Opportunistic routing in wireless sensor networks powered by ambient energy harvesting

Energy consumption is an important issue in the design of wireless sensor networks (WSNs) which typically rely on portable energy sources like batteries for power Recent advances in ambient energy harvesting technologies have made it possible for sensor nodes to be powered by ambient energy entirely without the use of batteries However since the energy harvesting process is stochastic exact sleep and wakeup schedules can not be determined in WSNs Powered solely using Ambient Energy Harvesters (WSN-HEAP) Therefore many existing WSN routing protocols cannot be used in WSN-HEAP In this paper we design an opportunistic routing protocol (EHOR) for multi-hop WSN-HEAP Unlike traditional opportunistic routing protocols like ExOR or MORE EHOR takes into account energy constraints because nodes have to shut down to recharge once their energy are depleted Furthermore since the rate of charging is dependent on environmental factors the exact identities of nodes that are awake cannot be determined in advance Therefore choosing an optimal forwarder is another challenge in EHOR We use a regioning approach to achieve this goal Using extensive simulations incorporating experimental results from the characterization of different types of energy harvesters we evaluate EHOR and the results show that EHOR increases goodput and efficiency compared to traditional opportunistic routing protocols and other non-opportunistic routing protocols suited for WSN-HEAP (C) 2010 Elsevier B V All rights reserved