Real and Complex Monotone Communication Games

Noncooperative game-theoretic tools have been increasingly used to study many important resource allocation problems in communications, networking, smart grids, and portfolio optimization. In this paper, we consider a general class of convex Nash Equilibrium Problems (NEPs), where each player aims to solve an arbitrary smooth convex optimization problem. Differently from most of current works, we do not assume any specific structure for the players' problems, and we allow the optimization variables of the players to be matrices in the complex domain. Our main contribution is the design of a novel class of distributed (asynchronous) best-response- algorithms suitable for solving the proposed NEPs, even in the presence of multiple solutions. The new methods, whose convergence analysis is based on Variational Inequality (VI) techniques, can select, among all the equilibria of a game, those that optimize a given performance criterion, at the cost of limited signaling among the players. This is a major departure from existing best-response algorithms, whose convergence conditions imply the uniqueness of the NE. Some of our results hinge on the use of VI problems directly in the complex domain; the study of these new kind of VIs also represents a noteworthy innovative contribution. We then apply the developed methods to solve some new generalizations of SISO and MIMO games in cognitive radios and femtocell systems, showing a considerable performance improvement over classical pure noncooperative schemes.Comment: to appear on IEEE Transactions in Information Theor

Envisioning the Future Role of 3D Wireless Networks in Preventing and Managing Disasters and Emergency Situations

In an era marked by unprecedented climatic upheavals and evolving urban landscapes, the role of advanced communication networks in disaster prevention and management is becoming increasingly critical. This paper explores the transformative potential of 3D wireless networks, an innovative amalgamation of terrestrial, aerial, and satellite technologies, in enhancing disaster response mechanisms. We delve into a myriad of use cases, ranging from large facility evacuations to wildfire management, underscoring the versatility of these networks in ensuring timely communication, real-time situational awareness, and efficient resource allocation during crises. We also present an overview of cutting-edge prototypes, highlighting the practical feasibility and operational efficacy of 3D wireless networks in real-world scenarios. Simultaneously, we acknowledge the challenges posed by aspects such as cybersecurity, cross-border coordination, and physical layer technological hurdles, and propose future directions for research and development in this domain

Essays on optimal spectrum management for expanding wireless communications

Wireless communications are experiencing an unprecedented expansion. The increasing mobility of the communication society and the pace of technological change are growing pressure for more spectrum to support more users, more uses and more capacity. Thus, spectrum management has become an extremely important part of wireless communications. A few regulators are changing their traditional ‘command and control’ approach. Nevertheless, many features of optimal spectrum management are still widely discussed. This work is aimed at contributing to that discussion. The key insight is that spectrum management can benefit from more liberal spectrum sharing. This work set out to answer three main research questions: (i) whether there is a theoretical framework which can be used to analyze and guide spectrum policy reform, when moving from a traditional ‘command and control’ regime to a market-inspired one; (ii) whether it is possible to design a plausible mechanism which can promote efficient allocation and assignment of spectrum commons; (iii) whether (and how) technological developments could enable band sharing methods outside the traditional management framework and without harmful interference. The literature on transition economics and policy was used to help answer the first research question. Evidence from liberalizing countries was positively analyzed to discuss reforms of spectrum allocation and assignment methods. Most countries have adopted strategies that gradually change their spectrum policies and started by using more liberal methods to assign spectrum. It is also argued that future spectrum reforms might benefit from insights presented in the transition economics literature. A translation of a model on cartel quotas under majority rule is proposed to answer the second research question. The work verifies, firstly, that an analogous set of properties is satisfied under our assumptions and that the median-index theorem applies, mutatis mutandis, to our setting. Thus firms bidding to acquire spectrum commons contribute a minimum amount of their wealth; the sum of contributions offered is then compared to other bids for the same spectrum, which is allocated to the highest bidder. The last research question considers novel ways of spectrum sharing that might be enabled by technological developments. The work explores contributions, from various research areas, regarding management of scarce resources. Those contributions are discussed with respect to shared spectrum access. It is suggested that spectrum management might benefit from methods which enable the management of pooled (intermittent) demands for access, especially methods in line with fair sojourn protocols