Social-Aware Forwarding Improves Routing Performance in Pocket Switched Networks

Abstract

Several social-aware forwarding strategies have been recently intro- duced in opportunistic networks, and proved eective in considerably in- creasing routing performance through extensive simulation studies based on real-world data. However, this performance improvement comes at the expense of storing a considerable amount of state information (e.g, history of past encounters) at the nodes. Hence, whether the benets on routing performance comes directly from the social-aware forwarding mechanism, or indirectly by the fact state information is exploited is not clear. Thus, the question of whether social-aware forwarding by itself is eective in im- proving opportunistic network routing performance remained unaddressed so far. In this paper, we give a rst, positive answer to the above question, by investigating the expected message delivery time as the size of the net- work grows larger. In order to make a fair comparison with stateless, social oblivious forwarding mechanisms such as BinarySW, we introduce a simple stateless, social-aware forwarding mechanism exploiting a notion of similarity between individual interests. We then compare the asymp- totic performance of interest-based forwarding with that of BinarySW under two mobility scenarios, modeling situations in which node pairwise meeting rates are independent of or correlated to the similarity of their in- terests. We formally prove that, while asymptotic expected delivery time of BinarySW is highly dependent on the underlying mobility model, with unbounded expected delivery time in presence of correlated mobility, this is not the case with interest-based forwarding, which provides bounded expected delivery time with both mobility models. Thus, our ndings for- mally prove that social-aware forwarding, even when not exploiting state information, has the potential to considerably improve routing perfor- mance in opportunistic networks over traditional forwarding mechanisms