Theoretische Grundlagen der Kommunikationstechnik

Invitation to a talk by Dr. An Liu, Hong Kong University of Science and Technology, China

Time27 July 2016, 11:00 AM  
LocationHFT - Hochfrequenztechnik building, 6th floor, Room HFT-TA 617, Einsteinufer 25, 10587 Berlin  
TitleClosed-Loop and Structured Compressive Channel Estimation for Massive MIMO  


Acquisition of accurate channel state information (CSI) at the transmitter (CSIT) is a major challenge of deploying frequency-division duplexing (FDD) massive MIMO systems. Although compressive sensing (CS) based channel estimation (CE) approaches have been proposed to reduce the pilot training overhead for massive MIMO systems, the existing schemes cannot properly dimension the minimum required pilot symbols to estimate the CSIT of all users at the required CSIT quality, because of the loose bounds on the required number of measurements for successful CS recovery and the unknown sparsity levels of user channels. In this talk, we propose a robust closed-loop pilot and CSIT feedback resource adaptation framework which not only exploits the joint burst-sparsity of the multi-user (MU) massive MIMO channels to improve the CSIT estimation performance, but also has the built-in learning capability to adapt to the minimum pilot and feedback resources needed for successful CSIT recovery under unknown and time-varying channel sparsity levels. We establish the convergence of the proposed closed-loop adaptation algorithm under mild conditions. We also accurately characterize the channel estimation error of the proposed compressive CE algorithm. Both simulations and analysis show that the proposed framework has substantial performance gain over conventional open-loop algorithms and is very robust to dynamic sparsity as well as model mismatch. 



An Liu received the Ph.D. and the B.S. degree (Distinguished Graduate in Beijing City) in Electrical Engineering from Peking University, China, in 2011 and 2004 respectively. From 2008 to 2010, he was a visiting scholar at the Department of ECEE, University of Colorado at Boulder, USA. From 2011 to 2013, he was a Postdoctoral Research Fellow with the Department of ECE, Hong Kong University of Science and Technology, and he is currently a Research Assistant Professor. His research interests include Wireless Communications (focusing on 5G wireless networks), Stochastic Optimization, Advanced RRM and Interference Mitigation, and Compressive Sensing. His industry experience includes one year's internship at Intel China Research Center Beijing, and 2 years' R&D experience as a Chief Technician and one of the Founders in D-rate Corporation, Beijing. He has contributed to 8 US/CN patents on wireless systems and signal processing. Academically, he has published 16 papers on IEEE Transactions on Signal Processing, 2 papers on IEEE Transactions on Wireless Communications, 1 paper on IEEE/ACM Transactions on Networking, and many IEEE conference papers. He has served as Member of Technical Program Committees for several major IEEE conferences in wireless communications, such as IEEE Globecom and IEEE ICC.