Communication networks (wired or wireless) have traditionally been assumed to be connected at least most of the time. However, emerging wireless applications such as emergency response, peer-to-peer wireless, smart environments, VANETs, etc. coupled with node heterogeneity and volatile links (due to wireless propagation phenomena and node mobility) will likely change the typical conditions under which such networks operate. In fact, in such scenarios, networks may be mostly disconnected, i.e., most of the time, end-to-end paths connecting every node pair do not exist. Under such conditions, a number of assumptions made by commonly used protocols break. Arguably though, one of the most challenging problems in this context is that of routing, as traditional routing protocols fail to deliver any data when no end-to-end paths exist. To overcome this problem "opportunistic routing" algorithms have been proposed. In this talk we'll explore the problem space of mobility-assisted, opportunistic routing for intermittently connected wireless networks. We will describe a family of protocols that manage to achieve very good performance in terms of both packet delivery and resource usage, under a large range of scenarios. Finally, we will briefly touch upon some issues related to theoretical modeling and analysis of routing in intermittently connected environments.
Thrasyvoulos Spyropoulos has received a Ph.D. from the department of Electrical Engineering at the University of Southern California (USC), in May 2006, and a Diploma in Electrical and Computer Engineering from the National Technical University of Athens, Greece, in 2000. In the past, he has also worked at the USC-Information Sciences Institute (ISI) and at the Telecommunications lab at the National Technical University of Athens. His research interests include delay tolerant networks, mobility modeling, wireless networking using directional and smart antennas, and pervasive/ubiquitous computing, and he has been supported by NSF, and DARPA grants. He is currently a post-doctoral researcher at INRIA, Sophia-Antipolis, France.