This research project has been focused on the development of novel information theoretic
concepts and techniques and their usage, as to identify the ultimate communications
limits and potential of different cloud radio access networks (C-RAN) and fog radio
access networks (F-RAN) structures, in which the central signal processing is
migrated from the radio units to the cloud (remote central units), via
fronthaul/backhaul infrastructure links. Moreover, it was directed also, to introduce and
study the optimal or close to optimal strategies for those systems that are to be
motivated by the developed theory. We focus on wireless networks, having future
cellular technology in mind, but the basic tools and approaches to be built and
researched are relevant to other communications networks as well. Cloud
communication networks motivate novel information theoretic views, and
perspectives which put in center backhaul/fronthaul connections deviating thus
considerably from standard theoretical studies of communications links and
networks, which is applied to this domain. Further, our research demonstrates
intimate connections of C-RAN to distributed information bottleneck, which are used
in some insightful theoretical analyses of communications systems. The theoretical
understanding which results from this research will facilitate the design and
implementation of efficient, robust and reliable communications techniques, the
demand for which is steadily increasing. The change of paradigms from 'how to do' to
'what to do' due to the available advanced technologies turns the information
theoretic understanding to a leading practical tool, guiding the constriction of
advanced communications networks.
Our achievements addressing these basic theoretical questions, account for:
* Information Theoretic perspective of up and down link C-RAN: New technologies, concepts and information theoretic characterization.
* Fog radio access networks: an information theoretic view.
* Network information theoretic view:
- Cooperative networks: The impact of cooperation on performance enhancement, as measured via an information theoretic approach has been examined for useful network models. models and understanding the theoretical impact of number of cooperation rounds.
- Physical layer secrecy over cooperative and C-RAN networks.
- Central aspects of (ultra) reliability and latency in networks.
* Information theoretic bottleneck views of C-RAN networks and beyond.
* Networks, processing, systems aspects and practical implications:
* An Information-estimation view of communications networks, accounting for the impact of cognition and cooperation, broadcast approach strategies, feedback and aspects and practical constraints.
* Impact of learning on Ultra-Reliable Communication.
To conclude, our achievements, as reflected in the dozens of published and presented work, at the best journals in the field and at top international professional gatherings has addressed all the planned aspects, and way beyond.
