Multiuser Diversity in Wireless Networks: Smart Scheduling, Dumb Antennas and Epidemic Routing

Friday, August 10, 2001 - 2:00pm - 3:00pm
Keller 3-180
David Tse (University of California, Berkeley)
A central feature of mobile wireless networks is the random fading of the channel strengths of the underlying communication links. Channel fading has traditionally been viewed as a form of unreliability that has to be compensated for. In this talk, we argue a different point of view, that channel fading is a form of randomization that can be taken advantage of in the design of wireless networks. This viewpoint is particularly relevant in a network with multiple users, each having independent fading channels.

We first motivate this notion of multiuser diversity from information theoretic considerations. We discuss how this concept is used in the design of the downlink packet scheduling algorithm for Qualcomm's HDR wireless data system. We then show how multiple transmit antennas can be used to randomize the channel and increase the multiuser diversity gain in environments with limited fading. Finally, we explain how the idea of multiuser diversity can be used to greatly increase the throughput of mobile ad-hoc networks for delay tolerant applications.

Joint works with P. Viswanath, R. Laroia and M. Grossglauser.