Proactively Placing Static Relays with Social-Link Awareness in Mobile Social Networks

Mobile social networks have been exploited for data forwarding due to its low cost and better robustness. Existing data forwarding strategies in mobile social networks rely on the pairwise contacts among mobile users. However, these pairwise contacts only provide limited forwarding capabilities and most data fail to be delivered before the expiration time. In this paper, we improve the performance of data forwarding by proactively placing low-cost static relays to increase the opportunistic contacts among the mobile nodes. Based on this idea, an important question is where to place the static relays in the network to best facilitate data forwarding among nodes. To answer this question, we first analyze four real-world datasets of mobile social networks, and identify that data forwarding only appears in a small group of social links. Then, we formalize the problem of static relay placement as an optimization problem, and propose a heuristic based solution to improve the data forwarding performance along these social links. Considering the fact that the social links may evolve over time, we also propose an efficient relay replacement algorithm which replaces the outdated relays with new relays to further improve the data forwarding performance. Evaluation results show that the proposed relay based solutions can significantly improve the performance of data forwarding in mobile social networks.