Princeton Wireless Distinguished Seminar Series
Speaker: Danijela Cabric, UCLA
Title: Exploiting Abundance Millimeter Wave Spectrum for Low Latency Communications and Massive Connectivity Beyond 5G
Day: Friday, February 18, 2022
Time: 4:30 pm
Room: Zoom, Please Register
Host: Yasaman Ghasempour
Abstract: Future generations of millimeter wave (mmW) networks will operate in the upper mmW frequency band where ≥ 10 GHz bandwidth can be used to meet the ever increasing demands. While these abundant spectrum resources have been leveraged to increase data rates in 5G cellular, the next goal is to further diversify 5G performance for applications requiring low latency, high reliability, and massive connectivity. These new requirements demand fundamental rethinking of radio architectures, signal processing, and networking protocols to address challenges of extremely wide bandwidths, large antenna array sizes, and high cell density at mmW frequencies. First, we will discuss latency bottlenecks at the physical layer due to beam training overhead required to achieve beam alignment for different array architectures. By exploiting sparse propagation of mmW channel, the beam alignment can be accelerated using compressive sensing (CS) methods, however its practical realizations suffer from dictionary mismatch due to array hardware impairments and computational complexity. We have developed a machine learning assisted CS algorithm (mmRAPID) that self-calibrates array mismatches and experimentally demonstrated reduction of training overhead by 90% compared to exhaustive search performed by phased antenna arrays using a 60GHz Terragraph testbed.
Further reductions of beam training latency can be realized using a novel True-Time-Delay (TTD) array architectures. TTD arrays use delay elements in addition to phase shifters and can realize frequency dependent beamforming over a very wide bandwidth. We have developed a novel rainbow beam design for TTD arrays that uniquely maps frequencies into spatial direction and enables one-shot beam training using a single OFDM training pilot. We will discuss the requirements for TTD array parameters and trade-offs in different analog and hybrid architectures for their scalability over wide bandwidths and large antenna arrays. Lastly, we will explore how rainbow beamforming can be exploited for the design of ultra-reliable massive (Internet of Things) IoT network based on alignment-free and grant-free multiple access for both single and multiple antenna IoT devices. The proposed rainbow-link protocol achieves below 1ms user-plane latency and Mbps user rates with 0.99999 reliability of packet delivery in a 400m radius cell with 5 active single antenna narrowband (~10MHz bandwidth) IoTs per second per m2 (total of 500,000 users with sporadic traffic) using a 64 element analog TTD antenna array IoT gateway operating over 1GHz of bandwidth.
Bio: Danijela Cabric is a Professor in the Electrical and Computer Engineering Department at the
University of California, Los Angeles. She received M.S. from the University of California, Los Angeles in 2001 and Ph.D. from University of California, Berkeley in 2007, both in Electrical Engineering. In 2008, she joined UCLA as an Assistant Professor, where she heads Cognitive Reconfigurable Embedded Systems lab. Her current research projects include novel radio architectures, signal processing, communications, machine learning and networking techniques for spectrum sharing, 5G millimeter-wave, massive MIMO and IoT systems. She is a principal investigator in the three large cross-disciplinary multi-university centers including SRC/JUMP ComSenTer and CONIX, and NSF SpectrumX.
Prof. Cabric was a recipient of the Samueli Fellowship in 2008, the Okawa Foundation Research Grant in 2009, Hellman Fellowship in 2012 and the National Science Foundation Faculty Early Career Development (CAREER) Award in 2012, and Qualcomm Faculty Award in 2020 and 2021. She is serving as an Associate editor for several IEEE journals and on the IEEE Signal Processing for Communications and Networking Technical Committee. She was the General Chair of IEEE Vehicular Networking Conference (VNC) in 2019 and IEEE Dynamic Spectrum Access (DySPAN) in 2021, and a Distinguished Lecturer for IEEE Communications Society from 2018 to 2019. Prof. Cabric is an IEEE Fellow.
- Electrical and Computer Engineering
- Computer Science