Small-World Phenomena in Communications Networks: A Cross-Atlantic Comparison

Abstract

One of the key features of our modern world is its gradual transition to a network society. Many networks like the Internet have been found to possess scale-free and small-world network properties exhibited by power law distributions. Scale-free properties evolve in large complex networks through self-organizing processes and more specifically, preferential attachment. New nodes tend to attach themselves to other vertices that are already well-connected. Because traffic is routed mainly through a few highly connected vertices, the diameter of the network is small in comparison to other network structures, and movement through the network is therefore efficient. At the same time, this efficiency puts scale-free networks at risk for becoming disconnected or significantly disrupted, when super-connected nodes are removed either intentionally or through a targeted attack. This paper will examine and compare three communication networks: bandwidth capacity between major metropolitan areas within the United States (97-01), interdistrict phone traffic in Italy (1989-1993) and a particular peer-to-peer data exchange network. Each network will be examined in terms of its network topology and specifically whether or not they are evolving into scale-free networks. Finally, the paper will conclude with some preliminary thoughts and reflections aiming at a consolidation and exploration of further comparative studies on communication networks in Europe and North America, in the light of the STELLA objectives.