Ang LiProfessor, School of Information and Communications Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China
Speech Title: Practical Interference Exploitation Precoding without Symbol-by-Symbol Optimization for MU-MISO Downlink: A Block-Level Approach
Abstract: In this talk, we share a new constructive interference (CI)-based block-level precoding (CI-BLP) approach for the downlink of a multi-user multiple-input single-output (MU-MISO) communication system. Contrary to existing CI precoding approaches which have to be designed on a symbol-by-symbol level, here a constant precoding matrix is applied to a block of symbol slots within a channel coherence interval, thus significantly reducing the computational costs over traditional CI-based symbol-level precoding (CI-SLP) as the CI-BLP optimization problem only needs to be solved once per block. For both PSK and QAM modulation, we formulate an optimization problem to maximize the minimum CI effect over the block subject to a block- rather than symbol-level power budget. We mathematically derive the optimal precoding matrix for CI-BLP as a function of the Lagrange multipliers in closed form. By formulating the dual problem, the original CI-BLP optimization problem is further shown to be equivalent to a quadratic programming (QP) optimization. Finally, numerical results validate our derivations, and show that the proposed CI-BLP scheme achieves improved performance over the traditional CI-SLP method, thanks to the relaxed power constraint over the considered block of symbol slots.
Biography: Ang Li received his Ph.D. degree in the Communications and Information Systems research group, Department of Electrical and Electronic Engineering, University College London in April 2018. He was a postdoctoral research associate in the School of Electrical and Information Engineering, The University of Sydney from May 2018 to February 2020. He joined Xi’an Jiaotong University in March 2020 and is now a Professor in the School of Information and Communications Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, China. His main research interests lie in the physical-layer techniques in wireless communications, including MIMO/massive MIMO, interference exploitation, symbol-level precoding, and reconfigurable MIMO, etc. He currently serves as the Associate Editor for IEEE Communications Letters, IEEE Open Journal of Signal Processing, and EURASIP Journal on Wireless Communications and Networking. He is the recipient of the 2021 IEEE Signal Processing Society Young Author Best Paper Award. He has been an Exemplary Reviewer for IEEE Communications Letters, IEEE Transactions on Communications, and IEEE Wireless Communications Letters. He has served as the Co-Chair of the IEEE ICASSP 2020 Special Session on 'Hardware-Efficient Large-Scale Antenna Arrays: The Stage for Symbol-Level Precoding', and has organized a Tutorial in IEEE ICC 2021 on 'Interference Exploitation through Symbol Level Precoding: Energy Efficient Transmission for 6G and Beyond'.