File transfer in Vehicular Delay Tolerant Networks using fountain coding

Data communication in Vehicular Delay Tolerant Networks (VDTN) poses serious challenges on file transferring due to intermittent connectivity and packet loss. To improve file transfer in VDTN, we propose a mechanism that includes fountain coding in the application layer, UDP in the transport layer, and AODV-DTN in the network layer in our new architecture. Of the characteristics of fountain codes is that the source data can be rebuilt thoroughly from any subset of the encoded packets at destination. Furthermore, no feedback is required to guarantee reliable delivery. Therefore, we use UDP in contrast to classical use of TCP, while reliability is still preserved. A new routing algorithm, named AODV-DTN, is presented and developed in the network layer based on AODV and Store-Carry and Forward policy. The cross-layer mechanism is used as an alternative to preliminary layer design so as to develop communication between the network layer and application layer. We have conducted extensive simulations to evaluate the performance of our architecture. The results show that our architecture outperforms in terms of file delivery ratio and byte throughput when compared with FOUNTAIN and classic FTP scenarios. In addition, the negative effect of increasing file size is mitigated in the proposed architecture in comparison to other alternatives. It is shown that for delay tolerant and long-distanced inter-RSU communications the proposed architecture behaves sufficiently well.