In the multiuser orthogonal fraqt}ncy division multiplexing(OFDM)system

system capacity and fairness can not be simultaneously achieved in general.A novel resource allocation algorithm

which jointly considers the system capacity and fairness

is proposed in this paper.Based on each user's real-time channel state infomration(CSI) and required data rate

the proposed algorithm makes full use of multiuser diversity to maximize the system capacity and guarantee the fairness by choosing suitable access time

and achieved the purpose of optimizing system in both time and frequency domains.Simulation results indicate that the proposed algorithm can effectively increase the system capacity without increasing the algorithm complexity and losing the fairness among users.