Follow the Rays: Understanding the Interplay between Environment and System through In-Situ Wireless Modelling

The Internet of Things and Cyber-Physical Systems rely on wireless interconnections. The importance of understanding the behaviour of wireless communication in practice has promoted many experimental studies, characterising signal propagation in specific environments. Despite the gathered knowledge, the perceived discrepancy between abstract models and actual network performance has supported the belief that system design and debugging can rely only on direct experience and trial-and-error. As a result, reasoning about wireless systems is nowadays a tedious, manual process. This work walks the playground between model and reality to make wireless networks understand their own behaviour in the environment where they operate. First, we introduce a practical method able to efficiently and accurately characterise wireless signal propagation in 3D environments with obstacles. We then exploit the model to make systems autonomously derive the impact of obstacles such as doors and windows on the link conditions. With an outline of the operational scenario and measurements from deployed devices, it is possible to effortlessly generate a situated, dynamic wireless map. We demonstrate our approach in an indoor testbed, showing its practicability and effectiveness. Our evaluation shows that our approach attributes up to 91% of the measurements to the corresponding obstacles correctly. We also show that different modelling techniques have an impact on such detection accuracy, promoting the use of 3D environment descriptions.