Congestion phenomena on complex networks

TL;DR

This paper introduces a minimal traffic flow model on complex networks that captures real routing trade-offs, revealing how traffic control impacts congestion differently in homogeneous versus inhomogeneous networks.

Contribution

It provides an analytical framework for understanding traffic phenomena on complex networks, highlighting the effects of traffic control strategies on congestion.

Findings

Traffic control is ineffective in homogeneous networks.

In inhomogeneous networks, traffic control can improve performance.

Beyond a critical point, traffic control may cause abrupt congestion.

Abstract

We define a minimal model of traffic flows in complex networks containing the most relevant features of real routing schemes, i.e. a trade--off strategy between topological-based and traffic-based routing. The resulting collective behavior, obtained analytically for the ensemble of uncorrelated networks, is physically very rich and reproduces results recently observed in traffic simulations on scale-free networks. We find that traffic control is useless in homogeneous graphs but may improves global performance in inhomogeneous networks, enlarging the free-flow region in parameter space. Traffic control also introduces non-linear effects and, beyond a critical strength, may trigger the appearance of a congested phase in a discontinuous manner.