Currently, the OFDMA transmission scheme seems to be a promising candidate for future broadband radio systems. The crucial part which determines the performance is thereby the combination of dynamic subcarrier allocation, transmission power allotment, and adaptive modulation. In this paper, the general effects of OFDMA scheduling concerning QoS for packet based data transmissions are described. Based on that information a basic scheduling algorithm which provides both fairness and exploitation of multiuser diversity is proposed for the deployment in centrally controlled systems like IEEE 802.16. Furthermore, a detailed performance evaluation of the algorithm is given for an exemplary scenario. The results show the impacts of multi-user diversity regarding packet delay and capacity.