Rate-optimal multiuser scheduling with reduced feedback load and analysis of delay effects

In this paper we propose a multiuser scheduling algorithm that has the maximum average system spectral efficiency, but obtains a significant reduction in feedback load compared to full feedback by using a feedback threshold. An expression for the threshold value that minimizes the feedback load is found. Novel closed-form expressions are also found for the system spectral efficiency when using M-ary quadrature amplitude modulation. Finally, we analyze the impact of scheduling delay and outdated channel estimates.