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Capacity of Oblivious Cloud Relay Access Networks by Shlomo Shamai

Information Theory Society

Abstract: In this overview talk we will address Cloud Radio Access Networks and put focus on the up-link setting, operating in an oblivious (nomadic) mode. Specifically, we present networks in which users send information to a remote central destinations through relay nodes (radio units) that are connected to the destination (central processor) via finite-capacity error-free links. The relays are constrained to operate without knowledge of the users’ code books, i.e., they operate in an oblivious manner. The central processor, however, is informed about the users’ code books, and attempts to decode the users’ information. In particular, we establish a single-letter characterisation of the capacity region of this model for a class of discrete memory-less channels in which the outputs at the relay nodes are independent given the users’ inputs.

We show that both relaying `a-la Cover-El Gamal, i.e., compress-and-forward with joint decompression and decoding, and quantise-map-forward or noisy  network coding, are optimal. The new converse part establishes, and utilises, connections with the Chief Executive Officer (CEO) source coding problem under a logarithmic loss distortion measure. Memory-less vector Gaussian channels are also investigated and the capacity under Gaussian signalling, is established.

For general memory-less models (i.e., networks in which relay outputs are arbitrarily correlated among them, and with the channel inputs), we develop inner and outer bounds on the capacity region. Comparisons with unconstrained operation of the relays will also be presented gaining insights to the penalty associated with the oblivious processing. (Joint work with Abdellatif Zaidi, Inaki Estella Aguerri and Giuseppe Caire. This research was supported by the European Union’s Horizon 2020 Research And Innovation Programme under grant agreement no. 694630.)


About the speaker:  
Shlomo Shamai (Shitz) received the B.Sc., M.Sc., and Ph.D. degrees in electrical engineering from the Technion—Israel Institute of Technology, in 1975, 1981 and 1986 respectively.

During the period 1975-1985 he was with the Communications Research Labs in the capacity of a Senior Research Engineer. Since 1986 he 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.

Dr. Shamai (Shitz) is an IEEE Fellow,  a Member of the Israeli Academy of Sciences and Humanities and a Foreign Member of the US National Academy of Engineering.  He is the recepient of  the 2011 Claude E. Shannon Award, the 2014 Rothschild Prize in Mathematics/Computer Sciences and Engineering and the 2017 IEEE Richard W. Hamming Medal.

His research work encompasses a wide spectrum of topics in information theory and statistical communications to which he has contributed fundamentally. Some highlights of his scientific work comprise: Conclusive results on the capacity of the multi-input-multi-output broadcast Channels; Establishing basic connections between information theory and statistical estimation theory; Introducing pioneering concepts of interference alignment for communications networks and currently providing a unified information theoretic framework of cloud and fog radio access networks.

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 and 2015 European Commission FP7, Network of Excellence in Wireless COMmunications Best Paper Awards, the 2010 Thomson Reuters Award for International Excellence in Scientific Research, the 2014 Europian Association for Signal Processing (EURASIP) Best Paper Award, and the 2015 IEEE Communications Society Best Tutorial Paper Award. He is a Highly Cited researcher and is listed in the 2015 Thomson Reuters “The World’s Most Influential Scientific Minds”. 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 twice on the Board of Governors of the Information Theory Society. He has also served on the Executive Editorial Board of the IEEE Transactions on Information Theory and on the IEEE Information Theory Society Nominations and Appointments Committee.