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This paper studies the performance of proportional fair space time scheduling in the presence of imperfect channel state information (CSI). We consider the uplink scheduling in the multiuser single-input-multiple-output (SIMO) system. There are K mobiles (with single antenna) and a base station (with nR receive antennas) in the system. The space time scheduling problem is formulated with proportional fair (PF) utility function and a novel heuristic solution is presented. We found that in general, with perfect CSI, the system performance improves as nR increases due to the extra spatial dimensions. However, at moderate CSI errors, the system performance saturates with respect to SNR and nR. This is due to the misscheduling and packet outage problem. To address the poor performance in the presence of CSI error, we proposed a low-complexity enhancement, namely proportional rate discounting, to enhance the scheduler's robustness in the presence of CSI error.