| Abstract: |
Wireless embedded systems are networks of wireless nodes that perform tasks that involve communication, sensing, and actuation, embedded in the environment. Since these networks can be large
and must run unattended and safely for a long period of time, costs and energy are important design factors. As a consequence, system designs are commonly characterized by very little resources
in terms of available energy, memory, communication bandwidth and processing power. Due to these resource constraints, inspecting and building such systems is a challenging task. In this thesis,
we present approaches that increase the observability and controllability when testing wireless embedded systems in a pre-deployment testbed setting. By measuring several functional and
non-functional properties, tightly time synchronized across the entire network, studying these systems becomes possible in an unprecedented level of detail. For this purpose, we propose a new
testbed architecture, present new time synchronization protocols and develop algorithms to trace the program execution. The main contributions of this thesis are: - We design and build a new
testbed architecture that enables multi-modal inspection and control of devices under test. The combination of the testbed's services provide a previously unattained level of visibility into
wireless embedded systems. - We study the effect of time-of-flight in multi-hop time synchronization protocols, and we propose a new protocol that can effectively compensate propagation delays
that stem from dissimilar wave propagation times between nodes. Compared to previous approaches, our protocol achieves up to 6.9 x better synchronization accuracy. - We design and implement a new
distributed data acquisition system that combines fast data acquisition with accurate time synchronization to increase the possible level of detail of observations in a testbed. - We describe a
new algorithm that can be used to automatically place instrumentation code into existing programs for control flow tracing. The novelty stems from using time information of the program to keep
the induced overhead of instrumentation code low. - We showcase the usability of the testbed by employing it in a project that uses a sensor network to count devices based on radio
interference. |
