Stigmergic Communication for Self-Organized Multi Ferry Delay Tolerant Networks

This paper presents an Adaptive On-the-fly Decision maker for Multi Ferry (A-ODMF) delay tolerant networks. A-ODMF chooses the next node to visit for controlled mobility data ferries. In our assumptions, there is no direct communication among ferries. Therefore, we apply a stigmergic communication among ferries for their coordination. Nodes are employed to act as relays for an indirect signaling of control information among ferries to decrease redundant visits to nodes. Moreover, the self-organized decision maker in A-ODMF adapts its decision functions based on the local observations of a ferry from the delay of delivered messages in the network to increase the efficiency of ferry decisions. A-ODMF also considers the priority of messages in the ferry buffer and delivers high priority messages earlier. The simulation results show that A-ODMF outperforms existing on-the-fly approaches in terms of message latency. In scenarios with high number of ferries, the impact of indirect signaling and the adaptive decision maker in A-ODMF is more significant on the performance improvement. A-ODMF decreases unnecessary visits to nodes and therefore improves the travel time of messages in a ferry buffer. Finally, we study and discuss the impact of increasing the number of ferries and increasing the ferry speed on the performance and cost of a message ferry network. We show that a required performance can be achieved with less cost by increasing the speed of ferries than increasing the number of ferries.