Multi-tier probabilistic polling in Wireless Sensor Networks powered by energy harvesting

Wireless Sensor Networks (WSNs) that consist of battery powered sensor nodes start to lose operational capability once the nodes´ batteries run out of power. To ensure the sustainability of WSNs, researchers have turned to alternative energy sources for power. Harvesting ambient energy from the environment to power WSNs is a promising approach but energy harvesting devices of the same footprint as wireless sensors are unable to provide sufficient energy for sustained operation. More likely, the energy harvested over a period is only enough for a sensor to sense and transmit a few packets before it needs to harvest more energy. Furthermore, the availability of energy varies depending on the environmental conditions and energy harvesting technology used. With sensor nodes operating in discontinuous periods, relaying data over multiple wireless links to remote data acquisition systems is a daunting challenge. In this paper, a multi-tier probabilistic polling scheme is proposed for multi-hop data delivery in wireless sensor networks that rely solely on energy harvesting for power. Unlike existing work which rely on simulations, we have implemented the scheme on commercial-off-the-shelf hardware and validated it experimentally to demonstrate its viability.