How much feedback is multi-user diversity really worth?

TLDR

Wireless scheduling exploits multi‑user diversity by prioritizing users with the best instantaneous channel conditions, but this requires feedback of channel rates from all active subscribers. The authors propose a technique that can reduce this feedback by up to 90 % while maintaining the performance of the scheme. They analyze the feedback load as a function of ergodic and outage capacity for both the conventional MUDiv scheme and the proposed scheme. The study finds that the feedback load is largely unjustified.

Abstract

Wireless scheduling algorithms can extract multi-user diversity (MUDiv) via prioritizing the users with best current channel conditions. One drawback of MUDiv is the required feedback carrying the instantaneous channel rates from from all active subscribers to the access point/base station. This paper shows that this feedback load is, for the most part, unjustified. To alleviate this problem, we propose a technique allowing to dramatically reduce the feedback (by up to 90%) needs while preserving the essential of the scheme performance. We provide a theoretical analysis of the feedback load as function of the system's ergodic and outage capacity for both the traditional MUDiv scheme and the new scheme.