CIF: Small: Collaborative Research: When Small Changes Have Big Impact: Improving Network Reliability and Security via Low-Rate Coordination

The last decade has seen the emergence of a wide variety of networked communication systems, affecting nearly every aspect of our society. In particular, there is a growing trend towards distributed and multiuser applications, simultaneously with an exponential increase in data use per capita. To support this data revolution, further technological advances beyond emerging wireless technologies such as 5G are required to increase the bit-carrying capacity of the existing network infrastructure. Despite recent advances in network communication, such as cooperative and opportunistic communication and multiple access techniques to improve network capacity, the design of communication systems is still mostly based on the so called separation principle, in which communication across point-to-point channels is done independently of the surrounding network. While having the advantage of simplicity, this separation principle ignores approaches that could bring even better performance. This project looks for small changes to the design of communication networks that can have a disproportionately large impact on the network's reliability and security. Thus, the gains from moving beyond separation can be obtained at low cost.

In particular, the project explores the use of coordination, in which a small amount of data is shared among devices so that they can jointly optimize their behavior. This use of a small amount of coordination breaks the separation paradigm, but only a little bit, so that the existing networking infrastructure can remain mostly intact. Coordination techniques are explored both in terms of the theoretical, fundamental limits, as well as practical approaches toward achieving them. The project is divided into three interrelated thrusts. The first thrust focuses on improving network reliability via low-rate coordination in networks composed of mutually trustworthy nodes. A key aspect of this work is the edge removal problem, which constitutes the mathematical foundation for the power of low-rate coordination, and is intimately related to many important questions in the study of the fundamental limits of communication networks. The second thrust investigates networks that contain either channel fading or malicious adversaries. In the presence of such intrusions, coordination can significantly benefit the network?s ability to work around them. The third thrust introduces a new divide-and-conquer framework for coordination in communication networks wherein nodes agree upon a network factorization into small blocks and perform simple coding within each block. This new architecture outperforms naive separation without introducing debilitating complexity.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.