Wake-up radio-enabled wireless networking: measurements and evaluation of data collection techniques in static and mobile scenarios

Abstract

Multi-hop wireless networks such as Wireless Sensor Networks and in general, networks without the support of a fixed infrastructure, enable most applications of the Internet of Things. These networks are comprised of wirelessly communicating nodes that are often powered by batteries. In many relevant scenarios-ranging from precision agriculture to oceanographic surveillance-it is inconvenient or impossible to replenish or to replace the energy systems of these nodes, which limits the operational lifespan of the network. One of the most significant sources of power consumption comes from idle listening on the node's wireless transceiver (main radio). This consumption can be reduced by endowing the nodes with Wake-up Radio (WuR) technology: Nodes keep their main radio off while listening for a signal via an ultra-low power auxiliary radio used only for wake-up purposes. When the appropriate signal is received, the node turns its main radio on, conducts the necessary exchange of packets, and then turns off its main radio. This strategy allows for a considerable reduction in power consumption. This dissertation investigates data collection approaches that leverage WuR technology to maximize the lifespan of multi-hop networks for data gathering, via routing and via a Mobile Data Collector (MDC). We analyze contemporary WuR technology, isolating the main criticalities of the state-of-the-art, including range and data rates. We use WuR prototypes with highly desirable characteristics to conduct experiments to measure effective communication ranges, in both static and mobile scenarios. We then examine the application of WuR technology to data collection based on multi-hop routing. We devise new techniques and evaluate the effects of different WuR characteristics on the performance of routing, considering what the network performance could be if we could overcome the limitation of current WuRs. The culmination of this dissertation focuses on mobile data collection protocols and approaches. We conduct a comprehensive survey of mobile data collection studies and protocols. We develop a robust taxonomy to set the framework for our analyses of various methodologies and elements of mobile data collection. We define two collection strategies: a simple naïve strategy, and a novel AI-driven adaptive strategy. Both strategies leverage WuR technology to minimize the amount of time SNs remain awake. Considering both duty cycle-based and WuR based scenarios, we conduct extensive experiments with a quad-rotor UAV-MDC and a network of WuR-enabled wireless sensor motes. We replicate these experiments in our simulator, informed by the parameters and characteristics observed in our real-world experiments. Having validated our simulations, we proceed to execute exhaustive simulation-based experiments. We evaluate the effects of scale (namely, network size and deployment region size) on the performance of the naïve and adaptive strategies, and we contrast the energy efficiency. The WuR-based scenarios experience considerably lower time spent awake, which gives rise to longer network lifespan. The adaptive strategy minimizes the time taken for each collection cycle, thereby reducing the amount of time spent awake in the duty cycle-based scenarios. The adaptive strategy also results in a noticeable reduction in both the awake duration and latency for the WuR-based scenarios.--Author's abstract