Ahmed of The Hong Kong University of Science and Technology (HKUST)

ABSTRACT: The demand for higher data rates and increased network capacity has driven the transition to millimeter-wave and sub-THz frequency bands, which offer vast, untapped spectral resources. However, achieving high-performance wireless links at these frequencies presents significant challenges, including high propagation path loss, limited semiconductor device performance, and stringent signal integrity requirements. Overcoming these obstacles requires a holistic system-level optimization approach to physical layer design, integrating circuit innovations, advanced modeling, digital signal processing, and enhanced measurement techniques. In this talk, I will present key research contributions aimed at addressing these challenges. First, I will introduce a novel approach for modeling and mitigating nonlinearities in beamforming arrays, where antenna mutual coupling induces steering-dependent distortions. Next, I will present a near-field probe antenna designed to enable in-situ feedback for beamforming array calibration and linearization training. The discussion will then shift to a new architecture for sub-THz signal generation using frequency multipliers, addressing the operational frequency limitations inherent in traditional signal generation methods. Finally, I will introduce a novel measurement methodology that enables the characterization of high-frequency components under wideband modulated signals, leveraging frequency extenders—bridging the gap between CW-only and modulated-signal testing at millimeter-wave and sub-THz frequencies. I will conclude by outlining future research directions, including the development of multi-input multi-output (MIMO) array systems for both mid-band (FR3) and high-band applications, novel measurement techniques for emulating large-scale antenna arrays, and advanced frequency multiplier design and linearization methods tailored for high-fidelity signal generation at increasingly higher frequencies.

Biography:

Dr. Ahmed Ben Ayed is an Assistant Professor in the Department of Electronic and Computer Engineering at The Hong Kong University of Science and Technology (HKUST), where he leads the Intelligent Radio and Integrated Systems (IRIS) Laboratory. Prior to joining HKUST, he was a Postdoctoral Researcher at the University of Waterloo, Canada. He received the BEng degree in Electronic Engineering, with a Minor in Mathematics, from HKUST in 2017, and the MASc and PhD degrees in Electrical and Computer Engineering from the University of Waterloo in 2019 and 2024, respectively. Dr. Ben Ayed’s research focuses on advancing physical-layer modeling, design, and optimization for next-generation wireless and satellite communications (SATCOM) systems. His work integrates nonlinear behavioral modeling and linearization, hardware-aware signal processing, beamforming antenna-array systems, high-efficiency RF circuit design, and advanced test and measurement techniques.