(A) social transitivity aware data dissemination scheme for opportunistic networks

Abstract

An existing social-based routing protocol for opportunistic networks, SimBetTS, uses similarity, betweenness centrality and tie strength as its forwarding metrics. Although similarity shows how likely a pair of nodes belongs to the same community, it does not express how closely these nodes are connected. Tie strength indicates the degree of closeness between the nodes and complements the limitation of similarity, but it ignores the indirect link probability through neighbor nodes. To overcome this problem, we propose to incorporate transitivity, which considers the indirect link probability through intermediate nodes, as one of the forwarding metrics. As considering the indirect link probability, it is inevitable that the number of forwarding is increased. Overhead, which presents the amount of generated message traffic to deliver a message, is a crucial metric when evaluating the delivery performance. The proposed scheme uses the threshold of difference between total utility values, which is derived from the average difference of total utility values per hop for all delivered messages to destination nodes, to reduce the overhead from the increased amount of forwarding. As using a simulator with real world trace data sets, we compare the proposed scheme with the existing protocols, Epidemic routing and SimBetTS. Compared with SimBetTS, the proposed scheme increases delivery ratio by 1.5 percent and decreases delay time by 2 percent while reducing overhead by 30 percent. The performance of delivery ratio and delay time is comparable to Epidemic routing without additional overhead.