Energy-Efficient Detection Using Ordered Transmissions in Energy Harvesting WSNs

We propose a novel energy-efficient ordered transmissions scheme for Bayesian hypothesis testing in energy harvesting (EH) wireless sensor networks (WSNs), in which the EH nodes harvest energy from the environment and can replenish their batteries. The proposed scheme exploits the distributed timer scheme to ensure that the nodes transmit their readings to the fusion node in the decreasing order of their log likelihood ratios without any node knowing the readings of any other node. It addresses the new problem of missing transmissions that arises in EH WSNs because the energy harvested by the nodes is random. We show how the disruption caused in the sequence of ordered transmissions by these missing transmissions can be tackled. The proposed scheme not only reduces the number of transmissions, but also reduces the error probability compared to the conventional unordered scheme in which all the sensor nodes attempt to transmit in a pre-determined order. This is unlike several energy-efficient techniques that reduce the number of transmissions but increase the error probability.