提出一种多用户OFDM（orthogonal frequency division multiplexing）系统下行链路，具有信道变化实时性的动态子载波、比特和功率分配联合算法（UA），在满足各个用户数据速率和BER要求的同时使总的发送功率最小。提出的算法与动态子载波分配算法（WSA）相比，计算复杂度相当，在移动信道环境下仿真结果表明性能有一定的改善。

A realtime united algorithm for dynamic subbcarrier, bit and power allocation according to the change of channel (UA) is presented in this paper, which can be used into the down-link of multi-user orthogonal frequency division multiplexing (OFDM) system. With the algorithm the total transmission power is the minimum while the data rate of each user and the required BER performance can be achieved. Comparing to the subcarrier allocation algorithm (WSA) , the simulation results show that the algorithm presented in this paper has better performance while both have equal calculating complexity.