研究了一种用于大气激光通信自适应调制编码技术中的模式选择阈值的选取算法。分析了大气弱湍流信道性能, 并对高斯信道中阈值选取算法进行修正, 提出了一种信噪比-湍流强度选择方法来确定阈值区域模式, 并给出了阈值选取方程。分析了湍流强度分别为0, 0.1, 0.2, 0.3时3种传输模式下自适应调制编码系统的误码率, 得到了最大误码率为10-4的条件下3种模式选择的信噪比与湍流强度阈值区域的对应关系。仿真结果表明, 所提方法可行且能够准确地进行模式选择。

A selection algorithm of mode selection threshold is proposed to applied to adaptive modulation coding technology for atmospheric laser communication is proposed. The performance of atmospheric weak turbulence channel is analyzed, the threshold selection algorithm for Gauss channel is modified. A selection method named signal to noise ratio-turbulence intensity is proposed to determine the mode for threshold region, and a equation for threshold selection is presented. The bit error rates of the adaptive modulation coding system are analyzed under three transmission modes when the turbulence intensity is 0, 0.1, 0.2, 0.3 respectively. The corresponding relationships between signal-to-noise ratio and turbulence intensity threshold region of the three transmission modes are obtained under the condition that the maximum bit error rate is 10-4. Simulation results show that the proposed method is feasible, and it can accurately realize mode selection.