Multiuser Diversity in Delay-Limited Cellular Wideband Systems

We consider the uplink and the downlink of a multiuser wireless system with one base station and K user terminals. Each user is affected by a propagation path loss, fixed in time, and by a slowly time-varying frequency-selective fading channel, modeled as M parallel block-fading channels. We investigate "multiuser diversity", i.e., the gain achieved by a multiuser system over a single-user system. In particular, we compare "delay-limited" systems with "delay-tolerant" systems based on proportional fair scheduling. Our analysis allows us to quantify the loss incurred by a strict delay constraint in a cellular environment, for given M, K and channel statistics