Power management unit for a self-sustaining Low Power Wide Area (LPWA) base station

In the design process of base stations, reliability and maintenance expenses are probably the dominant optimization targets. Yet, it was observed, that especially energy efficiency and environmental sustainability have been emerging concerns in the layout of base station systems in recent years. This process established the term of a Green Base Station, a base station that is operated by a hybrid energy feed via the mains grid and regenerative energy resources like wind and sun. In a previous paper related to the so-called BATS project, we introduced the design of a Low Power Wide Area (LPWA) sensor network base station, receiving vitality data of sensor nodes attached to bats. In this paper, we present the extension of the aforementioned telemetry-related base station in line with the Green Base Station concept, aiming at a self-sustaining operation. Therefor, the hardware design of a specialized Power Management Unit (PMU) is presented, serving the needs of telemetry base stations in the BATS project. Moreover, we address the software framework that runs the PMU and illustrate the design considerations of both, its hardware and software modules. Initial results of a field trial in Berlin, Germany are presented, showing possibilities for even further improvements.