Alpha-Rule Scheduling for MIMO Broadcast Wireless Channels with Linear Receivers

This paper considers a multi-user MIMO broadcast wireless channel where a MAC layer scheduler is used to improve system efficiency and provide quality of service improvements (fairness) to users. In particular, an alpha-rule scheduler is considered that uses rate estimates from users to make user selection decisions. The main challenge faced by the scheduler is that users need to estimate the interference caused by other users before transmit antenna allocation has been done. The paper examines two techniques for estimating data rates. The first technique assumes no interfering signals are present and the second technique includes the dominant interfering signal. We show that the scheduler can be tuned to significantly increase fairness with little reduction in mean sum rate to users and we show that both mean sum rate and fairness can be increased by including the dominant interfering signal to estimate data rates.