中文摘要：

该文基于对多用户多速率正交频分复用（OFDM）系统性能的分析,提出了子载波分配和功率控制方案.在采用P-QAM调制的下行链路中,如已知所有子信道的信息状态（CSI）,在满足每一个用户的服务质量的前提下,先给固定速率的用户分配最优子信道,再给变速率的用户按照子信道链路增益最大化分配剩余的子信道;每一个用户分配的子信道数目,由链路增益的取值区间决定.信号发射功率则按照＂注水＂法则分配：链路增益大的子信道分配的功率大,链路增益小的子信道分配的功率小,则系统的总传输速率可达最大.仿真结果证明了该文提出的分配方案优于Jang的分配方案.

英文摘要：

Based on the performance analysis of the Orthogonal Frequency Division Multiplexing （OFDM） system, this paper proposes a scheme for sub-carrier allocation and power control in a multi-user multi-rate OFDM system. For the downlink transmission employing P-QAM, if all Channel State Information （CSI） are known, under the constraint of the Quality of Service （QoS） of each user being satisfied, the CBR （Constant Bit Rate） users are allocated with channels prior to the VBR （Variable Bit Rate） users. The VBR users are allocated with remain channels with the rule of link gain maximization. Signal powers are assigned with the water-filling policy： the larger is the link gain of the sub-channel, the more power is assigned. Simulation results show that the proposed sub-carrier allocation and power distribution scheme can achieve higher system capacity than Jang＇s method.