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Communication and Computation - Two Sides of One Tapestry

Final Report Summary - COMCOM (Communication and Computation - Two Sides of One Tapestry)

Networks have been studied in depth for several decades, but one aspect has received little attention: Interference.
Avoiding interference is the dominant strategy, implemented via clever algorithms. This has proved effective for traditional supply-chain or wired communication networks. However, the emergence of wireless networks revealed that simply avoiding interference leads to significant performance loss. A wealth of cooperative communication strategies have recently been developed to address this issue. Two fundamental roadblocks are emerging: First, it is ultimately unclear how to integrate cooperative techniques into the larger fabric of networks (short of case-by-case redesigns); and second, the lack of source/channel separation in networks (i.e. more bits do not imply better end-to-end signal quality) calls for ever more specialized cooperative techniques.

This research project develops a new understanding of interference as computation: Interference garbles together inputs to produce an output. This can be thought of as a certain computation, perhaps subject to noise or other stochastic effects. Recent work has revealed that this computational potential can be exploited advantageously. The basic underlying building block, termed “Compute-and-Forward,” has received the 2013 IEEE Communications & Information Theory Society Paper Award. In this project, this approach was leveraged as a new foundation for Network Information Theory. In particular, while the previous art relied on explicit lattice arguments applicable to linear network models, the new approach developed under this project is applicable in full generality to all network models. This required new tools for codes with algebraic structure and a much refined analysis of the behavior of such codes under optimal decoding. As side results, the project also led to a wealth of new concrete applications of our framework, most notably to the classical problem of multiple-access communication. Other applications that were studied in detail pertain to Random Access communications, Sensor Networks, and communication scenarios with Secrecy requirements.