Prepared using dacauth.cls [Version: 2010/03/27 v2.00]

Peer-to-Peer (P2P) overlay networks and Mobile Ad-hoc Networks (MANETs) share many key characteristics such as self-organization and decentralization; they also face the crucial challenge of providing connectivity in a decentralized, dynamic environment. However, when considering ad-hoc networks composed by mobile devices such as smartphones, we cannot rely on the continuous end-to-end path between peers as for classic Internet P2P applications; rather, we have to deal with low node density that creates mobile disconnected networks. Porting the P2P paradigm into mobile networks to create a Mobile-to-Mobile (M2M) file sharing application will create a modern type of Delay Tolerant Network (DTN). In this context, we discuss our new approach for P2P file sharing that considers networks composed by mobile smartphones. As innovative feature, we leverage on peer mobility to reach data in other disconnected networks by implementing a DTN-like store-delegate-and-forward communication model, where a peer can delegate unaccomplished file download tasks to other peers. In order to increase the chances of eventually receiving the requested file while reducing the number of transmitted messages and data, social awareness is exploited by nodes to delegate unaccomplished tasks only to peers that are expected to be encountered again in the future. Copyright c © 2011 John Wiley & Sons, Ltd