We propose an efficient frame-based two-dimensional frequency-time grid (FTG) allocation algorithm to maximize the system throughput while satisfying users' rate requirements in a multiuser and multirate service environment. The FTG scheduling algorithm is done per OFDM frame, allocating each frequency-time grid to different users according to both channel state information (CSI) and users' QoS constraints. The performance of the frame-based FTG algorithm is obtained in a multiuser frequency selective fading environment. The results show that the system using the proposed FTG algorithm has significant lower outage probability and higher capacity which is very near the upper bound (maximum allocation method).