中文摘要：

研究了认知正交频分复用（OFDM）系统的容量极限及最优功率分配策略．基于干扰温度模型，建立了在主用户接收端干扰温度受限下最大化认知用户传输速率的数学优化问题；利用拉格朗日乘数法，得到了该数学问题的最优解．最优算法需要同时知道干扰链路和认知链路的信道边信息（CSI），具有较高的复杂度．因此提出了3种次优功率分配算法，分别为功率平均法、功率控制法和功率分配法．通过仿真实验，比较了各种分配算法下认知用户的信道容量．结果表明，利用所有信道边信息的最优功率分配算法能取得最好的性能．

英文摘要：

The capacity limit and optimal power allocation strategy of cognitive orthogonal frequency division multiplexing （OFDM） system were studied. The mathematical optimization problem was formulated maximizing the capacity of cognitive user under the constraint of interference temperature at the primary receiver based on the interference temperature model. The optimal solution to the problem was obtained by utilizing the Lagrange method. The optimal algorithm had high complexity requiring the channel side information （CSI） of both interfering channel and cognitive channel. Therefore, three suboptimal algorithms, namely power average method, power control method and power allocation method, were proposed. The capacity of cognitive user was compared using different algorithms. Simulation results show that the optimal algorithm utilizing all CSI achieves the best performance.