Toronto Networking Seminar

Balancing Distance and Lifetime in Delay Constrained Multihop Wireless Communication

Ben Liang
Department of Electrical and Computer Engineering
 University of Toronto

Date:  Friday, September 22,  3pm
Location: BA1170 (Bahen Center)


In this talk, we discuss the problem of optimizing the packet transmission schedule in a multihop wireless network with end-to-end delay constraints. The emphasis is to determine the proper relative weights assigned to the remaining distance and the remaining lifetime in order to rank the urgency of a packet. We consider a general class of cross-layer transmission schemes that represent such relative weights using a single lifetime-distance factor, which includes, as special cases, schedules such as Earliest-Deadline-First and Largest-Distance-First. We propose an analytical framework, based on recursive non-homogeneous Markovian analysis, to study the effect of the lifetime-distance factor on packet loss probability in a general multihop environment, with different configurations of peer-node channel contention. Numerical results are presented to demonstrate how various network parameters affect the optimal lifetime-distance factor. We demonstrate quantitatively how the proper balance between distance and lifetime in a transmission schedule can significantly improve the network performance, even under imperfect schedule implementation.


Ben Liang received honors simultaneous B.Sc. (valedictorian) and M.Sc. degrees in electrical engineering from Polytechnic University in Brooklyn, New York, in 1997 and the Ph.D. degree in electrical engineering with computer science minor from Cornell University in Ithaca, New York, in 2001. In the 2001 - 2002 academic year, he was a visiting lecturer and post-doctoral research associate at Cornell University. He joined the Department of Electrical and Computer Engineering at the University of Toronto as an Assistant Professor in 2002. His current research interests are in mobile networking and multimedia systems. He received an Intel Foundation Graduate Fellowship in 2000 toward the completion of his Ph.D. dissertation, the Best Paper Award at the IFIP Networking conference in 2005, and the Runner-up Best Paper Award at the International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks in 2006. He is a senior member of IEEE and a member of ACM and Tau Beta Pi. He serves on the organizational and technical committees of a number of major conferences each year.