Optimizing multi-copy two-hop routing in mobile social networks

In this paper, an opportunistic multi-copy two-hop routing algorithm is proposed for mobile social networks (MSNs) to minimize the expected data delivery delay, using local information. For each source-destination pair, the source dynamically maintains a forwarding set consisting of relay nodes. The forwarding set selection is based on the number of remaining message copies, as well as the number and quality of relays that have not received a message copy. The source only forwards its message to the relay nodes in its forwarding set, which will in turn forward the message to the destination directly. We propose a greedy approach to select the forwarding set with n message copies at the source, in an MSN with m (m>n) relays. All forwarding sets can be determined with a time complexity of O(m log m+nm). Then, the proposed multi-copy two-hop routing algorithm is applied to a feature space routing scheme, where the contact frequencies are estimated by social feature distances. Finally, the competitive performance of the proposed schemes are shown in real trace-driven simulations.