Hao Chen, Exploiting Opportunistic Scheduling in Cellular Data Networks

Third Generation (3G) cellular networks utilize time-varying andlocation-dependent channel conditions to provide broadband services. They employ opportunistic scheduling to efficiently utilize spectrum under fairness or QoS constraints. Opportunistic scheduling algorithms rely on collaboration among all mobile users to achieve their design objectives. However, we demonstrate that rogue cellular devices can exploit vulnerabilities in opportunistic scheduling algorithms, such as Proprotional Fair (PF), to usurp the majority of time slots in 3G networks. Our simulations show that only five rogue device per 50-user cell can use up to 90% of the time slots, and can cause 2 seconds of end-to-end inter-packet transmission delay on VoIP applications for every user in the same cell, rendering VoIP applications useless. To defend against these attacks, we explore several detection and prevention schemes, including modifications to the PF scheduler and a secure handoff procedure.This is a joint with with Denys Ma, Radmilo Racic, and Xin Liu. About the speaker: Hao Chen is an assistant professor at the Department of Computer Science at the University of California, Davis. He received his Ph.D. in Computer Science from the University of California, Berkeley in 2004. His primary research interest is computer security, with an emphasis on wireless security, Web security, and software security. He received an NSF CAREER award for supporting his research on wireless security in 2007. More information is available at:http://www.cs.ucdavis.edu/~hchen/