This letter investigates the effect of imperfect channel state information (CSI) on the performance of radio resource management for a downlink multi-user OFDMA system. It is shown that the imperfect CSI introduces a signal-and-power dependent noise term, which makes the symbol error rate (SER) constellation-point dependent, and yields an error floor on the SER. In addition, a two-step multi-user channel, power and constellation allocation algorithm is proposed to maximize the total network throughput
