ABSTRACT: Tradeoffs between the packet delivery delay and other metrics are a recurring theme in Delay Tolerant Networks (DTNs). In this work we study these tradeoffs, first in a general, and then in a more specific, mobile wireless setting. We first develop a general setting in which the packet delivery delay can be traded off with a packet transportation cost that is comprised of a transmission cost and a storage cost. We capture this tradeoff on the cost-delay plane using Optimal Cost/Delay Curves (OC/DCs), for the case where the nodes route packets optimally, and Achievable Cost/Delay Curves (AC/DCs), for the case where the nodes route packets according to a suboptimal routing protocol. We then apply this framework to mobile wireless DTNs. We develop a class of geographic routing protocols with delay-tolerant features and we compare them with other state-of-the-art routing protocols, using their respective AC/DCs, and with the performance achieved with optimal routing, in terms of the OC/DC. Our protocols are shown to achieve cost/delay tradeoffs much closer to the optimal one than all other protocols we examine.

BIO: Stavros Toumpis received the Diploma in Electrical and Computer Engineering from the National Technical University of Athens, Greece, in 1997, the M.S. degrees in Electrical Engineering and Mathematics from Stanford University, CA, in 1999 and 2002, espectively, and the Ph.D. degree in Electrical Engineering, also from Stanford, in 2003. From 1998 to 1999 he worked as a Research Assistant for the Mars Global Surveyor Radio Science Team, providing operational support. From 2000 to 2003 he was a Member of the Wireless Systems Laboratory, at Stanford University. From 2003 to 2005 he was a Senior Researcher with the Telecommunications Research Center Vienna (ftw.), in Vienna, Austria. From 2005 to 2009 he was a Lecturer at the Electrical and Computer Engineering Department of the University of Cyprus. Starting from 2009, he is an Assistant Professor in the Computer Science Department of the Athens University of Economics and Business. His research is on wireless ad hoc networks, with emphasis on their capacity, the effects of mobility on their performance, medium access control, and information theoretic issues.