Impact of mobile nodes for few mobility models on delay-tolerant network routing protocols

Delay-Tolerant Networks (DTNs) are sparse dynamic wireless networks, where most of the time a complete end-to-end path from the source to the destination does not exist. There are many real networks that follow this model, for example, military networks, vehicular ad-hoc networks (VANETs), wildlife tracking sensor networks, etc. In this context, conventional mobile ad-hoc routing schemes would fail, because they try to establish complete end-to-end paths, before any data sent. Therefore, performance analysis of different DTN routing mechanisms plays an important role in understanding the design of DTNs that encourages one to choose proper routing protocol for a particular scenario. This paper investigates the performance of replication-based DTN routing protocols, namely Epidemic, Probabilistic Routing Protocol using History of Encounters and Transitivity (PRoPHET), MaxProp, Resource Allocation Protocol for Intentional DTN (RAPID), Binary Spray-and-Wait (B-SNW), and Spray-and-Focus (SNF) in DTN scenario against varying number of mobile nodes for three mobility models, namely Random Walk (RW), Random Direction (RD) and Shortest Path Map Based (SPMB) movement. Performance has been evaluated and analyzed using Opportunistic Network Environment (ONE) simulator by considering three metrics: delivery probability, average latency and overhead ratio. Simulation results show that the investigated DTN routing protocols, in general, exhibit better performance in the SPMB movement model than other movement models, i.e., RW and RD, because they yield maximum message delivery probability, minimum overhead ratio (for B-SNW and SNF), and minimum average latency.