University of Minnesota


DTC Seminar Series

Omnidirectional Precoding for Massive MIMO with Uniform Rectangular Array


Xin Wang
Department of Communication Science and Engineering
Fudan University, China

Thursday, March 21, 2019
1:30 p.m. reception
2:00 p.m. seminar

401/402 Walter Library

Xin Wang

In the public channels, it is desirable to transmit the common signals omnidirectionally to ensure cell-wide coverage. In this talk, we first develop low-cost closed-form omnidirectional precoding designs for a massive multiple-input multiple-output (MIMO) system equipped with a uniform rectangular array (URA). In particular, we derive an optimal solution based on the complementary set (CS) or the complete complementary codes (CCC). We prove that the precoding vectors based on the CS or CCC sequences can generate a perfectly flat radiation-power pattern. Since both CS and CCC sequences are binary and constant-modulus, the proposed schemes are well suited to be implemented in the radio frequency (RF) analog domain with low hardware cost and suppressed peak-to-average power ratio (PAPR). The design of the proposed closed-form schemes relies on the existence of the corresponding CS or CCC for a given URA configuration. To overcome the limitations, we further develop an iterative rank-reduction algorithm. It is shown that the proposed algorithm can always obtain three precoding vectors to generate a perfectly flat radiation-power pattern for any URA configuration. By further imposing the constant-modulus constraints for every entries of the precoding matrix, we propose a Newton’s method, which can always obtain a rank-4 omnidirectional precoding matrix for a general URA. The proposed numerical optimzation based schemes complement well the CS- and CCC-based schemes. Overall, this work provides a unified approach to omnidirectional precoding for massive MIMO equipped with URA.


Xin Wang (SM'09) received the B.Sc. and M.Sc. degrees from Fudan University, Shanghai, China, in 1997 and 2000, respectively, and the Ph.D. degree from Auburn University, Auburn, AL, USA, in 2004, all in electrical engineering. From September 2004 to August 2006, he was a Postdoctoral Research Associate with the Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis. In August 2006, he joined the Department of Electrical Engineering, Florida Atlantic University, Boca Raton, FL, USA, as an Assistant Professor, then was promoted to a tenured Associate Professor in 2010. He is currently a Distinguished Professor and the Chair of the Department of Communication Science and Engineering, Fudan University, China. His research interests include stochastic network optimization, energy-efficient communications, cross-layer design, and signal processing for communications. He served as an Editor for the IEEE Transactions on Vehicular Technology and as an Associate Editor for the IEEE Signal Processing Letters. He currently serves as an Editor for the IEEE Transactions on Wireless Communications and as an Associate Editor for the IEEE Transactions on Signal Processing. He is an IEEE Distinguished Lecturer for the Vehicular Technology Society.

Contact Information

Digital Technology Center

499 Walter Library, 117 Pleasant Street SE, Minneapolis, MN 55455

P: (612) 624-9510

Connect on Social Media