Princeton University

School of Engineering & Applied Science

Cloud Radio Access Downlinks, with Backhaul Constrained Oblivious Processing

Dr. Shlomo Shamai (Shitz),Technion---Israel Institute of Technology
Engineering Quadrangle B-205
Wednesday, February 5, 2014 - 12:15pm to 1:15pm

The downlink of cloud radio access networks is considered. The central encoder is connected to multiple multi-antenna base stations (BSs) via finite-capacity backhaul links. The processing is done at the central encoder, while the distributed BSs employ only oblivious (robust) processing. First current state-of-the-art approaches are reviewed, where the signals intended for different BSs are compressed independently, or alternatively the recently introduced structured coding ideas (Reverse Compute-and-Forward) are employed.
We propose to leverage joint compression, also referred to as multivariate compression, of the signals of different BSs in order to better control the effect of the additive quantization noises at the mobile stations. We discuss the theoretical framework of this approach and address specifically the maximization of a weighted sumrate. For joint compression this is associated with the optimization of the the precoding matrix and the joint correlation matrix of the quantization noises, subject to power and backhaul capacity constraints. An iterative algorithm is described that achieves a stationary point of the problem, and a practically appealing architecture is proposed based on successive steps of minimum mean-squared error estimation and per-BS compression.
We conclude by comparison of different processing techniques, discussing a robust design concerning the available accuracy of the channel state information and overviewing some aspects for future research.
Joint work with S.-H. Park, O. Simeone (NJIT), and O. Sahin (InterDigital)
Shlomo Shamai (Shitz) is with the Department of Electrical Engineering,Technion---Israel Institute of Technology, where he is now a Technion Distinguished Professor, and holds the William Fondiller Chair of Telecommunications. His research interests encompass a wide spectrum of topics in information theory and statistical communications.
Dr. Shamai (Shitz) is an IEEE Fellow, a member of the Israeli Academy of Sciences and Humanities and a Foreign Associate of the US National Academy of Engineering. He is the recipient of the 2011 Claude E. Shannon Award. He has been awarded the 1999 van der Pol Gold Medal of the Union Radio Scientifique Internationale (URSI), and is a co-recipient of the 2000 IEEE Donald G. Fink Prize Paper Award, the 2003, and the 2004 joint IT/COM societies paper award, the 2007 IEEE Information Theory Society Paper Award, the 2009 European Commission FP7, Network of Excellence in Wireless COMmunications (NEWCOM++) Best Paper Award, and the 2010 Thomson Reuters Award for International Excellence in Scientific Research.  He is also the recipient of 1985 Alon Grant for distinguished young scientists and the 2000 Technion  Henry Taub Prize for Excellence in Research. He has served as Associate Editor for the Shannon Theory of the IEEE Transactions on Information Theory, and has also served twice on the Board of Governors of the Information Theory Society. He is a member of the Executive Editorial Board of the IEEE Transactions on Information Theory.