Transport layer issues in delay tolerant mobile networks

The tremendous increase in wireless devices and user mobility have ultimately resulted in a new set of networking challenges that previously did not exist. Some of these challenges include large delays, intermittent connectivity and most importantly, the absence of an end-to-end path from sources to destinations. Networks characterized by one or more of these challenges are called Delay Tolerant Networks (DTNs). Researchers have studied DTNs with a major focus on routing issues in such extreme environments. As a result, in this paper, we shift this focus towards addressing and studying transport layer issues in extreme networking environments. We particularly concentrate on investigating and comparing several reliability approaches in a specific category of DTNs known as Delay Tolerant Mobile Networks (DTMNs). We present four different reliability approaches in DTMNs. We also evaluate these approaches under various network conditions via simulation. Our goals from this study are to examine the impact of these reliability approaches, understand the tradeoffs between them, and open the way for further work in transport layer issues in delay tolerant networks.