Degrees of Freedom Analysis for Multipath-Assisted Imaging Systems
Master of Science
We study the resolution limits of multipath-assisted imaging systems, a special class of computational radar/wireless imaging systems that exploit the multipath effects inherent to wireless propagation in order to increase the imaging resolution. Prior multipath-assisted system designs have demonstrated large resolution gains over line-of-sight (LOS) only imaging systems for error-free setups with no calibration errors. However, practical wireless imaging system designs suffer from phase synchronization errors and time-varying multipath. In this thesis, we first derive conditions for and demonstrate a multipath-assisted resolution gain over LOS-only imaging systems in the error-free case. We then quantify the effect of phase synchronization errors and channel matrix mismatch (due to time-varying multipath) on the achievable resolution limits. Our results show that channel matrix mismatch results in a large resolution loss compared to the error-free case; however, under certain conditions, resolution equivalent to the error-free case is achievable in the presence of phase synchronization errors. This indicates that a redesign of current multipath-assisted imaging systems is required as the performance gain of current designs (that calibrate only once prior to imaging) is limited in practical wireless environments with mobility.
Calibration; Computational Imaging; Degrees of Freedom; Multipath; Wireless Communications