In this talk we study the issue of cross-layer design for rate control in multihop wireless networks. We have developed an optimal cross-layered rate control scheme that jointly computes both the rate allocation and the stabilizing schedule that controls the resources at the underlying layers. However, the scheduling component in this optimal cross-layered rate control scheme has to solve a complex global optimization problem at each time, and is hence too computationally expensive for online implementation. Thus, we study the impact on the performance of cross-layer rate control if the network can only use an imperfect (and potentially distributed) scheduling component that is easier to implement. We study scenarios with both fixed number of users as well as when the number of users change due to arrivals and departures in the system. In each case, we establish desirable results on the performance bounds of cross-layered rate control with imperfect scheduling. Our cross-layered approach provides provably better performance bounds when compared with a layered approach (that does not design rate control and scheduling together). The insights drawn from our analyses also enable us to design a fully distributed cross-layered rate control and scheduling algorithm under a restrictive interference model.

Ness B. Shroff received his Ph.D. degree from Columbia University, NY in 1994. He is currently a full Professor in the School of Electrical and Computer Engineering at Purdue University. His research interests span the areas of wireless and wireline communication networks. He is especially interested in fundamental problems in the design, performance, scheduling, capacity, pricing, and control of these networks. His research is funded by various companies such as Intel, Hewlett Packard, Nortel, AT&T, BAE systems, and L. G. Electronics; and government agencies such as the National Science Foundation (NSF), Defense Advanced Research Projects Agency (DARPA), Indiana Dept. of Transportation, and the Indiana 21st Century fund. Dr. Shroff is an editor for IEEE/ACM Trans. on Networking and the Computer Networks Journal, and past editor of IEEE Communications Letters. He was the conference chair for the 14th Annual IEEE Computer Communications Workshop (in Estes Park, CO, October 1999) and program co-chair for the symposium on high-speed networks, Globecom 2001 (San Francisco, CA, November 2000). He is also the Technical Program co-chair for IEEE INFOCOM'03 and panel co-chair for ACM Mobicom'02. He received the NSF CAREER award in 1996 and the best paper of the year award for Computer Networks, 2003.