Mobility Models and their Impact on Wireless Protocols in Mobile Networks

A Vehicular Ad Hoc Network (VANET) on a one-dimensional highway exhibits a bipolar behavior in terms of network topology: fully connected topology with high traffic volume during the rush hour or sparsely connected topology when traffic volume is low. We develop a statistical traffic model based on the empirical data collected via real-world experiments in order to study key performance metrics of interest in disconnected VANETs, such as average re-healing time (or the network restoration time). Our results indicate that, a new ad hoc routing protocol should be designed such that it can operate in any traffic conditions (i.e., heavy traffic, traffic jam, light traffic, etc.) since the conventional ad hoc routing protocols will not work with long re-healing times in sparse VANETs. Detailed implementation and performance evaluation of such a protocol will be presented.
On the other hand, modeling traffic behavior in two-dimensional urban areas is more complicated and difficult than that of highway traffic. We employ a powerful Cellular Automata concept to construct an urban traffic mobility model. Based on the developed model, characteristics of global traffic pattern in urban areas are studied. In addition to these traffic characteristics, we provide a comprehensive framework for network connectivity of urban VANETs using a number of key metrics of interest (such as link duration, connection duration, and re-healing time).

Dr. Fan Bai is a Senior Researcher in the Electrical & Control Integration Lab., Research & Development and Planning, General Motors Corporation, since Sep., 2005. Before joining General Motors research lab, he received the B.S. degree in automation engineering from Tsinghua University, Beijing, China, in 1999, and the M.S.E.E. and Ph.D. degrees in electrical engineering, from University of Southern California, Los Angeles, in 2005.
His current research is focused on the discovery of fundamental principles and the analysis and design of protocols/systems for next-generation Vehicular Ad hoc Networks(VANET), for safety, telematics and infotainment applications. Dr. Bai has published about 40 book chapters, conference and journal papers, including INFOCOM, MobiHoc, SECON, ICC, Globecom, WCNC, JSAC, IEEE Wireless Communication Magazine, IEEE Communication Magazine and Elsevier AdHoc Networks Journal.
He received Charles L. McCuen Special Achievement Award from General Motors Corporation “in recognition of extraordinary accomplishment in area of vehicle-to-vehicle communications” He serves as Technical Program Co-Chairs for IEEE WiVec 2007 and IEEE MoVeNet 2008, and serves as guest editors for IEEE Wireless Communication Magazine, IEEE Vehicular Technology Magazine and Elsevier AdHoc Networks Journal on vehicular wireless networks. He is also serving as a Ph.D. supervisory committee member at Carnegie Mellon University.