Event
Ph.D. Research Proposal Exam: Ahsan Nazar
Friday, October 9, 2026
3:30 p.m.
AVW 2328
Souad Nejjar
301 405 8135
snejjar@umd.edu
ANNOUNCEMENT: Ph.D. Research Proposal Exam
Name: Ahsan Nazar
Committee:
Professor Sennur Ulukus (Co-Chair)
Professor Zhambyl Shaikhanov (Co-Chair)
Professor Behtash Babadi
Date/time: Friday, October 9, 2026 at 3:30pm
Location: AVW 2328
Title: Toward mmWave and THz Wireless Systems and Wavefront Engineering for Sensing, Communication, and Privacy
Abstract: The growing demand for higher data rates and more capable wireless sensing is driving emerging systems toward millimeter-wave (mmWave), sub-terahertz (sub-THz), and terahertz (THz) frequencies. Large bandwidths enable high-rate communication and fine range resolution for sensing, while short wavelengths support electrically large antenna arrays with high angular resolution and precise beam steering. At these frequencies, the radiative near field can also extend over practical communication distances, where spherical wavefronts introduce range-dependent spatial structure. These properties provide new opportunities for communication, sensing, and wavefront engineering.
The first research thrust exploits the range-dependent structure of near-field propagation for integrated sensing and communication (ISAC). We develop a full-duplex framework that jointly supports downlink communication, uplink communication, and multi-target sensing. Near-field focusing adds range as a spatial degree of freedom, allowing targets at similar angles to be separated by distance while improving power efficiency relative to half-duplex and far-field benchmarks.
The second research thrust exploits the fine range resolution of wideband automotive mmWave radar through LuGuardian, a system for low-clearance bridge and tunnel safety. A passive multi-lane butterfly retroreflective tag spatially encodes the entrance clearance profile, which is recovered using super-resolution processing and geometry-aware decoding. During traversal, controlled auxiliary sensing beams reconstruct the roadway and overhead structure while preserving the primary forward-looking beam. Experiments using a 77-GHz automotive radar demonstrate centimeter-scale clearance estimation in real bridge and underpass environments.
The proposed research explores how the extended near field at high frequencies can be used to directly shape how a wavefront propagates through space, opening new applications beyond conventional beam steering and focusing. One such application is physical-layer location privacy. The wide bandwidths and large electrical apertures available at high frequencies enable increasingly precise time-of-flight and angle-of-arrival measurements, allowing a receiver to infer a transmitter's location directly from the received wavefront. WaveLoc investigates whether this same wavefront can instead be engineered so that these measurements correspond to a controllable virtual location while preserving the communication link. Curved wavefronts have also been shown to maintain communication around obstacles, but existing approaches assume that the blocker location and size are already available through external sensing. We instead propose to use structured wavefronts intended for communication to also probe the environment. Wideband observations at the receiver will estimate the blockage location and extent, and these estimates will guide the optimization of the curving-wavefront parameters. Together, these research thrusts progress from exploiting high-frequency propagation for communication and sensing to actively controlling how wireless signals propagate and interact with their environment, enabling new applications in sensing, resilient communication, and physical-layer privacy.
