2019年7月29日，美国特拉华大学Xiang-Gen Xia教授应徐正元教授邀请做了一场题为“Omnidirectional Transmission in Massive MIMO Systems and Sequences”的学术报告。报告会由徐正元教授主持，共50余名校内师生参加。此次报告会得到了“中科院无线光电通信重点实验室系列讲座”的支持，由中科大信息科学技术学院、中科院无线光电通信重点实验室承办。
本次报告中，Xiang-Gen Xia教授重点介绍了一些用于大规模MIMO系统的全向传输设计。Xiang-Gen Xia教授首先介绍了全向传输设计的背景，包括设计的动机、目标应用场景，如基站侧控制信息的发送等。紧接着Xiang-Gen Xia教授以详细的公式表达向我们展示了大规模MIMO系统中全向传输的系统模型。然后，Xiang-Gen Xia教授介绍了有限离散方向的设计准则，在这些设计中，每个发射天线的发射功率在每个瞬时时间对于所有发射天线是相同的，每个时刻每个方向上的接收功率也是恒定的，并且分别以1个、2个和4个信号流为例进行了详细介绍。
在上述基础上，Xiang-Gen Xia教授讨论了针对所有方向的互补序列设计准则，空时码的设计以及码字的选择等，具体讲述了由点阵到线阵再到面阵的不同设计。在Xiang-Gen Xia教授团队的研究中，生成并采用了可以携带信息的具有理想的自相关和互补的序列，当在发射机处使用较低维空时编码时，可以实现全空间分集。Xiang-Gen Xia教授同时给出了上述研究的仿真结果。报告结束后，Xiang-Gen Xia教授与在座的老师和同学们进行了深入的交流，达到了学术交流迸发思想的目的。
报告人介绍：
Xiang-Gen Xia received his B.S. degree in mathematics from Nanjing Normal University, Nanjing, China, and his M.S. degree in mathematics from Nankai University, Tianjin, China, and his Ph.D. degree in electrical engineering from the University of Southern California, Los Angeles, in 1983, 1986, and 1992, respectively. He is currently the Charles Black Evans Professor, Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, USA. Dr. Xia was the Kumar’s Chair Professor Group Professor (guest) in Wireless Communications, Tsinghua University, during 2009-2011, the Chang Jiang Chair Professor (visiting), Xidian University, during 2010-2012, and the WCU Chair Professor (visiting), Chonbuk National University, during 2009-2013. Dr. Xia’s current research interests include space-time coding, MIMO and OFDM systems, digital signal processing, and SAR and ISAR imaging. He is the author of the book Modulated Coding for Intersymbol Interference Channels (New York, Marcel Dekker, 2000).
Dr. Xia received the National Science Foundation (NSF) Faculty Early Career Development (CAREER) Program Award in 1997, the Office of Naval Research (ONR) Young Investigator Award in 1998, and the Outstanding Overseas Young Investigator Award from the National Nature Science Foundation of China in 2001. He is currently serving and has served as an Associate Editor for numerous international journals including IEEE Transactions on Signal Processing, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing, IEEE Transactions on Vehicular Technology, and Science China -- Information Sciences. Dr. Xia is Technical Program Chair of the Signal Processing Symp., Globecom 2007 in Washington D.C. and the General Co-Chair of ICASSP 2005 in Philadelphia. He is a Fellow of IEEE.
