On Resilience Challenges in Opportunistic Networks

In opportunistic networks, due to node mobility and sporadic connectivity, disconnection and network partitioning are prevalent. Nonetheless, the network resilience against such sporadic connectivity can be provided through adapting store-carry-and-forward-based routing protocols which exploit users’ mobility to flow the data in the network even in the absence of end-to-end connectivity. Opportunistic networks, however, are exposed to some other challenges such as jamming attacks or buffer limitations which limit the usage of node contacts or node behavior. The main objective of this thesis is to understand the impact of these challenges on the resilience of the network. The challenges are applied in different network topologies using different forwarding protocols. Generally, we find that store-carry-and-forward routing, by exploiting diversity in space-time paths, provides a high degree of resilience in the network, which depends on the network topology. The network resilience is maintained as long as significant number of nodes or node contacts are not affected. In the case of jamming, the studied routing protocols behave similarly with the exception of spray and wait routing which for some messages results in delay improvement while intensifying the challenge. For limited buffer sizes, spray and wait again shows different behavior in the low-traffic network where the average delay of delivered messages improves much more significantly compared to the other studied routing protocols, though with increasing the buffer size many more messages get delivered