A taxonomy of congestion control and reliability approaches in opportunistic DTNs

Delay and Disruption Tolerant Networking (DTN) has been aiming to tackle the communication challenges originating from the lack of continuous end-to-end connectivity, for a diverse set of mobile/wireless networking environments and applications. Among its basic concepts, DTNs support data storage at intermediate hosts, as a means of application sessions surviving connectivity disruptions. To this end, delivery reliability can be ensured on a hop-by-hop basis for environments were the node contacts which offer communication opportunities are predetermined (scheduled). However, in a large majority of terrestrial DTN settings, the mobility patterns of the communicating peers lead to rather randomly occuring (opportunistic) contacts.

In such conditions, ensuring reliable data delivery is more challenging and it might not be feasible to achieve based on the basic hop-by-hop paradigm. On top of that, buffer congestions taking place at the DTN nodes can worsen the situation. In the current report we review and classify existing congestion control and reliability approaches that exist in the literature, for opportunistic DTNs.