中文摘要：

提出了一种新的多用户OFDM系统中的快速子载波和比特分配算法。在给定每个用户数据传输的误比特率和数据速率的前提下，首先根据各用户的信号状况信息进行简单的初始分配确定最初的子载波分配方案并用贪婪算法进行比特分配，在此基础上按照文中的方法对初始分配结果进行子载波之间的交换，不断迭代优化实现最终的子载波和比特分配，以达到系统总的发射功率最小化的目的。同时，还分析了传统的静态子载波分配方案和几种自适应子载波、比特分配方案。通过不同算法的具体实施方案，比较了它们之间的优缺点。仿真结果表明：本文算法在性能上优于传统的静态子载波分配算法，且权值收敛速度较快，接近性能较好的拉格朗日松弛算法，而算法复杂度大大降低。

英文摘要：

In this paper, a new fast sub - cartier and bit allocation algorithm in multi - user OFDM systems is proposed. Under the BER and each user＇s rate requests, according to the information of channel state of all users, first the sub - carriers are pre - allocated, then, bit allocation is performed to every sub - carrier. Based on the above, After this, we exchange the pre - allocated subcarriers using the method intruduced in this paper and optimize iterativly to achieve the final allocate to realize the minimize the transmiting power. At the same time, this paper analyses the tradition static subcarrier - allocation method and several adaptive subcarrier and bit allocation method. According to comparing the method of different algorithms, compare the merit and defect of them. The simulation resuits show that the proposed algorithm performances better than the tradition static subcarrier - allocation method and convergences quickly, the performance being close to the Lagrange algorithm, while the complexity is low.