Design an Efficient Community-based Message Forwarding Method in Mobile Social Networks

Mobile social networks (MSNs) are a special type of Delay tolerant networks (DTNs) in which mobile devices communicate opportunistically to each other. One of the most challenging issues in Mobile Social Networks (MSNs) is to design an efficient message forwarding scheme that has a high performance in terms of delivery ratio, latency and communication cost. There are two different approaches for message forwarding: the single copy and the multi copy. In the single copy schemes, only one copy of a message exists in the network, which is carried by a custodian relay. On the other hand, in multi copy schemes more than one copy of the message exist. Although the multi copy schemes generally have superior performance in terms of delivery ratio and latency, they incur high congestion in the network, which consequently degrades the network performance and increases message forwarding cost. Therefore, we present a scheme for managing the number of replica and selecting appropriate relays in order to increase the performance and decrease the forwarding cost.In this paper, we present a novel message forwarding scheme, named Multi Copy Community Aware Forwarding (MCCAF), for managing the number of message replicas and selecting appropriate relays in order to increase the performance and decrease the forwarding cost. MCCAF only forwards one replica of message to each community that the destination node belongs to it. In order to find communities and nodes’ future communities, MCCAF exploits a hidden semi-Markov model (HSMM). In the proposed method, hidden states represent communities and environmental chronological information such as location, visited nodes and access points are modeled as observation in HSMM. To have a more precise community prediction, the semi-Markov model is extended to compute the likelihoods of a node being in a particular community after N transitions. After that, appropriate relays are selected to forward a message with taking into account the message expiration time, future communities of relays and the number of message replica. Evaluation results on real traces demonstrate that the MCCAF has superior performance over rival schemes in terms of delivery ratio, latency, and forwarding cost. Specifically, MCCAF yields on average about 8% better delivery ratio and about 23% less delivery delay than the nearest rival method.