Message forwarding with ferries in delay-tolerant networks

Routing in delay-tolerant networks exploits node mobility to distribute messages among inter-contact of mobile nodes in intermittently connected environments. However, only depending on node movements to deliver messages between any two nodes in a network could result in lower successful delivery ratio, longer latency and high transmission overhead. Recent research intends to add ferries which can itinerate around some strategic places in a network to expedite message distribution and improve network performance. This paper designs a ferry-travel scheduling approach for efficiently message forwarding in delay-tolerant networks. In this approach, multiple ferries attempt to sense the intensity of message exchanges in geographic proximity, discover hotspot areas by contact history and then autonomously plan travel routes to go through those hot spots. To examine the network performance elevated by ferries, this paper incorporates this ferry-aided approach into several typical delay-tolerant routing schemes, including Epidemic, Spray and Wait, and PRoPHET. Relative comparison among these combined schemes is shown under synthetical Random Waypoint and real NCUTrace mobility models.