非理想Nakagami-m信道下DF协作系统的最优功率分配

针对Nakagami-m衰落信道下的多中继DF协作系统，研究信道估计误差存在时功率分配对系统性能的影响．首先基于全概率公式和矩母函数(MGF)方法，给出M-QAM调制下的近似误符号率(SER)和渐进SER解析式; 其次，基于简洁的渐进解析式，将功率分配问题转换为典型的凸优化求解问题．得出了在总功率一定的条件下，最小化系统SER的最优功率分配的理论计算公式．计算机仿真结果表明: 信道估计误差存在时，相比较等功率分配策略，最优功率分配能显著提高中低信噪比下的协作系统性能，但不能改善高信噪比下系统的错误平层．

Optimal power allocation of the DF cooperation system over imperfect Nakagami-m fading channels

The impacts of power allocation under imperfect channel estimation on the symbol-error-rate(SER) are investigated for a cooperative network with multiple decode-and-forward(DF) relays over Nakagami-m fading.First,the approximate SER and asymptotic SER for M-QAM are provided by using the Theorem of Total Probability and the moment generating function(MGF).Then based on the presented compact asymptotic SER,the optimal power allocation is transformed to a typical convex optimization problem so that the optimal power allocation is reached to minimize the SER under the total power constraints.Simulations show that compared to the uniform allocation scheme,optimal power allocation scheme can significantly improve the performance of the cooperative system at the low to medium SNR,but can not improve the error floor at the high SNR under the imperfect channel estimation.