Enhanced multiuser scheduling using modified SLNR metric with outdated partial CSI

In this paper, we study the problem of multiuser (MU) scheduling in a MU-MIMO system with imperfect channel state information (CSI) feedback. The CSI feedback for scheduling is considered as a channel direction quantization with feedback delay effect. Inspired by the conventional zero-forcing (ZF) based user scheduling, we present an improved user selection scheme by using a modified signal-to-leakage-and-noise ratio (SLNR) based metric under only quantized CSI feedback with a channel quality information (CQI) indicator. Different from the traditional ZF-based beamforming(BF), we find that a simple channel-norm based CQI feedback will be sufficient for our modified SLNR-based scheduling. Numerical results show the effectiveness of our proposed scheduling under outdated and quantized CSI feedback.