Thomas Kunz, Carleton University

Professor Systems and Computer Engineering Ottawa, Ontario tkunz@sce.carleton.ca Office: (613) 520-3573

Bio/Research

Thomas Kunz received a double honors degree in Computer Science and Business Administration in 1990 and the Dr. Ing. degree in Computer Science from the Technical University of Darmstadt, Federal Republic of Germany, in 1994. Before joining the Department of Systems and Computer Engineering at Ca...

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Bio/Research

Thomas Kunz received a double honors degree in Computer Science and Business Administration in 1990 and the Dr. Ing. degree in Computer Science from the Technical University of Darmstadt, Federal Republic of Germany, in 1994. Before joining the Department of Systems and Computer Engineering at Carleton University, he spent three years as Assistant Professor in the Department of Computer Science at the University of Waterloo.

His research focuses on various problems in mobile computing and distributed systems. One of his earlier projects addressed the issue of load balancing in distributed systems. Later, he developed a system to facilitate distributed object-oriented programming on a network of workstations. At Waterloo, he was involved in the design and implementation of Poet, a Partial Order Event Tracer. Poet visualizes the partial order of event occurrence in distributed executions, and can be used as a distributed debugging tool, a monitoring tool, or as the basis for a management environment. Some of the unique features of Poet are its abstraction facilities, allowing a user to view distributed executions at different levels of abstractions. Suitable abstraction hierarchies can be derived automatically, with tools utilizing reverse engineering ideas. A paper describing one abstraction facility, event abstraction, won the best PhD student paper award at the 1994 CASCON in Toronto.

He also started, with two colleagues, a project on client-server computing in wireless networks. Some of the research problems addressed in this area are the management of subscriber location, improving TCP over wireless links by transparently offering supplementary services, and the design and development of adaptive mobile applications. Given the unpredictable, varying, and often poor network connectivity that mobile clients typically encounter, a user cannot expect the application to transparently hide the state of the current network connection. Rather, applications should dynamically adapt to the current environment. To achieve this, they need to obtain information about the environment (through a special API that was developed) and react to changes in an appropriate way. One avenue currently being investigated is the use of mobile agent technology based on Java to explore automatic migration of (parts of) the application.

More recently, he also started to explore ad-hoc networks. "Mobile ad-hoc networks" (MANET) are autonomous systems of mobile routers (and associated hosts) connected by wireless links--the union of which form an arbitrary graph. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet, see http://www.ietf.org/html.charters/manet-charter.html. Finding routes to communicate between arbitrary hosts is challenging (the communication paths change over time) and an active area of future research. Since all mobile devices are battery-powered, power consumption is a crucial aspect of any routing protocol. We use a network simulator (NS2, see http://www-mash.CS.Berkeley.EDU/ns/) to run experiments to evaluate, compare and develop point-to-point and multicast routing protocols. In particular, we are interested in the power consumption aspects and performance comparison between routing protocols (point-to-point or multipoint) with the goal to propose modifications to existing protocols and to develop our own set of protocols. Other interesting and challenging issues in this context are QoS support and maximizing the capacity of the MANET through appropriate MAC and routing protocols. Finally, we are looking at the performance of TCP in such an environment. Most existing work explored TCP performance in a cellular architecture, with proposals either improving the (rare) handoff case or utilizing the base station (wireless access point) to overcome the high error rate over the wireless link. In ad-hoc networks with a gateway that connects the nodes in the ad-hoc network with the rest of the Internet, TCP support needs to address packet loss due to route failures, packet loss over one of numerous wireless links, and packet loss due to congestion in the fixed network. If mobile devices can move between different MANETs, all of which are connected to the Internet, handoff losses have to be taken into account as well.

Dr. Kunz published well over 60 technical papers in journals and conferences. He is a member of ACM and the IEEE Computer Society.



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