Optimal transmission policies for energy harvesting node with non-ideal circuit power

This paper develops a unified approach to obtain optimal transmission schedule for an energy-harvesting node with non-ideal circuit power consumption. For both time-invariant and time-varying fading channels, we show that the optimal transmission between any two consecutive channel or energy state changing time, termed epoch, can only take one of the three strategies: (i) no transmission, (ii) transmission with an energy-efficiency (EE) maximizing power over part of the epoch, or (iii) transmission with a power greater than the EE-maximizing power over the whole epoch. Taking into account this structure, we develop efficient algorithms capable of computing the optimal scheduling schemes with a low complexity. The proposed approach can provide the optimal benchmarks for practical schemes in energy-harvesting powered transmissions, and can be employed to develop efficient online scheduling schemes.