Vehicular Delay Tolerant Network (VDTN): Routing perspectives

Recently, the Delay Tolerant Networks (DTN) have been utilized in various operational communication paradigms. This includes the communication scenarios that are subject to disruption and disconnection as well as the scenarios with high delay and frequent partitioning, i.e., Vehicular Ad hoc Networks (VANETs). Due to several characteristics match, a new research paradigm named as Vehicular Delay Tolerant Network (VDTN) is introduced. Through relays and store-carry-forward mechanisms, messages in VDTNs can be delivered to the destination without an end-to-end connection for delay-tolerant applications. However, the choice of routing algorithms in VDTNs is still under study. Numerous routing protocols have been proposed to meet requirements of many applications. In this paper, we therefore provide some detailed study of recently proposed routing schemes for VDTNs. We also perform comparative analysis on the basis of unique criterion such as forwarding metrics with their implementations. In addition, open challenges and future directions are provided to make room of interest for the research community.