Chinese Academy of Sciences (CAS) researchers are improving network transmission efficiency by identifying certain links or edges that can be removed to decrease the overall congestion. These links, known as black sheep, are those that connect the busiest hubs. "Our main findings reveal the effect of enhancing network capacity of edge-removal in networks and the prerequisite of the effect," says CAS's Guo-Qing Zhang. The researchers demonstrated that modifying the network does not require a complicated redesign and that significant improvement is possible by deleting just a few well-chosen links. The researchers analyzed a network model that simulates packet traffic to choose which links to remove. Removing the black sheep links significantly increased the network's transmission capacity. The researchers also recently found that for this method to work effectively the network structure must be heterogeneous in terms of node betweenness values. "Our recent paper doesn't further improve network capacity of the method, but points out that heterogeneity of network structure is a necessary condition for the effect's existence, highlights the rationality based on betweenness, and discusses the effect's applications in engineering practice," Zhang says.