Title: Omnidirectional precoding for massive MIMO with uniform rectangular array
Time: 10:00 on November 22, 2019
Location:Information Building 240
Speaker: Wang Xin
Moderator: Qiao Deli
Introduction of the speaker:
Wang Xin, received his bachelor's and master's degrees in electrical engineering from Fudan University in 1997 and 2000, and received his doctorate in electrical and computer engineering from Auburn University in 2004. He was engaged in post-doctoral research at the University of Minnesota from 2004 to 2006, and taught at Florida Atlantic University (FAU) from 2006 to 2012. In 2010, he received a lifetime faculty position two years in advance and was promoted to be an associate professor. Now he is a distinguished professor and the head of the Department of Communication Science and Engineering of Fudan University. He mainly engages in the research of broadband wireless network, communication signal processing, cross-layer network design, and energy-efficient green communication.
He has published 65 SCI papers in IEEE International Journals, including 63 papers in the most important IEEE journals in the field of wireless communications. He won the title of National Youth Distinguished Expert and Shanghai Distinguished Expert, and served as IEEE Distinguished Lecturer, Senior Area Editor of IEEE Signal Processing Flagship Periodical TSP, and Editor of IEEE Wireless Communications Flagship Periodical TWC.
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.