Betweenness of expanded ego networks in sociality-aware delay tolerant networks

Recently, the consideration of social characteristics present a new angle of view in the design of data routing and dissemination in delay tolerant networks. Many social network studies have been undertaken using a ego network because it has the benefit of simplicity in data collection and gives statistically significant features about the entire network in many cases. In this paper, we newly define the expanded ego network by comprising the ego's 2-hop neighbor nodes as well as the ego's 1-hop ones. In delay tolerant networks, the expended ego network can be easily self-configured at a node and it can contain more network information than the ego network. Therefore, it is expected that the effectiveness of the expanded ego network will be higher than the one of the ego network in terms of data routing and dissemination. We examine that the relationship among the expanded ego betweenness, the ego betweenness, and the betweenness of the entire network for a node. By a simulation study, we show that the expanded ego betweenness is highly correlated with the betweenness of the entire network when the network is dense and its nodes are highly inter-related.