IEEE / UBC ECE Seminar

7 January 2022 @ 10:30 – 11:30

UBC ECE Seminar, co-sponsored by the IEEE Vancouver Joint Communications Chapter

Title: Learning to maximize a convex quadratic function with application to intelligent reflection surface for wireless communication

Presented by: Prof. Zhi-Quan (Tom) Luo
Vice President (Academic), Professor
School of Science and Engineering
The Chinese University of Hong Kong (Shenzhen)

Date and time: Friday, January 7, 2022, from 10:30 am to 11:30 am

Zoom link 
Meeting ID: 631 414 5651
Passcode: 431623

Abstract: In this talk we consider learning and optimizing a rank-2 convex quadratic function over N variables, each taking K discrete values on the unit circle. This problem arises from optimal design of a passive beamformer for intelligent reflecting surface (IRS) in order to maximize the overall channel strength. When K=2 and the quadratic function (or channel state information) is known, we propose a linear time algorithm that is capable of reaching a globally optimal solution of the problem. When the quadratic function is unknown (i.e. in the absence of channel state information) we propose a random max sampling (RMS) method and a conditional sample mean (CSM) method to maximize the quadratic function. We show that RMS method can provide a SNR boost that is linear in N (the number of reflective elements in IRS), while the CSM can boost the SNR quadratically (in N), all with polynomial number of samples.  Field trial results demonstrate the effectiveness of the proposed CSM method in the commercial 5G communication networks, providing >10dB SNR gain in both typical indoor and outdoor scenarios, and with no need to modify the current communication protocols and design.

Biography: Zhi-Quan Tom Luo received his B.Sc, Applied Mathematics, from Peking University in 1984 and PhD from MIT in 1989. He was with the McMaster University, Canada, from 1989 to 2003, where he served as the Head of the ECE Department and held a Canada Research Chair in Information Processing. He has been with the ECE Department at the University of Minnesota (Twin Cities), since 2003-2014. He is Vice President (Academic) and Professor of School of Science and Engineering, the Chinese University of Hong Kong (Shenzhen) (2014-present). His research interests lie in optimization algorithms for signal processing, data analytics and digital communication. He is a Fellow of IEEE and SIAM. In 2014 he was elected to the Royal Society of Canada, and to the Chinese Academy of Engineering as a foreign member in 2021. He has been an active IEEE volunteer (e.g., serving as the EIC for the IEEE Transactions on Signal Processing) and has received numerous awards and recognitions (e.g., best paper awards, the 2010 Farkas Prize, the 2018 prize of Paul Y. Tseng Memorial Lectureship in Continuous Optimization).