Seminar by
Kağan Gökbayrak
Department of Industrial Engineering
Wireless mesh networks (WMNs) are communication networks that provide last mile Internet access. They consist of radio nodes organized in a mesh topology that communicate via wireless media in a multihop fashion. A few of these nodes (we call them gateways) have wired connections to the Internet, and provide access for the whole network. Wireless interference caused by simultaneous transmissions over the same frequency channel complicates the design problems of WMNs. In order to avoid wireless interference, link capacities are divided in time or frequency into transmission slots, and these should be allocated to non-interfering transmissions. In this presentation, we consider the problem of designing and operating a WMN, whose node demands increase at the same rate over time. Our goal is to determine a gateway deployment plan that meets the demand at all times and minimizes the total present value of the investment costs. We present an integer programming formulation that jointly determines the locations of the gateway nodes, their deployment times, the routing trees rooted at these gateways, and the transmission slot assignments to wireless links. We determine tight upper and lower bounds on the optimal cost of this NP- hard problem. We introduce valid inequalities and heuristic solution methods, and provide numerical examples to evaluate their performances.
Kagan Gokbayrak received the B.S. degrees in mathematics and in electrical engineering from Bogazici University, Istanbul, in 1995, the M.S. degree in electrical and computer engineering from the University of Massachusetts, Amherst, in 1997, and the Ph.D. degree in manufacturing engineering from Boston University, Boston, MA, in 2001. From 2001 to 2003, he worked as a network planning engineer at Genuity, Inc., Burlington, MA. In addition to preparing demand forecasts and IP-layer capacity plans of the AS1 backbone, Dr. Gokbayrak played a key role in adapting emerging IP technologies. Since 2003, he has been a faculty member in the Industrial Engineering Department, Bilkent University, Ankara, Turkey. During his sabbatical leave in 2013, he was a visiting scholar at Massachusetts Institute of Technology and an adjunct professor at Boston University. His research interests include the optimization of discrete-event and hybrid systems, wireless mesh networks, and sensor networks, and computer simulation with applications to inventory, healthcare and manufacturing systems.
