and fixed fraction policy as special cases, is provided. The notions of maximin optimal linear policy for given battery capacity $c$ and mean-to-capacity ratio $p$ as well as its $c$-universal versions are introduced. It is shown, among others, that the fixed fraction policy is $c$-universal additive-gap optimal but not $c$-universal multiplicative-factor optimal. Tight semi-universal bounds on the battery-capacity-threshold for the optimality of the greedy policy are established for certain families of energy arrival distributions.