Princeton University

School of Engineering & Applied Science

On the Capacity of Oblivious Cloud Relay Access Networks

Shlomo Shamai, Technion-Israel Institute of Technology
E-Quad, B205
Tuesday, September 19, 2017 - 4:30pm

Abstract: In this overview talk we will address Cloud Radio Access Networks and put focus on the uplink 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' codebooks, i.e., they operate in an oblivious manner.
The central processor, however, is informed about the users' codebooks, and attempts to decode the users' information. In particular, we establish a single-letter characterization of the capacity region of this model for a class of discrete memoryless 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 quantize-map-forward or noisy network coding, are optimal. The new converse part establishes, and utilizes, connections with the Chief Executive Officer (CEO) source coding problem under a logarithmic loss distortion measure. Memoryless vector Gaussian channels are also investigated and the capacity under Gaussian signaling, is established. For general memoryless 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.

Bio:  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 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. His research interests encompass a wide spectrum of topics in information theory and statistical communications.
Dr. Shamai (Shitz) is an IEEE Fellow, an URSI 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 recipient 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.