Broadcast Channel Games: Equilibrium Characterization and a MIMO MAC-BC Game Duality

TL;DR

This paper models the strategic behavior of receivers in Gaussian broadcast channels and transmitters in sum power MACs as generalized Nash equilibrium problems, establishing equilibrium existence, uniqueness, and a duality that links MAC and BC scenarios.

Contribution

It introduces a game-theoretic framework for analyzing receiver and transmitter strategies in Gaussian BC and MAC, revealing equilibrium properties and a duality between the two channel types.

Findings

All GNEs are Pareto-optimal, indicating no efficiency loss.

Existence and uniqueness of equilibrium strategies are characterized.

A duality between Gaussian MAC and BC is established, enabling transfer of results.

Abstract

The emergence of heterogeneous decentralized networks without a central controller, such as device-to-device communication systems, has created the need for new problem frameworks to design and analyze the performance of such networks. As a key step towards such an analysis for general networks, this paper examines the strategic behavior of \emph{receivers} in a Gaussian broadcast channel (BC) and \emph{transmitters} in a multiple access channel (MAC) with sum power constraints (sum power MAC) using the framework of non-cooperative game theory. These signaling scenarios are modeled as generalized Nash equilibrium problems (GNEPs) with jointly convex and coupled constraints and the existence and uniqueness of equilibrium achieving strategies and equilibrium utilities are characterized for both the Gaussian BC and the sum power MAC. The relationship between Pareto-optimal boundary points of the capacity region and the generalized Nash equilibria (GNEs) are derived for the several special cases and in all these cases it is shown that all the GNEs are Pareto-optimal, demonstrating that there is no loss in efficiency when players adopt strategic behavior in these scenarios. Several key equivalence relations are derived and used to demonstrate a game-theoretic duality between the Gaussian MAC and the Gaussian BC. This duality allows a parametrized computation of the equilibria of the BC in terms of the equilibria of the MAC and paves the way to translate several MAC results to the dual BC scenario.