Understanding the Trade-Off Between Multiuser Diversity Gain and Delay - An Analytical Approach

R. Srinivasan and J. S. Baras

2004 IEEE 59th Vehicular Technology Conference, Milan, Italy, May 17-19 , 2004

 

Abstract

Innovative scheduling algorithms for paeketswitched air-interfaces have been shown to support higher data rates by exploiting the multiuser diversity inherent to cellular wireless systems. While such oppor?unistic schedulers significantly improve the system throughput, they could degrade the user experience through unfair resource allocation and increased variability in the scheduled rate and delay. The growing demand for service differentiation between real-time multimedia traffic and data traffic underscores the need for these schedulers to incorporate delay constraints. The analytical results in this paper not only highlight the inherent trade-off between system throughput and the delay experienced by mobile users with opportunistic scheduling, but they also provide a novel way of quantifying the Quality of Service(Q0S) offered by a general opportunistic scheduler.Our analysis is stmngly supported by system simulations of a time-slotted cellular downlink shared by multiple mobile users with independent, time-varying channels. In addition, we use a continuous approximation to compute closed form expressions for the scheduler statistics.