Utilizing Multiuser Diversity for Efficient Support of Quality of Service over a Fading Channel

Prof. Rohit Negi

Assistant Professor
Dept. of Electrical and Computer Engg.
Carnegie Mellon University
5000 Forbes Ave., Pittsburgh, PA 15213

Friday, November 8th, 3:00 PM, ENS 302

negi@ece.cmu.edu

Abstract

We consider the problem of quality of service (QoS) provisioning for K users sharing a downlink time-slotted fading channel. We develop simple and efficient schemes for admission control, resource allocation, and scheduling, which can yield substantial capacity gain. The efficiency is achieved by virtue of recently identified multiuser diversity. A unique feature of our work is explicit provisioning of statistical QoS, which is characterized by a data rate, delay bound, and delay-bound violation probability triplet. The results show that compared with a fixed-slot assignment scheme, our approach can substantially increase the statistical delay-constrained capacity of a fading channel (i.e., the maximum data rate achievable with the delay-bound violation probability satisfied), when delay requirements are not very tight, while yet guaranteeing QoS at any delay requirement. For example, in the case of low signal-to-noise-ratio (SNR) and ergodic Rayleigh fading, our scheme can achieve approximately Σ_{k={1, 2, ..., K}} (1 / k) gain for K users with loose-delay requirements, as expected from the classic Knopp and Humblet (K&H) scheme for multiuser diversity. But more importantly, when the delay bound is not loose, so that simple-minded K&H scheduling does not directly apply, our scheme can achieve a capacity gain, and yet meet the QoS requirements.

Other current research projects will also be briefly described.

Biography

Rohit Negi received the B.Tech. degree in Electrical Engineering from the Indian Institute of Technology, Bombay, India in 1995. He received the M.S. and Ph.D. degrees from Stanford University, CA, USA, in 1996 and 2000 respectively, both in Electrical Engineering. He has received the President of India Gold medal in 1995.

Since September 2000, he has been with the Electrical and Computer Engineering department at Carnegie Mellon University, Pittsburgh, PA, USA, where he is an Assistant Professor. His research interests include signal processing, coding for communications systems, information theory, networking and cross-layer optimization.

A list of Wireless Networking and Communications Seminars is available at from the ECE department Web pages under "Seminars". The Web address for the Wireless Networking and Communications Seminars is http://signal.ece.utexas.edu/seminars