Wireless Sensor Networks Powered by Ambient Energy Harvesting: An Empirical Characterization

Wireless Sensor Networks Powered by Ambient Energy Harvesting (WSN-HEAP) can perform the task of continuous and remote monitoring of the environment without the need for replacement of batteries. We identify three important design considerations for wireless networking protocols in WSN-HEAP: the unpredictable energy supply, the propagation losses in different environments and the suitable power level to use. In this paper, we perform an empirical characterization of commercially available solar and thermal energy harvesting sensor nodes. We deploy a transmitter-receiver pair at different distances and in various environments to conduct link measurements to determine the packet delivery ratio and RSSI values. We also quantified the energy harvesting characteristics of the sensor node. Then, we analyze the collected data to provide insights and guidelines for designing networking protocols for WSN-HEAP. Our analysis shows that the transmission range of the node is highly dependent on the environment in which it is deployed in and the RSSI values can only be used to estimate the transmitter-receiver distance in some environments. Furthermore, the charging time exhibits large variances even in the absence of mobility.