It is a huge challenge to run IoT devices/sensors powered solely through ambient harvested energy. Since the harvested energy is less and is stochastic in nature, it is extremely challenging to achieve low latency and high reliability. To this end, we propose a distributed, energy-management module called ReNEW, using Constructive Interference (CI) to achieve our target of increased reliability, especially in the low harvesting regimes. We choose CI-based protocols to leverage low latency guarantees. Specifically, we propose a Markov-Decision model to maximize the energy utility in the infinite horizon by allocating energy optimally using a threshold-optimal policy. Since an energy scheduler is insufficient we propose distributed techniques to conserve energy on redundant nodes in the network, and dynamically activate them based on feedback. We implement ReNEW on Indriya and FlockLab testbeds for real-world scenarios in a network of 20 source nodes out of the 30 nodes. ReNEW collects data periodically with 2.5 times higher packet reception compared to LWB when the harvested energy is as low as 50μ J/s for 100B packets every 30s with a saving of 25% higher residual energy. In a nutshell, by integrating ReNEW with CI based protocols, we enable guaranteed latency and increased reliability in battery-less devices/networks.

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With the advent of low-cost, embedded sensor-actuator devices, the applications of cyber-physical systems have spread multi-fold in domains like infrastructure, manufacturing, automation, etc. Wireless sensor-actuator networks (WSANs) act as the backbone for applications in these domains. Typical WSAN deployments focus on energy-efficiency (in-turn lifetime) as replacing batteries is labor intensive and expensive. However, many CPS applications require highly-reliable data delivery with strict time bounds. Unfortunately, the classical approach of scheduling/prioritizing flows for bounded time communication is hard to implement with energy-constrained embedded devices. In this work, we present FLEET, a communication primitive that guarantees timely data delivery with 1) low latency by scheduling a maximum number of end-to-end flows within a short time span; 2) highly energy-efficient networking; and 3) reliable data delivery. Using a smart parallelization technique, FLEET achieves simultaneous transmissions while guaranteeing data delivery. This reduces the average duty-cycle of the nodes and makes it more energy-efficient than many state-of-the-art protocols. By combining multiple routing strategies, FLEET not only simplifies the schedulability problem but also accommodates more flows within a time span reducing delay considerably. Overall, with respect to the state of the art, FLEET offers a delay and duty cycling reduction by 2.2 and 2.8 times, respectively.@en