Reliable and efficient message delivery in delay tolerant networks using rateless codes

In this paper, we consider the problem of multiple unicast message delivery in Delay Tolerant Networks (DTNs). Long delays, mobility of nodes, and lack of connectivity that are characteristics of such network make this problem very challenging. Additionally, expiry of packets in a network, considered a useful means of regulating resource consumption, reduces reliability and increases the latency of message delivery. Traditional approaches to message delivery in such networks was based on transmitting multiple copies of entire message blocks. Recently, the application of simple erasure-based codes to messages were considered. This option opened up an interesting area of research. In this paper, we effect reliable message delivery with improved latency even in the presence of packet expiry and intermittent connectivity by applying rateless codes at the source where a message is generated. We perform extensive simulations on a variety of trace data from mobility models such as the UMassDieselNet testbed, an area-based random waypoint model, and a simple campus bus model. Results reveal the superiority of our scheme in comparison to other present schemes.