Date of Award
Master of Science (MS)
The synchronization of the clocks used at different devices across space is of critical importance in wireless communications networks. Each device’s local clock differs slightly, affecting the times at which packets are transmitted from different nodes in the network. This thesis provides experimentation and software development on POWDER, the Platform for Open, Wireless Data-driven Experimental Research, an open wireless testbed across the University of Utah campus. We build upon Shout, a suite of Python scripts that allow devices to iteratively transmit and receive with each other and save the collected data. We introduce WATCH, an experimental method to estimate clock differences using cross-correlation between the transmitted and received packets and considering both propagation delay and noise in the channel. WATCH sets up a matrix of node interactions for the chosen seven POWDER campus rooftop radios to find the difference between each node's local clock from the network's global clock, as well as any additional delay at each node before sending the transmitted packet. We set up a linear matrix equation to represent the node relationships and allow for the estimation of the clock offsets and transmit delays. WATCH was tested with collected data from transmitting both plain-text messages and PN codes. Several methods for reducing and analyzing error were used to evaluate the results, including the methods of least squares. This thesis concludes with WATCH, a tool for estimating distributed clock time offsets using data from iterative transmission across a wireless network.
Neal Patwari, Electrical & Systems Engineering
Joseph O’Sullivan, Jason Trobaugh