The central problem in multi-user communications is the design of mechanisms for resource sharing. The development of these mechanisms is influenced by the stochastic nature of data traffic as well as the choice of coding and modulation schemes. Traditionally, these two sets of issues have been analyzed in virtual isolation from each other: some bodies of literature focus mainly on network-layer throughput and delay, while others concentrate on physical-layer channel modeling, coding, and detection. We present a unified, cross-layer view of multi-user communications over fading channels. This approach combines basic communication limits with network quality-of-service issues such as throughput and delay. We consider both multiple-access (uplink) and broadcast (downlink) communication models with random packet arrivals and queueing at the transmitters. Optimal coding is assumed at the physical layer, so that all rates in the information-theoretic capacity regions are achievable. We then consider resource allocation policies which assign power and rate dynamically as a function of the joint fading state and the queue state. Policies which optimize network throughput and delay are characterized. Joint work with Aaron Cohen, Brown University.

Edmund Yeh received his Bachelor of Science in Electrical Engineering with Distinction from Stanford University in 1994. In the same year, he was awarded one of ten Winston Churchill Scholarships for overseas study in science and engineering at Churchill College, University of Cambridge, in the United Kingdom. He received his Master of Philosophy in Electrical Engineering from the University of Cambridge in 1995. As a doctoral student, he studied under Professor Robert Gallager at the Laboratory for Information and Decision Systems at the Massachusetts Institute of Technology. He received his Ph.D. in Electrical Engineering from MIT in 2001. Since July 2001, he has been an Assistant Professor of Electrical Engineering and Computer Science at Yale University, New Haven, Connecticut. Dr. Yeh is a recipient of the Army Research Office (ARO) Young Investigator Program (YIP) Award. He received the National Science Foundation and Office of Naval Research Fellowships for graduate study, and is a member of Phi Beta Kappa, Tau Beta Pi, and IEEE. He has spent a number of summers working at industrial labs, including the Mathematical Sciences Research Center at Bell Laboratories, Murray Hill, New Jersey.