ENERGY HARVESTING COMMUNICATIONS WITH NON-IDEAL BATTERIES AND CIRCUIT POWER

Abstract

Modern Internet of Things devices will increasingly rely on energy harvested from the environment. In such systems, the harvested energy is usually stored (charged) in and drawn (discharged) from batteries for smoothening its inherent random fluctuations. In practical batteries, the charging and discharging processes incur energy losses, where the losses are non-linear functions of charging and discharging powers. This necessitates low power charging and discharging for higher energy efficiency in the battery. Further, in many energy harvesting applications, the circuit power, the power required to run the circuitry, is in the order of the harvested power. This necessitates bursty transmissions with high power discharge for higher energy efficiency in the circuit. To account for the above conflicting effects, we jointly consider: (a) the non-zero circuit power and (b) the non-linear battery charging and discharging losses, and optimize information rates by finding power allocation policies under several different wireless communication scenarios. From the study, we observe that (a) and (b) significantly impact the design, optimization and the performance of energy harvesting wireless communication systems.