Modulation and coding optimization for energy harvesting transmitters

Energy harvesting communication devices, which are able to convert different forms of ambient energy to electrical energy and use it for communications, have emerged as an alternative to the conventional devices powered by fixed utilities or batteries, due to their potential to be deployed in less accessible environments and to operate for longer time without any human intervention. As the energy input to such systems is in general non-constant, new resource management principles and resource allocation algorithms need to be developed. In this work, we evaluate the performance limit of energy harvesting transmitters in terms of throughput when only discrete modulation levels and coding rates are applicable, assuming perfect knowledge of energy arrivals and constant channel state during the time slot of interest. In addition, we employ a detailed circuit power model to account for the energy consumption within the transmitter circuitry. A throughput-maximizing energy expenditure trajectory can be obtained with the construction algorithm we propose which utilizes the Pareto boundary of the system on the powerrate graph, and it corresponds to an optimal adaptive modulation and coding strategy that the transmitter should employ.