Context- and Social-aware Middleware for Opportunistic Networks

Opportunistic networks are multi-hop ad hoc networks in which nodes opportunistically exploit any pair-wise contact to share and forward content, without requiring any pre-existing Internet infrastructure. Opportunistic networks tolerate partitions, long disconnections, and topology instability in general. In this challenging environment, leveraging users' mobility represents the most effective way to deliver content to interested users. In this paper we propose a context- and social-aware middleware that autonomically learns context and social information on the users of the network, and that uses this information in order to predict users' future movements. In order to evaluate the proposed middleware on a realistic scenario, we have designed and implemented a context- and social-aware content sharing service, exploiting the functionality of the middleware. Both the middleware and the content sharing service have been integrated with an existing data-centric architecture (the Haggle architecture) for opportunistic networks. Finally, we have validated the proposed content sharing application on a small-scale testbed and, on a larger scale, we have investigated the advantages provided by context- and social-aware sharing strategies by means of extensive simulations. The main result of this paper is the definition and implementation of a context- and social-aware middleware able to share context information with all the interested components improving the efficiency and performances of services and protocols in opportunistic networks. With respect to content sharing strategies that do not exploit context and social information, we have obtained up to 200% improvements in terms of hit rate (probability that users receive the content they request) and 99% reduction in resource consumption in terms of traffic generated on the network.