<FONT face=Verdana>The power allocation problem to maximize the multicast rate in one multicast group under the total power constrain is investigated in multicast Orthogonal Frequency Division Multiplexing (OFDM) system. The greedy algorithm is applied to reduce the complexity. To improve the multicast rate

two power allocation algorithms based on subcarrier pairwise exchange are proposed. The proposed algorithms both have two steps: initial power allocation and adjustment. During the adjustment period

power is exchanged between subcarriers and the algorithms are terminated only when the multicast rate cannot be increased any more. Simulation results show that the proposed algorithms can achieve near optimal result with low complexity.